Search

Die „Chinolone” stellen eine moderne Klasse von breit wirksamen antibakteriellen Mitteln dar. Ausgehend von der 1962 beschriebenen Nalidixinsaure mit einer vergleichsweise geringen Wirkung wurde diese Substanzklasse schrittweise weiter optimiert. Wahrend die fruheren Chinolone der 1. Generation nur zur Behandlung von Harnwegsinfektionen eingesetzt wurden, konnten Chinolone der 2. Generation, die in 6-Stellung ein Fluoratom tragen („Fluorchinolone”)auf Grund ihrer besseren Aktivitat und Pharmakokinetik auch fur systemische Infektionen eingesetzt werden. Eine gesteigerte Wirksamkeit gegen grampositive Bakterien, atypische Erreger (Chlamydia,Mycoplasma,Legionella u.a.)sowie Anaerobier zeichnet die neueren Chinolone der 3. Generation aus. Auch eine Ausweitung der Indikationen (z.B.Helicobacter pylori) erscheint moglich.

Systems for weighing vehicles while they are in motion are in widespread use in many countries. The accuracy of these weigh-in-motion (WIM) systems is strongly influenced by the road profile and vehicle dynamics. Systems based on sensors that are embedded in the pavement or placed on top of the road surface can measure the axle load only for the fraction of a second for which the wheels are present on the sensor. An alternative to pavement WIM systems that increases the length of the load-sensitive element is to use an existing bridge as a weighing scale (Bridge WIM). A major test of a Bridge WIM system at a test site near the Arctic Circle is described in this paper. The test was conducted along-side a larger test of pavement WIM systems. A large number of trucks from random traffic were weighed statically and the results compared to those from the Bridge WIM system. The accuracy of the system is assessed in accordance with the COST 323 WIM specification, which provides a standardized method of accuracy classification. The Bridge WIM system is proven to perform satisfactorily and consistently for a wide range of temperatures in near-Arctic climatic conditions.

A disadvantage of metal matrix composites (MMCs) is their assumed brittleness, which results in a low KIc. A possible way to make aluminum MMCs tougher is to heat treat them. In this investigation the influence of three different heat treatments on the KIc of AA6061 and AA6061 with 20 vol% Al2O3 is investigated. Special attention is paid to the set of requirements needed to obtain a valid KIc, as in some studies these are given little attention. In MMC material, the specimen geometry is governed by the delivered shape, which increases the risk of obtaining KQ instead of KIc values. It proves to be possible to obtain valid KIc data for the MMC using the standard disk-shaped compact tension geometry. The KIc of the MMC is around 21 MPa √m and the influence of the heat treatments on the KIc seems to be very small. The reduction in KIc by the addition of 20 vol% Al2O3 particles to AA6061 is moderate, in view of the KIc of the matrix material, which on average is 27 MPa √m.

There are many test methods to measure the impact resistance of fiber-reinforced concrete that are complicated, time consuming, and expensive. A practical test method has been developed to measure the impact resistance of high-strength fiber-reinforced concrete (HSFRC). The equipment developed can also be used for testing aggregate impact values by simply changing the base plate of the machine. A machine was developed to measure the surface abrasion resistance of HSFRC. Testing fiber-reinforced concrete for surface abrasion resistance was found to be extremely difficult if realistic and practical results were desired. In this study the influence of silica fume on the properties of HSFRC was investigated by using silica fume at two different percentages and with three different hooked-end fibers, namely, 30/0.50, 60/0.80, and 50/0.60 length/diameter (mm/mm). Fibers were added to concrete in three different percentages of 0.5, 1.0, and 2.0% by volume of concrete. The results show that including fibers in high-strength concrete improves impact resistance, surface abrasion, and splitting tensile strength. Due to copyright restrictions, the access to the publisher version (published version) of this article is only available via subscription. You may click URI (with DOI: 10.1520/JTE12166) and have access to the Publisher Version of this article through the publisher web site or online databases, if your Library or institution has subscription to the related journal or publication.

An X-ray piping diagnostic system was developed more than ten years ago. It was used to evaluate old piping in buildings and to calculate the remaining years of functional use. It was originally developed for application to corroded pipes without rust because there was no way of calculating the remaining thickness. However, by using a new simulation code EGS4 it has become possible to calculate the true thickness of steel pipes containing rust and the actual number of years of practical use remaining. Each factor of X-ray radiography was simulated and each absorbed energy was obtained. Using this result, combinations of steel and rust for the same absorbed energy were classified. Experimental measurements of steel thickness were done with about 90 % precision.

This paper describes development of an automated technology to quantify surface segregation seen during construction of hot mix asphalt concrete pavements. Segregation manifested on the surface produces nonuniform surface macrotecture. A laser-based system was used for detection of nonuniform surface macrotexture caused by segregation. Two segregated test sections and a control test section were tested to evaluate the laser texture method. Laser texture data were gathered from three sites, and sand patch and nuclear density tests were performed at 25 ft (7.62 m) intervals along three sections. In addition to the above, visual surveys were performed to confirm the measurements. Based on the test results, it was found that the nuclear density test could not be used to detect surface segregation but it could be used as a confirmation test. Test results from the control section were used to establish a correlation between the sand patch tests and the laser texture data.

