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In the present paper, generalized Paris and Wohler equations are derived according to dimensional analysis and incomplete similarity concepts. They provide a rational interpretation to a majority of empirical power-law criteria used in fatigue. In particular, they are able to model the effects of the grain size, of the initial crack length, as well as of the size-scale of the tested specimen on the crack growth rate and on the fatigue life. Regarding the important issue of crack-size dependencies of the Paris’ coefficient C and of the fatigue threshold, an independent approach, based on the application of fractal geometry concepts, is proposed to model such an anomalous behavior. As a straightforward consequence of the fractality of the crack surfaces, the fractal approach provides scaling laws fully consistent with those determined from dimensional analysis arguments. The proposed scaling laws are applied to relevant experimental data related to the crack-size and to the structural-size dependencies of the fatigue parameters in metals and in quasi-brittle materials. Finally, paying attention to the limit points defining the range of validity of the classical Wohler and Paris power-law relationships, correlations between the so-called cyclic or fatigue properties are proposed, giving a rational explanation to the experimental trends observed in the material property charts.

This paper investigates the role of the vapor barrier in exterior wood-frame stucco walls with the help of a two-dimensional hygrothermal simulation tool, hygIRC-2D. For this purpose, the wall is subjected to the exterior weather conditions of six different North American geographic locations and three different interior climatic conditions. Seven different vapor diffusion strategies, generated by varying the water vapor permeance of the vapor barrier, installed outboard of the interior finish, have been studied to generate critical understanding on the role of vapor barrier in the wood-frame stucco walls. The outputs from the simulations have been analyzed with the help of a novel moisture response indicator called RHT index. Simulation results indicate that the vapor transmission characteristics of the vapor barrier, in terms of water vapor permeance, play a very important role in the overall moisture response of the wood-frame stucco wall. A very high or low vapor permeance of the vapor barrier does not produce the optimum moisture management strategy for the wood-frame stucco wall. Moreover, simulation results indicate that the removal of vapor barrier from the wall system can result in a heightened moisture response and a considerable accumulation of moisture in the interior gypsum board that may lead to severe consequences in particular, the premature deterioration of the interior facing gypsum board. It has also been observed from the simulation outputs that the optimum vapor diffusion strategy, that of limiting the vapor permeance of the vapor barrier, is not a function of interior climatic conditions considered in this study. It is hoped that the results reported in this paper will shed some light on a number of concerns raised in recent years on the role of vapor barrier in wood-frame stucco wall construction.

The ability of a wall assembly to manage rainwater and control rain penetration depends on the assembly configuration, including interface details for penetrations, and on the rain loads to which the wall is subjected. There are a variety different protocols for evaluating the ability wall systems to resist water intrusion. Generally they involve spraying varying amounts of water while maintaining a pressure difference across the specimen. Across the conterminous United States hourly weather data for extended periods (climatic data) is available for many locations. From this climatic data estimates of wind-driven rain loads can be determined. We answer the question of how often these combinations of rainfall intensities and pressure are likely to present a problem with respect to moisture management of the assembly and how often these are likely to occur over the expected life of the wall assembly. Climate information related to rainfall and wind-driven rain for Boston, Miami, Minneapolis, Philadelphia, and Seattle are provided. A methodology for generating rates of water spray impinging on and pressure differences acting across the wall assembly is also developed. Although the methodology was primarily developed to select the proper testing criteria and test conditions to mimic real events, it can also be used by designers and practitioners to: (i) determine the response of the wall assembly to the effects of wind-driven rain; (ii) estimate design loads below which adverse effects on the assembly are minimized; (iii) assess the likelihood and degree of damage to the assembly when design loads are exceeded; (iv) estimate the long-term performance of the wall assembly based on watertightness and moisture management the wall assembly.

[EN] The main difficulty for the application of Rp on site is the vanishing of the current with the distance which has been overcome with the use of a modulated confinement of the current only feasible if the guard ring is monitored during the measurement by means of electrodes able to detect the distance reached by the current. In the present paper after a short review of existing corrosion rate meters to measure on site, results of a comparison made of reinforced concrete slabs with various degradations such as carbonation or chloride among several using a guard ring with modulated confinement of the current is presented in order to have a reproducibility and repeatability for the measurements. Results show a good correlation among all the methods used for the corrosion rate evaluation.

Promoted ignition testing [1–3] is used to determine the relative flammability of metal rods in oxygen-enriched atmospheres. In these tests, a promoter is used to ignite each metal rod to start the sample burning. Experiments were performed to better understand the promoted ignition test by obtaining insight into the effect a burning promoter has on the preheating of a test sample. Test samples of several metallic materials were prepared and coupled to fast-responding thermocouples along their length. Various ignition promoters were used to ignite the test samples. The thermocouple measurements and test video were synchronized to determine temperature increase with respect to time and length along each test sample. A recommended length of test sample that must be consumed to be considered a flammable material was determined based on the preheated zone measured from these tests. This length was determined to be 30 mm (1.18 in.). Validation of this length and its rationale are presented.

In North America, more than 50 % of low slope roofing applications uses faced rigid cellular polyisocyanurate (hereafter abbreviated as ISO) board as thermal insulation. Long-term performance of a roof assembly is critically dependent on the ISO characteristics during the service period in various environmental conditions. For this reason, the ASTM C 1289-02, “Standard Specification for Rigid Cellular Polyisocyanurate Thermal Insulation Board,” outlines the physical and thermal property requirements for the ISO boards. However, these requirements are based on the available knowledge, information, and consensus at the time of drafting and balloting of the ASTM standard. Nevertheless, the standard gets updated and revised when more credible data are available that solicits revisions of the current standard. This paper presents experimental results from an ongoing pilot research study that critically evaluates the ASTM C 1289-02 specification requirements for the ISO on three engineering properties: (1) dimensional stability, (2) thermal resistance, and (3) compressive strength. Preliminary results from this study reveal many unknown phenomena, particularly regarding the dimensional stability and compressive strength of ISO boards.

