bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine Aggregate Angularity: Conventional and Unconventional Approach
Authors: Chowdhury A , Button JW 
Published: April 2008

Superpave adopted ASTM Test Methods for Uncompacted Void Content of Fine Aggregate (C1252 Method A) to determine fine aggregate angularity (FAA). This is an indirect method for estimating fine aggregate angularity and texture. The FAA test is based on the assumption that more fractured faces will result in higher void content in the loosely compacted sample; however, this is not always true. The paving and aggregate industries have found that cubical shaped particles, even with 100 percent fractured faces, may not meet the FAA requirement for high-volume traffic. State agencies are concerned that local materials previously considered acceptable and which have provided good field performance, now cannot meet the Superpave requirements.
A study was undertaken to evaluate the ability of current Superpave FAA method to measure fine aggregate angularity, to determine if it can distinguish between good performing and poor performing aggregates, and compare FAA test results with other measures of particle angularity. Fine aggregates from different regions of USA were collected along with their performance history. Those aggregates were tested with ASTM C 1252, Method A, ASTM Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions (D 3080), Compacted Aggregate Resistance (CAR) test, visual inspection, and surface area analysis. SHRP-LTPP database was also used to find any correlation between FAA and field rutting.
Wind Load Design and Performance Testing of Exterior Walls: Current Standards and Future Considerations
Authors: Prevatt DO 
Published: April 2008

Although the main structural systems of fully engineered buildings perform adequately during extreme wind events, costly losses happen to buildings once the components of the exterior walls and claddings fail. In response to these failures, new design methods have been developed that result in higher design wind loads applied to components, and prescribe additional tests on cladding to determine the structural resistance of exterior wall elements.
This paper discusses some recent changes to the wind load design provisions of the American Society of Civil Engineers (ASCE) Standard, ASCE 7-98, that apply to exterior building walls. ASCE 7-98 includes new concepts for cladding design that consider impact resistance and topographic effects on overall wind loads. Examples compare the wind design loads obtained using ASCE 7-98 with loads obtained with 7–95 and 7–88 for regular-shaped buildings. The changes may eventually influence the exterior wall design throughout the U.S. because the recently published International Building Code (IBC-2000), formed under a partnership agreement of the three existing model building codes, has adopted ASCE 7-98.
Improving the wind performance of exterior walls depends equally on improved wind design codes as well as on improved test procedures that determine the structural capacity of installed cladding systems. The current state-of-the-art in full-scale testing of building components is discussed, and a summary of current full-scale tests is presented. The author proposes that the current fragmented design process for different cladding materials and the reliance on materials-specific performance tests is too complex and needs to be streamlined in order to improve the overall performance of building envelope systems.
The Importance of Studying Exemplars when Designing Stone Facades
Authors: McDonald WH , Lewis MD 
Published: April 2008

The facades of contemporary buildings clad with dimension stone buildings all too often perform poorly, compared with the walls of much older buildings; despite they're being developed with computers and assembled using space-age parts. At the same time, structures using centuries-old methods often serve their occupants better than buildings many decades younger. Many facades built recently as architects' masterpieces now need major restoration simply to continue service. Their leaks, drafts, and dilapidated states shorten their useful lives.
Problems occur in new facades because their designers rarely understand the complex natural forces acting upon them. Earlier builders observed the performance of successful buildings, exemplars, and borrowed from them to suit their needs. In this way, the solid wall of antiquity evolved into a high architectural and structural art that has endured for centuries. The solid wall changed over the last hundred years to become cladding covering a separate structural skeleton. Although this concept offered aesthetic freedom and factory-expediency, a comparatively small portion of the last century's building inventory remains as healthy exemplars. Few of them have escaped major restoration efforts. And in the past fifty years, new material combinations spawned unprecedented problems. Leaks progressively attacked their concealed supports, inevitably damaging cladding and spiraling damage claims.
Contemporary builders repeat mistakes, partly because structural theory insists this procedure works, even as similarly constructed buildings fail. Poorly-performing exemplars are duplicated because their poor performance is ignored. Meanwhile, many existing older buildings, time-proven examples of sensible construction procedures and systems that perform well, continue to serve. In engineering's evolution from an empirical process to a theoretical one, stone façade construction has changed dramatically. Unfortunately, contemporary builders often ignore exemplars in a continuing but failed effort to fashion new images. To reduce expensive failures, successful builders study past performance. This paper examines the melding of empirical wisdom with new philosophies in producing useful buildings.
A Verification Method for Prevention of Penetration of Moisture to Prove Compliance of Performance-Based Building Codes
Authors: Benge C 
Published: April 2008