This paper describes the development of a fracture test for determining the fracture energy of asphalt concrete. The test will be used in combination with numerical analysis and field studies to obtain a better understanding of the mechanisms of reflective cracking in asphalt concrete overlays. A review of the literature revealed that a single-edge notched beam (SE(B)) test specimen was the most promising fracture test for the objectives of the reflective cracking study. Existing servohydraulic testing equipment was modified to perform the SE(B) test along with new loading fixtures, sensors, data collection, and analysis procedures. Preliminary tests were conducted to develop test procedures, to obtain a better understanding of crack-front characteristics, to investigate test repeatability, to examine variations of fracture energy with temperature, and to investigate mixed-mode fracture. The results from the tests follow expected trends and test variability appears to be within a range typical for asphalt concrete fracture testing.

Many state departments of transportation (DOTs) have incorporated a pay factor system into their quality assurance/quality control (QA/QC) programs. Currently, there is no standard sampling method for QA/QC programs nor for pay factor systems. This paper examines dissimilar types of sampling processes and their effects on pay factors along with different pay factor methods. The results can aid in establishing a pay factor system and selecting an appropriate sampling method based on the volumetric characteristics and a chosen type of pay factor system. A pay factor system based on sample means and a pay factor system based on risk analysis of hot mix asphalt (HMA) quality characteristics were examined. Hot mix asphalt mixtures standard in Michigan were used for the case study, along with five Michigan Department of Transportation (MDOT) sampling methods. The final analysis indicated that using a measured asphalt binder content probability-based pay factor system sampled via a Plate and Shovel method was the most precise system. Using a consistent sampling method ensures that pay factor systems are fair. A sampling method that is consistent in measuring results will be beneficial to contractors and owner/agencies by making payment based on HMA qualities that are representative.

The objective of this paper is to examine the variation of shear strength with respect to suction and develop a simple method for prediction of suction from shear strength data. The measured values of total suction and the shear strength of the soils are used to predict a fitting parameter that defines the nonlinear variation of suction with shear strength. The equation proposed by Vanapalli and Fredlund isused. The parameter is estimated for two types of soils, red soil and black cotton soil, available in the state of Karnataka, using measured values of total suction and unconfined compressive strength by nonlinear regression analysis. The nonlinear equations developed between suction and unconfined shear strength are useful in unsaturated soil engineering practice.

Implosion of vaporous cavities is exothermal, thereby heating the cavitating liquid. In vibratory cavitation erosion (VCE) tests the erosion rate increases with test liquid temperature. In order to obtain the erosive properties of a given material at a given temperature, it is necessary to control the test liquid temperature. The prevailing ASTM standard specifies cooling of the test liquid, and allows a maximal temperature rise of 4°C during the VCE test. However, cooling alone does not ensure the required uniformity of test liquid temperature near the specimen. In order to obtain a uniform test liquid temperature near the specimen during VCE tests, a thermal control system is recommended. This system consists of three subsystems for cooling, heating, and mixing the test liquid. Correct location of the temperature sensor and operation of the thermal control system improve the thermal control appreciably. This control method was used during 24 VCE tests with water as a test liquid. The average temperature rise in these tests was 1.5°C during the transient stage and 0.2°C during steady state operation.

Fly ash is a finely divided mineral residue resulting from the combustion of coal in power plants that occupies large extents of land and also causes environmental problems. Hence, concerted attempts are being made to effectively use fly ash in an environmentally friendly way instead of dumping. Several studies have been carried out for its bulk utilization, such as its addition to improve the California bearing ratio (CBR) of soil in roads and embankments. But a thorough mixing of fly ash with soil may not be possible in the field. Hence a study has been carried out on the CBR behavior of black cotton soil and Raichur fly ash (which is class F) in layers and compared with the same in mixes. The results show that the CBR values of soil-fly ash mixes are better than layers, as expected. To improve the strength of layers, cement is used as an additive to fly ash. The results show that black cotton soil can be improved with stabilized fly ash, solving its strength problem as well as the disposal problem of fly ash.

