Proceedings, 

Sixth International 

Symposium: 

Moisture and Creep 

Effects on Paper, 

Board and 

Containers

United States

Department of

Agriculture

Forest Service

Forest

Products

Laboratory

General

Technical

Report

FPL–GTR–196
February 2011

Considine, John M.; Ralph, Sally A. 2011. Proceedings, sixth international 

symposium: moisture and creep effects on paper, board, and containers. 

General Technical Report FPL-GTR-196. Madison, WI: U.S. Department 

of Agriculture, Forest Service, Forest Products Laboratory. 166 p.

A limited number of free copies of this publication are available to the 

public from the Forest Products Laboratory, One Gifford Pinchot Drive, 

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Abstract

The USDA Forest Products Laboratory sponsored the 6th 

International Symposium: Moisture and Creep Effects on 

Paper, Board and Containers at the Monona Terrace Convention Center, Madison, WI, USA on 14-15 July 2009. 

Attendees heard 20 technical presentations; presenters were 

from seven different countries and three continents. Session 

topics included Corrugated Performance, Moisture Flow, 

Component Behavior, Industry Efforts, Other Materials, 

Moisture and Creep Response. 

Keywords: cellulose, paper, paperboard, corrugated 

containers, moisture, humidity, creep, relaxation, 

mechano-sorption, proceedings
Proceedings, 

Sixth International 

Symposium: Moisture 

and Creep 

Effects on Paper, 

Board and Containers

Madison, Wisconsin, USA

14–15 July 2009

Organized by the U.S. Forest Service, 

Forest Products Laboratory (FPL)

Editors: John M. Considine, Sally A. Ralph

Sponsors: TAPPI, International Paper Physics Committee 

Proceedings, Sixth International 

Symposium: Moisture and Creep Effects 

on Paper, Board and Containers

Madison, Wisconsin, USA

14–15 July 2009

Organized by the U.S. Forest Service, Forest Products Laboratory (FPL)

Editors: John M. Considine, Sally A. Ralph

U.S. Forest Service, Forest Products Laboratory, Madison, Wisconsin

Sponsors: TAPPI, International Paper Physics Committee 

Preface

The 6th International Symposium: Moisture and Creep 

Effects on Paper, Board and Containers was held at the 

Monona Terrace Convention Center, Madison, Wisconsin, 

USA, on 14–15 July 2009. 

Locations and dates of previous symposia in this series were 

as follows:

•	 1st Symposium, September 1992, Madison, Wisconsin, USA. Coordinated by Ted Laufenberg, FPL, and 

Dr. Craig Leake, National Starch & Chemical Company, 

Bridgewater, New Jersey, USA

•	 2nd Symposium, December 1994, Stockholm Sweden.

Coordinated by Dr. Christer Fellers, STFI (now INNVENTIA, Stockholm, Sweden) and Ted Laufenberg, 

FPL

•	 3rd Symposium, February 1997, Rotorua, New Zealand. Coordinated by Dr. Ian Chalmers, PAPRO (now 

SCION, Rotorua, New Zealand) 

•	 4th Symposium, March 1999, Grenoble, France. Coordinated by Dr. Jean-Marie Serra-Tosio, EFPG, and Dr. 

Isabelle Vullierme, EFPG

•	 5th Symposium, April 2001 Victoria Australia. Coordinated by Dr. Ian Parker, Monash University, Victoria, 

Australia

These symposia are held on an irregular basis. At the Paper 

Physics Committee meeting held at the International Paper 

Physics Conference in Gold Coast, Australia, 2007, members voted to invite FPL to host the next Moisture Symposium.

Demographics on this Symposium

• Presentations: 1 keynote, 20 technical

• 50 authors/co-authors 

• Presenters from 7 countries and 3 continents

• 19 at-large attendees came from the USA, Canada, and 

New Zealand

Readers will notice a variety of format and style in these 

proceedings. The authors were given great flexibility for 

their material content; formats include full length papers, 

extended abstracts, and short abstracts, and are included as 

received from the authors.

The question and answer time after each presentation was 

lively; coffee breaks and social gatherings allowed for active 

interaction and development of potential scientific collaboration. 

An informal vote taken at the final session suggested Rome 

as an excellent choice for the next Moisture Symposium 

with an undecided date.

Acknowledgments

This book was made possible through extensive assistance 

from the FPL Office of Communications, especially Susan 

Paulson, Tivoli Gough, James Anderson, and Madelon Wise.

Furthermore, financial and material support by TAPPI, 

University of Wisconsin – College of Agriculture and Life 

Sciences (CALS) Conference Planning Services and FPL. In 

particular the support of Rich Lapin, TAPPI, Raj Lal, FPL 

Office of Communications, and Heather Cooper, CALS, 

was timely and effective.

1

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
2

Introduction

The interaction of moisture and cellulose is beneficial and 

problematic. It is beneficial for manufacturing, processing, 

and converting needs, where water is used for fiber transport and softening. It is problematic because it can reduce 

performance. This symposium, like others in this series, was 

devoted to understanding, characterizing, and reducing the 

detrimental effects of this interaction.

Synthetic petrochemical plastics have made serious inroads 

within the packaging sector; however, recyclability of cellulosic materials is a significant advantage. Hybrid plastic/

cellulose composites, which try to enhance each constituent material’s benefits and reduce their liabilities, create 

even more demand for investigations of moisture/cellulose 

interactions. 

Papermaking additives are used to enhance physical, mechanical, and optical properties. Sophisticated syntheses, 

layer-by-layer technology, and nanoparticles comprise but 

a few of the many methods to improve paper properties. 

Retention of the additives and maintaining the achieved 

behavior are often affected by moisture transport. 

Even the paper machine is not exempt from examination for 

techniques and methods to enhance properties. Local fiber 

orientation, residual drying stresses, and formation can be 

affected during paper production and can influence moisture 

behavior.

After paper is made, it is converted or processed to produce 

an end product. Interaction of multiple paper (or non-cellulose) components requires advanced modeling techniques 

because analytical solutions exist for only the most basic 

configurations. These models often need to account for postconverting damage.

These symposia provide a venue for government, academic, 

and industrial researchers to share results and exchange 

ideas on the important topic of the interaction of moisture 

and cellulose. Industrial competition is strong, so the introduction of value-added products and consumer education 

can provide real advantages for economic viability. Immediate feedback encourages the researcher to clarify ideas and 

identify shortcomings. New research directions, acknowledgement of well-solved problems, and regular involvement 

of graduate researchers suggest that this series is meeting 

the needs of the community it is seeking to serve.

Scientific Committee

Conference Chairman 

JunYong Zhu

U.S. Forest Service, Forest Products Laboratory, USA

Conference Secretary

John Considine

U.S. Forest Service, Forest Products Laboratory, USA

International Scientific Committee

Marco Evangelos Biancolini 

University of Rome, Italy

Jean-Francis Bloch 

CFPG, France

Ian Chalmers 

Scion, New Zealand

Doug Coffin 

Miami University, USA

Christer Fellers 

INNVENTIA, Sweden

Benjamin Frank 

Packaging Corporation of America, USA

Terry Gehardt 

Sonoco Products Company, USA

Yanfeng Guo 

Xi’an University of Technology, China

General Technical Report FPL–GTR–196
3

Some Thoughts on Fundamental Aspects of Mechanosorption

Coffin, D. ...................................................................................................................................................................................5

Session 1: Corrugated Performance (Benjamin Frank, Chair) ..........................................................................................11

Failure of corrugated board panels at different loading rates and during creep

Alfthan, J....................................................................................................................................................................................12

Crush damage of corrugated board and its effects on cyclic humidity creep performance of boxes

Chalmers, I.................................................................................................................................................................................19

Effects of medium strength properties and component rotation on corrugated endurance

Popil, R.. ....................................................................................................................................................................................24

Session 2: Moisture Flow (JY Zhu, Chair) ............................................................................................................................27

Steady-state moisture diffusion through corrugated fiberboard

Glass, S.V...................................................................................................................................................................................28

The effect of hysteresis on moisture sorption of paperboard

Lavrykov, S................................................................................................................................................................................29

Analysis of the hygroexpansion of paperboard and small flute corrugated board by digital 

correlation of images obtained by X-ray microtomography

Viguié, J. ....................................................................................................................................................................................30

Session 3: Component Behavior (Doug Coffin, Chair).........................................................................................................31

Formation and edgewise compressive creep properties

Fellers, C....................................................................................................................................................................................32

Effect of moisture on defect interaction in paper and paperboard

Considine, J................................................................................................................................................................................33

Experimental characterisation of paper for corrugated board

Biancolini, M.E..........................................................................................................................................................................35