The New Zealand building code is performance-based, and to facilitate proof of compliance the Building Industry Authority publishes Approved Documents that provide tests or calculation methods (Verification Methods) and “cookbook” solutions (Acceptable Solutions).
Currently the Acceptable Solution for the prevention of penetration of moisture into a building that will cause undue dampness or damage to the building deals only with generic materials such as timber weather boards, brick veneer and stucco on light timber framing.
The Verification Method contains test methods to be carried out in a laboratory. Not only can such tests be costly, but they may also not take account of site conditions or of the protection provided by the layout and orientation of a building.
This paper will examine the possibility of an additional Verification Method that will show compliance with the performance based building code by dealing with the adequacy of the building envelope in terms of such issues as its materials and systems, the joints within and with other claddings, any secondary defense methods, disposal of moisture that does penetrate, and exposure and durability considerations.
It is hoped that the result of this and further studies will be a Verification Method for the building envelope useful for manufacturers to predict that their product will comply with the code and for designers who are dealing with unique situations to prove compliance without costly testing.
Influence of Preload in Flexibility Testing of Native and Instrumented Lumbar Spine Specimens
Authors: Linke B , Meyer G , Knöller S , Schneider E 
Published: April 2008

In-vitro investigations on spine specimens are usually performed to evaluate the biomechanical behavior of the native spine, or to determine the stabilizing effects of different types of implants. These investigations are currently performed by the application of pure moments in the anatomic directions. The inclusion of an additional preload is heavily discussed, but seldom used in the experiments. Investigators often mention that different preloads have an influence on the results, but a detailed analysis of the influence on specific outcome parameters is still missing. The aim of this study was to show the effects of preload on the load-displacement behavior of spine specimens and to give basic data upon which investigators of future studies may decide on the necessity of its inclusion, depending on their specific question. A six degree-of-freedom loading device has been developed and was used to load the specimens. It has a parallel architecture and is equipped with a hybrid position/force controller. Sixteen human lumbar spine specimens L1-L3 were investigated. The spines were tested native and in two stabilized corpectomy situations. An anterior stabilization with VentroFix and SynEx was used with and without posterior USS fixation. Compressive preloads of ON - 400N were applied and the flexibility tests carried out. The orientation of the preload was changing in accordance to the movement of the specimen.
A general reduction of the range of motion (ROM) of up to 40% due to 400 N of preload was observed. It could be shown, that this is not a general stiffening effect in the case of a strong sigmoid shape of the hysteresis curve. Whenever the low-stiffness (LS) is considerably lower than the high-stiffness (HS), HS is not affected by preload, but LS is strongly increased (50– 80% in native case). With increasing rigidity of additional instrumentation the stiffening effect is reduced on LS and increased on HS. The stiffness-ratio (SR = HS/LS) is reduced to about 50% due to 400 N preload in the native case. If implants are evaluated by an instrumented-to-native (I/N) comparison, the effect of preload on the I/N ratio of the characteristic parameters is only minimal and specific to the instrumentation used.
Characterization of Sandvik Bioline High-N — A Comparison of Standard Grades F1314 and F1586
Authors: Haraldsson C , Cowen S 
Published: April 2008

