bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydraulic Fluid Wear Test Design and Development
Authors: Young KJ
Published: March 2009

The current widely accepted “industry standard” pump test employs a Vickers V104C (or V105C) vane pump to assess the antiwear performance of hydraulic fluids. The two main versions of the test are documented as ASTM and IP methods. This pump test method, which was first developed in the 1960s, assesses only the steel-on-steel antiwear performance of hydraulic fluids, and this under constant speed, constant volume, and constant high pressure conditions. Constant conditions are not experienced in practical applications and it can be shown that hydraulic fluids which perform well at high pressure can fail to provide adequate antiwear performance at low pressure. Although other pump types may have different materials in contact, standard universally accepted procedures have not yet emerged to cover these. It can be shown that hydraulic fluids which have good steel-on-steel antiwear performance can have poor performance in steel-on-yellow-metal contacts. There is therefore a need for wear test procedures to be developed which cover the full range of operating conditions and material types found in practical applications. This paper will review experience gained in the author's laboratory, with different hydraulic fluid types, during the development of wear test procedures which more adequately cover the range of operating conditions and material contacts experienced in practical operating environments.
Contamination Sensitivity of Hydraulic Pumps and Valves
Authors: Lehner S , Jacobs G
Published: March 2009

The article describes the methods and results of the examinations of the wear behavior of pressure controlled pumps and proportional valves. For the purpose of examination, pressure controlled pumps are exposed to a reproducible wear load in highly contaminated oil by means of a special developed test procedure. An analysis of the damage process that occurs in several tribological systems shows that the wear behavior of pumps and valves is highly dependent on the constructive design and materials of single tribological systems. On the basis of examples, provisions for wear design to minimize wear are pointed out.
Tradition Bound Resistance Hinders Youth Baseball Safety
Authors: Glassman RH
Published: March 2009

The National Youth Sports Safety Foundation, formerly the National Youth Sports Foundation For The Prevention Of Athletic Injuries, a non-profit 501 (C) (3) educational research organization dedicated to reducing the number and severity of injuries youth sustain in sports activities, has been involved in injury prevention efforts in youth baseball since 1989. During that time the Foundation has worked both at the national and local level joining other organizations in their efforts to promote youth baseball safety. However, one vital issue yet to be addressed effectively is the number of deaths due to impact with a baseball or softball. While injury prevention interventions have been identified and continue to be developed, the lack of acknowledgment that the deaths are a health issue and a barrier dubbed “tradition bound resistance” have hindered injury prevention efforts.
A Comparative Test Method for Dynamic Response of Baseballs and Softballs
Authors: Chauvin DJ , Carlson LE
Published: March 2009

Sports organizations recently are concerned with means to control their respective games but ball testing appears not to have kept pace with changes in materials and construction. To increase ball durability, manufacturers have increased ball hardness so players are throwing harder balls today than in years past. Industry testing of sports balls has generally been limited to a few static tests and one performance test, the Coefficient of Restitution (COR). Dynamic ball hardness affects batted ball performance and varies with materials, construction, temperature and speed. Measuring dynamic hardness can require expensive equipment and sophisticated procedures. This paper discusses the use of pressure sensitive films as a cost effective method to measure the relative impact pressure and impact area of a ball impacting an object. The described test method can also be useful in evaluating the impact efficiency of protective padding.
The Mechanism of Ball Throwers’ Fractures and Their Prevention.
Authors: Miyasaka Y , Ohyama M , Kokubun S , Yokobori TA
Published: March 2009

In order to clarify the mechanism of ball throwers’ humeral fractures, two types of mechanical tests were done. Torsional or bending load was applied to produce experimental fractures of in eight canine whole humeri. Canine humeri were easily broken by torsion, but could tolerate tensile stress by bending. The ratio of torsional strength to bending strength was calculated to be 0.156. Our ten clinical cases and 118 cases in Japanese literature were reviewed on radiograms and clinical situations of injury: position, type of throw, kind of pitches, type of ball. All cases were amateurs and no professional players. No clinical factors on these situations were specified. All fractures were brittle and spiral in shape and were inter-preted to be produced not by bending, but by torsion. When we combine the mechanical analysis in our experiment with review of the data in 172 clinical fracture cases, the following conclusion is obtained: throwers’ fractures can be produced by torsion of relatively small torque, while they aren't induced by bending even by a maximal muscular strength in a skilled pitcher. The key point of prevention is education about correct pitching forms to minimize torsion to the humerus.
In Situ Damage Progression in General Layup Composites
Authors: Fan J
Published: March 2009