Session 4: Industry Efforts (Ian Chalmers, Chair)...............................................................................................................39

End-user focused creep

Wikström, A...............................................................................................................................................................................40

Effects of strain rate on the stress relaxation of wet paper

Kekko, P. ....................................................................................................................................................................................49

Repulpable water vapor barrier coatings made easy

Hostetler, R ................................................................................................................................................................................59

Session 5: Other Materials (David Vahey, Chair).................................................................................................................67

Strength properties of low moisture content yellow-poplar and Southern Pine

Kretschmann, D.E......................................................................................................................................................................68 

Hygroexpansion of plant-based fiber mats for “green” composites

Dumont, P.J.J..............................................................................................................................................................................69

Contents

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
4

Modelled and measured bending stiffness of polyethylene coated multi-layer paperboard at two moisture contents

Paunonen, S................................................................................................................................................................................70

Session 6: Modeling and Creep Response (Sergiy Lavrykov, Chair)..................................................................................81

Corrugated board box design using full detailed FEM modelling

Biancolini, M.E..........................................................................................................................................................................82

Mechanical model on creep properties of double-wall corrugated paperboard

Guo, Y. .......................................................................................................................................................................................84

Compression fatigue creep of paperboard

Scott, C.T....................................................................................................................................................................................92

Session 7: Moisture and Time Response (M.E. Biancolini, Chair)......................................................................................93

Use of ultrasonic velocity measurement to investigate moisture-induced stress relaxation in paper

Vahey, D.....................................................................................................................................................................................94

Wood fibres do indeed show mechano-sorptive creep

Salmén, L. ..................................................................................................................................................................................97

Hygroexpansivity of thermally aged papers

Turner, K. ...................................................................................................................................................................................98

Participants...............................................................................................................................................................................99

Index of Authors.....................................................................................................................................................................103

Appendix—5th International Symposium, courtesy of Dr. Ian Chalmers.......................................................................105

General Technical Report FPL–GTR–196
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Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
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General Technical Report FPL–GTR–196
7

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
The average moisture content at any given time is 

       

 











 



  

    1

2 1

2 2

2

2 1

8 1 ( ) n

D

h

n

f i f e

n

m t m m m





(12)

Assuming the modulus as a function of moisture is given as E(t)  E0  km(t), the mechanosorptive strain is given as 

       

 

 

 

























































  













 



  









 



  

1

2 1

1

2 1

1

8 ( ) 2

1

2 1

2

1

2 1 2

2 2

2

2

2

n

D

h

n

n

D

h

n

ms f

e

n

e

n

m m

E

k

t 



 

 (13) 

Figure 1 illustrates the effect that Equation (13) has on the strain. 

Figure 1. Strain based on bulk properties compared to total strain including mechanosorptive strain for a case of transient 

moisture increase. 

The effect shown in Figure 1 is small, but it is important in that it is a predicted behavior even for the simple case of a linear

elastic material coupled with simple diffusion. For the case shown here the response is transient and at equilibrium there are 

no lasting effects. In the case of real materials, and the necessary complications of energy dissipation would cause sustained 

effects.

 The important conclusions from this analysis are the following: 

 One cannot predict the transient deformation based on bulk properties alone. 

 The transient response is caused by a coupling of the spatial distribution of stresses arising from the effects of 

moisture on swelling and magnitude of intrinsic material properties. 

 Interpreting experimental data that only measures the bulk response is difficult when trying to understand the causes 

of mechanosorptive effects. 

8

General Technical Report FPL–GTR–196
9

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
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General Technical Report FPL–GTR–196
11

Session 1

Benjamin Frank, Chair 

Packaging Corporation of America

Corrugated Performance

Corrugated board represents the great majority of materials used 

for packaging, protection and transportation. Failure of corrugated 

board ranges from excessive deformation and box bulging to damage 

of contents. Understanding and characterizing moisture effects on 

corrugated board have the potential to save significant property loss 

and maintain the market segment in the paper industry. Innovative 

geometry, design, and production that use paperboard orthotropy to 

its advantage may prospectively increase market share.

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
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General Technical Report FPL–GTR–196
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Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
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General Technical Report FPL–GTR–196
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Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
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General Technical Report FPL–GTR–196
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Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
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General Technical Report FPL–GTR–196
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Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
24

Effects of medium strength properties 

and component rotation on corrugated 

endurance

General Technical Report FPL–GTR–196
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General Technical Report FPL–GTR–196
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Session 2

JY Zhu, Chair 

U.S. Forest Service, Forest Products Laboratory

Moisture Flow

Paperboard is a porous material and so moisture migration affects 

its material properties but also the amount of protection it can 

offer in packaging applications. Moisture hysteresis, as measured 

in diffusion experiments, and hygroexpansion are quantifiable 

measures of moisture sensitivity that are affected by processing, 

chemical additives, and other means. Environmental moisture 

changes should be considered in the material selection procedure.

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
28

Steady-state moisture diffusion through 

corrugated fiberboard

Samuel V. Glass

U.S. Forest Service, Forest Products Laboratory, Madison, Wisconsin

Abstract

Moisture transfer through corrugated fiberboard is measured under steady-state conditions. Several types of corrugated 

fiberboard are investigated, differing in flute size, number of flutes, and component basis weights. The experimental apparatus consists of two chambers, each of which has control of temperature and relative humidity. A specimen is sealed between 

the chambers, a gradient in humidity is established, and the rate of mass transfer is measured on both sides of the specimen. 

Experiments are carried out at 25°C over a range of relative humidity levels. The measured water vapor fluxes through the 

various types of corrugated fiberboard are used to construct a model for the effective diffusivity of the components as a function of relative humidity.

General Technical Report FPL–GTR–196
29

The effect of hysteresis on moisture 

sorption of paperboard

Sergiy Lavrykov and B.V. Ramarao

Empire State Paper Research Institute

Department of Paper and BioProcess Engineering

State University of New York ESF

Syracuse, NY 13210

Paperboard is subjected to high magnitude stresses and large deformations in many converting operations. The use of finite 

element analysis can enhance understanding and provide a convenient optimization tool. Creep of linerboard under changing 

relative humidity reduced the performance of corrugated boxes and can lead to premature box failure. If accelerated creep 

can be further understood and robust models for its prediction can be developed, it is possible to engineer the products for 

better performance. Our objective is to analyze the impact of humidity cycling, sorption hysteresis and the resultant transient 

moisture distributions in linerboard on accelerated creep performance. 

A model for accelerated creep of linerboard was developed based on (a) a transient moisture diffusion model accounting 

for multiple diffusion paths within the pore spaces and the fiber matrix and localized sorption dynamics, (b) a robust local 

sorption equilibrium including sorption hysteresis (c) temperature transients due to adsorption heat effects within the paperboard and (d) a suitable material model for the linerboard incorporating elasto-plastic response under different moisture and 

temperature conditions. We conducted a parametric study to identify the impact of sorption hysteresis on moisture induced 

creep. Experimental results on sorption hysteresis and transient moisture uptake are presented.

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
30

Analysis of the hygroexpansion of paperboard and small flute corrugated board by 

digital correlation of images obtained by 

x-ray microtomography

J. Viguié1, P.J.J. Dumont1, I. Desloges1, S. Rolland du Roscoat2, P. Vacher3, E. Mauret1, J.-F. Bloch1

1. Laboratoire de Génie des Procédés Papetiers (LGP2), CNRS / Institut polytechnique de Grenoble (Grenoble 

INP) - BP 65 - 38402 SAINT MARTIN D’HERES CEDEX 9 e-mail : pierre.dumont@efpg.inpg.fr

2. Laboratoire Sols-Solides-Structures-Risques (3S-R), CNRS / Universités de Grenoble (UJF & Grenoble INP) - 

BP 53 - 38041 SAINT MARTIN D’HERES CEDEX 9

3. Laboratoire SYMME, Polytech Savoie, Université de Savoie Domaine Universitaire BP 80439 – 74944 

ANNECY-LE-VIEUX

Paperboard and small flute corrugated board are increasingly used as stiff packaging materials in food, cosmetic, and pharmaceutical industries. They form stratified materials where specific pulps are used for each layer. The integrity of board packaging can be affected by moisture changes that can be induced by a variation of the relative humidity of the ambient air. An 

increase of relative humidity from 20 to 80% may be related to a hygroexpansion of a board sheet varying in a range of about 

0.2 to 2% in its plane and about 8 to 12 % in its thickness direction. In parallel, a decrease of mechanical parameters such as 

the Young’s moduli from 30 to 50% may be noticed. The degree of beating, the kinds of pulps and the drying conditions are 

significant parameters affecting the hygroexpansion behavior. Nonetheless, scarce information is available on the micromechanisms of hygroscopic strains of paperboard and small flute corrugated board. This is the purpose of this experimental study.

