Abstract: This need is met by the present invention wherein structural stress in a fatigue-prone region of a structure is determined by using the nodal forces and displacement values in the fatigue-prone region, or equilibrium-equivalent simple stress states consistent with elementary structural mechanics in the fatigue-prone region. The determination is substantially independent of mesh size and is particularly well-suited for applications where S-N curves are used in weld fatigue design and evaluation, where S represents nominal stress or stress range and N represents the number of cycles to failure. The present invention is directed to structural stress analysis through various combinations of modeling, calculation, and direct measurement schemes.

Abstract: A method for screening fabric handle of an array of fabric samples (i.e., a plurality of fabric materials) comprising providing an array of at least two fabric samples, protruding the fabric samples through openings, and monitoring response of said fabric samples to the protrusions.

Abstract: A column assembly for use in conjunction with a test machine, for inducing high-cycle fatigue (at kilohertz vibration rates) in a specimen of a material under test. The column assembly has isolation masses, a specimen grip, and two actuators, the latter for imparting dynamic forces to the test specimen. The actuators are arranged on the column assembly asymmetrically relative to the test specimen.

Abstract: A weight measurement method and apparatus for measuring and monitoring the weight load on a vehicle such as a tractor trailer rig. A load pin and bearing assembly mechanically couples the weight of a trailer and its payload to the leaf springs of a tractor trailer truck. The shackle pin is intersected by a longitudinal bore in which multiple strain gage sensors are mounted. A miniature signal processing unit is totally enclosed and shielded within the longitudinal bore and is electrically connected to the strain gage sensors. The signal processing unit develops weight signals that are communicated by conventional low voltage signal cabling to a load display unit in the tractor cab. An offset lubricant passage provides a means for lubricating the load pin bearings while preventing contact of the lubricant with the strain gages, internal wiring and signal conditioner components housed within the main longitudinal bore.

Abstract: A method of testing athletic shoes is provided. The testing subjects athletic shoes to different temperature conditions in one test or different kinetic forces in another test. After undergoing the stressor (temperature, kinetic forces, other) the axial resistance exhibited by the shoe is measured by placing the shoe in the shoe testing device. The device ascertains the amount of torque required to rotate or twist each shoe to a standard amount. These results permits the different models and brands of athletic shoe to be independently categorized and grouped based on their performance with relation to the different stressor placed on the shoe. This would then permit the consumer, health professional and/or consultant to choose an athletic shoe which would assist in correcting pain caused by various degrees of motion in the foot or lower leg. By utilizing the categorizations, along with the needs of the individual, one may select an athletic shoe which can treat the effects of pronation and improper gait.

Abstract: A multiaxial high cycle fatigue test system for testing bending, torsion, and tension of a test unit, comprises servo-hydraulic components, including a hydraulic service manifold, two small high frequency actuators along a first axis, and one large main actuator along a second axis The large main actuator is used to apply a radial centrifugal force, and the two small actuators are used to apply vibratory loading; the two small side actuators being offset independently of each other, to enable the machine to apply both bending loads and torque to the test unit. The test unit is subjected to torsion loading when the traverse actuators move in phase, that is when both actuators move either in or out at the same time. The test unit is subjected to bending loading when the actuators move out-of-phase, that is one actuator moves in when the other moves out or vice-versa.

Abstract: An apparatus, program product, and method for estimating the stress intensity factor ratio (SIFR) of a material. The material is supported on a support and a load is applied to the material using a load member. A pair of strain components are measured using a strain gage attached to the material, and are stored in memory. The strain gage may be a rosette strain gage, for example. A processor calculates a ratio of the stored pair of strain components to thereby provide an estimate of the SIFR of the material. Advantageously, this estimate of the SIFR of the material is readily provided. Also advantageously, the estimate may be provided in a manner that is non-destructive to the material. The processor may additionally calculate the stress level of the material based on the estimated SIFR.

Abstract: A system (200) monitors a load associated with a load carrying member. The system (200) may include a voltage divider (240) and a computer device (250). The voltage divider (240) measures inductance associated with load sensing elements (210) that monitor the load carrying member. The computer device (250) determines displacements of the load sensing elements (210) based on the inductance associated with the load sensing elements (210) and determines the load associated with the load carrying member based on the displacements of the load sensing elements (210). The system may be designed to be portable and/or DC powered.