In this paper, a methodology for progressive matrix cracking-delamination interaction is proposed. Two damage variables and a five-layer equivalent constraint model (ECM) are introduced. After a mesoscopic stress analysis is conducted for the ECM, concepts of continuum damage mechanics are applied to obtain the effective moduli by the approach proposed by Fan and Zhang in 1993. The critical matrix cracking densities at which the transition from matrix cracking to delamination occurs are found to be dependent on the number of plies of the weakest layer and almost independent of the layups. These numerical results of general layups are consistent with those obtained by Nairn and Hu in 1992 for cross-ply laminates. Results also show connections between the calculated energy release rates with the experimental data of the least required energy for damage initiation of T300/976 composite beams.
Damage, Fatigue, and Failure of Ceramic-Matrix Composites
Authors: Burr A , Hild F , Leckie FA
Published: March 2009

Matrix cracking, interfacial debonding and sliding, fiber breakage and fiber pullout induced loss of stiffness, inelastic strains, hysteresis loops, and crack closure. These mechanisms are analyzed within the framework of continuum mechanics through the introduction of internal variables. Two models that are faithful to the micromechanical analysis are studied. They provide guidance on the choice of the relevant internal variables to describe the mechanical behavior of unidirectional fiber-reinforced composites. Ultimate strength properties of fiber-reinforced composites are derived and compared with results related to localization. Extensions to cyclic load histories are discussed in terms of ultimate strength reached after cycling.
A Micromechanical Fatigue Damage Model for Unidirectional Metal-Matrix Composites
Authors: Voyiadjis GZ , Echle R
Published: March 2009

Improvements in design and the enhancement in performance of aerospace vehicles calls for the development of advanced materials capable of sustaining the increasing loading conditions while maintaining their structural integrity. Special consideration must be given to the behavior of such materials under fatigue loading conditions that dominate the flight regime loads. A micromechanical fatigue damage model for unidirectional metal-matrix composites is proposed. Damage evolution is considered at the constituent level through the application of the Mori-Tanaka averaging scheme. Individual damage criteria for the constituents are proposed and employed to define damage evolution equations for each of the consultants. The numerical results for high cycle fatigue loading are presented for variations in the material and model parameters.
A Statistical Evolution Equation of Microdamage and Its Application
Authors: Bai Y , Han W , Bai J
Published: March 2009

A general equation governing the evolution of number density of microdamage in the phase space has been derived previously, based on the concept of ideal microdamage. The phase space consists of necessary mesoscopic variables describing the state of microdamage. In the cases of parallel penny-shaped microcracks and spherical microvoids, two independent variables, that is, their current and initial sizes, play a significant role in the evolution. This paper focuses on the two-dimensional (current and initial sizes) version of the equation and its solution. These results constitute a basis for the understanding of the underlying mechanisms governing damage evolution. Experimental techniques dealing with the statistical evolution of microcracks under impact and fatigue loadings are reported. These include specimen design, testing methods providing multifrozen stages of microdamage evolution, counting of microdamage, etc. Data processing, especially the conversion from sectional counting to volumetric distribution of microdamage, is provided. In this way, the microdamage evolution is measured. As applications to the damage evolution under impact loading, two inverse problems are discussed, that is, nucleation and growth rates are deduced from the measured data of statistical evolution of microcracks. Another application is the prediction of the evolution of continuum damage in terms of nucleation rate, nN, and microdamage front, cf D.j=α∫0∞cfj(t,c0;σ)nN(c0;σ)dc0 This expression concisely links continuum damage evolution to its underlying mesoscopic dynamics. This approach can be effective until a cascade of coalescence of microdamages leads to an evolution-induced catastrophe—a critical failure.
Solid Mechanics Modeling of Erosion Damage
Authors: Woytowitz PJ , Richman RH
Published: March 2009

The erosion process is studied from a solid mechanics perspective. This paper describes the analysis of multiple coincident particle impacts of an elastic steel sphere on an elastic-plastic copper target material. The analysis is performed using the DYNA2D nonlinear dynamic finite element code. The results of the DYNA2D analysis are compared against experimental results for the single impact case. Next, three methods of computing the damage induced by the impact process are studied; a strain-life approach using rainflow counting, the technique of cyclic plastic work, and a continuum damage mechanics based fatigue criterion. The damage predicted by each technique is presented and reviewed. Extensions of the procedures are discussed.
Use of an Optic Lever as a Short Gage Length Extensometer
Authors: Houser GM , Walrath DE
Published: March 2009

A short gage length extensometer, based on the principle of an optic lever, was designed and tested as a medium resolution, short gage-length displacement transducer. The goal was to develop a short gage-length extensometer as a potential replacement for foil resistance strain gages. The optic lever used step-index optical fibers to modulate reflected light as a function of target displacement. This provides the basis for a responsive displacement (strain) transducer that is small in size, insensitive to electrical noise, and resistant to elevated temperature and radiation levels. Transducer design was facilitated through use of an analytical model to predict performance. A prototype transducer was tested and compared to foil resistance strain gage results. The prototype demonstrated 25 microstrain resolution over a 10% strain range.
New Applications of the Interferometric Strain/Displacement Gage
Authors: Sharpe WN , Yuan B
Published: March 2009