The objective of this research was to investigate the stripping problem in bituminous mixtures using both conventional and image processing techniques (IPT). Partial factorial combinations of asphalt mixture slabs were fabricated. A Marshall mold was modified to produce slabs of 300 mm × 300 mm × 60 mm. The mixtures were prepared using different combinations: two types of aggregates (limestone and valley gravel), two asphalt penetration grades (80/100 and 60/70), three types of additives (lime, cement, and a mixture of lime and cement), and one aggregate gradation (average of ASTM boundaries). The slabs were exposed to one of four environmental conditioning techniques: wet-dry (W-D), freezing-thawing (F-T), water immersion (I), and surface bonding (S-B). Eighty-one slabs were prepared, 19 were tested without conditioning (control slabs), and the rest were exposed to different weathering conditioning. Four cores were prepared from each slab, two for the indirect tensile strength test and the others for the Marshall stability test. A normal-based camera was used to map the surfaces of the control and conditioned slabs as well as cross-sections generated from cores tested under the indirect tensile strength test. The Silicon Video Image Processing (SVIP) software was used to digitize images for the surfaces of slabs and cores. Images were analyzed to prepare statistical parameters, intensity diagrams, and histograms for intensities based on two approaches: area-based analysis and line-based analysis. Results of the analysis indicated that 1) conventional and image processing techniques proved that surface bonding increased stability and tensile strength for conditioned slabs more than for unconditioned slabs; 2) IPT predicted stripping in limestone mixtures with AC 80/100 using the retained intensity concept and this result agreed with that of retained Marshall stability (RMS); however, it did not consistently predict the stripping potential of mixtures consisting of valley gravel due to the tone intensity effect of aggregate; 3) lime additive demonstrated the best indirect tensile strength and Marshall stability; however, the additive mix consisting of lime and cement exhibited reduction in water damage for mixtures with AC 60/70; 4) slab mixtures resisted weather conditioning more than conventional cylindrical Marshall specimens; and 5) an area-based analysis scheme using peaks, not averages of intensities, was more reliable in predicting stripping than the line-based analysis, and it was more reliable for core cross-sections than slab surfaces.

Tensile stress-strain properties in the hoop direction were obtained for 100-mm diameter SiC/SiC ceramic matrix composite cylinders using ring specimens machined form the cylinder ends. The cylinders were fabricated from 2D balanced SiC fabric with several material variants, including wall thickness (6,8, and 12 plies), SiC fiber type (Sylramic, Sylramic-iBN, Hi-Nicalon, and Hi-Nicalon S), fiber sizing type, and matrix type (full CVI SiC, and partial CVI SiC plus slurry cast + melt-infiltrated SiC-Si). Fiber ply splices existed in all the hoops. Tensile hoop measurements are made at room temperature and 1200 C using hydrostatic ring test facilities. The failure mode of the hoops, determined through microstructural examination, is presented. The hoop properties are compared with in-plane data measured on flat panels using same material variants, but containing no splices.

Differential expansion and contraction between the top and bottom of a concrete slab results in curling. Curling affects slab stresses and deflections and is an important component of any mechanistic-empirical design procedure for concrete pavements. Although some curling is caused by temperature and moisture gradients that fluctuate daily, a significant portion of the curling can be attributed to the combined effects of nonlinear “built-in” temperature gradients, irreversible shrinkage, and creep, which can be represented by an effective built-in temperature difference (EBITD). A procedure for estimating EBITD of in situ slabs using a falling-weight deflectometer and a finite-element program is presented. This procedure was used to estimate EBITD for instrumented slabs at Palmdale and Ukiah, California. Differences in restraints (from adjacent slabs, shoulder, base friction) and variability in concrete material properties resulted in EBITDs ranging from -5°C to greater than -30°C.

A full-scale field test was carried out on a loosely-compacted fill slope that had been installed with soil nails. The slope was brought to limit equilibrium by subjecting it to a surcharge at the slope crest in combination with induced rise in phreatic surface and precipitation. Heavy instrumentation comprised of in-place inclinometer, vibrating wire piezometers, vibrating wire extensometer, earth pressure cell, tensiometer, and strain gages along the soil nails had been monitored throughout the test. Surface movement was monitored using a GPS system and a 3-D laser scanning technique. This paper focuses on the use of a 3-D laser scanner in capturing the formation of cracks and surface movement during the failure. It is demonstrated that with the use of this technique, the surface movement of the slope can be accurately recorded without the need of physically accessing the slope surface.

C-ring specimen geometries are used to ascertain Weibull parameters for spatially distributed flaw populations in ceramic gun barrels. A review of previously published results used to compute effective areas and effective volumes for this test specimen geometry is presented along with deficiencies associated with these computations. In addition, the results of the numerical analyses presented utilizing finite-element analysis and component level reliability algorithms clearly indicate that geometric constraints called out in the current ASTM standard for C-ring testing must be revised.

The monitoring of fatigue crack initiation and propagation in cruciform joints is very complex and time consuming. The amount of technical information generated by a single fatigue test can vary from a terse noting of the cycles to the point till the specimen breaks, to a continuous observation of crack lengths. A wide variety of experimental methods are available to study the changes in bulk properties taking place in a test specimen (with simple geometry) while it is subjected to alternating stresses. However, in many fatigue test situations (for instance, in cruciform joints), it is very difficult to monitor the changes due to multiple possible crack initiation points. In this paper, a method has been developed to monitor the crack initiation for cruciform joints with different geometry by resistance-type strain gages. Also, the application of a relatively new, thin-film bondable transducer, commercially available under the name ‘crack propagation gage,’ was evaluated for fatigue crack propagation tests for cruciform joints at room temperature. Additionally, the strain gage and the crack propagation gage instrumentation system can be used for direct test machine control, permitting completely automated fatigue crack growth testing.