Abstract: An apparatus and method for screening combinatorial libraries of materials by measuring the response of individual library members to mechanical perturbations is described. The apparatus generally includes a sample holder for containing the library members, an array of probes for mechanically perturbing individual library members, and an array of sensors for measuring the response of each of the library members to the mechanical perturbations. Library members undergoing screening make up a sample array, and individual library members constitute elements of the sample array that are confined to specific locations on the sample holder. During screening, the apparatus mechanically perturbs individual library members by displacing the sample array (sample holder) and the array of probes. Typically, all of the elements of the sample array are perturbed simultaneously, but the apparatus also can also perturb individual or groups of sample array elements sequentially.

Abstract: An apparatus and method for screening combinatorial libraries of materials by measuring the response of individual library members to mechanical perturbations is described. The apparatus generally includes a sample holder for containing the library members, an array of probes for mechanically perturbing individual library members, and an array of sensors for measuring the response of each of the library members to the mechanical perturbations. Library members undergoing screening make up a sample array, and individual library members constitute elements of the sample array that are confined to specific locations on the sample holder. During screening, the apparatus mechanically perturbs individual library members by displacing the sample array (sample holder) and the array of probes. Typically, all of the elements of the sample array are perturbed simultaneously, but the apparatus also can also perturb individual or groups of sample array elements sequentially.

Abstract: The invention relates to a crack testing system using the dye penetration method or for magnetic crack testing, having an illumination unit, a device for applying testing material and an evaluation station, which has light-emitting diodes (LEDs) as illumination units.

Abstract: A weight measurement method and apparatus for measuring and monitoring the weight load on a vehicle such as a tractor trailer rig. A load pin and bearing assembly mechanically couples the weight of a trailer and its payload to the leaf springs of a tractor trailer truck. The shackle pin is intersected by a longitudinal bore in which multiple strain gage sensors are mounted. A miniature signal processing unit is totally enclosed and shielded within the longitudinal bore and is electrically connected to the strain gage sensors. The signal processing unit develops weight signals that are communicated by conventional low voltage signal cabling to a load display unit in the tractor cab. An offset lubricant passage provides a means for lubricating the load pin bearings while preventing contact of the lubricant with the strain gages, internal wiring and signal conditioner components housed within the main longitudinal bore.

Abstract: A fretting fixture accessory for a_test machine (10) that induces high-cycle fatigue (at kilohertz vibration rates) in a specimen of a material under test. The fretting fixture (20) is clamped to the test specimen (21), for the purpose of testing for fretting damage. The fixture (20) is designed to provide both the normal and shearing forces that result in fretting damage.

Abstract: A stress testing apparatus includes a cylinder block 2 with twelve cylinders 4, each housing a piston 14. Hydraulic pressure is provided to each of the cylinders 4 by a common supply bore 6 for urging each piston 14 out of its respective cylinder 4. A stress testing device 16 is mounted over each cylinder 4 and piston 14. For tensile testing (see FIG. 3) of a specimen (X), a piston (14a) acts on the housing (28a) of the device (16a) through pins (26), to push the housing (28a) away from the cylinder block 2. The specimen X is mounted between the housing (28a) and the cylinder block 2. For compressive testing (see FIG. 4), of a specimen Y the housing (28b) is rigidly secured to the cylinder block 2, and the cylinder (14b) acts to compress the specimen Y between the housing (28b) and the cylinder block 2 through a shaft (22b).

Abstract: A force transducer assembly for measuring compressive and tensile loads applied to a force transmission device, the assembly includes a housing, a sleeve assembly and a sensor device. The housing has a hollow interior. The sleeve assembly is coupled within the interior of the housing. The sensor device is secured within the interior of the housing between a portion of the sleeve assembly and a portion of the housing. The sensor device includes first and second sensors each including an isolation diaphragm at least partially defining an oil-filled cavity, and a piezoresistive sensor positioned so as to be effected by a change in pressure in the oil-filled cavity. When a first force is applied to the apparatus in a first direction via the force transmission device, one of the isolation diaphragms is deflectable in response thereto, and when a second force is applied in a second direction opposite to the first direction, the other of the isolation diaphragms is deflectable in response thereto.