This paper presents a proposed qualitative framework to discuss the heterogeneous burning of metallic materials, through parameters and factors that influence the melting rate of the solid metallic fuel (either in a standard test or in service). During burning, the melting rate is related to the burning rate and is therefore an important parameter for describing and understanding the burning process, especially since the melting rate is commonly recorded during standard flammability testing for metallic materials and is incorporated into many relative flammability ranking schemes. However, whilst the factors that influence melting rate (such as oxygen pressure or specimen diameter) have been well characterized, there is a need for an improved understanding of how these parameters interact as part of the overall melting and burning of the system. Proposed here is the ‘Melting Rate Triangle’, which aims to provide this focus through a conceptual framework for understanding how the melting rate (of solid fuel) is determined and regulated during heterogeneous burning. In the paper, the proposed conceptual model is shown to be both (a) consistent with known trends and previously observed results, and (b)capable of being expanded to incorporate new data. Also shown are examples of how the Melting Rate Triangle can improve the interpretation of flammability test results. Slusser and Miller previously published an ‘Extended Fire Triangle’ as a useful conceptual model of ignition and the factors affecting ignition, providing industry with a framework for discussion. In this paper it is shown that a ‘Melting Rate Triangle’ provides a similar qualitative framework for burning, leading to an improved understanding of the factors affecting fire propagation and extinguishment.

The purpose of the paper is to open discussion for an alternative methodology for stability testing of spinal fusion devices that does not require cadaveric tissue. A simulated single level functional spinal unit (FSU) model was used to evaluate spinal fusion devices as an alternative to using cadaveric human tissue models. Initially, this study was proposed as a feasibility investigation prior to investing in a cadaveric study, but was then developed into an alternative, stand-alone method that eliminates variabilities associated with cadaveric tissue testing for providing comparison testing between spinal devices. The objective of this paper is to present the development of the synthetic FSU model and the apparatus for providing kinematic stability testing on lumbar interbody spinal devices. The synthetic model geometry was based on morphological parameters for the lumbar spine using rigid foam per ASTM F1839. A universal servo-controlled test frame provided the pure moment loading through a system of cables and pulleys for the application of flexion-extension, lateral bending, and axial rotation. Comparable testing was performed using short cyclical, fully reversing runs up to 50 cycles where the last ten cycles were evaluated.

The weatherability of construction sealants is a highly important performance criterion for the prediction of their service lives. Currently, the evaluation of a sealant’s surface weatherability is carried out mainly via qualitative visual judgment. One objective of this paper is to establish a quantitative method for the assessment of surface degradation. A further objective is the evaluation of the relationship between outdoor and accelerated exposure with regard to surface degradation. The understanding of this relationship is important for the shortening of the development cycle and the prediction of a sealant’s service life. The paper presents information on the weatherability of construction sealants based on a recently developed test specimen design that allows simultaneous exposure of the sealant to forced compression and extension movement in a single specimen with cyclic movement and weathering carried out simultaneously. A quantitative method for the assessment of surface cracks is employed, and the relationship between outdoor and accelerated weathering exposure is evaluated by using metrics that indicate the degree of surface cracking as a new semi-quantitative criterion of surface degradation.

The analysis of in-service lubricating fluids is a useful tool in determining the state of both the fluid and the equipment being lubricated. Many laboratories provide analysis services for in-service lubricating fluids. The results of the analyses performed are often tracked over time to allow for the observation of trends in the test results. The analysis of in-service lubricating grease is a more challenging task; since the amount of grease in many applications is quite small, the grease may be partially or totally replaced each time new grease is added, and access to the lubricated contact zone may be difficult. Many commercial in-service lubricant analysis laboratories lack the specialized test equipment required for grease analysis, so that type of analysis is performed by a limited number of laboratories, primarily those of the grease manufacturers. Various techniques are employed to determine both the macro and micro condition of in-service lubricating grease. The strengths and weaknesses of those techniques are discussed herein.

This paper shows the evolution of the surface crack front in round bars constituted of different materials (determined by the exponent m of the Paris law), subjected to fatigue tension loading (with free ends) or fatigue bending loading. To this end, a numerical modeling was developed on the basis of a discretization of the crack front (characterized with elliptical shape) and the crack advance at each point perpendicular to such a front, according to a Paris-Erdogan law, using a three-parameter stress intensity factor (SIF). Each analyzed case was characterized by the evolution of the semielliptical crack front, studying the progress with the relative crack depth a/D of the following three key variables: (i) crack aspect ratio a/b (relation between the semiaxes of the ellipse which defines the crack front); (ii) maximum dimensionless SIF; and (iii) minimum dimensionless SIF.

Currently, the (pozzolanic) strength activity indices of fly ashes and natural pozzolans are typically evaluated using the procedures outlined in ASTM C311 [“Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete,” Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2007]. In this test, the 7 and 28 d compressive strengths of mortar cubes with a 20 % mass replacement of cement by pozzolan are compared to those of a control without pozzolan, at constant flow conditions. In its current form, this procedure confounds two other properties of the pozzolan with its strength activity, namely its density and its water-reducing/increasing capabilities. In this study, the current C311 testing procedure is evaluated against an alternative in which the 20 % fly ash replacement for cement is performed on a volumetric basis and the volume fractions of water and sand are held constant, which should provide a true evaluation of the strength activity index of the pozzolan, free of these confounding influences. Class C and Class F fly ashes, a natural pozzolan, and a sugar cane ash are evaluated using both approaches, with some significant differences being noted. For a subset of the materials, the strength measurements are complemented by measurements of isothermal calorimetry on the mortars to an age of 7 d. For the constant volumetric proportions approach, a good correlation is exhibited between the cumulative heat release of the mortar at 7 d and the measured 7 d strength, suggesting the potential to evaluate 7 d pozzolanic activity via calorimetric measurements on much smaller specimens.

The heat flow during the unidirectional downward solidification of Al-7Si and Al-12Si alloys was analyzed using thermal analysis technique and inverse modeling. Chills instrumented with thermocouples were brought into contact with a small pool of liquid metal so as to minimize the effect of convection caused by pouring and temperature gradients. Modification melt treatment resulted in an increase in the cooling rate of the solidifying casting near the casting–chill interfacial region. The corresponding interfacial heat flux transients were also found to be higher. The thermal diffusivities of alloys were measured using a laser pulse technique and were found to be higher for modified alloys. However, the increase in the heat flux transients was attributed mainly to the improvement in the casting–chill interfacial thermal contact condition brought about by the decrease in the surface tension of the liquid metal upon the addition of sodium.