Tests were performed on two 450 g/m2 paperboards composed by 11 layers made up of virgin pulps for the first one and 

recycled pulps for the second one. A 450 g/m2 corrugated board with G flutes was also studied. The evolution of the moisture 

content with respect to the relative humidity of the ambient air was measured using a specially designed apparatus at constant ambient temperature for various relative humidity cycles. The hygroexpansion of these materials was evaluated by two 

methods for the same changes in relative humidity. At the macroscopic scale, the dimensional in-plane variations of rectangular samples (dimensions of 150×15 mm2) were measured by a dedicated apparatus. Samples were cut along the machine 

and cross directions of the boards, as well as in off-axis directions. At the microscopic scale, the fields of displacement and 

strain of the fibrous networks were measured by using a Digital Image Correlation (DIC) method. For that purpose, images 

of cross-sections of volumes obtained by X-ray microtomography at ESRF (European Synchrotron Radiation Facility) were 

analyzed, as well as some images obtained using an Environmental Scanning Electron Microscope SEM (ESEM).

Experimental results permit to calculate the average in-plane and out-of-plane hygroexpansivities of the tested boards for 

variation ranges of the moisture content. Hygroexpansivities are found to be highly anisotropic. Moreover out-of-plane 

hygroexpansivities are preponderant compared to in-plane ones. The DIC method permits to reveal that the hygroexpansion 

is highly heterogeneous. For instance, in the case of a paperboard made up of virgin pulps, out-of-plane hygroscopic strains 

mainly occur in the core layers of samples. This might be related to the nature of the layers. Core layers are indeed essentially 

made of pulps obtained by a mechanical process whereas external layers are composed of chemical pulps.

General Technical Report FPL–GTR–196
31

Session 3

Doug Coffin, Chair 

Miami University, Oxford, Ohio

Component Behavior

An accurate constitutive model for corrugated components is a 

fundamental element of packaging design. Several models exist and 

have their proponents; recently, those models easily incorporated in 

numerical analysis software, such as finite element programs, have 

gained increased acceptance. The ability to identify the effect of 

formation or periodic defects on constitutive behavior may allow 

more precise safety factors in packaging design formulations.

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
32

Formation and edgewise compressive 

creep properties

Christer Fellers, Anne-Mari Ohlsson, Anders Mähler, and Lucina Lason

STFI-Packforsk, Sweden

The mechanical properties of paper depend on unevenness of the paper on different structural levels. It is not yet known 

which structural level has the greatest influence on these properties but it is well known that the formation, chemical additives, and forming concentration plays a great role for the mechanical properties of paper. Few studies have reported actual 

magnitudes of the effects and it is of fundamental interest to increase the knowledge in this area. 

The experimental paper machine FEX at STFI-Packforsk was used for the trials. Different formation levels were achieved by 

varying the forming concentration and by adding chemicals that increased or decreased the formation. 

The focus of the investigation was on creep properties of which there are very little results available in the literature but also 

tensile and edgewise compressive properties were investigated. 

The creep properties were measured in various constant or changing climates between 50 and 90% RH and were expressed in 

terms of isochronous and isocyclic creep curves and corresponding creep stiffness index values, respectively. An isochronous 

or isocyclic stress-strain curve may be viewed as a stress-strain curve at a specific time, i.e., 3 days or different number of 

cycles, i.e., 3 cycles (Panek, Fellers, Haraldsson 2004). From the initial slope of the curve, the isochronous or isocyclic creep 

stiffness may be extracted.

The following figure shows one significant finding.

Isocyclic compressive creep 

curves for papers with different 

formation. 

When the formation number 

increased (worse formation), 

no change in stress at a given 

strain was noted at small strains 

(constant isocyclic creep stiffness 

index). 

Only at higher strains, a decrease 

in stress due to a worse formation 

was noted.

Reference

Panek, J., Fellers, C., Haraldsson, T. (2004) Principles of evaluation for the creep of paperboard in constant and cyclic 

humidity. Nordic Pulp and Paper Research Journal 19(2): 155–163.

General Technical Report FPL–GTR–196
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Effect of moisture on defect interaction in 

paper and paperboard

J. Considine1, J. Decker2, D. Vahey1, K. Turner2, R. Rowlands2

1. U.S. Forest Service, Forest Products Laboratory, Madison, Wisconsin

2. University of Wisconsin, Madison, Wisconsin, USA

Poor formation in paper, as denoted by large local variation of mass, tends to reduce maximum tensile strength, but this 

reduction has not been quantified. The effect of grammage variation and moisture on tensile strength was studied by introducing carefully placed holes in tensile specimens made of five different paper materials and testing at static 50% and 90% RH. 

The point-stress criterion (PSC) [1] was used to estimate inherent defect size and predict maximum potential tensile strength 

for each RH level.

The goal of this research was to estimate inherent defect size and predict maximum possible tensile strength, i.e., tensile 

strength of a defect-free material made from the same furnish, with the PSC (point-stress criterion) and to examine the effect 

of relative humidity on these parameters. Successful completion of this work will provide the paper industry will necessary 

tools to perform cost-benefit analysis on papermachine modifications to improve formation and strength.

Five commercial paper materials were examined in this work. Their physical and mechanical properties are given in Table 1. 

Sheet thickness was measured with a Mitutoyo® (Kawasaki, Japan) 543-396B Digital Indicator equipped with a 4-mm-diameter ball tip. Elastic moduli and Poisson’s ratio were obtained ultrasonically with a Nomura Shoji Corporation (Tokyo, Japan) 

Sonic Sheet Tester (SST). The SST is equipped with one sensor pair, which operates at 25 kHz; measurements were taken at 

5° intervals by rotating the sample on a turntable.

Materials A and L are commercial unbleached kraft, single-ply linerboards. Material C is a commercial copy paper, containing about 8% ash. Material E is a commercial envelope paper. Material F is a commercial filter paper, manufactured by 

Whatman® International (Maidstone, Kent, UK) and identified as Chromotography Paper, Model 3MM CHR. The latter was 

chosen as it is 100% cellulose.

Table 1. 50% RH properties of materials 

A C E F L 

Grammage (g/m2) 268 76 92 187 209 

Thickness (mm) 0.38 0.11 0.13 0.31 0.30 

Density (kg/m3

) 717 721 734 603 688 

E11 (GPa) 7.80 7.82 7.38 4.52 7.75 

E22 (GPa) 3.71 2.56 3.40 2.12 3.73 

G12 (GPa) 2.10 1.63 1.85 1.27 2.15 

ν12 0.20 0.17 0.23 0.18 0.23 

E11/E22 2.10 3.05 2.20 2.13 2.08 

Tensile tests were performed employing an Instron® (Norwood, Massachusetts) Model 5865 test machine equipped 

with line-clamp pneumatic grips. Specimens were 25 mm 

wide with a gage length of 125 mm. The test sequence 

started with a pre-load to 1 N at 12 N/min followed by displacement at a constant speed of 1.5 mm/min that continued 

to specimen failure. Load and grip displacement data were 

collected at 10 Hz. Tests were performed in one of two 

controlled environments, either 50% RH, 23°C or 90% RH, 

23°C. To prevent possible long-axis buckling, all specimens 

were restrained transversely with glass plates. The two 

100-mm-long glass plates that were used as restraints were 

separated by a gap of twice the specimen thickness and 

placed at the vertical center of the tensile specimen.

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
34

Tests were performed in the MD (machine direction) and CD (cross-machine direction) for each material. Six specimen geometries were tested: (1) standard tensile test, (2) 0.5 mm radius hole, (3) 1.25 mm radius hole, (4) 1.88 mm radius hole, (5) 

2.5 mm radius hole and (6) 5.0 mm radius hole. Holes were centrally located in the specimens with an alignment fixture and 

made with an inside-taper hole punch.

The Whitney and Nuismer [1] failure criterion predicts that a sheet containing a central circular hole of radius R fails when 

the longitudinal stress, σy at a characteristic distance, d0, from the hole edge achieves the unnotched tensile strength of the 

material in the y-direction, σU (i.e., failure occurs when ). This theory is called the point-stress criterion (PSC) 

and intuitively suggests that failure occurs when the longitudinal stress throughout the distance adjacent to the edge of the 

hole, d0, exceeds the unnotched tensile strength, σU. 