The Interferometric Strain/Displacement Gage (ISDG) is an established laser-based technique that measures the relative displacement between two gage points on a specimen surface. The gage points are reflective markers illuminated with a low-power He-Ne laser to form interference patterns that are monitored with a computer-controlled system. Features of the technique are short gage length (50 – 300 μm) and no mechanical contact. Two new applications of the ISDG are described in this paper. The first is the measurement of strain on metal microspecimens that are 3 mm long with cross-sections typically 0.3 mm square. Details of the test procedure and results from 52 tests conducted as part of an ASTM-sponsored cross-comparison test are summarized. The second is strain measurement on 3.5 μm thick polysilicon film specimens; this capability has enabled measurement of the Young's Modulus and the tensile strength of this material which is used in microelectromechanical systems (MEMS).
Observation on the Growth Behavior of Small Surface Cracks Using Remote Measurement System
Authors: Nahm SH , Suh CM
Published: March 2009

A new experimental system which uses a remote measurement system (RMS) constructed by means of an image processing technique was applied to the observation of small surface fatigue crack behavior in 1Cr-1Mo-0.25V steel and type 304 stainless steel at room temperature as well as at elevated temperature. This system consists of a long distance focusing microscope, a CCD camera, a light source, a 3-axis controller, a personal computer and a data translation card. The resolution of this system is 1.1 μm. This system allows one to observe the surface crack length down to 30 μm. Using this system, the growth rates of small surface cracks on smooth specimens were studied in terms of stress intensity factor range and compared with those of long cracks.
Optical Measurement of Biaxial Strain in Thin Film Polymers
Authors: Rand JL , Grant DA
Published: March 2009

A non-contacting optical method for the measurement of strain simultaneously in two directions has been developed in the process of characterizing the behavior of thin film polymers. The thin film specimen geometry is a cylinder created by heat sealing two layers of the material together. The technique utilizes a random speckle pattern that is painted on the surface of the specimen. Images are captured by a CCD camera of a small portion of the painted region as the material creeps under load. A digital image correlation technique is used to analyze the movement of the speckle pattern over time. The resulting displacement field obtained from these images is then used to determine the strain on the surface of the specimen. This strain measurement technique has also been extended to the measurement of biaxial strains on the surface of thick sheets as well as thin films.
Quantitative Analysis of Extraneous Matter in Fabricated Ultra-High Molecular Weight Polyethylene (UHMWPE)
Authors: Fesmire RS , Asiala SP , Evans MA
Published: March 2009

The existence of extraneous particles in both extruded and compression molded ultra-high molecular weight polyethylene (UHMWPE) is a leading cause of scrap during the fabrication of orthopaedic implants from the material. ASTM Specification for Ultra-High-Molecular-Weight Polyethylene Powder and Fabricated Form for Surgical Implants (F 648-96) permits a given level of extraneous particles in both the resin and fabricated forms. However, material with particulate levels at the top end of the specification would result in an average of one to two particles open to the surface of each tibial or acetabular implant. Due to the application of UHMWPE as a wear surface in joint replacement surgeries, it is unacceptable for a product to have any particles open to the surface. As a result, most material would be rejected if it ran at the upper level of the specification. This research determined that the use of a volume counting method coupled with statistical process control tools and control parameters based on historical performance is superior to the current surface count analysis used in ASTM F 648 to determine the cleanliness of the fabricated material.
Fourier-Transform Infrared (FTIR) Oxidation Analysis of Ultra-High Molecular Weight Polyethylene (UHMWPE) Implants: Possible Contamination from Synovial Fluid and Serum
Authors: Sun DC , Halleck A , Schmidig G , Wang A , Stark C , Dumbleton JH
Published: March 2009

Oxygen-containing chemical species may cause an artificially high level of measured oxidation in the infrared (IR) analysis of clinically retrieved or hip wear simulator tested ultra-high molecular weight polyethylene (UHMWPE) implants. Esterified fatty acids from the synovial fluid or calf serum commonly used in the hip or knee wear simulators are the most likely source of contamination. No such interference is encountered in the IR analysis of shelf-aged UHMWPE components that have never been implanted. When the contamination is observed, an additional IR peak at 1740 cm-1 appears along with the IR peak at 1717 cm-1 commonly assigned to the ketone group. A two-step decontamination procedure, with components first washed ultrasonically in a deionized water bath followed by an ultrasonic washing in heptane, was used in the study to remove possible contamination. This procedure is similar to one reported by James et al. Change in oxidation index before and after the two-step washing varied from 30 to 58% in the articulating region from a depth of 0 to 200 μm. From these results, the effect of contamination is significant and therefore a two-step washing procedure prior to IR analysis to remove water-soluble and organic contaminants is recommended.
Analysis of Morphological Alteration Accompanying Post-Irradiation Aging in Montell 1900 Ultra-High Molecular Weight Polyethylene (UHMWPE)
Authors: Bellare A , Spector M , Cohen RE
Published: March 2009