The objective of this study was to investigate how the axial gripping capacity can be affected by varying the tightening torques applied to the set screws in a pedicle screw ASTM F1798 subassembly. Although the current ASTM F1798 standard indicates that all tightening loads to the locking mechanism be applied as specified by the manufacturer, the torque limiting instruments used in the field can have nominal upper and lower torque limits. The interconnection assemblies were assembled using a multi-axial screw, spinal rod, and set screw. Six groups were assembled using different types of spinal rods. Each group was sub-divided into three groups each containing five interconnection assemblies. The three sub-groups of interconnection assemblies were locked to the nominal torque value as indicated by the manufacturer technique, lower limit, and higher limit respectively. Static axial grip testing was performed according to ASTM F1798 guidelines. Axial gripping capacity was influenced by the nominal tightening torque and lower tightening torque and holds true regardless of rod diameter and rod material. There is no significant difference in the axial gripping capacity between the nominal tightening torque and higher tightening torque. These results indicate that the set screw tightening torque has an effect on the gripping capacity and could potentially affect yield load, ultimate load, and failure modes when performing ASTM F1717 compression bending testing. With the wide range of materials used to manufacture pedicle screw systems and the processing techniques that are currently available, e.g., anodization and shot peening, critical thinking should be put into determining if the torque applied to the system represents a worst-case scenario.

A close correlation between the mechanical behavior changes of metal-metalloid glasses and their relaxation spectrum heat emissions has been found. The criteria of crystallization and ductile-brittle transition for these kinds of metallic glasses (MGs) have been established. They correspond to the heat emission balance between the low- and high-temperature parts of the relaxation spectrum. The model of MGs as a system constituting an additive sum of elementary two-level transitions with continuously distributed activation energies is proposed for the analytical description of the relaxation spectrum and its parameters. The methods developed in the approximation of the model permit the determination of the current state of MG materials at an arbitrary temperature, as well as forecasting of their ductile-brittle transition and crystallization according to heat emission alterations of the relaxation spectrum.

Until now, most of the detailed characterizations of the M5 corrosion behaviour were performed under standard PWR operating conditions, under moderate Li content and moderate temperature of the primary coolant. In this study, in addition to these standard conditions, two demanding operating conditions were explored: increased Li chemistry and elevated temperature. The objective is to establish whether these more demanding conditions have an impact on the structure of the oxide layers formed, on Nb, Li and B contents in these layers and on Hydrogen pickup of the cladding. The structure of oxide layers was studied by microscopy, the Nb content and distribution by Electron Probe Micro Analysis, the Li and B contents and distributions by Nuclear Reaction Analysis and the hydrogen pickup by gas extraction. It was observed that the stability of the corrosion behaviour of M5 is not affected by increased Li or elevated temperature conditions. The hydrogen pickup fraction of M5 is not modified by increased Li conditions or by irradiation temperature with measured contents (

In vitro wear tests results and 2-year follow up radiographic analyses of implanted fixed- and mobile-bearing LPS Flex knees are compared. The two knee designs use gamma-sterilized GUR 1050 ultra high molecular weight polyethylene (UHMWPE) patellae and tibial inserts, and the same CoCrMo alloy (ASTM F 75) femoral components. The in vitro wear tests were performed on six fixed- and six mobile-bearing knee implants using modified ISO 14243-3 load and kinematic waveforms. Tests were conducted at a frequency of 1 Hz for 5 × 106 cycles (Mc) in bovine serum lubricant. Two year follow up radiographic analyses were performed on 341 patients implanted with 173 mobile- and 168 fixed-bearing implants. Average accumulative in vitro polyethylene wear rates of the mobile- and fixed-bearing knees were 19.9 ± 5.1 mg/Mc and 14.2 ± 2.1 mg/Mc, respectively. There is no statistically significant difference in the wear rates of both devices (p > 0.05, Mann–Whitney test). Overall survivorship at two years with revision for any reason as the endpoint was 99.3 % for the mobile group and 100 % in the fixed group. There was no evidence of tibial, femoral, or patella bone loss at the two year follow up. The mean active range of motion increased from 110.8° to 127.0° in the mobile- bearing group and from 110.7° to 127.2° in the fixed-bearing one. Overall, radiographic evaluation showed similar performance of both devices.

In the current version of ASTM F2624, the center of rotation (COR) is not specified. Potentially, each device can be tested using a different COR, which subsequently makes a direct design comparison of results difficult. Four posterior dynamic stabilization (PDS) devices (Dynesys, DYN, Zimmer; DSS, Paradigm Spine; and two Aesculap implant concepts) were tested in comparison to a rigid-fixation device and to the native situation of the lumbar spine on fresh-frozen human lumbar spines (L3–L5). The instrumented level was L4–L5. The PDS systems have axial compressive stiffness values ranging from 10 N/mm to 230 N/mm and were all made compatible to connect with the pedicle-screw system. The specimens were loaded in a spinal simulator, applying pure moments for flexion/extension, lateral bending and axial rotation (+/−7.5 Nm) with a defined velocity. The COR was analyzed based on the data measured with a 3-dimensional (3D) motion-analysis system. The effect of the PDS on the location of the COR is most pronounced in the sagittal plane. In general, the higher the implant stiffness, the more the COR shifted in a posterior direction. The DYN had a similar COR to the rigid fixator. However, the PDS systems with low axial compressive stiffness values (range: 10–70 N/mm) showed very similar results on CORs, which are located in the region of the posterior border of the intervertebral disc. In the frontal and transversal plane, the COR was found to be close to the native situation for each system. Therefore, for PDS devices with low implant stiffness, the location of the COR varies only marginally and can be specified for a test setup. An initial proposal that will allow side-by-side comparison for these kinds of PDS systems is given and the feasibility of the new test setup could be proven for all three loading conditions.

