Abstract: The alternating current potential drop ACPD technique is used to monitor surface cracks in electrical conductors. At high frequencies, the current flows in a superficial skin layer. Two distinct solutions are currently available for the thin and thick skin cases. However, there is no general solution that bridges these two modes in a seamless fashion. A numerical model is used to analyze the ACPD of a surface crack with uniform depth. A general solution is given that bridges the thin and thick skin solutions, which closely matches the numerical results, irrespective of the skin thickness. Methods for estimating depth of cracks are provided for surface penetrating cracks and back cracks.

Abstract: A method for detecting a crack in a frame is disclosed. The method includes sensing with a first pressure sensor a first pressure within a first sealed cavity. The first sealed cavity is interior to a first structure of the frame. Additionally, the method includes detecting a first change in the sensed first pressure. The method also includes determining preliminarily that a crack has formed in the first structure based on the detected change in the sensed first pressure. In addition, the method includes determining a criticality of the crack.

Abstract: Vacuum sensor application and method for firmly joining a sensor workpiece to a body component, where a) firstly, an adhesive layer which is provided by a cross-linked transfer contact adhesive is laminated to a sensor contact surface of the sensor workpiece, b) then, by using known radiation methods, the geometric patterns of a plurality of galleries to be arranged in a laminar fashion are transferred to the sensor contact surface by a light beam that penetrates the transfer contact adhesive, are subsequently introduced into the sensor workpiece and, in the process, are removed congruently with the structures of the adhesive layer introduced into the sensor workpiece, c) the adhesive-laminated patterned sensor contact surface is then arranged on a defined surface region of the body component surface, d) after that, a mechanical pressure is exerted on the two joint partners, with which the adhesive-laminated patterned sensor contact surface and the body component surface region (3) are pressed together.

Abstract: A finite element method for predicting crack opening and propagation entails defining a succession of overlapping interface elements at a potential crack plane, each element having a bound node pair and side node pairs spaced from the bound node pair to sense approach of a crack. An energy-based fracture mechanics criterion determines whether release occurs at the bound nodes and, if so, the displacement between the bound nodes is calculated based on a strain softening law. The process is repeated for each element in sequence.

Abstract: Methods and apparatus for detecting particles flowing in a fluid within a conduit involve analysis of acoustic pressure signals detected with an array of at least two pressure sensors. The analysis can include monitoring for attenuation in power of the acoustic disturbances within the fluid and/or a reduction in a speed of sound in the fluid. This attenuation in power or reduction in the speed of sound can be detected to provide an output or otherwise indicate that particles are present in the fluid.

Abstract: In a method and system for evaluating sub-critical fatigue crack growth in a semiconductor device, a plurality of energy pulses generated by an energy source are repeatedly impinged onto the semiconductor device for a predefined time interval. The repeated impinging of the plurality of energy pulses induces a mechanical stress within the semiconductor device. The induced mechanical stress, maintained below a threshold and repeated for a predefined number of cycles, causes a formation of a sub-critical fatigue crack within the semiconductor device. A detector detects the presence of the sub-critical fatigue crack leading to a fatigue failure. A rapid determination of a pass or fail status for a fatigue test of the semiconductor device is made by comparing a total number of cycles to fatigue failure to a predefined benchmark.

Abstract: The aim of the invention is to create a method that is as accurate and reliable as possible for metrologically determining the end of a test interval (PI) which is to be maintained to perform a periodical test on pressure vessels (1) subject to load variations within operating cycles (AZ). Said aim is achieved by a method in which the maximum working pressure (p) actually reached inside the pressure vessel (1) per working cycle (AZ) is measured by means of a pressure sensor (2), a load variable (BG) is determined per working cycle (AZ) based on the working pressure (p) measured per working cycle (AZ), a resulting load value (BW) is determined for several successive working cycles (AZ) based on the respective load variables (BG) determined per working cycle (AZ), and the resulting load value (BW) is compared to a predefined comparative value (VG)).

Abstract: The present invention relates to a method of measuring residual stress and, more particularly, to a residual stress measuring method using a continuous indentation tester. Due to pile-up and sink-in of a material or a blunted tip, a conventional residual stress measuring method cannot compensate for error of a real contact (indentation) depth or directly remove stress through a thermal or mechanical technique in the conventional method of measuring residual stress of a weldment, so that it is very difficult to estimate a stress-free reference curve or to quantitatively measure residual stress. However, the present invention can precisely estimate a stress-free curve of a weldment using an indentation strength ratio (OIT ratio) of a stress-free base metal to the weldment, and compensates for error, occurring in the measurement of a material having a weldment or an anisotropic stress structure, based on the indentation strength ratio, thereby more precisely measuring residual stress.