The PSC can be formally written as 

Where is the tensile strength of the material containing the central circular hole

 tensile stress concentration factor for an infinite plate

For our case, we have made two modifications to Equation (1). First, using the same technique as Kortschot and Trakas [2], 

the stress concentration factor for an infinite plate, , is replaced in Equation (1) by that for our finite-width specimens, , 

according to the following equation developed by Tan [3]:

σ y R + d = σ U ( ,0) 0

















































+ − 















+ − − 















+

+ 















+ = + ∞

∞ 8

0

6

0

4

0

2

0

2 3 ( 3) 5 7

2 R d

R

R d

R K

R d

R

R d

R T

H

U

σ σ Eq. (1)

∞ σ H

∞ KT

∞ KT KT

[2 (2 ) (2 ) ] 2 (2 ) ( 3)[1 (2 ) ] 2 2 4 6 2 R W R W R W K R W

K

K T

T

T = − − + − − ∞

∞

Eq. (2)

Where: W is the specimen width, 25 mm.

Second, we assume σU is an unknown. This last modification seems reasonable in that all commercial material have inherent 

defects due to the manufacturing process

We will show how inherent defect size and maximum possible tensile strength vary with humidity and relate these parameters 

to formation measurements.

References

Whitney JM, Nuismer RJ. (1974) Stress fracture criteria for laminated composites containing stress-concentrations. Journal 

of Composite Materials,8: 253-265.

Kortschot MT, Trakas K. (1998) Predicting the strength of paper containing holes or cracks with the point stress criterion. 

Tappi Journal,81: 254-259.

Tan SC. (1988) Finite-width correction factors for anisotropic plate containing a central opening. Journal of Composite Materials,22: 1080-1097.

General Technical Report FPL–GTR–196
Experimental Characterisation of Paper for 

Corrugated Board

M.E. Biancolini, C. Brutti, S. Porziani

Department of Mechanical Engineering, Tor Vergata University, Rome

Contact: biancolini@ing.uniroma2.it

Corrugated board is widely used to ship and keep any kind of goods across the entire world. Due to ecological and economical reasons, the main goal in box design is to fit required box performances while minimizing paper material consumption.

An efficient utilisation of raw materials can be achieved if all design parameters affecting the performance of a container, as 

box dimensions number of layers and paper material, are carefully controlled. Predictive tools that rely on design formula or 

complex structural models require a complete characterisation of paper material constants.

Paper, due to its manufacturing process, can be treated as an orthotropic, fibrous material. As can be seen in Fig.1, it is 

possible to identify three main directions: Machine Direction MD, Cross Direction CD, and Thickness Direction TD (those 

direction can be also be applied in corrugated cardboard panels). Using this paper model and referring to the paper reference 

coordinate system, a complete characterisation of paper can be achieved considering five elastic constants and five strength 

constants. For an orthotropic 2D fibrous material, stress strain relation can be expressed as

1 21 1

12 21 12 21

1 1

12 2 2

2 2

12 21 12 21

12 12

12

0

1 1

0

1 1

0 0

E E

E E

G

ν

νν νν σ ε ν σ ε νν νν τ γ

 

  − −         =     − −         

 

Eq. (1)

Where index 1 refers to MD and index 2 refers to CD (stresses and strains in TD are neglected considering a 2D material). 

Matrix components in Eq. 1 can be identified performing simple tensile tests with a general purpose testing machine (Fig. 2) 

on differently oriented paper specimen (fig.4): for each material several specimens in three directions (0°-Machine direction, 

90°-Cross direction, 45° direction) by means of a CNC cutter has been extracted. Elastic constants were computed as reported 

in Table 1. Five strength constants have been computed for each paper: tensile strength in CD and MD, compression strength 

in CD and MD, and shear strength (Table 2). Strength constants reported in Table 2 can be used to verify tensional state of paper subject to a specific load, by means of an appropriate failure criterion, such as Tsai-Wu or Tsai-Hill, which can take in account paper’s different behaviour in both principal directions. A wide test campaign has been carried on, based on the actual 

papers used at Smurfit-Kappa Anzio Plant. The complete range of paper tested is reported in Table 3. Computed constants are 

reported in Table 4 and Table 5.

Table1. Elastic constants 

E1 Young Modulus from 0° specimen 

E2 Young Modulus from 90° specimen 

G12 Theoretical relation: 

1

12

12

1 1 2 45

2 11 4 G

E EEE

 



 

     

 12 Empirical relation: 12 2 1   0.293 E E

 21 Theoretical relation:  21 12 2 1    E E

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Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
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Table 2. Strength constants 

1t tensile strength in MD Ultimate stress in 0° specimens 

 2t tensile strength in CD Ultimate stress in 90° specimens 

1c compression strength in MD SCT tests 

 2c compression strength in CD RCT tests 

12  shear strength Empirical relation: 12 1 2 c c    

Table 3. Paper commonly used for facings. Class names following GIFCO 

nomenclature. 

Code Grammage [g/m2

] Class Code Grammage [g/m2] Class

KB3 140 White Kraft F2 112 Fluting 

KB5 175 White Kraft F4 140 Fluting 

K3 140 Kraftliner S4 127 Semichemical

K5 170 Kraftliner S6 150 Semichemical

LB3 135 White test 2 S9 175 Semichemical

LB5 185 White test 2 SS4 130 Semichemical

TB3 145 White test 3 SS6 160 Semichemical

T2 115 Testliner 4 SS9 180 Semichemical

T3 135 Testliner 4 

T5 185 Testliner 4 

L3 150 Testliner 3 

L5 185 Testliner 5 

L6 200 Testliner 6 

KL3 140 Testliner 1 

KL5 200 Testliner 1 

KL6 230 Testliner 1 

Table 4. Elastic constants for tested papers. 

Density 

[ 3 kg m ]

E1

[Mpa]

E2

[Mpa]

G12

[Mpa] 12  21

K 5 656.49 3678 1473 1361 0.185 0.074 

K 3 638.53 4363 534 579 0.103 0.013 

TB 3 684.65 2567 1129 746 0.194 0.086 

LB 5 817.26 4024 2036 1172 0.208 0.105 

LB 3 807.22 4619 1611 1166 0.173 0.060 

KB 5 800.48 3280 1978 1138 0.228 0.137 

KB 3 805.75 4874 2257 1711 0.199 0.092 

KB 3 696.43 3262 1672 1031 0.210 0.107 

T 5 548.48 2577 1354 758 0.212 0.112 

T 3 614.04 3490 1273 980 0.177 0.065 

T 2 610.11 3822 1256 971 0.168 0.055 

L 6 649.71 2673 1759 984 0.238 0.156 

L 5 643.27 2646 1589 914 0.227 0.136 

L 3 648.71 3576 1607 1023 0.196 0.088 

KL 6 655.14 2803 1723 964 0.230 0.141 

KL 5 653.07 3167 1577 1129 0.207 0.103 

KL 3 675.47 4134 1806 1122 0.194 0.085 

SS 9 645.19 2968 1643 1054 0.218 0.121 

SS 6 683.04 3752 1689 1027 0.197 0.088 

SS 4 689.47 4179 2124 1288 0.209 0.106 

S 9 645.45 3396 1764 1014 0.211 0.110 

S 6 665.24 3980 1876 931 0.201 0.095 

S 4 648.48 4245 1965 1241 0.199 0.092 

F 4 569.92 3858 801 618 0.134 0.028 

F 2 593.75 3600 960 733 0.151 0.040 

General Technical Report FPL–GTR–196
Table 5. Strength constants for tested papers. 

1t  2t 1c  2c 12 

[Mpa] [Mpa] [Mpa] [Mpa] [Mpa] 

K 5 56.16 15.38 9.45 6.80 8.02 

K 3 72.80 17.65 9.08 5.18 6.86 

TB 3 18.41 6.50 5.95 4.53 5.20 

LB 5 39.37 10.80 8.96 7.00 7.92 

LB 3 37.65 9.54 7.64 5.78 6.64 

KB 5 48.62 12.39 11.04 8.96 9.95 

KB 3 66.58 19.40 10.12 8.32 9.17 

KB 3 46.54 12.16 9.81 6.88 8.21 

T 5 18.95 7.55 6.66 4.92 5.72 

T 3 25.31 6.89 6.27 4.44 5.27 

T 2 25.29 7.29 5.49 3.64 4.47 

L 6 32.62 10.92 9.24 6.94 8.01 

L 5 26.55 8.96 8.37 6.77 7.53 

L 3 30.01 9.51 7.93 5.98 6.89 

KL 6 48.79 12.37 11.08 8.06 9.45 

KL 5 48.12 11.39 11.14 8.45 9.70 

KL 3 40.58 11.97 9.75 6.98 8.25 

SS 9 35.39 10.61 8.65 6.88 7.71 

SS 6 33.67 11.31 7.95 6.17 7.00 

SS 4 42.77 13.16 8.36 6.26 7.24 

S 9 33.23 11.36 8.21 6.76 7.45 

S 6 38.09 11.89 7.28 6.17 6.70 

S 4 38.07 12.07 6.87 5.38 6.08 

F 4 32.44 4.35 6.29 3.66 4.80 

F 2 22.27 5.78 4.89 3.06 3.87 

Figure 1. Paper reference coordinate system

Figure 2. Testing Machine

Figure 3. Specimen preparation at Smurfit-Kappa 

Anzio Plant

Figure 4. Specimen orientations.