For many years, ultra-high molecular weight polyethylene (UHMWPE) components of joint replacement prostheses have been sterilized with a 25 to 37 kilograys dose of gamma radiation in an air environment. Gamma radiation is known to cause chemical and morphological changes in polyethylene that continue to occur with both in vivo and shelf-life age. Generation of free radicals leading to predominantly crosslinking and chain scission (to a lesser extent) are immediate chemical effects. Slow oxidation of the free radicals contributes to further chain scission, thereby lowering the overall molecular weight of UHMWPE components with aging. Since lower molecular weight polyethylenes have a lower resistance to wear, oxidation-induced chain scission is believed to lower the wear resistance of UHMWPE components used in joint replacement prostheses.

We have studied mechanisms of morphological alterations in UHMWPE components (Montell 1900) that accompany radiation-induced chemical changes with shelf-life aging. Differential scanning calorimetry on aged and unirradiated Montell 1900 UHMWPE revealed that there was an increase in crystallinity in components of post-irradiation aged Montell 1900 UHMWPE, in agreement with previous studies. Small-angle X-ray scattering measurements on unirradiated Montell 1900 UHMWPE revealed that there was a low degree of morphological order. One-dimensional correlation functions obtained by Fourier transformation of the scattering curves were employed to characterize the morphology of Montell 1900. The long period or the most probable center-to-center distance between neighboring crystalline lamellae, was 940 ± 15 and 550 ± 15Å. In the case of post-irradiation aged Montell 1900 UHMWPE, a new long period of 480 ± 15 Å was present in addition to the original long period. The emergence of a new long period along with an increase in crystallinity showed that recrystallization with post-irradiation aging occurred by growth of new crystallites in the amorphous domains in-between crystallites rather than by thickening of original crystallites. Growth of new crystallites was attributed to oxidation in the amorphous domains that releases constraints on interlamellar tie molecules by chain scission, thereby allowing the chains to form new crystallites.
Tribological Properties of Extruded, Pressed, and Modified Ultra-High Molecular Weight Polyethylene (UHMWPE)—A Ring-on-Disc Screening Test
Authors: Huber J , Plitz W
Published: March 2009

The creep and wear behaviors of pressed ultra-high molecular weight polyethylene (UHMWPE), extruded UHMWPE, and modified UHMWPE were compared by means of testing the following materials: GUR 1150 pressed, GUR 1150 extruded, and GUR 1120 pressed with 0.1% Vitamin E. Using the ring-on-disc method, the wear and deformation volumes for 360 000 cycles and 1 million cycles were determined. A static universal testing device was used to determine the deformation behaviors of the several materials, while the testing time corresponded to that of the ring-on-disc tests.
Wear of Non-Articulating Surfaces in Modular Acetabular Cups
Authors: Shea JJ , Lambert RD , McLean TW
Published: March 2009

As a result of histological studies, there have been new developments in the field of modular acetabular cup design. Osteolysis has been isolated as one of the major causes of aseptic loosening of the femoral component in total hip arthroplasty (THA). Histological studies of retrieved tissue during revision THA have revealed a high content of polyethylene (PE) particles which are submicron in size in the surrounding tissue of the loose femoral component. The source of the polyethylene can be easily traced to the liner in the acetabular component. Great efforts have been made in reducing PE wear at the femoral head/liner interface through the use of ceramics, better CoCr polishing techniques, and improved processing of polyethylene. Until recently, however, not much attention has been given to the liner outside diameter/shell inside diameter interface, sometimes known as the “second articulating surface”. The first aspect of this paper provides background on various studies which examined metal shell/polyethylene liner interfaces of several commercially available acetabular components. Movement of the liner was confirmed and measured. Various types of surface abrasion were noted on the liners. The second aspect of this paper examines two modular adjunctive fixation methods for debris generation potential. Recommendations for design improvements are included.
Test Method for Fatigue of a Modular Posterior-Stabilized Tibial Component
Authors: Anthony ME , Cooper MB , Holbrook JA
Published: March 2009

Posterior-stabilized (P/S) total knee replacements are designed o replace the function of the knee joint in the absence of the posterior cruciate ligament. The most prevalent P/S tibial components are modular, consisting of a plastic tibial insert which is secured by the locking mechanism to a metallic tibial tray. While these tibial components offer the advantages of modularity including increased flexibility and decreased inventory, they must withstand loading that will be transferred to the tibial insert post, without excessive deformation of the post or disassociation of the tibial insert from the tibial tray. The objective of this study is to develop a test method to determine the fatigue integrity of a modular P/S tibial component under physiologic loading.