Abstract: A system and method for evaluating flexible structures such as textiles under load generally. A specific embodiment is shown for parachutes. A plurality of first sensors and second sensors are attached to the parachute on its canopy and suspension lines. Preferred first sensors are fiber Bragg gratings (FBG) type sensors, and preferred second sensors are modal power distribution (MPD) type sensors. A fiber optic network interconnects the pluralities of first and second sensors to provide sensor outputs which are converted to electronic signals, modulated and transmitted to a receiving station for receiving and processing the transmitted modulated electronic signals. The preferred fiber optic network includes a plurality of light emitting diodes positioned at one end of each fibers and a photodiode array positioned to receive light from each of the fibers.

Abstract: A stress evaluation method for evaluating stress acting on a test piece includes the steps of transmitting acoustic waves including a surface wave, a longitudinal wave, and a shear wave through the test piece; receiving the acoustic waves after they have propagated through the test piece; obtaining acoustic velocities of the surface wave at a non-loaded portion and a loaded portion of the test piece based on the received acoustic waves; evaluating a stress in a surface layer of the test piece based on a difference between the surface wave acoustic velocities at the non-loaded portion and the loaded portion and a predetermined relationship between surface wave acoustic velocities and stresses; obtaining an acoustic velocity of the longitudinal wave at the non-loaded portion based on the received acoustic waves; calculating an acoustic velocity of the shear wave at the loaded portion based on the received acoustic waves and the longitudinal wave acoustic velocity at the non-loaded portion; evaluating an interna

Abstract: To detect changes of a load on a vehicle in two directions simultaneously by itself. A width-direction load sensor (3) and a thickness-direction load sensor (4) are mounted on a sensor portion (2b) of a sensing device (1) interconnecting fixing portions (2c) and (2c) defined respectively by opposite end portions of a plate-like member (2) spaced from each other in a longitudinal direction (X) of the plate-like member (2) having an insulating film coated on a surface thereof, the two load sensors being spaced from each other in the longitudinal direction (X) of the plate-like member (2).

Abstract: A stress composite sensor has sensor elements each including a base plate having a rectangular configuration and a first main surface and a second main surface opposite the first main surface, a pair of first strain gauges disposed on the first main surface crossing one another, a pair second strain gauges disposed on a the second main surface crossing one another, the first pair of strain gauges and the second pair of strain gauges being symmetrically disposed with respect to a center plane of the base plate; and bridge circuits incorporating the first pair of strain gauges and the second pair of strain gauges. The sensor elements include X-sensor elements for measuring stress in an X-direction, Y-sensor elements for measuring stress in a Y-direction, and Z-sensor elements for measuring stress in a Z-direction. Arithmetic circuits calculate stress from outputs of the bridge circuits.

Abstract: A method and apparatus for measuring ligand binding to DNA or protein uses changes in the mechanical properties of strips of the DNA or protein to detect the formation of ligand complexes. Samples strips are prepared by pouring protein solution onto a glass surface, drying the solution, and causing the protein to be cross-linked; the cross-linked film is scraped off, cut into strips, and mounted in the stress/strain measuring apparatus, which includes force and strain transducers. The sample is held by arms and can be immersed into solutions. The arms are attached to transducers. The apparatus includes a sample holder. The sample films may include end reinforcements and may be pinned or glued to the arms.

Abstract: A golf club shaft blank is clamped at its butt end and deformed at its tip end to establish the longitudinal deformation characteristics of the shaft blank. The shaft is repositioned relative to the clamp and then reclamped at a new location which, when deformed, has the desired longitudinal deformation characteristics. The shaft is sawed to the desired length by removing material from the butt end and the tip end of the shaft.

Abstract: A plurality of strain gages are installed on a structural body at n positions thereon. A concentrated reference load is applied to the structural body at one of the n positions and strains developed in the structural body at the respective n positions are measured when the concentrated reference load is applied to the structural body. The measured deformations are divided by the concentrated load reference to produce strains per unit load. The above process is repeated at each of the n positions to generate the practical equations given below: ##EQU1## where .kappa.11.about..kappa.nn represent strains per unit load, A1.about.An represent estimated loads (unknowns), and .epsilon.1.about..epsilon.n represent measured strain data.