The current American Association of State Highway and Transportation Officials standard on crushed concrete in base applications (M 319-02) allows up to 5 % brick by mass, and more with the approval of the engineer; however, in some regions the brick content may be greater than 10 %. More than 41 states allow the use of crushed concrete in highway applications, but only a handful allow the use of building derived concrete (BDC) or mixed stream crushed concrete. Barriers to increasing the appropriate use of BDC in highway applications include a lack of data comparing BDC properties and performance to natural aggregates, as well as data that pavement engineers can use for design. This research has focused on characterizing BDC that was screened to meet New Hampshire Department of Transportation specifications. The gradation, optimum water content, unit weight, and resilient modulus were measured for the BDC and for the control materials, which were a crushed stone and a sand. The resilient modulus was measured using both a laboratory triaxial cell, and a light falling weight deflectometer (LWD) in a test pit. The resilient modulus of the BDC exceeded that of the control materials as measured in the laboratory and using the LWD. In addition, the laboratory resilient modulus showed good correlation with the LWD stiffness. These results suggest that BDC would perform as well as natural aggregates in base course applications.

To estimate the temperature distribution, stress distribution, and stress direction in a blade in service, the morphology of γ′ precipitates in Ni-based superalloy serviced in the first stage low pressure turbine (1st LPT) blade of a jet engine was investigated before and after aging. Using a field emission scanning electron microscope, microstructures were observed in forty portions of the blade. Most of the γ′ precipitates remained cuboidal in the serviced blade. Many secondary γ′ precipitates were observed in the γ matrix at the root part. In contrast, there were no secondary γ′ precipitates at the leading edge of the tip part. After simple aging, low-completion rafted γ/γ′ structures appeared on the suction side of the 70 mm part, while in other portions, coarsening of the γ′ precipitates was observed. Therefore, the leading edge of the 1st LPT blade tip was exposed to the highest temperatures in service. However, the stresses were extremely low in all portions of the blade.

The objective of this study was to investigate the influence of the filler metal on the microstructure and mechanical properties of ferritic stainless steel AISI 444 welded using two types of filler metal of austenitic stainless steel. Microstructure examinations showed that in both welded joints grain growth occurred in the heat affected zone (HAZ). The results also showed that the fusion zone of the weld joints using E309L filler metal presented a discontinuous network of delta ferrite unlike the fusion zone of the weld joint using E316L. Tensile tests showed that the failures of specimens always occurred in the HAZ and that the weldments using E316L filler metal presented tensile strength lower than that of the weldment using E309L filler metal. In the fusion zone of the weldments using E316L filler metal, values for hardness were found to be higher than those found in the fusion zone of the E309L filler metal.

In Japan acrylic sealants are traditionally the sealant products of choice when specified for use between autoclaved lightweight concrete (ALC) panels. Although, in general terms, the mechanisms of the deterioration of acrylic sealants are well known its long-term durability to outdoor exposure has not, however, been fully investigated. The research described in this paper focuses on the change in the properties and deterioration of acrylic sealant products when exposed to outdoor testing. The two stage project consisted of (i) on-site investigations of deteriorated acrylic sealants that had been placed in external joints of ALC-clad buildings; and (ii) outdoor exposure testing of different types of acrylic sealant in three climate regions located in Japan. The results of the work from the first stage of the study revealed the following. Two-sided adhesion joint configurations installed in deep panel ALC cladding were more reliable than three-sided adhesion joints used for thin panel ALC cladding from the viewpoint of the durability of the sealed joint installed in actual buildings. Most fractures of the sealed joint could be characterized as failure in peel (or thin layer cohesive failures), in which the sealant ruptured at the interface with the ALC substrate to which it was applied. Additionally, in 47 of 62 locations surveyed, surface cracks were apparent on the coating that had been applied to protect the sealant. The second stage of the project focused on the degree of deterioration of coated and non-coated acrylic sealants subjected to outdoor exposure testing in a cold, a warm, and a subtropical climate. Results from this stage showed that aging of the sealant, as determined by the degree of surface cracking, expectedly depended on the local temperature and the respective degree of exposure to solar radiation. It was determined that the longer the exposure period, the lower the tensile performance of the acrylic sealants. The elongation of three-sided adhesive joint configurations after 5 years exposure testing decreased remarkably and their maximum elongation was less than 50%. A significant number of sealed joints after 5 years ofexposure had ALC substrate failure, 4th Durability of Building and Construction Sealants and Adhesives, 16 June 2011 through 17 June 2011, Anaheim, CA

This work presents a survey of the mechanical properties (hardness and modulus of elasticity), tribology (friction coefficient and wear rate), and metallography analysis of the ASTM A283 carbon steel subjected to the sulphidation process. The samples were submitted to the sulphidation process at an atmosphere with 0.2 % H2S (hydrogen sulphide) and 98.8 % H2 (hydrogen gas) for different time (5,10, 20, 60, and 120 min)at 300°C. After exposure to sulphidation environment the growth kinetics was analyzed. The results obtained with the sulphidation process indicate that the ASTM A283 carbon steel follows a parabolic law with a equilibrium constant in terms of pressure Kp = 1.47· × 10−12 g2 cm−4 s−1 for the material analyzed. The experimental results for the hardness and surface modulus of the samples show an increase in the values for the sulphide sample for 120 min.

Pavement rehabilitation and reconstruction generates large volume of reclaimed asphalt pavements (RAP) aggregates. Also, large quantities of sawdust are generated by logging industries worldwide. This paper presents results of the laboratory evaluation of the characteristics of sawdust ash (SDA) stabilized RAP with a view to determine its suitability for use as subbase and base material in flexible pavements. The RAP-SDA mixtures were subjected to British standard light (BSL) (standard Proctor) compactive effort to determine the compaction characteristics and California bearing ratio (CBR). Test results show that the properties of RAP improved with SDA treatment. The particle grading improved from 99 % coarse aggregate and 1 % fines, with AASHTO classification of A-1-a for 100 % RAP to 29–95 % coarse aggregate and 5–71 % fines, with AASHTO classification that range from A-1-a (granular materials), for the various RAP-SDA mix proportions to A-4 (silty materials) for 100 % SDA. Maximum dry density (MDD) and optimum moisture content (OMC) increased with higher SDA content in the mixes. The CBR values initially decreased with higher SDA content to a minimum value of 11 % recorded for 30%RAP/70%SDA mix and thereafter increased. With the potential of time-dependent increase in strength in view, the 90%RAP/10%SDA mix that recorded a CBR value of 26 % (soaked for 24 h) can be used as subbase material in flexible pavements. This research provides an initial lead to the evaluation of SDA stabilized RAP as highway construction material, as it is based on CBR determination, a limited parameter that does not provide information concerning all important solicitations that bases and subbases are subjected to. Further work may be encouraged to assess resilient modulus of this material under cyclic load, as well as the assessment of permanent deformation of SDA stabilized RAP. Insignificant expansion and insignificant water absorption were observed.