References

[McKee1963] - McKee, C.; Gander, J. W. & R., W. J. “Compression strength formula for corrugated boxes” - Paperboard 

Packaging, 1963, 55, 149-159 

[Baum1981] - Baum, G.; Brennan, D. & Habeger, C. “Orthotropic elastic constants of paper” - TAPPI Journal, 1981, 64, 97-

101 

[Bronkhorst2003] - Bronkhorst, C. “Modelling paper as a two-dimensional elastic-plastic stochastic network” - International 

Journal of Solids and Structures, 2003, 40, 5441-5454 

[Campbell1961] - Campbell, J. “The in-plane elastic constants of paper” - Australian Journal of Applied Sciences, 1961, 12, 

356-357

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Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
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General Technical Report FPL–GTR–196
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Session 4

Ian Chalmers, Chair 

Scion, Rotorua, New Zealand

Industry Efforts

Ultimately, the paper and paperboard manufacturing industries 

need to educate their customers on the effects of moisture-induced 

behavior of cellulose-based materials. Several manufacturers have 

modernized mills to create unique linerboards or mediums that 

behave impressively in variable moisture environments. Such product 

differentiation improves profit margins and retains customers. 

By providing knowledge of paper behavior during converting or 

printing, customers recognize methods to reduce losses in their 

processes. Novel materials, e.g., paperboard with vapor barriers, 

offer alternatives to products that are ultimately landfilled.

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Repulpable water vapor barrier coatings 

made easy

Ronald E Hostetler

U.S. Paper Consulting, Vancouver, WA, USA 

 

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General Technical Report FPL–GTR–196
Session 5

David Vahey, Chair 

U.S. Forest Service, Forest Products Laboratory

Other Materials

67

All cellulose-based composite materials experience reduced 

strength and stiffness and increased failure strain in high moisture 

environments, but these changes occur at different magnitudes 

depending on material. Each species of solid wood has different 

moisture sensitivity that needs to be accounted for in structural 

applications. Composite material manufacturers often take 

advantage of the high strength to weight ratio of cellulose fibers for 

production of innovative products, using moisture sorption within 

their design. Other manufacturers need the high strength to weight 

ratio with very low moisture sensitivity and rely on impervious 

laminations.

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Strength properties of low moisture 

content yellow-poplar and Southern Pine

David E. Kretschmann, Research Engineer

David W. Green, Supervisory Research Engineer, Emeritus

U.S. Forest Service, Forest Products Laboratory, Madison, Wisconsin

Contemporary engineering design practices in the United States require information on the strength of lumber for moisture 

contents as low as 4%. Efficient design of experimental studies on lumber properties at low moisture contents requires a 

better understanding of the basic mechanisms controlling moisture-property relationships. A study is being conducted on the 

effect of moisture content on strength and stiffness in bending, tension and compression parallel and perpendicular to grain, 

and longitudinal shear in yellow-poplar (Liriodendron tulipifera L.). Results of this study and one previously conducted on 

Southern Pine (Pinus taeda) will be compared and there implications on structural performance discussed.

General Technical Report FPL–GTR–196
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Hygroexpansion of plant-based fiber mats 

for “green” composites

P.J.J. Dumont1, J.-F. Bloch1, L. Orgéas2, B. Vermeulen3, P. Vroman3, S. Rolland du Roscoat2

1. Laboratoire de Génie des Procédés Papetiers (LGP2), CNRS / Institut polytechnique de Grenoble (Grenoble 

INP) - BP 65 - 38402 Saint-Martin-d’Hères cedex9, France

e-mail : pierre.dumont@efpg.inpg.fr

2. Laboratoire Sols-Solides-Structures-Risques (3S-R), CNRS / Université de Grenoble (UJF & Grenoble INP) - 

BP 53 - 38041 Saint-Martin-d’Hères, cedex 9, France

3. École Nationale Supérieure des Arts et Industries Textiles (ENSAIT), 2 allée Louise et Victor Champier, BP 

30329, 59056 Roubaix cedex 1, France

Keywords: composites, plant fibers, dimensional stability, hysteresis, anisotropy, X-ray microtomography

There is a growing interest in making renewable and sustainable composite materials. Plant fibers are suitable to reinforce 

composites due to their high strength and stiffness with respect to their low density. Nonetheless, they have intrinsic drawbacks such as their poor dimensional stability when subjected to changes in temperature or moisture.

This study aims at describing the microstructural deformation phenomena of plant-based fiber mats that are induced by 

changes in the relative humidity (RH) of the ambient air. Tested mats were formed with flax fibers of various qualities. They 

were produced by opening the fiber bales by carding and subsequently orientated to cross-machine direction by using a crosslapper to form a web of required basis weight. Finally they were needle-punched and hydro-entangled. 

At the macroscopic scale, the in-plane dimensional variations of these mats were studied by using a specially developed 

device. At the microscopic scale, an in situ analysis of the 3D evolution of their microstructure was carried out by using the 

synchrotron X-ray microtomography (European Synchrotron Radiation Facility, Grenoble, France). In parallel, their sorption 

properties were studied. During these various experiments, samples were subjected to the same relative humidity (RH) cycles 

(RH varying between 20 and 80%) at a constant temperature of 23°C.

Results show hysteresis phenomena for the absorption and desorption properties, as well as for the hygroexpansion of these 

fibrous mats. In this latter case, results emphasize also the influence of the anisotropic structure of the tested fibrous mats. At 

the microscopic scale, the analysis of the X-ray microtomographies highlights the combined evolutions of the porosity and of 

the geometry of the fibrous phase during the RH cycles. Accounting for these various observations, a model for the hygroexpansion of these mats is proposed.

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Session 6

Sergiy Lavrykov, Chair 

Empire State Paper Research Institute (ESPRI), Syracuse, New York

Modeling and Creep Response

Recent advances in corrugated container modeling incorporate 

nonlinear, viscoelastic behavior of medium and linerboard along 

with sophisticated geometry. Powerful numerical analysis is now 

possible on desktop computers. These developments allow box 

designers to analyze multiple, non-related failure mechanisms 

while optimizing container weight and cost.

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
Corrugated board box design using full 

detailed FEM modelling

M.E. Biancolini, C. Brutti, S. Porziani

Department of Mechanical Engineering, Tor Vergata University, Rome

Contact: biancolini@ing.uniroma2.it

Due to its large use in shipping and keeping goods, interest in corrugated board box design is grown in the last period. The 

main request for a box is to support its own weight and of any other box stacked on it without damage. 

The performance can be predicted by means of design formula or complex structural models. An accurate prevision allows 

an optimisation of the product that can be achieved finding the best composition (i.e., number of layers, corrugation type 

and materials). Furthermore a local analysis of the stress field allows the optimisation of ventilation holes and handles holes 

shape and position. 

Finite Elements Modelling (FEM) allows to estimate the local stress field an can be conducted at two level of complexity. 

The first one consists in the modelling each wall of the container with shell elements, condensing the internal structure by 

means of the lamination theory or homogenisation, the second one consists in the complete modelling of each layer of paper 

material representing its actual shape. The last approach is very difficult to implement for two reasons: the numerical cost of 

the calculation, and the complexity of the model. For this reason such kind of analysis is still confined to research field.

This paper is focused on the full detail modelling of corrugated board containers. A dedicated software has been developed 

for FEM model preparation (Fig.1). The tool allows to generate a detailed mesh of a generic container. Starting parameters 

include: paper materials (selected from a database), number of wave (single or double wall, Fig.5), box dimensions (including flaps, Fig.3), creasing shape (Fig.4) and adhesive stiffness (adhesive joining is represented by single node to node connectors), meshing parameters (local refining can be prescribed in the critical areas, Fig.2).

Proposed tool allows to quickly set-up parametric analysis with a minimum man effort (of course a lot of CPU is required for 

the non linear analysis completion). Numerical previsions are discussed from different perspective: 

• a detailed modelling allows to better understand the structural behaviour of the container and its failure mechanism; 

• a wide parametric analysis allows to define design maps that would be very expensive to obtain experimentally; 

• a comparison between experiments and numerical prediction can be performed to understand the differences between the 

 FEM model (representative of an ideal container) and reality; 

• full detail modelling can be used as a reference for the tuning of simplified models based on design formula or shell based 

 FEM.