Modular P/S tibial components are subjected to a combined compressive and nteroposterior shear load transferred from the femoral component to the tibial insert post and the condylar surfaces. A test method was developed to reproduce this loading by placing a P/S implant at 30° of flexion and transferring load to the tibial component as would occur in vivo. By applying a 5 Hz, sinusoidal load in this manner for ten million cycles, the fatigue integrity of the modular component can be evaluated. Additional information may be gained by measuring the angular deformation of the tibial insert post and determining the static locking strength of the tibial construct after fatigue loading. Failure criteria for the modular component would be either disassociation of the tibial insert or gross deformation of the tibial insert post.
Test Method for Evaluating Motion between the Polymeric Articulating Surface and the Tibial Tray of Modular Total Knee Systems
Authors: Kirkpatrick LA
Published: March 2009

Anatomic loads that are exerted on the tibial component can result in forces which exert compressive, tensile, and shear stresses in the modular connection between the articular surface and the tibial tray. Stability, as well as strength of the onnection, are important to the long-term function of the implant. Consequently, new modular knee designs should be subjected to rigorous analysis and testing to evaluate the modular connection stability.

Component tolerances and locking mechanism design are important to the stability of the interlock. Stability of the interlock is important when evaluating the ability of the design to limit relative motion and the generation of material debris. A static testing technique has been utilized to quantify the amount of relative motion that may occur between the articulating surface and the tibial tray. The method applies a transverse load to the locking mechanism in the plane of the articular surface/tibial tray interface while relative displacement versus load information is collected. With sufficiently low forces, multiple loadings may be applied to the same components for statistical analysis. Tests with displacements ranging from 0.13 to 0.56 mm have shown standard deviation ranges of 0.6 percent to 8.6 percent.

A plot of the force versus displacement data is useful in the analysis of the locking mechanism performance. Regions of movement, or sliding, between the components are indicated by a relatively low slope in the curve. A relatively high slope will indicate regions of stiffness of the mechanism. The results may then be used to compare the performance of the specimens with clinically successful designs.
Influence of the Ball/Stem-Interface on the Load Bearing Capability of Modular Total Hip Endoprostheses
Authors: Richter HG , Willmann G , Wimmer M , Osthues FG
Published: March 2009

An extremely high level of mechanical reliability is required of total hip joint replacement systems. The reliability has to be proven in part by testing for resistance to static load using test tapers. There is evidence that the load bearing capability of the ball/stem-system is influenced by the surface structure of the taper. However, no systematic investigation is available in which this influence is studied in more detail. In the present study the surface structure of metal tapers is varied systematically in order to evaluate the influence of groove depth and pitch on the resistance to static load. Test tapers were produced from both a Titanium-alloy and a Cobalt-Chrome-alloy. The test results show that the burst strength increases with increasing “deformability” of the metal taper surface structure. A simple formula is put forward for estimating of the “deformability”.
Fatigue Integrity Test of a Modular Tibial Stem Extension
Authors: Cooper MB , Anthony ME , Salehi AB , Holbrook JA
Published: March 2009

With the frequent use of modular knee systems today, component integrity at the modular interface is often questioned. Many knee systems use modular stem extensions that attach to the tibial or femoral component. The use of these modular stems raise issues about the fatigue integrity of the construct, fretting of the modular connection, and modular attachment strength. These must be addressed through testing in order to validate the safety and efficacy of a product. Three test methods that can be used to investigate the fatigue integrity of the modular tibial tray and stem interface will be discussed. The three test methods discussed are the Cantilever Test, the Unsupported Stem Test, and the Partial Bone Support Test. Each of these test methods is compared and contrasted on their ability to mimic clinical conditions, ease of use, and ease of analysis. The test methods attempt to address several issues relevant to modular tibial stem extensions. The presentation of the test methods is meant to provide information on current stem extension testing in order to fuel the emergence of a standardized testing protocol.
Test Method Comparing Torsional Fatigue of Modular Acetabular Components
Authors: Lambert RD , McLean TW
Published: March 2009

The acetabular component is the focus of new testing methods dedicated to the development of improved total hip prostheses. Test methods had previously been developed to assess the performance of the femoral component in both the static and dynamic modes. These methods were designed in accordance with standards generated by such organizations as ASTM, ISO, and by research institutions. However, acetabular components were generally tested in the static mode to evaluate engagement strength and torsional resistance of the liner. While these tests are important and give a measure of the mechanical integrity of the device, they do not fully address clinical performance.