Bone surrogates are proposed alternatives to human cadaveric vertebrae for assessing interbody device subsidence. Polyurethane foam blocks are an accepted surrogate for cancellous bone but do not share their heterogeneous bone density distribution. Synthetic vertebrae have been recently developed as an alternative bone surrogate with representations of cortices, endplates, and cancellous bone. The efficacy of each surrogate was evaluated by uniaxially indenting it with an interbody device. The force-displacement curve profiles, failure forces, and depth of implant subsidence were compared for devices seated centrally and peripherally on the surrogates. The synthetic endplate mimicked human endplates through a gradually increasing endplate thickness toward the periphery. This enabled the synthetic vertebrae to provide additional subsidence resistance to implants seated at the periphery. By contrast, the foam block was insensitive to implant placement. Absence of failure in synthetic vertebrae from peripheral implant indentation suggests the synthetic endplate is stronger than human endplates but further study with human cadaveric vertebrae is needed.

Dynamic stabilization systems may be subject to anterior-posterior shear loading. However, there is no standard method established for testing a vertebrectomy model in anterior-posterior translation (as may be seen with dynamic spondylolisthesis). A new anterior-posterior shear fatigue test was devised to test one such dynamic stabilization system in anterior-posterior translation. Similar to ASTMF1717 assemblies, constructs were assembled so that screws were placed in ultra high molecular weight polyethylene blocks to attach to the test fixture. The test setup ensures that the entire shear load is transmitted by the implant system. Unlike ASTMF1717 assemblies, the blocks were rotated 180 deg from each other to facilitate loading in the test frame. This configuration is modified from an expected in vivo usage. However, the resultant load vectors are appropriately similar to the shear loads being simulated. The constructs include polymeric components and thus were tested at body temperature in a fluid bath. The blocks were moved ±5 mm with respect to each other. The constructs were cycled at 2 Hz for a minimum of 5 × 106 cycles. The constructs successfully survived 10 × 106 cycles of anterior-posterior shear displacement. Examination of the constructs demonstrated similarities between components tested via this new method and components retrieved from patients. Comparisons indicate that the shear fatigue test may stress the components as much or perhaps more than what was seen clinically.

Some well-known mobile bearing designs have had truly excellent long-term clinical results. Their lower constraint and ability for some self-alignment might have helped reduce the shear forces and torques transmitted to the prosthesis–bone interface, thereby lowering the risk of loosening. However, the most commonly assumed benefit of mobile bearings is the reduction in wear due to less contact stress and reduced cross shear. In a rotating platform, wear can be reduced because the rolling/sliding motion is separated from the transverse rotational motion, which reduces cross-shear. Although it has not been categorically proven clinically, such lower wear expectations with mobile bearings might have influenced the thinking of some total knee replacement (TKR) designers and test engineers. This paper amalgamates invitro TKR wear results from two separate laboratories (in Nebraska and Germany) to present the largest data set ever published on wear, across the widest variety of fixed and mobile bearing TKR designs. Many hundreds of TKR samples were tested with largely similar methodologies using the ISO 14243-1 force-control method. These tests covered 133 different fixed and mobile bearing designs and materials, in total (bicondylar) and unicompartmental forms, and of a wide range of sizes. Clear differences in wear resulted with known superior bearing materials. This illustrates how sensitive and capable of discriminating between low and high wearing implants the force-control wear testing methodology is. However, between both labs, and across all tests, no statistically significant differences were found in wear overall between fixed and mobile bearings. Therefore, the wear of mobile bearing knees is not necessarily less than that of fixed bearings. In both, it depends on the detailed design and materials of the TKR. Testing appears to be necessary with all implant designs, regardless of the history of clinically successful predicates of seemingly similar generic design.

This paper reports the results of experiments aiming to identify the properties of ferrochromium slag when it is used as an artificial aggregate for preparation of granular layers of flexible pavements. The experimental program consisted of three stages: (1) study of the physical and chemical properties of slag, (2) leaching of heavy elements of slag in terms of environmental impact, (3) study of the mechanical properties of specimens made with ferrochromium slag and limestone as aggregate. In the laboratory, cylindrically prepared specimens were tested in a repeated load triaxial (RLT) test apparatus. In addition, particle size analysis, abrasion, frost resistance, compaction, CA bearing ratio, and leaching tests were performed on the materials prior to RLT testing. The results indicate that the physical and mechanical properties of air-cooled ferrochromium slag are as good as those of natural aggregates. It can be used as a base or sub-base material in highway pavements and as an embankment material. Furthermore, the use of the slag as aggregate in pavement layers reduces the requirement for natural aggregates and saves the existing natural resources.

A mathematical simulation of the evolution of nitrogen concentration profiles in iron samples is presented. The nitrogen concentration profiles are produced by a nitrogen microwave post-discharge. This mathematical model takes into account the nitrogen concentration evolution from the very beginning of the process and describes the formation and growth of compact nitride layers. This model also proposes a description of how the solubility limits in each growing phase are attained during the layer formation. An approximate analytical solution of Goodman’s type for the model is sought. This leads to a system of differential algebraic equations (DAE). Then, the DAE is finally numerically solved. The steady state of the process is also studied within the model. In this case, analytical representations of the nitrogen concentration profiles and the diffusion coefficients are found

The introduction of new materials, the innovative use of various construction methods, and the popularity of vegetative (green) roofs make it timely to update and expand the 1990 article, “Principles of Design and Installation of Building Deck Waterproofing” [Ruggiero, S. S. and Rutila, D. A., “Principles of Design and Installation of Building Deck Waterproofing,” Building Deck Waterproofing, ASTM STP 1084, L.E. Gish, Ed., ASTM International, West Conshohocken, PA, 1990, p. 5. We review the state of the art for materials and practices, and apply the lessons learned over the past 20 years of below-ground and building deck waterproofing. Of particular importance are the following: Performance and durability advancements in fluid-applied systems have resulted in increased use. New chemical formulations as well as recognition of settled technologies that work allow some fluid-applied membranes to demonstrate proven durability equal to sheet membrane systems. Sodium bentonite-polymer composite systems resolve many past performance questions and often provide advantages over other options. Blind-side and other foundation waterproofing systems are increasingly driven by foundation forming and concrete placement, and support of excavation designs. Vegetative (green) roofing has created challenges not completely addressed by “plaza waterproofing” designs, but key principles of deck waterproofing must still be applied to vegetative roofing.