Abstract: The invention is a machine for the cyclic load testing in tension, compression, torsion, shear, or any combination thereof of any one of a number of different sizes, types and configurations of test specimens at a fixed or adjustable predetermined load and cycle rate and comprising a machine frame in which is mounted a drive shaft, any number of intermediate shafts as required, and a camshaft or crankshaft. At the workstation of the machine, appropriate fixtures and tooling are either fixed, rotating, or in motion, as required to conduct the particular test to be performed. When the test specimen is to be in motion, the motion may be derived from a driving source separate from the primary mover or camshaft, for instance but not limited to an independent motor or cylinder. This source of motion may also be taken through a drive train or any suitable means from the same driving source as the camshaft or from the camshaft itself or from any other moving member in the system.

Abstract: An improved technique to more accurately calculate pore pressure of sedimentary rock due to subsurface fluid expansion where the technique is built upon a combination of known force balanced in situ loading limb mineralogical stress/strain relationships with locally variable unloading stress/strain relationships, including that in stress/strain space, the material properties governed loading limb is an upper limit for the many possible unloading limbs; also, a method for relating these different natural stress/strain paths and applying the correct path to calculate pore fluid pressure from in situ force balance is disclosed such that the method is preferably calibrated with in situ stress/strain data which allows for a lithologic sealing caprock to be identified and the locally prevailing in situ unloading limb stress/strain relationship to be estimated, where the forced balanced loading and unloading calibrations are applied to more accurately determine well casing depths using either wireline or real-time "

Abstract: A system (50) for determining strain includes: a stimulating light source (54, 56); a device (64) for placing stress on an object (58); a number of local strain gauges (66) attached to the object (58); and an image capturing device (62, 64). A controller (52) is coupled to the stimulating light source (54, 56) and has a signal that turns on the stimulating light source (54, 56). The controller (52) receives a strain signal from each of the local strain gauges (66) located on the object (58). The controller (66) has an image signal that determines when the image capturing device (62, 64) captures an image.

Abstract: A method for non-destructive determination of a fatigue limit for a component includes two sub-methods which may be performed separately, or in any order. A direct-deformation sub-method includes measuring micro-plastic deformation corresponding to each of a plurality of different known values of stress applied to the component, and identifying a critical value of stress corresponding to a change in the relationship between stress and micro-plastic deformation. An internal-friction damping method includes initiating torsional oscillations in the component, measuring an initial angular amplitude of oscillation, A.sub.0, and a final angular amplitude of oscillation, A.sub.n at the end of the number, n, of oscillations. This process is repeated a number of times and, for each pair of measurements, a corresponding measure of damping is calculated. A critical value of initial angular amplitude corresponding to a change in the relationship between amplitude and damping is then calculated.

Abstract: Foundry sand testing apparatus, method and system are provided for testing foundry sand. A computer foundry sand testing system includes at least one sensor for sensing predetermined characteristics of the foundry sand and for generating a signal. A processor coupled to the sensor processes the generated signal. A display is operatively controlled by the processor for displaying predetermined test information responsive to the generated signal. Predefined displays for receiving user selections and for displaying of test information are automatically generated. The generated displays of test information include real-time stress-strain curves and multiple calculated values utilizing the stress-strain curves.

Abstract: A sand pack holder is provided for testing the properties of a sand sample or testing the performance of an oil recovery process in the sample. The sample is pressurized within the holder to simulate reservoir condition.

Abstract: The present invention is intended to provide a stress detecting and measuring method wherein in order to measure a shearing strain alone associated with a stress acting in an intended direction, the stress being one of the stresses acting on an axle of a vehicle or a structure having a fixed support point adjacent the axle, the conditions for the optimum position where a stress sensor is to be mounted are indicated. Further, the invention is intended to provide a stress detecting device which accurately measures a shearing strain alone associated with a stress acting in an intended direction by further separating a plurality of stresses acting on a stress sensor. For example, in the case where stresses are applied in two directions to a structure having a fixed support point, in order to measure a shearing strain alone associated with a stress acting in an intended direction, a stress sensor should be mounted in a position which is a transformation knot zone for the other stress strain, i.e.