References

[McKee1963] - McKee, C.; Gander, J. W. & R., W. J. “Compression strength formula for corrugated boxes” - Paperboard 

Packaging, 1963, 55, 149-159 

[Baum1981] - Baum, G.; Brennan, D. & Habeger, C. “Orthotropic elastic constants of paper” - TAPPI Journal, 1981, 64, 97-

101 

[Bronkhorst2003] - Bronkhorst, C. “Modelling paper as a two-dimensional elastic-plastic stochastic network” - International 

Journal of Solids and Structures, 2003, 40, 5441-5454 

[Campbell1961] - Campbell, J. “The in-plane elastic constants of paper” - Australian Journal of Applied Sciences, 1961, 12, 

356-357 

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Figure 1. Graphical User Interface

Figure 2. Box FEM model

Figure 3. Real box and 

symmetrical model.

Figure 4. Implemented creasing shapes.

Figure 5. Single and 

double wall corrugated 

board profiles.

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Mechanical model on creep properties 

of double-wall corrugated paperboard

Note: Travel difficulties prevented Professor Guo from presenting his paper.

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transient elastic deformation rule of spring, yet the second term 3 (1 )

t e eα α ε − = − is an

exponential function and accords with the deformation rule of Kelvin Model.[8]By the above

analysis, the first mechanical model may be established as the combined m el of damper, spring

and Kelvin Model, which is shown in Fig.1, and it consists of four parameters such as viscosity

factor

od

η1 , elastic modulus , viscosity factor E2 η3 and elastic modulus of Kelvin Model. E3

Fig.1 The first mechanical model with four parameters

For the first mechanical model with four parameters, the stress strain constitutive relations of

damper, spring and Kelvin Model are respectively described as follows:

Calculation of model parameters

0

1

1

2

3

0 3 / (1 ) ( ) t e

E E

τ

0

2

3 3

t

E

σ

ε

η

σ

ε

σ η ε τ − ⎪

⎪⎩

= − =

⎧

⎪ =

⎪

⎪⎪

⎨

⎪

⎪

= (3)

par ay be

(1) During the initial stage of loading (

So, by using coefficient method, the four ameters of mechanical model m calculated

according to the following procedure: 

t ≤1), by comparing the strain 1 0 ε = a t with the first 

expression of Eq.(3), the viscosity factor of damper is derived as 0

1

0 a

σ

η = . Then substituting the

characteristic factor and constant compression load a0 σ 0 at twenty different experimental

conditions in Table.1 into η1 , the viscosity factor of damper η1 are calculated and shown in 

Table.2.

Table.2 Viscosity parameter of damper η1 (104

Pa ⋅s)

Constant compression load σ 0 /10kPa

RH/%

60 10.5897 11.5053 11.3216 7.0700 4.9946

1.688 1.842 1.996 2.150 2.304

70 7.7396 7 6.6823 5.7920

90 4.7456 3.4346 2.8240 3.0346 2.6535

.9637 5.5212

80 5.9124 5.0041 5.0519 4.6376 4.6016

(2) During the creep stage of loading (1< t ≤168 ), by comparing 2 0a e 1 α ε = + −

ained as 

with the second

expression of Eq.(3), the elasticity parameter of spring is obt 0

2

0a e 1

E α

σ = . Then 

substituting the characteristic factors and 

+ −

0 a α , and constant compression load σ 0 at twenty

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Compression fatigue creep of paperboard

C. Tim Scott and Roland Gleisner

U.S. Forest Service, Forest Products Laboratory, Madison, Wisconsin

Mechanical fatigue creep is the imposition of a cyclic stress on a structural element causing irreversible deformation. Fatigue 

is typically characterized by a mean stress level about which a periodic stress is imposed whose amplitude and frequency 

can vary with time. Considerable effort has been made to characterize the fatigue properties of materials, principally metals, 

since catastrophic failures are often associated with cyclic fatigue stresses, particularly when defects are present. Both tension 

and compression fatigue stresses are present in many paper processes and applications. In the papermaking process itself, the 

paper web experiences periodic tensioning as it winds through the machine. It may again experience more cyclic stress as it is 

unwound and converted. The core on which it is wound and unwound may also experience considerable cyclic stresses which 

have been known to cause failures, particularly near the chuck. 

In a specific structural application of paper, corrugated boxes are designed to carry considerable stacking loads but may also 

experience cyclic compression stresses in the shipping environment. Even humidity variations can lead to considerable cyclic 

stresses in warehouse environments. Attempts have been made to measure the stacking strength of boxes exposed to various 

vibration loads and under cyclic humidity conditions. Likewise, attempts have been made to measure the compression creep 

response of linerboard and medium under cyclic humidity conditions. However, little is known about the fatigue strength of 

the paperboard exposed to cyclic compression stresses or how fatigue cycling may be used to predict moisture hysteresis. 

This paper will present an overview of the instrumentation and experimental approach developed to evaluate cyclic compression fatigue of paperboard. A heavy linerboard sample (BW = 260gsm), cut for cross-machine direction specimens, was 

selected for initial tests. Four cyclic frequencies were evaluated (.2, 2, 20, and 200 Hz). The mean compressive stress was 

chosen not to exceed 80% of the “static” compressive fail load. Specimens were subjected to cyclic fatigue for at least 1-hour 

or until they failed. The cyclic creep portion of the data was fit to a power-law function and creep rates were determined at 

various time intervals.

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Session 7

M.E. Biancolini, Chair 

University of Rome, Rome, Italy

Moisture and Time Response

Cellulose materials have hierarchal structure, and various 

degrees of viscoelastic behavior occur at all structural levels, but 

measuring these effects becomes particularly challenging when 

approaching microstructures. Improvements in test equipment 

allow more complete analysis of these behaviors. Recent work on 

cellulose fiber mechano-sorptive behavior helps define a range of 

performance in fiber webs, where continuum behavior is measured. 

The vast spectrum of time, temperature, and moisture behavior of 

cellulose materials provides an important area of future research.

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
94

Use of ultrasonic velocity measurement 

to investigate moisture-induced stress 

relaxation in paper

David Vahey, John Considine, Roland Gleisner

U.S. Forest Service, Forest Products Laboratory, Madison, Wisconsin 

Introduction

Convenient, non-destructive ultrasonic velocity testing is useful for studying the influence of moisture treatments on paper 

performance. Ultrasonic testing is sensitive to internal stresses developed during paper manufacture and responds to the loss 

of such stresses induced by moisture treatments. The goal of this work is to characterize the internal stresses in paper by 

monitoring their degradation under moisture cycling.

The present approach uses ultrasound to characterize the stiffness of a set of commercial papers covering a wide range of 

grammage and function. The papers were subjected to repetitive cycles of soaking, preconditioning at 30% RH, and reconditioning at 50% RH, all done without drying restraint. Following each cycle, the stiffness anisotropy and orientation-angle 

(the “peanut curve”) were determined ultrasonically. Both shear and tensile stiffnesses were measured. Dimensional changes 

in the samples were also measured.

This approach to study the relation between drying stresses and stiffness orientation is the reverse of that commonly taken. 

Wahlström and Mäkelä (2005) and Hess and Brodeur (1996) both related handsheet stiffness properties to fiber orientation 

and the degree of drying restraint [1,2]. They found that stiffness and fiber-orientation anisotropy were the same for sheets 

dried under full restraint. For sheets that were freely dried or dried under partial restraint (wet straining), they found that the 

stiffness anisotropy was higher than the fiber-orientation anisotropy. Hess and Brodeur (1996) also showed that the fiber 

misalignment angle was invariably larger than the stiffness misalignment angle. However, a theoretical basis for the observations was not provided.

A heuristic model suggested by the findings is

where E(θ) is the sonic modulus at orientation angle θ, EB is the (isotropic) modulus contribution from bonding, F is the 

contribution from fiber orientation anisotropy AF and orientation θF, and S is the contribution from stress orientation anisotropy AS and orientation θS. The analysis of our experiments will be based on this model, using the assumptions that (1), the 

fiber orientation distribution F is unchanged as a result of moisture cycling, and (2) the isotropic bonding contribution EB

is unchanged by moisture cycling. This leaves stress orientation S as the variable to be characterized by repeated soakingdrying cycles.