ASTM standard grades for surgical implants F1314 and F1586 are both N-strengthened austenitic stainless steels with high resistance to pitting corrosion. The latter is generally used in Europe while the former is preferred in the United States. In the present study, Sandvik grade Bioline High-N, conforming to ASTM F1586, has been characterized with respect to microstructure, mechanical properties, corrosion resistance and inclusion content and compared with ASTM F1314-material.
In the present comparison it has been shown that Bioline High-N3 compared to ASTM F1314 material has similar or slightly superior mechanical properties, pitting corrosion resistance and nonmetallic inclusion content. All these properties are of critical importance for medical implant material.
Fatigue Behavior and In-Vitro Biocompatibility of the Ni-Free Austenitic High-Nitrogen Steel X13CrMnMoN18-14-3
Authors: Tikhovski I , Brauer H , Mölders M , Wiemann M , Bingmann D , Fischer A 
Published: April 2008

Austenitic stainless steels generally have a favorable combination of strength and ductility as well as a sufficient resistance against corrosion. This and the reported biocompatibility lead to the use of 304- and later 316 L-type steels in medical applications. Especially in orthopedics these steels were applied as implants for e.g. fracture fixation as bone plates, intermedullary nails, and screws. But these steels contain a high amount of Ni, which was attributed to cause Ni-allergies for an growing amount of patients. Thus, alternatives were needed and — beside the already known CoCrMo-alloys — implants of Ti and its alloys emerged increasingly into the medical market. The aim of this paper is to introduce a new austenitic Ni-free CrMnMo-steel X13CrMnMoN18-14-3 (Material No.: 1.4452, brand name: P2000), which makes use of about 1 % N in order to gain a combination of high strength, high ductility, and a superior corrosion resistance.
In a first step the cyclic fatigue behavior in air and in Ringer solution in the solution annealed state is investigated. This is accompanied by electrochemical testing in Ringer solution as well as in-vitro cytotoxicity tests against MC3T3 cells in bovine serum.
The tests revealed that the solution annealed X13CrMnMoN18-14-3 at 5 Hz has an 50 % endurance limit of 346 MPa in air and of 302 MPa in Ringer solution, which is markedly higher compared to solution annealed CrNiMo-steels. In addition it was found that the CrMnMoN-steel shows no distinct susceptibility to stress-corrosion cracking in the entire region of finite life between stress amplitudes of 400 to 550 MPa. The pitting potential in Ringer solution was measured to be 1.1 V, which is in the range of common Ni-containing high-Nitrogen steels as well as of CoCr20Mo6 alloys. No reduction of MC3T3 cell adhesion could be observed.
Thus, the Ni-free CrMnMoN-steels might be a promising alternative to the CrNiMo- steels in medical applications.
An Examination of Interactions Between Various Dispersants and Other Surfactants in Wettable Powder Formulations
Authors: Butler BJ , Miller DJ , Sowa C , Zerrer R 
Published: April 2008

The purpose of this study was to identify combinations of dispersants and wetting agents that may show broad utility in dry flowable formulations. The study tested four types of dispersants in combination with six types of wetting agents. Wettable powder formulations using four different active ingredients were made with either kaolin clay or silica as a diluent. Each test formulation was evaluated for suspensibility at 1 and 2 hours, with promising surfactant and diluent combinations being chosen based on maximum suspensibility as a function of time. Surface tension data for the surfactant combinations are also presented.
The study demonstrated that diluent selection is important and influences the surfactant combination needed for adequate suspensibility. The study also revealed that certain combinations of surfactants show broad functionality. There was considerable variability in terms of surfactant requirements for adequate suspensibility as a function of the active ingredient, with some actives showing suitable suspensibility with a wide range or very narrow set of surfactant combinations.
On the Mechanism of Irradiation Embrittlement Enhancement in Reactor Pressure Vessel Steels at High Neutron Fluences
Authors: Pechenkin VA , Konobeev YV , Stepanov IA , Nikolaev YA 
Published: April 2008