Abstract: A stress evaluation method for evaluating stress acting on a test piece includes the steps of transmitting acoustic waves including a surface wave, a longitudinal wave, and a shear wave through the test piece; receiving the acoustic waves after they have propagated through the test piece; obtaining acoustic velocities of the surface wave at a non-loaded portion and a loaded portion of the test piece based on the received acoustic waves; evaluating a stress in a surface layer of the test piece based on a difference between the surface wave acoustic velocities at the non-loaded portion and the loaded portion and a predetermined relationship between surface wave acoustic velocities and stresses; obtaining an acoustic velocity of the longitudinal wave at the non-loaded portion based on the received acoustic waves; calculating an acoustic velocity of the shear wave at the loaded portion based on the received acoustic waves and the longitudinal wave acoustic velocity at the non-loaded portion; evaluating an interna

Abstract: Disclosed is a device for measuring lateral deformation in an material spmen which includes a generally ring shaped frame member displaced generally perpendicularly to the object being measured. The frame member itself comprises a first and a second generally arc shaped element which abut end to end. At least one spring arm member is fixed at one end on a mounting projection on the first arc shaped element and its movable end abuts a spring receiving projection from the second generally arc shaped element. Strain gauges are fixed to the spring arm member to detect changes in the flexture of the spring arm member resulting from relative movement of the two arc shaped elements which results from lateral deformation of the material specimen. A linear variable differential transformer having a lateral projection is also mounted on one of the arc shaped elements.

Abstract: Keratin fiber condition is evaluated by testing dry hair to determine analysis factors. For each factor, two values of elongation are determined by measuring the force required to obtain a first value and a second value of elongation of the fiber. The percent total elongation of the fiber to its break point is also determined. The ratio of the two measured forces is used with the percent total elongation in empirically derived nonlinear equations to determine analysis factors, such as a condition factor and a moisture factor. It is found that each factor is independent of fiber diameter or the source of the fiber. It is also found that the factors change as a function of subjective or objective measures of chemical damage to, and moisture content of, the hair fiber. The factors can, therefore, be used for identifying hair care products suitable for application to the hair without inducing unacceptable damage.

Abstract: An end-cap-to-piston coupling, with or without an integral load cell has been developed for triaxial test apparatus. One triaxial test apparatus shown has a housing, sample mounting apparatus in the housing, a load piston opening through the housing through which projects a load piston, and a load transfer coupling, with or without an integral load cell, interposed between the end cap and the load piston. In one aspect the coupling has a coupling body and a channel on one end into which the load piston is inserted to contact a shoulder of the coupling body. Another end of the coupling has a channel which receives a top end cap of a sample mounting arrangement. This channel may be sized and configured to receive a load transfer ball interposed between the coupling and the end cap or between the coupling and the piston. In one aspect a series of interchangeable top and bottom members are provided, each with a different diameter recess, to accommodate load pistons and sample end caps of different diameters.

Abstract: A multicomponent force and moment measuring arrangement wherein shear forces are converted into moments and transmitted via tensile-compressive forces onto piezoelectric rod elements, while axial compressive-tensile forces are transmitted directly onto the same piezoelectric rod elements. With appropriate arrangement of the piezoelectric rods and their signal evaluation, transducers and dynamometers of entirely new type can be constructed, in which the necessary electronics package can be located between the piezoelectric rod elements for certain applications.

Abstract: The present invention relates to a test cell 1 suitable for use in applying directionally variable three dimensional stress fields to cylindrical test specimens 6 normally obtained by conventional coring techniques used for sample recovery. The test cell 1 comprises a cell body 2 having a barrel 4 extending therethrough for receiving a test specimen 6. The barrel 4 has an array 8 of elongate tubes 10 mounted side-by-side so as to line the inside wall 12 of the barrel. The tubes 10 have flexible side walls 14 and are formed and arranged for connection to a pressurized fluid supply 16. The test cell 1 also includes a control system 15 so that at least one tube 10a can be supplied with pressurized fluid at a different pressure to that in another tube 10b so as to provide an angularly variable radial pressure loading on the test specimen 6 mounted in the barrel 2.