Samples and Tests

The samples used in the study were four boards and four office papers. The samples have had an extensive measurement 

history in connection with previous work on z-direction fiber orientation [3]. As part of previous work, two specimens from 

each sample were measured on commercial ultrasonic testing equipment offered by SoniSys Corporation, Atlanta, Georgia. 

Measurements included the “peanut curve” associated with the in-plane propagation of longitudinal sound waves. In addition, shear propagation was measured in the cross-machine direction (CD) and at 45o to the CD. In the current work, the 

same specimens were measured after each of five wetting/drying cycles using two Sonic Sheet Testers model SST-250, made 

by Nomura Shoji Corporation, Japan. One of the testers was used as produced. The other was modified to measure in-plane 

shear waves. Calibration of the shear velocity measurement was done by comparison to the shear measurements provided by 

SoniSys on the same samples.

Specimen shrinkage in the MD and CD was also measured after each moisture cycle. Measurement resolution was 0.25 mm. 

corresponding about 0.1%. After five moisture cycles, typical total shrinkage was about 1.0%, corresponding to 10 resolution 

elements.

( ) ( ) ( ) E θ = EB F AF θ −θ F S AS θ −θ S , , Eq. (1)

General Technical Report FPL–GTR–196
95

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
96

General Technical Report FPL–GTR–196
97

Wood	fibres	do	indeed	show	mechano-sorptive	creep.				

Lennart Salmén, Anne-Mari Olsson, Christer Fellers 

STFI-Packforsk

Box 5604,

SE 114 86 Stockholm, 

Sweden

Abstract

The phenomenon of increased creep during changing moisture has been observed for long, 

both for wood and paper products. This accelerated creep, termed mechano-sorptive creep, is 

a complex phenomenon that has been extensively studied from the time of its discovery in the 

late 1950ties. At a time it was argued that wood fibres did not show this mechano-sorptive 

creep and therefore the effect was sought in the structure of the paper and the bonding 

between the fibres. The claims for this arguing were mainly based on measurements of 

holocellulose fibres. However later studies to some extent questioned this result, as being a 

consequence of inadequate moisture sorption rates, but also due to observations that 

regenerated cellulose fibres did show mechano-sorptive creep. 

In order to clarify the behaviour for wood and pulp fibres a fibre testing methodology was 

adopted enabling single fibre testing under climatic variations. For this purpose single wood 

and pulp fibres were prepared either by careful microscopic isolation of native wood fibres 

from a single annual ring of a spruce tree or as holocellulose spruce pulp fibres isolated by 

maceration of the wood. These fibres were one by one glued, using a stiff moisture insensitive 

glue, to a tensile stage of a dynamic mechanical analyser, DMA, and tested. Each single fibre 

was first exposed to a tensile stress at a constant climate of 80% relative humidity, RH, 

followed by a cycling environment varying between 80 and 30 %RH. A number of fibres 

were measured in this way at different stress levels.

Contrary to earlier claims it was by these measurements demonstrated that single wood and 

pulp fibres exposed to a cyclic relative humidity indeed show a considerably higher creep 

than that corresponding to the highest RH experienced in the humidity cycle, i.e. showing a 

mechano-sorptive creep behaviour. The cyclic creep rate was also shown to be a function of 

the constant creep rate and to be an apparent linear function of the applied stress.

The ratio between the cyclic creep rate to the constant creep rate was about 2 for the wood 

fibres and around 2.9 for the holocellulose fibres. This should be compared to a ratio of 5 

shown to be the case for papers. If this discrepancy is related to influence of fibre-fibre bonds 

or to the fact that transverse fibre properties play a role have to be further investigated. 

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
Hygroexpansivity of thermally aged papers

J.M. Considine1*, M.J. Wald2, R.E. Rowlands2, and K.T. Turner2

1 U.S. Forest Service, Forest Products Laboratory, Madison, Wisconsin

2 University of Wisconsin, Madison, Wisconsin

*contact author: jconsidine@fs.fed.us

Confidence in the performance of engineered paper products can be increased through knowledge of how mechanical properties, such as strength, stiffness, and hygroexpansivity change with exposure to various conditions. Environmental effects 

present during storage of paper products can greatly degrade and change the mechanical performance. The primary aim of the 

present work is to characterize changes of mechanical properties, including tensile response and dimensional stability, with 

aging and to develop time-dependent models to describe the behavior. Specifically, this research evaluates the effects of thermal aging on the properties of two different papers using tensile testing and hygroexpansivity measurements. The change in 

stiffness, strength, and hygroexpansivity was measured for papers aged at different temperatures for various lengths of time. 

An Arrhenius relationship was used to shift the data collected at various temperatures to a master curve where possible. Full 

details of experimental results as well as insight into the underlying mechanisms of aging will be presented in this talk.

98

General Technical Report FPL–GTR–196
Participants

Johan Alfthan

Senior Research Associate

Innventia AB

Box 5604

Stockholm, Sweden

SE-11486

+46-8676-7268

johan.alfthan@innventia.com

Marco Evangelos Biancolini

Researcher

Mechanical Engineering

University of Rome

Via Politecnico 1

Rome, Italy

RM-000133

biancolini@ing.uniroma2.it

Ian Chalmers

Scientist

Scion

Private Bag 3020

Rotorua, New Zealand

Rotorua Mail Centre 3046

Ian.Chalmers@scionresearch.com

Douglas W Coffin

Professor

Paper and Chemical Engineering

Miami University

64 N Engineering Building, PCE

Oxford, OH 45056

513-529-0771

coffindw@muohio.edu

Jessica Coher

Quality Department

RockTenn

53 Industrial Drive

Syracuse, NY 13204

315-703-9376

jcoher@rocktenn.com

John Considine

Research Engineer

U.S. Forest Service, Forest Products Laboratory

One Gifford Pinchot Drive

Madison, WI 53726

608-231-9525

jconsidine@fs.fed.us

Nicola Dooley

Paper Scientist

Scion

Private Bag 3020

Rotorua, New Zealand

Rotorua Mail Centre 6046

Nicola.Dooley@scionresearch.com

Pierre Dumont

LGP-PAGORA

461 Rue De La Papeterie

St. Martin D'heres, France

38-38402

Pierre.Dumont@grenoble-inp.fr

Christer Fellers

Innventia AB

Box 5604

Stockholm, Sweden

SE-11486

christer.fellers@innventia.com

Benjamin Frank

Manager, Materials Optimization

Packaging Corporation of America

250 South Shaddle Avenue

Mundelein, IL 60060

847-482-2094

bfrank@packagingcorp.com

Terry Gerhardt

VP Technology & IP

Sonoco

125 West Home Avenue

Hartsville, SC 29550

843-383-7303

terry.gerhardt@sonoco.com

Samuel V Glass

Research Physical Scientist

U.S. Forest Service, Forest Products Laboratory

One Gifford Pinchot Drive

Madison, WI 53726

608-231-9401

svglass@fs.fed.us

Barry Hojjatie

Adjunct Associate Professor

Institute of Paper Science and Technology

Valdosta State

50 10th Street NW

Atlanta, GA 30332

404-894-6363

bhojjati@valdosta.edu

99

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
Ronald E Hostetler

Research Fellow

US Paper Consulting

2909 SE Blairmont

Vancouver, WA 98683, USA 

803-517-9720

ronald.hostetler@gmail.com

James W Huerta

Manager Materials Program Manager

Materials Engineering

Solo Cup Company

4444 West Grace Avenue

Mequon, WI 53092

847-405-2240

jim.huerta@solocup.com

Pasi Kekko

Senior Product Development Engineer

Metso Paper, Inc.

Kontinperänpolku 120

Toivakka 41660 

Finland

+358-4054-56129

Pasi.Kekko@Metso.com

David E Kretschmann

Research Engineer

U.S. Forest Service, Forest Products Laboratory

One Gifford Pinchot Drive

Madison, WI 53726

608-231-9307

dekretsc@wisc.edu

Sergiy Lavrykov

PBE - SUNY ESF

409 Walters Hall

1 Forestry Drive

Syracuse, NY 13210

315-470-6516

lavrykov@esf.edu

Walter Li

Norampac, Inc.