The study explores the frequency response characteristics of the control components in a pneumatic system, while developing a set of the most effective measurement methods and equipment that provides the closest dynamic characteristics of the pneumatic system. First, the study inputs square pressure wave signals, which have various frequencies and are generated by directional control valves, into the pneumatic system, which is comprised of an electromagnetic valve, pneumatic pipes, and pressure sensors. In addition, the study discusses the influences of the aforementioned electromagnetic valve, pneumatic pipes, and pressure sensors on the frequency responses of the pneumatic system through the analyses of outputted pressure signals. Next, the study replaces the electromagnetic valve with the square pressure wave generator developed in the study that emits pressure square waves with frequencies up to 500 Hz to be inputted into premeasured pressure sensors in the pneumatic system for testing the dynamic characteristics of the pressure sensors at high frequencies. The study proposes applying square pressure waves to the dynamic property analyses of pneumatic components, i.e., inputs square pressure waves into premeasured pressure sensors through the excitement method to the pressure sensor and utilizes spectrum analysis for analyzing the outputted voltage signals. The experimental results can be provided for designers of pneumatic systems as references for selecting components and rectifying the system properties.

Analytical protocols are presented for the determination of experimentally realizable relatively “simple” loading functions, consisting of concentrated loads that mimic actual quasistatic and/or dynamic more complicated loadings, to produce similar nearly equal equivalent deflection patterns. These computational simulations in essence represent a series of virtual experiments. Two protocols are formulated for the determination of equivalent loads. The first consists of “lumped loads” and in the second, Galerkin's method is used to determine the system of equivalent concentrated loads. The accuracy of the protocol is examined and shown that the simulation error can be made negligible with a manageable finite number of equivalent concentrated loads.

Difficulties experienced using ASTM Method E 582-88 for determination of minimum ignition energies of compounds more difficult to ignite than simple hydrocarbons are described along with remedies for overcoming those difficulties. Minimum ignition energies and associated quenching distances are reported for four hydrofluorocarbon compounds using a modified Method E 582-88 apparatus and procedure.

For a specific test method, ruggedness experiments are used to determine experimental conditions that significantly influence the measurement results and to determine how closely these conditions must be controlled to reduce their influence. In this paper, the results of ruggedness experiments using hot box test methods (ASTM C 1199, C 1363, and ISO 12567-1) that are used for the thermal transmittance measurement of fenestration systems are presented. A general procedure of ruggedness evaluations was conducted on the University of Massachusetts Research Calibrated Hot Box. Using ASTM E 1169, a Plackett-Burman (P-B) design with eight experiments was used to investigate the effects of the seven most important experimental conditions. Two experimental conditions, the weather side and metering side fan speeds, were found to have the most significant effects on fenestration systems thermal transmittance measurement results.

Significant differences occur in Rockwell B hardness (HRB) tests depending on whether the 1.588 mm diameter ball indenter that is used is made of steel or of tungsten carbide (WC). It is important to study and assess the effect of different indenter materials on the HRB tests since the Rockwell hardness test method standards, published by ASTM International and the International Organization for Standardization, now permit the use of either steel or tungsten carbide ball indenters. In this paper, finite-element analysis (FEA) is used to simulate the HRB indentation process using steel and WC ball indenters on the same test materials under the same testing conditions. The influence of the deformable steel and WC indenters on the HRB tests is analyzed by comparing their FEA results with those of a simulated nondeformable rigid indenter. The contact pressure, stress, strain, and deformations of both the indenters and the tested materials during the loading and unloading period are analyzed. The FEA simulation results show that the HRB difference between steel and WC ball indenters is about 0.4 HRB for 40–78 HRB levels, but increases to 0.56 HRB at the 23 HRB level. The FEA simulation results agree with experimental HRB results.

ISTA Procedure 2C and two options in NMFCC Item 181, stacked vibration and compression and vibration in separate tests, were compared to determine the equivalency of common U.S. furniture packaging performance tests. Containers constructed of two different corrugated fiberboard specifications were evaluated; Box A: a 32 lb/in. (5.6 kN/m) ECT rated board with a basis weight combination of 35HP/26/35HP, and Box B: a 200 psi (1378.95 kPa) Mullen rated board with a basis weight combination of 42/26/42. Ten corrugated fiberboard containers of each board type were tested following each of the test protocols. After testing, the contents were removed and the residual compression force at failure and deflection at failure of the containers were measured. These data were compared to the compression force and deflection at failure of control samples for the two board grades tested. Results showed that Item 181 Method A produced significantly different residual compression force at failure when compared to Item 181 Method B and Procedure 2C for both boxes. Item 181 Method B and Procedure 2C were not significantly different. Also, the two boxes showed significantly different residual compression force at failure results for each of the test protocols studied. The percent change in compression force at failure based on control samples, however, was not significantly different between the boxes studied.