Abstract: The invention relates to a test apparatus for carrying out analysis on fluids or components comprising two specimens which are movable with respect to each other by means of an oscillating driving means. Means are provided for applying a measurable load between the two specimens. The oscillating driving means further comprises a stiffness adjusting means in order to control the degree of lateral movement of the oscillating driving means. The test apparatus also comprises a force measuring means which is connected to a support which is relatively much heavier than the oscillating driving means and the specimens in order that accurate results are achieved.

Abstract: A method and apparatus for determining the stress-slip relationship of specimens in concrete including a pipe with a plurality of longitudinal slots evenly spaced around the circumference of the pipe, a specimen and concrete block located in one end of the pipe, a confining device for applying a constant force to the circumference of the concrete block before, during and after a test, a device for measuring the displacement of the specimen relative to the concrete block, and a device for measuring the radial displacement of the concrete block.

Abstract: A core sample from an oil or gas well can be quickly and easily inserted and removed relative to a reusable sealing sleeve fixed within a test housing wherein the core sample is tested for both longitudinal and lateral strain in response to applied stress. Young's modulus and Poisson's ratio can be determined from the strain and stress information. Pressures and temperature can be set to simulate downhole conditions inside the apparatus.

Abstract: An self-aligning biaxial loading apparatus for use in testing the strength of specimens while maintaining a constant specimen centroid during the loading operation. The self-aligning biaxial loading apparatus consists of a load frame and two load assemblies for imparting two independent perpendicular forces upon a test specimen. The constant test specimen centroid is maintained by providing elements for linear motion of the load frame relative to a fixed crosshead, and by alignment and linear motion elements of one load assembly relative to the load frame.

Abstract: A gyratory shear material compacting device in which a material sample is placed within a cylindrical mold having a wobble plate. The material sample is compressed by a piston while the mold is simultaneously gyrated. Gyration is achieved by tilting the mold and holding the wobble plate within rollers which revolve around the mold, controlling the selected angle of tilt while imparting oscillatory gyration. The selected angle of tilt of the mold may be precisely controlled at all times, preventing the mold from riding up on the sample, or from coming into contact with the base of the device. The mold is free to advance rotationally. The device is capable of measuring and recording the height of the sample, angle of gyration, and moment of gyration.

Abstract: Methods and apparatuses for measuring ultrasonic velocities in materials are disclosed which, in one embodiment, include such methods and apparatuses for triaxial tests of low permeability rock samples, the apparatus including top and bottom end caps for mounting to a sample to be tested, each end cap having an ultrasonic transducer mounted therein for disposition in contact with the material to be tested for measuring the velocities of ultrasonic waves through the material. In another embodiment, at least one end cap having channels and a sensor for sensing changes in sample pore pressure is disclosed. In another aspect, a pressure generator or microaccumulator for changing the amount of a pore pressure fluid in the channels, thereby changing sample water content and making possible an efficient multistage test is disclosed. In another embodiment an end cap for such measurements is disclosed.

Abstract: A femoral component of a hip endoprosthesis includes a lateral supporting wedge designed to be supported by the proximal lateral femur when in use. The wedge can be an integral part of the material of the femoral component or it can be placed on a standard component by cementing or preferably by a male/female socket fit. The lateral surface of the wedge forms an angle of about 10.degree.-20.degree. with the midline of the distal portion of the stem and has an anterior-posterior width of about 8.30 mm, preferably about 10-20 mm, and a medial-lateral extension of the lateral surface of the stem of at least 10 mm, preferably 10-30 mm. An apparatus for testing the endurance of femoral components includes a cable corresponding to the ilio-tibial band. Such an apparatus more accurately models hip biomechanics and thus permits a more accurate test of the stresses on femoral component designs.

Abstract: Methods and apparatuses for quantitatively measuring the strengths, pore pressures, and mechanical properties of low permeability geologic materials, such as shales, including test specimen preparation apparatus for adjusting test specimen water content and test apparatus with an end cap having a pore pressure transducer channel disposed adjacent a test specimen filled with an immiscible, inert fluid which does not wet the test specimen, and controlling the deviatoric load on the test specimen during the test to prevent premature failure.