Regulatory drivers both in the U.S. and in the European Union are attempting to promote the use of biodegradable lubricants in the marketplace. A base fluid that uses the first ever combination of biodegradable polyalkylene glycol (PAG) with a high oleic canola oil was developed to meet environmental accreditation standards. This combination utilizes the PAG to “upgrade” the vegetable oil in hydraulic fluid formulation and provide a base fluid that can solubilize the oxidation by-products and provide better deposit control compared to straight general purpose fluids that are based on vegetable oils. A general purpose bio-hydraulic fluid that use a blend of PAG and high oleic canola oil has shown enhanced performance characteristics in two critical tests namely an oxidation test (ASTM D 2893 B) and a hydraulic vane pump test (ASTM D 7043). These two tests clearly differentiate the superior attributes of the PAG-based bio-hydraulic fluid compared to a widely use general purpose biodegradable hydraulic fluid in the market place.

The goal of this project is to search for a testing procedure for roof covering products that will radiate both heat and light onto a roof covering and then measure the impact that a given roof covering product has on heat transfer through the entire roofing assembly. Identical roof assemblies were built with ethylene propylene diene terpolymer (EPDM) rubber roof membrane over a wood deck. Sixteen heat lamps were positioned 1.14 m [45 in.] above the roof covering product to provide both heat and light. Thermocouples were placed on the underside of the wood deck and were insulated from outside air. The roofing assembly and the roof covering temperatures were brought to 18°C to 21°C prior to testing. Heat and light were radiated onto the roof coverings for 360 min and the under deck temperature was recorded at 1 min intervals for 600 min. Tested roof coverings included gravel, growing media, coatings, and panels in the form of concrete, ceramic foam, and rubber. The results of the tests have shown data similar to that which were recorded during warm, sunny days. As expected, the highest temperatures were achieved by the uncovered and uncoated black EPDM roof assembly. The temperature of this assembly diminished almost immediately upon the removal of the heat and light source. Thicker layers of growing media and ceramic foam block did not reach the peak temperature until several hours after the heat lamps were turned off. The roof assembly covered with reflective coating showed realistic resistance to the heat and light source. This is a significant advancement in the effort to provide equitable data for all roof coverings. The test provides a standard method of collecting data for traditional roof coverings as well as emerging technology roof covering materials to evaluate a roofing assemblies’ thermal performance from solar heat gain.

Background–The purpose of this investigation is to measure the normal neck and trunk motion of daily living and to compare this to annualized movements as defined by the ASTM F2423-11 and ISO 18192-1:2011 standards. Methods–Ten volunteers wore a custom sensor system that monitored their upper and lower spine motion. The system allows continuous measurement of the frequency and magnitude of spinal motion about all three axes. The angular motion can then be determined for the upper and lower spinal segments. The results were extrapolated to yield the yearly frequency and magnitudes of movements. The data were compared to ASTM and International Organization for Standardization (ISO) standards. Results–The median magnitude of neck motion was 14.3°, 13.8°, and 21.6°, and the mean annual frequency of cervical motion was 10.6 × 106, 8.5 × 106, and 5.6 × 106 movements in flexion-extension, lateral bending, and axial rotation, respectively. The observed-to-standard (ASTM) ratio of annual cervical excursion was 1.22, 1.09, and 0.69, and for ISO the ratios were 1.22, 1.09, and 1.04 in flexion-extension, lateral bending, and axial rotation, respectively. The median range of motion for the thorax relative to the iliac crest (lumbar) was 11.2°, 10.3°, and 12.5°, and the estimated number of annual movements was 6.8 × 106, 5.2 × 106, and 3.8 × 106 in flexion-extension, lateral bending, and rotation. The observed-to-standard ratios from ASTM were 0.63, 0.56 and 1.6, and for ISO they were 1.5, 1.68, and 1.59, in flexion-extension, lateral bending, and rotation respectively. Discussion–Neck and lumbar movements in healthy young adults aremore frequent that 1 × 106 times per annum. The amplitude is smaller than specified in current standards. Overall, the total annual angular excursions specified by ASTM correlated well with results, whereas the ISO specified smaller ranges of motion for the lumbar spine, and therefore the observed angular motions were greater than specified. New testing standards should consider using more physiologic movement patterns.

Low-contact-stress rotating-platform knee replacements were the original mobile-bearing knees developed by the senior authors in 1978 to improve fixation and minimize wear, however, 1-2 % experienced “spin-out” and wear resulting in the development of a third generation rotating platform (Buechel-Pappas, or B-P) in 1991. The purpose of this study is to evaluate design modifications incorporated into the B-P device based upon clinical outcomes. Clinical results of the initial 310 cementless B-P rotating platform total knee replacements in 257 patients were analyzed using a strict knee scoring scale. Of that group, 259 total knees in 206 patients were followed for 2–18 years (mean: 7.6 years). The titanium alloy metallic implants had a 10 μm thick titanium nitride (TiN) coating on all bearing and fixation surfaces and sintered-bead porous-coating, pore size of 350 microns, on all fixation surfaces. The rotating-platform bearing allowed 45° of internal and external rotation with further rotation limited by a stop pin on the tibial component to block complete rotary subluxation/dislocation of the bearing in the event of significant flexion instability or rotational trauma. The study showed 86.4 % excellent, 12.3 % good, 0.3 % fair, and 1.0 % poor results using a strict knee scoring scale. Complications requiring revision included tibial component loosening in 2 super-obese (BMI >50), osteoarthritic patients (0.6%) and 1 late deep infection (0.3%) in a rheumatoid patient after 3.3 years. There were no cases of bearing wear, subluxation, or dislocation seen. Radiographic analysis, using >2 mm lucency in any implant zone, demonstrated 0 % of radiolucencies around femoral components, 2.6 % around tibial components, and 0 % around patella components. Survivorship, using an end point of revision for wear or component loosening was 99.4 % at the 18-year interval.