From retrieved components, it appears that a loose or failing locking mechanism allows torsional forces to transfer through the liner causing liner abrasion, burnishing, and in some cases degradation of the locking mechanism itself. Success of the device may be further compromised by the biological response to debris created by micromotion between the mating components. This study was undertaken to assess the rotational stability of the acetabular liner in a dynamic mode. Several acetabular component designs were torsionally fatigued at ±2.5 Nm at a rate of 3–5 hertz for 10 million cycles. The test components exhibited liner micromotion ranging from 0.059° to 2.89°, and damage to the nonarticulating interface and locking mechanism of tested liners was visually identified.

This method for dynamic testing of acetabular components provides an understanding of the performance of the device under torsional fatigue conditions. It demonstrates the importance of a rotationally stable liner, as damage to the nonarticulating interface of tested liners is similar to damage reported in the literature for retrieved components. Further, it determines the endurance of the liner locking mechanism when subjected to dynamic torsional forces.
The Importance of Fatigue Loading When Assessing Liner/Shell Distraction Resistance and Congruency for Modular Acetabular Components
Authors: Fosco DR , Buchanan DJ
Published: March 2009

Modular acetabular components are now widely used in total hip arthroplasty (THA). A primary performance requirement for these two-piece acetabular cup designs is to maintain in vivo locking integrity between the polyethylene liner and the metal acetabular shell. Standards have been proposed that include the measurement of static push-out and lever-out forces to evaluate the mechanical integrity between the shell and liner. However, there are many variables that may affect in vivo performance. A modification of the proposed test standards is recommended to include moderate fatigue cycling, since fatigue has a demonstrated effect on distraction resistance and the potential for in vivo disassembly.
Fundamentals of Metals Ignition in Oxygen
Authors: Wilson DB , Stoltzfus JM
Published: March 2009

Ignition is associated with the thermal energy input into the system occurring at a rate faster than thermal energy is being lost to the surroundings. The solution of an idealized model for ignition at a plane metal surface characterizes the material in terms of the property thermal inertia, kpc. The thermal inertia for six metals Al, Cu, Fe, Mg, Ni and Ti, at their ignition temperatures is compared to the relative burn resistance of the metals in terms of BRmp, BRbp threshold pressure, resistance to ignition by particle impact and frictional heating ignition, pv. Thermal inertia is in agreement and appears to be suitable property for characterizing metals ignition. In addition, considerations for relaxing the assumptions associated with the idealized model are described and thermal inertia is still a valid characterization for the material.

The five measures associated with burning do not describe the dynamic system at ignition, nor is the build-up of a condensed product layer addressed by either the ideal model or relaxed model. The effect of this product layer is qualitatively discussed in terms of a Van Heerden diagram for the system. The mechanisms for providing sufficient circulation within the product layer and their representation in terms of dimensionless groups is described. The need for property data and mixing rules (for alloy properties) is pointed out.
Ignitibility in Air, Gaseous Oxygen and Oxygen-Enriched Environments of Polymers Used in Breathing-Air Devices
Authors: Hirsch D , Hshieh F-Y , Beeson H , Bryan C
Published: March 2009

Autoignition temperature and mechanical impact tests were conducted on three rigid plastics and five elastomers in various oxygen concentrations. For Nitrile, Viton®, and Zytel®, increasing oxygen concentrations resulted in decreasing autoignition temperatures (AIT). The effect of oxygen concentration on the AIT was minimal for PTFE, Kel-F® 81, and Silicone. For the entire range of pressures evaluated (3.4 to 10.3 MPa), increasing pressures resulted in increased AIT's for the halogenated rigid plastics and for Nitrile Rubber. The pressure had a negligible effect on the AIT of Viton and Silicone Rubber for the entire range of oxygen concentrations. Materials ranking in decreasing order of autoignition temperatures remained unchanged within the oxygen concentrations and total pressures used. For all materials, increasing the test pressures from ambient to 20.7 MPa resulted in decreasing mechanical impact energy thresholds. With the exception of EPDM and Neoprene, this trend continued for all materials up to 34.5 MPa. The energy threshold for EPDM increased slightly with increasing pressures from 20.7 to 34.5 MPa, while for Neoprene, the energy threshold increased with increasing pressures from 20.7 to 27.6 MPa. Under most conditions, the rigid plastics had better performance than the elastomers in mechanical impact tests. Under conditions of higher impact energies, Nitrile Rubber was less reactive than Viton Under conditions of higher impact energies, Nitrile Rubber was less reactive than Viton and Silicone. The data indicates that for an adequate ignition-risk assessment, the mechanical impact results should be used in conjunction with other test results to simulate other possible operational failure conditions.
Field and Laboratory Evaluation of Superpave Level One Mix Design in California
Authors: Shatnawi SR , Lancaster F
Published: March 2009