Abstract: According to the method of this invention, a ski to be tested is supported at its mid-point and near its tip and tail respectively. It is clamped at the mid-point and just aft of the tip of the ski. The afterbody and the forebody of the ski are deflected through predetermined distances, whereupon the force necessary to produce the deflection is measured by a strain gauge. Similarly, the forces produced in the ski when the forebody of the ski is twisted by the application of a couple thereto to produce a predetermined torsional deflection are measured and recorded. The disclosure includes a suitable tip station, center station, and tail station mounted on an elongated base, which may comprise a pair of hollow metal cylinders that act as reservoirs for storage of compressed air for actuation of pneumatic means for application of forces to the ski.

Abstract: A flat cross-shaped test piece is made of sheet metal for biaxially testing of its material. This test piece includes a central region that defines an area of measurement. Four arms for applying loads to the central region extend from the central region along orthogonal axes. Each arm has one end integral with the central region and an opposite end with an end part for connection to a test device for the application of a test load. Tensile stresses can thus be applied to the central region along first and second orthogonal coordinate axes of the central measurement region. Slots in the load applying arms extend along the arms parallel to the first and second coordinate axes from the end part as far as and up to the area of measurement. The slots in the load applying arms prevent the escape of stress trajectories along the arms, thus making it possible to obtain a homogenous stressed state in the central measurement region.

Abstract: A method and apparatus for testing a test piece having opposing ends includes connecting the ends of the test piece to a first load head and to a plate which may be attached to a second test head, respectively. The device actuates a driving device to spatially adjust the load head to apply a variable load to the test piece. The device determines the magnitude and direction of load head displacement variables applied to the load head, measures the actual magnitude and direction of displacement of the load head in relation to a fixed plate, sets and varies boundary conditions of the test piece from the displacement of the load head, compares actual values of the boundary conditions with freely programmable predetermined desired values of the boundary conditions, and determines a control variable for the driving device.

Abstract: A knee loading and testing apparatus has tibia and femur bone mounting units, respectively, and a quadricep loading means and unit for automatically manipulating the mounting means to the quadricep loading means to derive data regarding the knee joint. The quadricep is variably controlled to allow variation in the torque and pull and at the same time, both the femur and tibia mountings are independently articulatable, and further, these various loadings may be controlled and recorded by a computer and the response to the joint to various loadings may be recorded for future study and analysis by any computer. Preset limits on the application of the quadricep force and body weight are provided and the operator is provided with a visual and audible signal indicating the overload. The machine also disables the control from further increasing these load functions and while the controls for decreasing this loading remain operable.

Abstract: A delamination test apparatus and method uses a single beam to simultaneously apply opening and shear stresses to a test specimen. A fulcrum extending downwardly from the beam produces shear stress in the specimen by downward movement, and opening stress by pivotal upward movement of the beam, which results by virtue of the fact that the applied load is on one side of the fulcrum while the test specimen is connected to the beam on the opposite side of the fulcrum.

Abstract: A device for allowing deformation measurement of a jacketed specimen when the specimen is loaded includes an elastomeric specimen container or jacket surrounding a specimen while the specimen is being loaded by a test apparatus. The specimen jacket wall is compressible, and the wall follows and allows deformation of the specimen. The jacket wall of compressible material is provided with at least one opening and a thin layer or shim of substantially non-compressible (metal) material covers and seals this opening. An extensometer is then positioned with its specimen engaging contact members engaging the substantially non-compressible material to measure the deformation of the specimen when the specimen is loaded, without compressibility effects of the jacket.

Abstract: A method of determining the mechanical behavior of solid materials by using stress field modified miniature specimens. The method is an improvement in the method of determining mechanical behavior information from specimens only so large as to have at least a volume or smallest dimension sufficient to satisfy continuum behavior in all directions. Mechanical behavior of the material is determined from the measurements taken during the loading of the specimen resulting in the formation of cracks and/or the further propagation of cracks in the miniature specimen. The specimens include construction features for applying additional stress field modifying loads upon the specimens during the test. These additional loads result in a desired stress state in the specimen which could not be achieved otherwise. A particular example is the introduction of a transverse tensile load during a bend test to increase the transverse stress field to achieve plane strain conditions in a thin specimen.