During fatigue crack growth, the two opposing faces of a fatigue crack can make physical contact while unloading from a maximum level of cyclic load, so that the crack tip state at the minimum cyclic load depends on the host geometry, material properties, and loading history. Although significant work has been performed in order to examine the effects of crack face contact, often called crack closure, under variations of applied loading history, little work has been done to understand the details of crack closure in materials that contain bulk residual stress fields. For an elastic material, variations of applied load history create changes in the crack tip behavior that are directly related to the current levels of cyclic stress, with no effect of prior loading. For an elastic-plastic material, variations of the applied load history cause the crack tip behavior to depend on the current and former loading cycles, because of plastic deformation in the crack wake. In an elastic material with bulk residual stress, crack closure occurs because the strain fields locked into the material, which are the source of the residual stress, alter the shape of the crack faces, so that the details of closure depend on the residual stress field and crack geometry. Residual stresses might therefore affect fatigue crack growth in two distinct ways: first, by combining with applied loads to affect the stress intensity factor (at the current crack size), and second, by altering crack closure. We emphasize that the effect of bulk residual stresses on crack closure described here is an elastic effect, which distinguishes it from the more commonly discussed forms of closure, such as arise from plasticity or roughness. The paper describes a means to forecast crack closure due to bulk residual stress fields and assesses schemes to account for its effects on fatigue crack growth.

Magneto-rheological (MR) fluids, as smart fluids, are suspensions of micron-sized magnetic particles, such as iron particles or cobalt, in a silicone or hydraulic oil carrier fluid, which can change from the liquid state to a semi-solid state in several milliseconds in the external magnetic field. In this paper, the produced chain, which will give rise to the MR effect, is investigated by the magnetic force between two particles, the relationship between the produced shear torque, and magnetic particles are proposed. A set of testing systems, including the plate-on-plate MR fluid shearing test rig, is built to study the percentage of magnetic particles in MR fluid. The magnetic field in the gap, before and after the gap is added with MR fluid, is investigated by measuring and calculating. The results validate the effect of the content of magnetic particles in MR fluid on the shear performance.

Reclaimed asphalt pavement (RAP) and granular base materials were collected throughout Texas to evaluate the properties of RAP and RAP blended with virgin or salvage aggregates for roadway base course application. Mixes containing RAP of 100 %, 75 %, and 50 % and treated with Portland cement of different dosages were utilized in a comprehensive laboratory testing program. The factors that affect the properties of cement-treated RAP mixes are identified and a mix design model based on typical RAP and granular base materials in Texas was proposed. The design model was verified by the data from the initial field trial on actual construction projects. The feasibility of using a modulus-based procedure for quality assurance/quality control during construction is discussed.

In this study, recycled asphalt shingles (RAS) were evaluated for potential use as structural fill in highway embankments or backfills behind retaining walls. Bottom ash (BA) and foundry slag (FS) were also investigated as additives to RAS to enhance its mechanical properties. The engineering properties of RAS:BA/FS mixtures including compaction characteristics, hydraulic conductivity, compressibility, shear strength, and the coefficient of lateral earth pressure at rest were evaluated in a systematic manner. The results show that the addition of bottom ash and foundry slag significantly reduces the compressibility of RAS while increasing the drainage capacity and shear strength. The RAS:BA/FS mixtures are a favorable light weight material for use as embankment fills or backfill behind retaining walls.

Between Dec. 1987 and Jan. 2002, twenty-five cases of clinical instability following mobile bearing total knee arthroplasty with meniscal bearings or rotating platforms presented for evaluation at our institution. These cases were retrospectively identified. All were performed at outside institutions by a variety of surgeons. All clinical examinations were performed by the authors. Nine cases were revised at our institution. All twenty-five cases had clinical evidence of severe coronal plane instability and pain. Eight cases had polyethylene dislocation or subluxation evident radiographically and clinically. Four cases had extensor mechanism dysfunction. Eighteen cases had symptoms immediately postoperatively. Twenty-three of the twenty-five cases had symptoms within two years postoperatively. Any potential long-term benefit of design innovations must be balanced with known problems leading to early failure. This paper is a review of a previously published manuscript by Dr.’s Moskal and Ridgeway [Ridgeway, S. R. and Moskal, J. T., “Early Instability with Mobile Bearing Total Knee Arthroplasty: A series of twenty-five cases,” J. Arthroplasty, Vol. 19, No. 6, 2004, pp. 686–693]. The current manuscript has been updated with additional discussion and references covered in his planned presentation.

For a number of years, luminescent bacteria have been used as an indicator species for acute toxicity of substances in aquatic marine environments. Various other higher organisms have been used for this exact same purpose. Many of the higher organism test evaluations have been used successfully, but they have a few limitations, such as a low number of organisms exposed to toxicant during a test, less than desirable precision and the need for highly trained individuals to run the tests. One luminescent bacterial bioassay includes many organisms, can be run rapidly and requires training in sample dilution techniques. ASTM Subcommittee D02.12 has been working to develop an ecotoxicity method to evaluate the effects of lubricant formulations on luminescent bacteria. The theory describing this method, as well as the D02.12 method development activities, will be discussed.

The main component in environmentally acceptable lubricants and grease is the base fluid. Typically it comprises greater than 70% of grease and 90% of a lubricant. Many biodegradable fluids have specific characteristics, which make formulating finished products difficult. Through a stepwise approach these characteristics will be discussed. The fluids for testing will comprise natural and synthetic esters and some petroleum based synthetics. The testing will find the extremes of performance at high and low temperatures and the effects of common additives to improve performance. Testing will include pour point, elastomer compatibility, oxidation and thermal stability. Based on the testing a blended fluid will be made to offset the drawbacks of the individual fluids and the performance discussed. This blend will serve as the base fluid to formulate an environmentally acceptable lubricating grease.