A standard method for the determination of the shear strength of a polymeric foam is a lap shear geometry. The accuracy and validity of this test was evaluated by means of finite-element modeling. Model results show that the shear stress is not constant over the length of the sample, with shear peaks at the ends, so that the average shear stress in the sample can be quite different than the maximum shear stress experienced. Normal stresses are also present at the sample ends giving rise to a combined stress field. Experimental results for a polymeric foam bonded to steel edge plates show that the measured shear strength can vary significantly with the sample geometry (length). Maintaining a minimum length/thickness ratio, as specified in the ASTM C 273 standard, does not necessarily result in a sample with the most uniform shear field, and therefore the most accurate measure of the true shear strength.

To be able to perform extended extrapolation of creep rupture data, i.e., extrapolation by more than a factor of three in time, a new procedure is proposed. A free temperature model for the time-temperature parameter is used that provides a high degree of flexibility. Postassessment tests are formulated to verify that the chosen time-temperature parameter has sufficient stability. In the analysis, criteria are introduced for the position of the predicted creep rupture curve in relation to the scatter band of data as well as criteria on derivatives of the predicted creep rupture curves. The procedure has been applied successfully to five common creep-resistant pressure vessel steels: one low-alloy steel (2Cr 1Mo) and four austenitic stainless steels: 304H, 316, 253MA, and 800H. The small deviations between the full datasets and strongly culled sets demonstrate the validity of the proposed procedure.

This paper presents the development of a test system to evaluate the ignition susceptibility of several common plastics in nitrogen trifluoride (NF3) as compared to gaseous oxygen. A test system was developed to allow for measurement of the autogenous ignition temperature (AIT) in both gaseous oxygen and NF3. The autogenous ignition temperatures of Kel-F® 81 PCTFE, Neoflon® PCTFE5, Teflon® PTFE, Nylon 101, PVDF, and PVC were determined in gaseous NF3 and in gaseous oxygen.

Roofing systems are exposed to wind pressures and thermal stresses. Through a North American roofing consortium (Special Interest Group for Dynamic Evaluation of Roofing Systems—SIGDERS) the National Research Council Canada fabricated a facility to evaluate roof assemblies under simultaneous wind and thermal effects. The overall objective of this paper is to present the commissioning process of the facility based on experimental investigations that were carried out on a single-ply roofing system with a PVC membrane. For this study, roofing system responses were measured under simulated simultaneous wind and heat/cold conditions. A systematic attempt also was made to quantify the system response and to characterize the membrane properties. This was performed on a cold-conditioned system as well as by subjecting the membrane samples to the same cold-conditioning program in a laboratory freezer. Membrane samples were characterized by mechanical and chemical methods. Comparison of laboratory-conditioned membranes and wind-tested systems revealed the effects of cold conditioning and wind loading. Neither the wind uplift nor the mechanical properties (tensile breaking strength, elongation at break, tear strength, and seam strength) nor the chemical properties (glass transition temperature and weight loss) were affected by the selected cold conditioning. Based on these findings, directives for further studies are presented for this ongoing project.

The fracture toughness of laser beam welded ferritic steel has been measured in the ductile-to-brittle transition regime using precracked bend specimens. The precracked welded specimens showed a complex fracture behavior, which involves crack path deviation. It was found that the large scatter of the cleavage fracture toughness and its temperature dependence can be characterized by the Master Curve Method (MCM). The results promote the validity of Engineering Lower Bound Method (ELBM) to derive lower bound toughness of laser beam welded steel. To enable a successful application of the Methods, it was necessary to add fracture toughness data censoring to the method, which takes into account the phenomenon of crack path deviation. The application of the censoring criterion requires additional fracture surface investigations, which can be performed easily using a conventional low magnification light microscope.

Experimental results showed that ASTM D 638 Type IV flat tension specimens, made of a Nylon-11 matrix containing a large volume concentration of Nd-Fe-B particulates, failed at a location where the straight gage section of the specimen ends and the curved transition region begins. The stress distribution in this specimen was analyzed using the finite-element method, and it was found that there is a stress concentration at this location. The stress distributions in tension specimens with both single- and double-arc transition regions were analyzed and stress concentration factors were calculated. A linear relationship between the magnitude of the stress concentration factor and the ratio of the width in the gage section and the arc radius of the transition region is identified. This study shows that it is possible to reduce the magnitude of the stress concentration factor for the ASTM D 638 Type IV flat tension specimen by redesigning the specimen geometry without changing its overall size.

ASTM standards are widely used to determine the plastic strain ratio r to characterize the normal anisotropy and the planar anisotropy of sheet metal. The values determined by mechanical testing are quoted at a strain of 15%. These are used for comparing two techniques of measuring the plastic strain ratio or the anisotropy of two materials. The present work reports the variation in the plastic strain ratio of prestrained material. The r values of biaxially prestrained steel sheet have been investigated using the ASTM as well as the magnetostrictive methods of measurement. An error analysis on the mechanical measurements has been performed to examine the agreement between the different definitions of the plastic strain ratio (rr, rint, rt, and rmx1) and the accuracy (based on coefficient of variation), in view of the need to measure the plastic strain ratio at low strain levels. Various means to ensure accuracy in measurement are described. Plastic strain ratio of sheet deformed to different biaxial prestrains has also been characterized using the magnetostrictive method (Modul r test). It is found that the difference between the r values determined using the ASTM and the Modul r methods changes with strain and strain path. The nominal difference between the two methods was found to be comparatively consistent over strain paths ranging from plane strain to equibiaxial tension. The Modul r values for prestrains along these strain paths investigated were found to be relatively consistent and hence usable. For prestrain along the strain path β = −0.45 (negative minor strain regime), the nominal difference was considerable. In view of the above, it is not appropriate to measure rapidly the r value of the material in the negative minor strain regime, in particular using magnetostrictive means, and to correct it using the “systematic error” between the two techniques. This restricts the usability of the Modul r test in measuring the plastic strain ratio of deformed sheet metal, particularly after a prestrain in the negative minor strain region.