Abstract: Acoustic weight or mass sensing technology (referred to here as Acoustic Weigh In Motion (AWIN)) provides accurate weighing of any type of moving load moving over a load bearing medium. Acoustic transducers are affixed to or embedded in the load bearing medium. One or more source acoustic transducers propagate an acoustic wave over an acoustic path through the medium between the source and receiver transducers when the medium is in an unloaded state. The wave is detected at one or more receiving acoustic transducers. A propagation time delay is determined for the unloaded state. When a moving load travels over the acoustic path in the medium, the acoustic propagation time delay for that loaded state is determined. The difference between the acoustic propagation time delays for the unloaded and loaded states is determined. That acoustic propagation time delay difference is used to determine the weight or mass of the moving load.

Abstract: The PENT value for a resin may be estimated within ±10% by determining the % of heat flow to melt a fraction of a polymer above or below a set point and comparing it to a graph or algorithm of PENT values related to the % of heat flow to melt entire sample for a number of resins made using the same catalyst system. In a similar manner one may estimate the process conditions to prepare a polymer having a target PENT value based on the conditions used to prepare the samples for the graph or algorithms. The invention provides a simple procedure that may be used at a manufacturing site to estimate PENT values.

Abstract: Vacuum sensor application and method for firmly joining a sensor workpiece to a body component, where a) firstly, an adhesive layer which is provided by a cross-linked transfer contact adhesive is laminated to a sensor contact surface of the sensor workpiece, b) then, by using known radiation methods, the geometric patterns of a plurality of galleries to be arranged in a laminar fashion are transferred to the sensor contact surface by a light beam that penetrates the transfer contact adhesive, are subsequently introduced into the sensor workpiece and, in the process, are removed congruently with the structures of the adhesive layer introduced into the sensor workpiece, c) the adhesive-laminated patterned sensor contact surface is then arranged on a defined surface region of the body component surface, d) after that, a mechanical pressure is exerted on the two joint partners, with which the adhesive-laminated patterned sensor contact surface and the body component surface region (3) are pressed together.

Abstract: A method and apparatus for estimating a depth of a crack from ultrasound scan data are provided. The method includes mapping multiple amplitude responses from the ultrasound scan data, each mapped amplitude response being representative of a signal from one of the sensors. The method further includes locating multiple linear responses among the mapped amplitude responses, each linear response being an indicator of a reflected signal from the crack. One or more sensor that corresponds to the linear responses from a given crack is identified. The depth of the crack is estimated using data from the identified sensors.

Abstract: A sensor has a plurality of carbon nanotube (CNT)-based conductors operatively positioned on a substrate. The conductors are arranged side-by-side, such as in a substantially parallel relationship to one another. At least one pair of spaced-apart electrodes is coupled to opposing ends of the conductors. A portion of each of the conductors spanning between each pair of electrodes comprises a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis. Because a direct correlation exists between the resistance of a carbon nanotube and its strain, changes experienced by the portion of the structure to which the sensor is coupled induce a corresponding change in the electrical properties of the conductors, thereby enabling detection of crack growth in the structure.

Abstract: The present invention is based on the recognition that some materials contain a magnetically susceptible or magnetic component. That is, they exhibit ferromagnetic, paramagnetic, diamagnetic or magnetic properties. According to the invention, it is possible to determine the presence of a magnetically susceptible or magnetic component in a sample of a material by obtaining a sample of the material, positioning the sample at a predetermined distance from a magnet and then measuring the magnetic force on the sample by the magnet. The force is measured using a force transducer. To obtain the magnetic force per unit gravitational force, the gravitational force on the sample is measured out of the presence of the magnet and the measured magnetic force is then divided by the gravitational force exerted on the sample. A sample thickness adjustment is necessary if comparing samples of different thicknesses.

Abstract: A multiple testing system has plural testing units which are disposed independently, and a single information processing device. The testing unit has a frame, a loading mechanism supported at the frame and applying a desired load quantity on a test body, and a detector detecting a load quantity applied on the test body. By multitasking control and with respect to the testing units, the information processing device carries out: feedback control processing for, on the basis of a detected load quantity, controlling the loading mechanism such that the detected load quantity becomes a predetermined target value; control processing at an abnormal situation when at least one of an abnormality of the test body, an abnormality of the testing unit, or an abnormality of a power source of the loading mechanism, is detected; and interface processing with an operator.