The use of a reclaimed asphalt pavement (RAP) and rice husk ash (RHA) mixture in the construction of pavements has benefits in not only reducing the amount of waste materials requiring disposal but can also provide construction materials with significant savings over new materials. The paper presents results of the laboratory evaluation of the characteristics of RAP stabilized with sawdust ash (RHA) with a view to determine its suitability for use as a subbase and base material in flexible pavements. The RAP-RHA mixtures were subjected to British Standard light, BSL (standard Proctor) compactive effort to determine the compaction characteristics and California bearing ratio (CBR). Test results show that the properties of RAP improved when treated with RHA. The particle grading improved from 99.8 % coarse aggregate and 0.2 % fines, with an AASHTO classification of A-1-a for 100 % RAP to 92.5–99.5 % coarse aggregate and 0.5–7.5 % fines, with an AASHTO classification that ranges from A-1-a (granular materials) to A-3 (nonplastic fine sand) for the various RAP-RHA mix proportions to A- 4 (silty materials) for 100 % RHA. Generally, maximum dry density (MDD) decreased and optimum moisture content (OMC) increased with higher RHA content in the mixes. The CBR values decreased with higher RHA content. However, the values increased from 35 (unsoaked) and 23 % (soaked for 24 h) for 100 % RAP to peak values of 41 (unsoaked) and 34 % (soaked for 24 h) for a 70 %RAP/30 %RHA mix that can be used as a subbase material in flexible pavements.

Vegetable oils and animal oils have been used as quenchants for metals for thousands of years; however, it hasn’t been until relatively recently that their cooling properties have been studied in a thorough, quantitative manner. This review will focus on the published data relating to the use of triglycerides from various animal and vegetable sources to quench-harden steels. Particular focus will be on the traditional selection and use of different vegetable and animal oils for steel hardening applications and the cooling time-temperature behavior of these fluids to characterize their quenching performance. This information has not been previously reviewed in this manner.

Conventional methods to estimate variable-amplitude fatigue life revolve either around cumulative damage analysis using the local stress-strain approach, or, around one of the crack growth load interaction models. Despite advances in modeling the mechanics of fatigue, none of these methods can faithfully reproduce the near-threshold variable amplitude fatigue response that determines the durability of machines and structures primarily because they fail to model the science behind the residual stress effect. Residual stress effects have a strong bearing on metal fatigue and owe their influence to the moderation of crack-tip surface chemistry and surface physics. This demands the treatment of threshold stress intensity as a variable, sensitive to load history. The correct estimation of crack closure is also crucial to determining the variable amplitude fatigue response and demands assessment of the cyclic plastic zone stress-strain response.

An adhesion testing device was built, based on the ASTM C 633-79 standard, to study the deposition of metallic coatings produced by the HVOF (high velocity oxygen fuel) thermal spray process with the materials 1342 VM, 1350 VM, and 8812, and by the arc spray (AS) process with the materials STELLIT 6 PM SD 38 EF, 97 MXC, and 140 MXC. This type of test is widely used as a tool to determine the influence of the conditions of the thermal spray technique, substrate surface and abrasive blasting on the strength, and adhesion of the sprayed layer on the substrate. The sprayed coatings were characterized based on their hardness, metallographic characteristics, and roughness measurements. They also underwent adhesion tests, and the fracture surfaces of each material were analyzed, revealing mixed results, i.e., different types of fractures involving cohesive fracture, adhesive failure, and adhesive fracture, according to the type of coating produced.

Our research aims to determine the optimal screw configuration of a dynamic compressive plate (DCP) implant on a human femoral bone. The number of screws and the positioning are sensitive parameters of DCP implant stress repartition. Several previous studies have assessed the influence of thescrew configuration of a DCP implant. Using a realistic geometry of a human left femur and the finite element method (FEM), the calculations in those papers were based on a safe femoral bone. This study evaluates the influence of the application of a simulated fracture gap in the diaphyseal part on the stress repartition of the bone, plate, and screws. The main purpose is to complete the existing studies in order to provide surgeons with information on an optimal prosthesis screw configuration. The plate and screws were modeled and assembled on a cracked femoral bone. The hip region of the femur was loaded with vertical and horizontal forces. The femoral bone was cut into two parts because of the gap: the top part, close to thehip, and the bottom part, close to the knee. The FEM analysis shows that the stresses in screws located in the top part of the femoral bone had significantly increased, whereas the stresses on the plate and the bone had been reduced.

In this paper, a method of intensive quenching in water salt solutions, known as the IQ-2 process, is considered. To realize the IQ-2 process, water salt solutions were used, including with NaNO3, Na2CO3, NaCl, CaCl2, MgCl2, Ca(OH)2, and others salts. It is shown that the effectiveness of intensive quenching can be improved via the use of water salt solutions of optimal concentration. In order to prevent the corrosion of steel parts, a small amount of Ca(OH)2 was added to water salt solutions of sodium and calcium chloride to create a pH of 8 to 12. The proposed technology is less expensive compared to conventional quenching methods while providing the same or better end results in terms of increasing the service life of steel parts and tools and components made of powder metal materials. It is shown that the intensive quenching of tools by water salt solutions of optimal concentration increases the service life of tools by 1.5 to 2 times as compared with the oil quenching process.

Dept. of Mechanical and Materials Engineering Portland State Univ., P.O. Box 751, Portland, OR, 97207-0751

Tensile loading of bonded point supports is considered as the critical load case for adhesive material, e.g., silicone applied to such kinds of fixtures. From a durability point of view, the following defects of two-component adhesives are expected to have a significant impact on the response to this loading regime: the wrong mixing ratios of the adhesive components, inhomogeneous mixing due to insufficient or poor mechanical mixing procedures, load degradation of the adhesive bonding material, local degradations of the bonding, e.g., bubbles or poor adhesion. In order to investigate these aspects, different experimental approaches have been pursued. Regarding the mixing ratio aspect, material tests were performed with systematically varied mixing ratios for the analysis of the elastic and strength properties while for the other topics, tensile tests of bonded point supports were evaluated in detail. Cyclic tests of point supports in the tensile load regime were set up, differing in amplitudes and maximum peaks of the cycles, in order to analyze the impact of load histories on the mechanical characteristics of the specimens. For point supports subjected to monotonically increasing loads the qualitative assessment of the fracture surfaces revealed the existence and the potential impact of disturbances inside the bonding, such as bubbles or locally lacking adhesion, on the damage behavior and on related inferior mechanical performance. The main motivation for this kind of research is to improve confidence in the durability of bonded designs. Thus, our activities were focused on aspects which might affect durability from an application point of view, not from a purely academic one. Especially in Germany, the confidence of the authorities in this joining technique has to be strengthened by demonstrating a high degree of robustness in the application, and in view of the risk associated with potential in-field problems.