This paper presents an evaluation of the volumetric (Level One) Superpave mix design procedure. The evaluation consisted of constructing field test sections in January 1996 and conducting various laboratory performance tests. The performance testing included repetitive simple shear test at constant height (RSST-CH), frequency sweep tests, repetitive direct tension test (RDTT), and Laboratoire Cenral des Ponts et Chaussées (LCPC) wheel track testing. This paper recognizes the importance of conducting performance tests to gain confidence in the volumetric mix design. It was concluded that all mixes placed on the project would be anticipated to perform adequately. Field performance has so far supported the laboratory findings. Further evaluation is recommended because this study addressed only one aggregate source, two gradations and two binder grades.
Criteria for Water Penetration Testing
Authors: Choi ECC
Published: March 2009

A major function of the envelope of a building is to protect the interior from weather and to provide a comfortable environment inside the building. Recently, there have been significant advancements in construction techniques and material science relating to building envelope construction. The information (the amount of wind and rain) required for the weathertightness design and testing of a building envelope is not as developed. There is no rational approach to obtain such criteria and the values used in the current practices involve significant uncertainties.

This paper proposes the use of a computational fluid dynamics (CFD) approach to obtain the intensity of wind-driven rain which impinges a building's faces. This wind-driven rain intensity and the associated wind pressure are estimated systematically using CFD method and extreme-statistics analysis. Results of the analysis, which give the criteria for water penetration testing for a building envelope, are obtained as a function of the return period. This method is applied to a sample rectangular building situated in Sydney, Australia, and finds that the testing pressure is significantly higher than the value currently specified in ASTM E331-86.
The Application of Local Weather Data to the Simulation of Wind-Driven Rain
Authors: Galitz CL , Whitlock AR
Published: March 2009

Due to the mismanagement of penetrating water, many masonry walls deteriorate long before the end of their intended life-span. The amount of penetrating water is dependent upon the permeability characteristics of the facade and the severity of wind-driven rain. Therefore, it would be useful to designers to know more precisely the environment in which their structures will be subjected, and also for investigators to have accurate means for assessing the performance of structures through the use of non-destructive water testing.

Current standards include methods for water test chamber, spray rack, and calibrated nozzle testing. Typically, these methods differ in water flow rates, impact velocity of water, air pressure differential and duration. These tests historically have not allowed the variation of testing parameters to compensate for realistic site conditions. The use of appropriate weather data can greatly improve the relevance of such testing.

This paper explores the conversion of published weather data to testing parameters which can be used to simulate weather conditions. Included is an analysis of the dynamics of rainfall and its impact on surfaces of various orientation. The analysis is based on the effects of wind speed, direction, surface orientation, and rainfall intensity. Also discussed are the appropriateness of water chamber, spray rack, and spray nozzle testing, with regards to accurate rainfall simulation.
Solution to Moisture, Mold and Mildew Problems in a Central Florida Hotel
Authors: Delaney RL , Goldsmith CB
Published: March 2009

A 12-story resort hotel in central Florida, built in the late 1980's, has an exterior insulation and finish system (EIFS) facade on steel studs. Interior walls have vinyl wall coverings. There were mildew problems in guest rooms. There were several contributing factors: water in stud cavities from condensation on chilled water lines; leaks into stud cavities from deteriorated exterior sealants; cracks in the EIFS; and condensation at the back of drywall and vinyl during summer. Summer temperature profiles were calculated for the exterior wall assembly based on modified ASHRAE methodology using published local temperature and humidity data.Solutions are preceding.
Lessons Learned from Investigation of Water Leakage Through Precast and Cast-In-Place Concrete Facades
Authors: Chin IR , Gerns EA
Published: March 2009

Rain water is expected to penetrate through joints in building facades. Consequently, a secondary line of defense is recommended in facades that contain frequent joints to collect, divert, and drain the water to the exterior. Concrete facades have historically been designed without this secondary line of defense because concrete walls have very few joints and it was believed that water would not penetrate concrete. However, due to shrinkage cracks in concrete, improper design, sealant joint failure, wall profile, and condensation water leakage has occurred through concrete facades. This water leakage may be controlled and be prevented from leaking into the interior of the building by a secondary line of defense. Details of a secondary line of defense against water leakage in concrete facades are presented in this paper.
Leakage at Interface Between Multiple Facade Components
Authors: Zwayer GL , Cook DF , Crowe JP
Published: March 2009

Buildings clad with multiple facade components perform well when they are properly designed and constructed. When water leakage does occur, typically it happens at the interface of the different components. The authors have performed numerous field investigations regarding water leakage of buildings and will discuss, through case studies, reasons for the leakage at the interface and examine how it could have been avoided. Additionally, design principles will be discussed regarding better water resistance performance of these interfaces. Problems with water leakage can be avoided if designers, manufacturers and installers perform a thorough study of each material and it's interface with adjacent materials. Through the cooperation of these parties in the development of a complete understanding of each component and its interface with the other components, proper design and detailing, pre-construction meetings with all parties, pre-construction mock-up testing, on-site field observation, and quality control testing, water tight buildings can be erected.
Water Leakage Through Sloped Glazing and Skylights: Case Studies
Authors: Scheffler MJ , Sass CJ
Published: March 2009