The DBTT shift in irradiated VVER pressure vessel steels is represented by standard guidelines with a power law dependence on fast neutron fluence multiplied by a material constant. However, from recent data on surveillance specimens for several units of VVER-440, an irradiation embrittlement enhancement has been observed at neutron fluences above (2–3)×1020 n/cm2 (E&gt;0.5 MeV) with a significant deviation from the standard guideline. This suggests an additional mechanism of irradiation embrittlement at high fluences.
In the present work it was supposed that such a mechanism could be intergranular embrittlement caused by grain boundary phosphorus segregation. A threshold dose was used that accounts for intergranular embrittlement, that occurs after sufficient phosphorus segregation, when the critical stress for intergranular fracture falls below that for cleavage fracture. The modeling of phosphorus accumulation on grain boundaries is performed taking into account the radiation-enhanced phosphorus diffusion by both vacancy and interstitial mechanisms, the radiation-induced segregation in the matrix near grain boundaries, and the Gibbsian adsorption on grain boundaries. Predictions of such a composite model are in agreement with surveillance data for VVER-440.
The Modeling of Radiation-Induced Phosphorus Segregation at Point Defect Sinks in Dilute Fe-P Alloys
Authors: Stepanov IA , Pechenkin VA , Konobeev YV 
Published: April 2008

Both the intergranular and intragranular segregation of phosphorus may significantly contribute to irradiation embrittlement of reactor pressure vessel steels. The modeling of phosphorus radiation-induced segregation at cylindrical (dislocations), spherical (precipitates and voids) and flat (sample surfaces, grain boundaries) point defect sinks has been carried out in order to compare the kinetics and extent of segregation at various point defect sinks. Dilute Fe-P alloys relevant to model and VVER-440 pressure vessel steels were considered.
It is shown that the time to reach steady state phosphorus concentration near dislocation or precipitate is much less than that near grain boundary. Although the steady state phosphorus concentration near dislocations or precipitates is much less than that near grain boundary, a “fast” phosphorus segregation at these sinks may lead to decreasing the free phosphorus content in the matrix and to reducing its subsequent accumulation on grain boundaries at high densities of internal sinks. A more significant effect on the kinetics of grain boundary phosphorus segregation could be caused by the contribution of precipitates to point defect sink strength.
Role of Variable Amplitude Fatigue Standards in Improving Structural Integrity
Authors: Hopkins SW , Mitchell MR , Ménigault J 
Published: April 2008

Fatigue failures of structural components continue to be a serious concern to the well-being and economics of our worldwide society because the majority of all such components fail by this mechanism. If some of these failures could be prevented through better design with our understanding of how materials behave, it would have a major impact on the economics of society.
American Society for Testing and Materials International (ASTM) Committee E08 on Fatigue and Fracture, International Organization for Standardization, Technical Committee 164, Subcommittee 5 (ISO/TC164/SC5) on Fatigue Testing of Metallic Materials and other relevant committees interested in the fatigue phenomena are involved in developing standards for testing and analysis under variable amplitude loading. Currently no variable amplitude fatigue testing standards exist. The organizational structures of some committees are provided along with examples of variable amplitude fatigue failures. There is some interaction between ASTM, European Structural Integrity Society (ESIS), and ISO, and it is hoped that additional interaction will occur so that all of the vast knowledge on fatigue from around the world may be focused to develop standards that will benefit everyone.
To demonstrate the need for such international standards, several examples of variable amplitude-type failures are presented and discussed. As a result of such failures, there is an obvious need to translate the constant amplitude and variable amplitude laboratory test data into the design of real structures.
The F/A-18E/F Full-Scale Static and Fatigue Test Programs — An Overview
Authors: Sullentrup MG 
Published: April 2008