Abstract: A system and method are provided for detecting cracks and their location in a structure. A circuit coupled to a structure has capacitive strain sensors coupled sequentially and in parallel to one another. When excited by a variable magnetic field, the circuit has a resonant frequency that is different for unstained and strained states. In terms of strained states, the resonant frequency is indicative of a region of the circuit that is experiencing strain induced by strain in a region of the structure in proximity to the region of the circuit. An inductor is electrically coupled to one end of each circuit. A magnetic field response recorder wirelessly transmits the variable magnetic field to the inductor and senses the resonant frequency of the circuit so-excited by the variable magnetic field.

Abstract: A method for predicting the location of stress corrosion cracking in a steel gas pipeline in which in-line stress corrosion cracking smart tool data, external low level metal loss data and soil characterization data are compiled to predict the location of stress corrosion cracking in a steel gas pipeline segment.

Abstract: One embodiment of the invention is a method for evaluating a material such as low-k dielectric, by a stress-generating test tool such as a needle. The evaluation object is shaped as a stack of adhering layers: low-k dielectric, first metal (preferably copper), barrier metal (preferably tantalum nitride), and second metal (preferably aluminum). A numerical correlation is established between a cracking in the barrier metal layer caused by probing and a damage in the layer of insulating material-to-be-tested. A predetermined number of locations of the top metal layer is selected for the probing step comprising touch-down, applying force, and lifting is repeated so that the number of repeats provide a pre-determined statistical confidence level.

Abstract: An apparatus for measuring relative displacement between a first shaft and a second shaft includes first and second rotor assemblies. The first rotor assembly is coupled to the first shaft and is centered on an axis. The second rotor assembly is coupled to the second shaft. The second rotor assembly has first and second stator plates. Each of the first and second stator plates includes an upper surface and a lower surface. The upper and lower surfaces are parallel. The first and second stator plates include a plurality of teeth extending in a direction radial of the axis. The first and second stator plates form a gap between the lower surface of the first stator plate and the upper surface of the second stator plate. The apparatus further includes at least one magnet having a magnetic field and disposed on the first rotor assembly and a sensing device disposed within the gap for sensing a magnetic flux of the magnetic field.

Abstract: Instrumentation for monitoring crack growth using a change in electric potential across a starter crack as the crack propagates is disclosed. The instrumentation includes a specimen of a material to be analyzed for crack growth propagation having a surface with a starter crack formed therein, a plurality of current leads to pass electric current through the specimen, a layer of insulating material disposed on each of opposite sides of the crack, a layer of conductive material disposed on each layer of insulating material, where a portion of each layer of conductive material is in electrical contact with the first specimen surface, and a pair of sensing leads, one sensing lead attached to each layer of conductive material. A method for using the instrumentation to monitor crack growth by measuring is also disclosed.

Abstract: A ceramic armor system with built-in conductive circuit attached to a ceramic component. The conductive circuit can be accessed by a user at contacts provided in the system. The circuit is arranged so that damage such as cracks that occurs within the ceramic component can propagate into the conductive material forming the circuit and thereby cause a rupture in the conductive circuit. An electrical probe such as an ohmmeter is used to measure the conductive circuit resistance that is then checked against an expected value. The results are used to determine if the ceramic armor component is in operable condition.

Abstract: An apparatus for monitoring the structural integrity of a component. A monitoring structure is applied to a component that is subject to structural degradation. The monitoring structure includes an electrical conductor that becomes cracked if the component becomes structurally degraded. When the component is a ductile metal component that may be degraded by bending, the electrical conductor is formed of a brittle material that cracks when the ductile metal component is bent. When the component is a brittle ceramic heat shield wherein a crack having a critical length is of concern, the electrical conductor is located at a predetermined location wherein a critical length crack in the component will propagate into the conductor. A crack in the electrical conductor is detected with a monitoring device to indicate a degraded structural condition in the component.

Abstract: A method and system for detecting, locating and quantifying a physical phenomena such as strain or a deformation in a structure. A minimum resolvable distance along the structure is selected and a quantity of laterally adjacent conductors is determined. Each conductor includes a plurality of segments coupled in series which define the minimum resolvable distance along the structure. When a deformation occurs, changes in the defined energy transmission characteristics along each conductor are compared to determine which segment contains the deformation.