A recent paper reported repeatability and bias test results for the variable incidence tribometer (VIT) and for the portable inclineable articulated strut slip tester (PIAST). These two tribometers approximate initial pedestrian heel-contact during walking, a critical consideration when attempting to quantify walkway slip resistance in a representative manner. Horizontal/vertical force-ratio settings on the tribometers were compared to measured ratios detected by a force plate. When these detected ratios were assessed mathematically by standard statistical methods, both tribometers displayed a high degree of repeatability and a low degree of bias. However, when assessed by graphical means, both tribometers exhibited patterns of indicated bias. An effort is made to identify the sources of the indicated bias. Results of the VIT analysis are consistent with its indicated bias being related to the influences of inertial forces. The PIAST appears systematically affected by the presence of elastomeric friction in its testing regime. Under elastomeric friction conditions, the ratio of the friction force developed divided by the applied normal force decreases as the applied normal forces increase. Under these conditions, the applied normal force and developed friction force are not directly proportional. The relevance of such conditions to pedestrian ambulation is discussed.

The rate of mass loss in vibratory cavitation erosion tests varies with time. As a consequence, this process is treated empirically. It is suggested by the author that the cumulative mass loss-time curve test results can be represented accurately by the Weibull cumulative distribution function. This model was verified for 26 tests of nine metals. Among these metals is Ni 200, which is a standard reference material for erosion tests. This model allows treating the results of vibratory cavitation erosion tests analytically, thereby obtaining invaluable information from the test data.

The test surface of a specimen for cavitation erosion testing is prepared by several machining operations. These operations induce alterations on the surface and in the material beneath it, thereby forming an affected material zone. The properties of this zone affect the mechanical and metallurgical properties of the material. As a consequence the erosive properties are affected too, but are not easily detected on the cumulative erosion-time curves. The cumulative erosion-time curves of Ni 200 erosion tests were modeled by the Weibull cumulative distribution function. The equivalent Weibull plot consists of two intersecting straight lines, thereby providing a bimodal plot with a decreasing slope. Each line describes a different erosion mode. The first mode, from test onset to the intersection point, describes the erosion process of the specimen's boundary layer. Since this layer is removed by means of the erosion process, it is designated as the erosive boundary layer. The second mode, from the intersection point onwards, describes the erosion process of the homogeneous material. Analysis of the Weibull plots of Ni 200 erosion tests enables determination of the erosive boundary layer thickness and erosion time; it further facilitates the evaluation of the erosive boundary layer effect on the entire erosion process. The Weibull method enables construction of plots describing the erosion process of an ideal specimen, with an erosive boundary layer of 1 μm thickness. Plots of this kind may be used to characterize Ni 200 and to compare erosion properties of various materials.

The effects of strain rate and temperature on the mechanical behavior of a magnesium alloy (ZC71) and its corresponding composite reinforced with SiC particles are investigated. The experimental procedures of testing at high strain rate and different temperatures are described. The tensile stress-strain responses of both the base and the reinforced materials were found to depend on the applied strain rate (0.003 ≤ έ ≤ 700 s−1), the test temperature (−150 ≤ T ≤ 200°C) and the presence of reinforcement. Comparative results are presented in terms of the main mechanical parameters, and quantitative conclusions are obtained of the influence of temperature and strain rate, using quasistatic and dynamic tests, on the mechanical behavior of these materials.

Fatigue crack growth behavior of through-the-thickness cracks emanating from the notch root in an aluminum alloy was investigated with particular emphasis on the evaluation of crack closure and its effects on fatigue crack growth rate. The tests were performed on SE(T) specimens both under constant amplitude (CA) and spectrum (modified FALSTAFF) loads. The near-tip strain measurement method was used for crack closure estimation in the short and long crack ranges. An attempt was also made to determine the crack closure value corresponding to the crack-tip shielding through fractographic analysis. In CA fatigue loading, short cracks grew faster than long cracks under the same nominal applied SIF range, ?K, and also grew below the threshold SIF range, ?Kth, for long cracks. The crack closure level gradually increased in the short crack range and was observed to stabilize at a crack length of about 0.5 mm. The discrepancy in the observed crack growth rates between long and short cracks was attributed partly to the difference in crack closure levels. The fatigue crack growth rates of short cracks under modified FALSTAFF loading were observed to be rather scattered, and the crack closure level was found to gradually increase and stabilize within a larger scatter band. These observations are explained on the basis of likely effects of several high-peak overloads present in the applied spectrum load. In the long crack range, the crack closure value obtained by the near-tip strain measurement method appears to provide an upper-bound value, whereas that obtained through fractographic analysis provides a slightly lower estimate, which may be considered as a lower-bound fatigue crack closure value.