525 Abilene Drive

Mississauga, ON

L5T 2H7

Canada

walter_li@norampac.com

Rick Markson

Director of Design

Sonoco CorrFlex

555 Aureole Street

Winston Salem, NC 27107

201-424-2102

rebecca.white@sonoco.com

Monica McCarthy

Senior Professional Scientist

Sonoco

455 Science Drive, Suite 150

Madison, WI 53711

608-231-3060

monica.mccarthy@sonoco.com

Ron M McInnis

CTS

Interstate Resources

111 Constitution Avenue

Reading, PA 19606

484-333-1878

ronm@interstatecontainer.com

Alan Neel

Lab Technician

Paper, Packaging and Distribution Test Lab

International Paper

4140 Campus Drive

Aurora, IL 60504

630-585-3392

Alan.Neel@ipaper.com

Tom A Newell

T&D Lab Analyst

Technology and Development

Huhtamaki Americas

9201 Packaging Drive

DeSoto, KS 66018

913-583-8665

tom.newell@us.huhtamaki.com

Lawrence C Nykwest

Customer Technical Service Mgr

Interstate Resources

44 PLeasant Drive

Bernville, PA 19506

610-662-9773

lnykwest@unitedcorrstack.com

100

General Technical Report FPL–GTR–196
Sara Paunonen

PhD Stipendiat

Department of Chemical Engineering

NTNU

Høgskoleringen 6B

Trondheim

NO-7491

Norway

sara.paunonen@chemeng.ntnu.no

Roman E Popil

Senior Research Scientist

Institute of Paper Science and Technology

Georgia Institute of Technology

500 10th Street NW

Atlanta, GA 30332

404-894-9722

roman.popil@ipst.gatech.edu

Robert Ramsay

Technical Manager

Liquid Ink

INX International

410 West 34th Street, Apt 306

Steger, IL 60475

708-799-1993 x3922

bob.ramsay@inxintl.com

Diana Russell

Lab Supervisor

Paper, Packaging, & Distribution Test Lab 

International Paper

4140 Campus Drive

Aurora, IL 606504

630-585-3570

Diana.Russell@ipaper.com

Javad-Reza Saberian

Scientist

Product Performance Program

FPInnovations

570 Saint-Jean Blvd.

Pointe-Claire

QC

H9R 3J9

Canada

+1-514-630-4100 x2364

javad.saberian@fpinnovations.ca

Michael Schaepe

Technical Manager-Corrugating

Cargill

7425 Hobgood Road

Fairburn, GA 30213

michael_schaepe@cargill.com

C Tim Scott

U.S. Forest Service, Forest Products Laboratory

One Gifford Pinchot Drive

Madison, WI 53726

tscott@fs.fed.us

Michael R St. John

Research Associate

Pulp & Paper Research

Nalco Company

1601 West Diehl Road

Naperville, IL 60563

630-305-2349

mstjohn@nalco.com

Joshua Tinch

Sales Representative

Humidity Control

Key Scientific for Parameter Generation & Control

1054 Old US Highway 70 West

Black Mountain, NC 28711

sales@humiditycontrol.com

Kevin T Turner

Professor

UW-Madison

1513 University Avenue

3031 Mechanical Engineering

Madison, WI 53706

608-890-0913

kturner@engr.wisc.edu

David Vahey

Materials Research Engineer

U.S. Forest Service, Forest Products Laboratory

One Gifford Pinchot Drive

Madison, WI 53726

dvahey@fs.fed.us

Yiming Wang

Sonoco

455 Science Drive, Suite 150

Madison, WI 53711

608-231-2992

yiming.wang@sonoco.com

101

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
Angelica Wikström

Development Engineer

Packaging Boards

Billerud AB

Storjohanns Väg 4

Grums

SE

66428

Sweden

+46-73-025-1033

angelica.wikstrom@billerud.com

Junyong Zhu

U.S. Forest Service, Forest Products Laboratory

One Gifford Pinchot Drive

Madison, WI 53726

jzhu@fs.fed.us

102

General Technical Report FPL–GTR–196
Index of Authors 

 

Alfthan, J...........................12

Biancolini, M. E................35, 82

Bloch, J.-F. ........................30, 69

Brutti, C.............................35, 82

Chalmers, I. R. ..................19

Coffin, D. ..........................5

Considine, J.......................33, 94, 98

Decker, J............................33

Desloges, I.........................30

du Roscoat, S.R.................30, 69

Dumont, P.J.J.....................30, 69

Fellers, C...........................32, 97

Fu, Y. .................................84

Glass, S.V. .........................28

Gleisner, R. .......................92, 94

Green, D.W. ......................68

Gregersen, Ø. ....................70

Guo, Y. ..............................84

Hansson, T.........................12

Hojjatie, B.........................24

Hostetler, R. ......................59

Kekko, P. ...........................49

Kouko, J. ...........................49

Kretschmann,D.E..............68

Lason, L. ...........................32

Lavrykov, S.......................29

Mähler, A. .........................32

Mauret, E...........................30

Ohlsson, A.-M...................32, 97

Orgéas, L...........................69

Paunonen, S.......................70

Popil, R.E..........................24

Porziani, S.........................35, 82

Ramarao, B.V. ...................29

Rutulainen, E.....................49

Rowlands, R......................33, 98

Salmén, L. .........................97

Schaepe, M.K....................24

Scott, C.T...........................92

Timonen, J.........................49

Turner, K. .........................33, 98

Vacher, P............................30

Vahey, D............................33, 94

Vermeulen, B.....................69

Viguié, J. ...........................30

Vroman, P..........................69

Wald, M. J. ........................98

Wikström, A......................40 

Zhang, J.............................84

Zhang, W...........................84

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Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
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General Technical Report FPL–GTR–196
Appendix

courtesy of 

Dr. Ian Chalmers

5th International Symposium

105

5th Symposium, April 2001 Victoria Australia. Coordinated by 

Dr. Ian Parker, Monash University, Victoria, Australia

Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
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

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



















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





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









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













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





















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







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









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













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





























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Proceedings, Sixth International Symposium: Moisture and Creep Effects on Paper, Board and Containers
The Influence of Heterogeneity on Tensile 

Accelerated creep in Paper

Chuck Habeger, Douglas Coffin

The Institute of Paper Science and Technology

Abstract

The presentation begins with a brief review of our preferred explanation for accelerated creep. We previously argued that 

accelerated creep is a result of the load dependence of the creep constitutive equation (JPPS 26(4) pp. 145–157 (2000)). 

Materials suffer more creep when subjected to a cyclic load than when held a constant load of the same average magnitude. 

Moisture cycling results in localized load cycling and therefore in additional creep. There are two ways this can happen. We 

call one of them “moisture-gradient-driven accelerated creep:” during sorption, transient moisture gradients pass through the 

sample, and differential swelling leads to stress gradients. The other is “heterogeneity-driven accelerated creep” Moisture 

cycling combined with spatial variability in hygroexpansion can also produce localized stress cycling.

If the humidity is changed rapidly compared to the sample sorption time, if the humidity cycle time is not much less than 

or much greater than the sample sorption time, and if the moisture transport conditions are such that a significant portion of 

moisture gradient is across the sample, moisture-gradient-driven accelerated creep will be observed in hydrophilic materials. 

Heterogeneity-driven accelerated creep doesn’t have the same stringent requirements on sorption conditions, but it can only 

occur in materials made of parts with disparate responses to moisture. We contend that, if properly cycled, all hydrophilic materials will exhibit extra creep. We attribute this general action to moisture-gradient-driven accelerated creep. Heterogeneitydriven accelerated creep is a rarer phenomenon that we suspect is also active in paper.

Because of the great difference between radial and axial hygroexpansion of wood fibers, paper has an unusual opportunity 

to display heterogeneity-driven accelerated creep. Fibers bonded together in the sheet will often have different orientations. 

Hygroexpansion results in dimensional incompatibilities, and cyclic humidity changes cause cyclic, fiber-level stress gradients. Compared to similar, but-homogeneous materials, paper suffers a great deal of accelerated creep. Cellophane has more 

hygroexpansion and greater creep enhancement through load cycling than does paper, yet it is less prone to accelerated creep. 

The reason for this may well be that paper is also subject to heterogeneity-driven accelerated creep.

To address the question of the role of heterogeneity in paper-accelerated creep, we tested papers made from a combination of 

furnishes. We selected bleached kraft softwood and thermo-mechanical pulps (TMP). When dried under full restraint, the pure 

TMP sheets had about 20% more hygroexpansion than the BKS ones. We compared sheets made from 50-50 blends of the 

two pulps with the single-furnish pulps and mixed-furnish multi-ply sheets with single-furnish multi-ply sheets. After deciding on a method to quantitatively rate accelerated creep, we concluded that heterogeneous layering did contribute to accelerated creep, whereas fiber blending did not. We surmise that the extra fiber-level heterogeneity contributed by fiber blending 

was small compared with that already present because of anisotropic fiber swelling. However, layering with plies of different 

hygroexpansion opened up a new scale for heterogeneity-driven accelerated creep.

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Top row from left: Doug Coffin, 

Jean-Marie Serra-Tosio, Ian 

Chalmers. Bottom row from 

left: Tom Urbanik, Ian Parker, 

Christer Fellers

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