The structural certification of F/A-18E/F airframe included fullscale fatigue and static test programs. This paper outlines the test programs, discusses test objectives, discusses test results, highlights some significant advancements in the state-of-the-art developed to support this test program, and offers recommendations for future full-scale certification test programs.
The method used to correlate static test measured strains to finite element model predictions is discussed. The method used to certify redesigned structural components without the benefit of a full-duration fatigue test is discussed. Innovations involving real-time data monitoring, rapid post-test analysis of results, characterization of measured endpoint strains during fatigue cycling, and comparison of block-to-block measured strain response are discussed.
There were many lessons learned during these test programs. These are summarized and discussed. Recommendations for future full-scale certification test programs are also discussed.
Crack Initiation at a Notch under Constant and Selected Variable Amplitude Loading Conditions
Authors: Gérard N , Leroy R , Girard O , Ranganathan N 
Published: April 2008

In a previous study, we showed that crack initiation life at a notch tip can be modeled as the micro crack propagation life from an initial microstructural defect up to a crack size of about 500 μm. This model is based upon the assumption that short cracks at a notch propagate without any significant closure effects. In our present experimental study, the results of fatigue tests to verify this hypothesis are presented and discussed.
The fatigue tests were conducted in ambient air on single edge notched specimens with a theoretical stress concentration factor of 3.14 on thin sheets of 1.2 mm thick Aluminum alloy 2024 T351. The test conditions studied are: constant amplitude tests at stress ratios of 0.1, 0.3, and 0.5 and variable amplitude tests using an extract from the TWIST spectrum. The tests were carried out at a nominal frequency of 10 Hz. At selected intervals, micro crack advance (if any) was determined using replicas. The measurements were made at the maximum stress for constant amplitude tests and at a chosen positive stress for variable amplitude tests (avoiding any overload). The smallest crack size detected is about 10 μm.
Calculation of Stress Intensity Factors for Cracks in Structural and Mechanical Components Subjected to Complex Stress Fields
Authors: Wu Z , Glinka G , Jakubczak H , Nilsson L 
Published: April 2008

One of the difficulties in using fracture mechanics is in determining stress intensity factors of cracked structural and mechanical components. The cracks are often subjected to complex stress fields induced by external loads and residual stresses resulting from the surface treatment. Both stress fields are characterized by non-uniform distributions, and handbook stress intensity factor solutions are seldom available in such cases. The method presented below is based on the generalized weight function technique enabling the stress intensity factors to be calculated for any Mode I loading applied to a planar semi-elliptical surface crack. The stress intensity factor can be determined at any point on the crack tip contour by using the general weight function. The calculation is carried out by integrating the product of the stress field and the weight function over the crack area.
Several examples of point-load weight functions and resulting stress intensity factors are presented in the paper. The method is particularly suitable for modeling fatigue crack growth in the presence of complex stress fields.
Periodic Overloads in the Near Threshold Regime
Authors: Tabernig B , Pippan R , Foulquier J , Rapaport A , Sereni S 
Published: April 2008

The effect of periodic overloads on the crack propagation behavior in the near threshold regime of long cracks and physically (extrinsically) short cracks is investigated. A 20 Vol. % SiC particle reinforced 359 cast aluminum alloy and a 17 Vol. % SiC particle reinforced 2129 aluminum alloy are examined. In the Paris regime the two alloys exhibit a different behavior. In the 2124 reinforced alloy a reduction of the mean crack propagation rate, which is typical for ductile metals, is observed. On the other hand the mean crack propagation rate accelerates in the 359 reinforced cast alloy, which is caused by generation of micro-cracks during the overload.
In the near threshold regime and at smaller stress intensity ranges in the physical short crack regime the behavior of both alloys is very similar. The effective threshold is not affected by the overload, i.e., if the constant amplitudes are smaller than the effective threshold they do not contribute to crack propagation. If both, the constant amplitudes and the overload amplitudes contribute to crack propagation, the build up of crack closure is affected by the load history.