We measured the shear strength of wood by the asymmetric four-point bending test using notched beam specimens of Todomatsu (Japanese fir, Abies sachalinensis Fr. Schmidt). The notches were cut on both longitudinal-tangential (LT) planes along the neutral axis, and the load was applied asymmetrically on the longitudinal-radial plane to obtain the shear strength of the LT plane. In the tests, the notch depth and span-to-thickness ratio, which was defined as span/depth ratio, varied and the influence of specimen configuration was examined. Independently of the bending tests, block shear and Iosipescu shear tests were performed and the shear strengths obtained were compared with those obtained by the bending tests. When the specimen had a proper configuration, the value of shear strength was stable over a wide span/depth ratio range and was close to that obtained by the Iosipescu shear test. Hence, we think that the asymmetric four-point bending test using a notched beam specimen is promising for evaluating the realistic shear strength of wood.

The Hveem stabilometer is used by several states to obtain materials characteristics for designing pavements. This paper presents equations that relate the Hveem stabilometer R-value and S-value with the elastic modulus. It is shown that the elastic modulus is dependent on the following: the R- or S-value, the exudation pressure, the overconsolidation ratio, the Poisson's ratio, and the angle of internal friction of the material. It is also shown how the compaction pressure might affect the calculation if the material is time-dependent or viscoelastic. An example problem is provided to show how to calculate the elastic modulus using these pertinent factors. Typical laboratory test data are also presented to demonstrate the relationship between the R-value and the elastic modulus for three different highway soil materials. It is shown that the exudation pressure is indicative of the moisture content of the test samples. The R-value and elastic modulus are shown to be quite sensitive to the moisture content.

Acoustic Emission (AE) has been used to detect onset of ductile tearing in instrumented Charpy impact tests to enable determination of dynamic ductile tearing initiation toughness using a single specimen method. An AE based method was developed whereby a conventional instrumented impact tester is instrumented with a commercial broadband acoustic emission sensor mounted on the anvil. The results obtained using the new AE based method were compared to the results obtained by other researchers using specially developed AE sensors located inside the tup. Tests using both AE and direct measurement of the load-line displacement during the instrumented Charpy testing were conducted simultaneously on a conventional ship grade steel. V-notched and fatigue precracked test pieces were tested in the temperature range +23°C to −80°C. The results obtained with AE monitoring were compared to those obtained using the optical Direct Displacement Interferometric Strip (DDIS) method developed by the authors. Good correlation was found between the initiation fracture toughness determined at 0.2 mm blunting and crack extension, J0.2, by the multispecimen Ductile-Brittle Transition (DBT) method and those derived from single specimens applying AE and the new interferometric method to detect ductile fracture initiation. Fast Fourier Transformation (FFT) was applied to analyze the AE signals. The results showed that the different phases of AE and fracture modes could be distinguished based on characteristic frequency and time variance.

The present paper reports methods and results of an extensive experimental project performed to assess the mechanical characteristics of ancient stone masonry walls of Tuscany (Italy). Some relevant considerations concerning the determination of common design shear strength parameters via experimental test results are also presented. Results from 22 in situ tests performed on nine large-scale stone masonry panels are reported. Test panels were selected as part of shear walls in six different old masonry buildings in the northern part of Tuscany so as to represent a reliable sample of the most common masonry types in this region. In situ tests were carried out according to experimental schemes for vertical compression, shear compression, and diagonal compression. After the first test, several panels were repaired and reinforced by means of cement mortar injections (full cement grouting) or reinforced concrete (RC) jackets, and then tested again to determine the effectiveness of the intervention. Particular attention was then devoted to evaluate the referential shear strength τk of these masonry assemblages in the original state. To this purpose, a fitting process for experimental data was used, adopting two different schemes for interpretation of the shear strength of masonry (the Coulomb and the Tumsek-Cacovic equations). The results from this work have shown that the Turnsek-Cacovic equation gives a better fit to experimental data than the Coulomb equation, especially for medium- and poor-quality masonry walls. Finally, conclusions are presented noting the difference between shear strength values calculated from fitting the data from test results and the values suggested by European and Italian standards.