This paper will describe two case studies of water leakage through sloped glazing and skylights. The authors have investigated and developed construction documents for the repair of numerous buildings with sloped glazing and skylights. Construction types examined include metal and glass systems.
Critical Review of Curtain Wall Mockup Testing for Water Penetration
Authors: Kaskel BS , Scheffler MJ , Chin IR
Published: March 2009

Current industry standard procedures exist for testing of curtain wall mockups for new construction. This paper will critically review how the standard procedures can provide an assessment of the capabilities of the curtain wall to control water and prevent leakage. The review is based on numerous mockup tests that the authors have prescribed and have reviewed during the course of their investigations of water leakage in many types of curtain walls, and during their peer review of the design of the curtain wall on new buildings. This review has revealed that additional test procedures and modifications to the standard test procedures for mockup testing will greatly aid in the value of the mockup towards assuring a leak-free curtain wall.
Evaluation of Water Resistance Testing Problems for Installed Facade Systems
Authors: Smith WD , Beers PE
Published: March 2009

The use of hose testing as a field check for water penetration of installed ssemblies has gained popularity throughout the construction industry because of its simplicity. This paper will detail the use of hose testing methods, variations of the procedure, intended application, and limitations. This information will be compared to ASTM E 1105 “Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Curtain Walls, and Doors by Uniform of Cyclic Static Air Pressure Difference.” A comparison of test results will allow the reader to evaluate the accuracy of hose testing procedures and to determine whether it is a reliable method of evaluating product performance. This paper will also detail variations in the use of ASTM E 1105 including application of the test procedure to wall assemblies of masonry, EIFS, and others.
Building Exterior Wall Water Infiltration Control Using Quality Assurance Programs
Authors: Johnson PG
Published: March 2009

Building exterior walls are complex construction systems with criteria hich vary according to project, design, and construction delivery systems. They are by nature subject to performance problems which may include water infiltration. A properly implemented Quality Assurance Program which begins during the Design phase of the project and follows through final acceptance of the construction offers an opportunity to reduce or eliminate these problems. These programs should involve all parties of the Design/Construct process since their success is highly dependent upon planning and communication. The successful implementation of a quality assurance program can result in higher performance of the wall system, better conformance to project schedule and budget requirements, and reduced likelihood of conflict including litigation. While there is a cost to implement such a program, the cost to benefit ratio is favorable and they are particularly beneficial for complex or high risk projects.
Using Modified ASTM E 1105 to Identify Leakage Sources in Building Wall Systems
Authors: Krogstad NV , Johnson DK , Weber RA
Published: March 2009

The paper reviews an evaluation procedure for addressing ater leakage problems. The procedure includes water leakage testing along with interviewing the building occupants, reviewing drawings and specifications, surveying the building components, and performing exploratory openings. The water leakage testing uses a modified version of ASTM E1105. This test utilizes a spray grid to apply water to the exterior surface of the wall. The primary modification from the ASTM specification is the longer time durations used on absorptive surfaces such as masonry. The test can be used on virtually any building material, including masonry, precast concrete, EIFS, metal panels and aluminum and glass curtain walls. Areas can be isolated by systematic positioning of the spray rack or by careful masking of the wall components or both. These procedures can be effective in identifying sources of water leakage problems. After repairs are performed, the test can be used to evaluate the effectiveness of such repairs. The test can also be included in a preconstruction testing program to locate potential leakage sources in a mock-up assembly. The paper outlines critical steps in using the procedure to reliably isolate the sources for water entry into buildings.
The Influence of Waterproof Coating on the Hygrothermal Performance of a Brick Facade Wall System
Authors: Salonvaara MH , Karagiozis AN
Published: March 2009

The effect of a waterproof coating on the long-term hygrothermal performance of a high-rise wall was investigated by combining experimental and numerical approaches. The water vapor permeances (WVP) of the waterproof coating on the brick and mortar masonry were experimentally determined as a function of relative humidity. These performance characteristics for the (WVP) of the waterproof coatings applied on the brick and mortar surface layers were included in the LATENITE version 1.2 hygrothermal model. A series of 1-D and 2-D simulations were performed studying the effects of waterproof coatings on a selected wall system. Additional simulations studied the effect of the existence of cracks. Results indicate that brick-mortar interaction as a system must be included in analysis of the hygrothermal performance of the waterproof coating. Simplifications to 1-D can lead to erroneous results. Rain penetration can be far more important than ambient surface diffusion fluxes and must be included in all hygrothermal analysis. The waterproof coating reduced the yearly average heat flux by 3 % for the city of Vancouver by reducing the latent heat effects of absorbed moisture from wind-driven rain.