Soil sampling and storage practices for volatile organic analysis must be designed to minimize loss of volatile organic compounds (VOCs) from samples. The En Core® sampler is designed to collect and store soil samples in a manner that minimizes loss of contaminants due to volatilization and/or biodegradation. ASTM D 6418, Standard Practice for Using the Disposable En Core® Sampler for Sampling and Storing Soil for Volatile Organic Analysis, describes the use of the En Core® sampler to collect and store a soil sample for volatile organic analysis. To support the ASTM practice, a study was performed to estimate the precision of the performance of the En Core® devices to store soil samples spiked with low concentrations (

In the past some studies have been carried out to investigate the melt strength of polymers with the purpose of comparing the results obtained with different materials and at different temperatures. In those experimental activities, once that the testing instrument had been chosen, the polymers were considered the object of the investigation and the attention was rarely focused on the testing geometry. The present work, instead, intends to analyze the influence that the geometry of the extrusion die has on the melt strength of polymers. In particular, attention is focused on the analysis of the differences produced on the melt strength of a material, when the extruded filament is subjected, via the use of two different dies specifically designed, to two distinct temperature profiles along the stretching axis. This investigation highlights that the testing geometry chosen for an experimental activity based on melt tension tests, via haul-off measurements, plays a fundamental role in the correct interpretation of the results. In fact it is demonstrated that the correct choice of the extrusion die allows one to obtain results much more similar to the real processing type that, using melt tension tests, has to be analyzed.

Advances in the materials and structure of modern baseball bats have spurred interest in measuring their hitting performance. Many test standards and performance measures have been developed to quantify bat performance. The ability of these tests to simulate a player-swung bat has been largely ignored, however. This study describes the operation of a machine that has been used to measure bat performance and durability. The strain responses of player- and machine-swung bats were compared to determine the ability of laboratory experiments to simulate play conditions. Over much of the range of a full swing, the machine-swung bats experienced considerably higher strain than player-swung bats. During the instant of impact with the ball, however, the response of the player- and machine-swung bats was nearly indistinguishable. The similarity between laboratory tests and a player's swing supports the use of controlled experiments to measure bat performance. The relative response of a bat was shown to depend on the measure used to quantify performance, however. Three measures of bat performance were compared for a series of solid and hollow bats. It was observed that bat-ball efficiency measures may be an unreliable indicator of bat performance in play. Studies have shown that the swing speed depends on the mass properties of the bat and has a large effect on the batted ball speed. Consideration of bat efficiency alone does not fully account for the contribution of a bat-dependent swing speed. It is suggested that bat performance be measured from the batted ball speed in tests using a bat-dependent swing speed.

Thermal power stations that use pulverized coal as fuel generate large quantities of fly ash, resulting in environmental and disposal problems. Increasing demand for power leads to a greater use of coal and hence a further increase in the quantity of fly ash. These problems can be solved if the fly ash is put to use in an environmentally friendly way. Among the various uses for fly ash, the most massive and effective use is in geotechnical engineering applications. The study of fly ash and its interaction with soil is a must towards this goal. In the present investigation, an attempt has been made to study the engineering properties of fly ash—black cotton (BC) soil mixes with special reference to their use as sub-base materials in pavement construction. The study aims to understand the effect of fly ash on the California bearing ratio (CBR) of BC soil. The CBR variation is observed to depend upon the particle size distribution and pozzolanic nature of fly ash. The study indicates that addition of fly ash increases the CBR of BC soil significantly.

The time-compression curve obtained from a laboratory one-dimensional consolidation test generally consists of three parts, namely initial compression, primary consolidation, and secondary compression. While the initial compression occurs immediately after the application of a load increment, the primary consolidation and the secondary compression are time-dependent. It is not known whether both primary consolidation and secondary compression occur concurrently or if the secondary compression begins after the end of primary consolidation, as assumed in general practice. This paper examines this aspect based on the pore water pressure measured at the base of the sample during consolidation. It was observed that the beginning of secondary compression strongly depends on the load increment ratio (LIR). For the inorganic soils tested, the secondary compression begins practically after the end of primary consolidation. When a small LIR of 0.2 is adopted, the secondary compression starts as early as about 55 % of the primary consolidation is over. For the organic soil tested, the secondary compression begins much earlier, compared to the inorganic soils even at a higher load increment ratio. The secondary compression-time relationship can be well represented by a hyperbolic model. The method adopted in this article is capable of separating the primary consolidation and secondary compression from time-compression data once the pore water pressure at the base of the sample is known.

The technique proposed here adopts short-term stress relaxation testing (SRT) to determine the metallurgical life of 1CrMoV large rotor steel. SRT has been performed at two temperature levels of 550°C and 600°C, on samples taken from the core region of a large rotor. At 550°C, five initial prestrains ranging from 0.2–1.0% strain were applied, while at 600°C, the specimens were relaxed from 0.6% and 0.8% prestrains. All test durations were kept between 4 to 5 h. To validate the results, a few conventional creep tests have been conducted at same temperature levels and at different stresses. The initial data, stress versus time, were converted into stress versus inelastic strain rate and the creep life was predicted with the help of the Monkman-Grant relationship (ˊes × tr) = C), where the value of the constant C is taken from experimental creep data. The comparison of creep life, predicted through SRT, with the actual creep data revealed that they were agreeing extremely well at higher test temperature, i.e. 600°C. The computed SRT data have delivered higher activation energy (600 kJ mol−1) than conventional creep testing (344 kJ mol−1). Detailed SEM and TEM studies revealed that degradation and/or development of microstructures had taken place and was commensurable to long-term creep exposure. Therefore, the methodology has the capacity to assess the inherent creep strength of any material.