Abstract: An acoustic energy-based, non-contact or contact testing approach provides low cost, highly accurate, and reliable information to (a) identify flaws and anomalies and (b) assess the integrity of a particular material. This approach is not hindered by surface conditions or impediments, and indeed, looks beneath the surface of the material by propagating an acoustic wave through the material using two differential transducers. A dynamic differential measurement is made of the material under a load condition and an unloaded condition that allows identification and assessment of various characteristics of the material. Multiple “windows” of information may be generated that permit (a) direct detection of flaws, defects, and anomalies using a scattering technique, (b) detection of crack closure and opening used to assess the stability of the material, (c) determination of strain on the material which relates to its performance, and (d) determination of defect dynamics linked to the defect size and stability.

Abstract: It is disclosed a method of detecting and quantifying subsurface defects (10) in an article (1) made of high strength non magnetisable materials after the use in a high temperature environment. A crack (8) or gap on a surface (7) of the article (1) is brazed and after the brazing operation the crack (8) or any remaining braze defect or subsurface crack (10) is detected and quantified by means of a multifrequency eddy current system.

Abstract: A method and system for detecting, locating and quantifying a physical phenomena such as strain or a deformation in a structure. A minimum resolvable distance along the structure is selected and a quantity of laterally adjacent conductors is determined. Each conductor includes a plurality of segments coupled in series which define the minimum resolvable distance along the structure. When a deformation occurs, changes in the defined energy transmission characteristics along each conductor are compared to determine which segment contains the deformation.

Abstract: A non-contacting sensor based on inductive coupling for detecting failure initiation, and crack propagation in composite materials is disclosed. A very low cost crack sensing transducer or test pattern that can be imbedded into a structural material, interrogated, and powered wirelessly is described. A detection method for interrogating the crack sensor utilizing RF inductive coupling is disclosed. The proposed sensor consists of minimal components resulting in maximum reliability.

Abstract: A method for detecting a change in permeability of a magnetostrictive object due to a change in strain. At least one first coil and at least one second coil are obtained and positioned such that magnetic flux lines induced by an electric current in the first coil(s) pass through at least one portion of the object in a direction substantially parallel to the strain direction, such that magnetic flux lines induced by an electric current in the second coil(s) pass through at least one portion of the object in a direction substantially parallel to the strain direction, and such that any electromagnetic interference sensed by the first coil(s) is sensed oppositely by the second coil(s). The total inductance of the positioned first and second coil(s) is measured over time. A change in permeability of the object is detected from a change in the measured total inductance over time.

Abstract: The onset of rolling contact fatigue in an object may be detected by measuring the residual stresses in the surface of the object, and monitoring changes in their magnitude or their direction. The values of residual stresses in the surface are those averaged over a depth that may be in the range say 0.1 mm to 8.0 mm, for example about 2.5 mm. For ferromagnetic objects such as rails, the method may utilize an electromagnetic probe. Prior to rolling contact fatigue the surface stresses are compressive, and the onset of rolling contact fatigue may be characterized by a marked decrease of the stress in the generally transverse direction.

Abstract: The invention involves an apparatus and method for calculating characteristics of materials, such as equivalent strain, using an indenter where the method used is independent of indenter geometry. The method includes performing a scratch test to calculate the strain for each of a plurality of indenter shapes, such as a theoretical sphere and cone, using known equations. The strain of a composite indenter, such as a cone with a rounded tip, can then be determined taking into account contributions from each of the plurality of theoretical shapes.

Abstract: An accelerated method of determining the failure time of a polyethylene resin by determining the minimum displacement rate, or the time at minimum displacement rate, using ASTM F 1473-01, then following one of these routes: (1) If failure has not yet occurred, cryogenically fracturing the resin specimen and examining it for slow crack growth to determine whether the anticipated, or desired, failure time is generally before or after the predicted failure time; or (2) Applying the minimum displacement rate, or the time at minimum displacement rate, in the appropriate mathematical formula to predict the failure time for the resin. The mathematical formula is derived from the discovery of a power law relationship between the failure time and minimum displacement rate, or between failure time and the time at minimum displacement rate.

Abstract: A sensor for measuring stress corrosion cracking and methods of using the sensor. The sensor is a MEMS device and has a cantilevered beam made from a material of interest. The sensor has on-chip electrical connections for measuring electrical characteristics that indicate cracking of the beam. The sensor may further have on-chip actuators for applying stress to the beam.

Abstract: A method and an apparatus for remotely and automatically monitoring for corrosion of a tank, pipe, or container with a gas or liquid environment using corrosion coupons that do not have to be removed from the environment for inspection and evaluation. The coupons are designed to fail when a specified level of corrosion occurs. A permanent magnet located on a coupon sensing system inside the corrosive environment is used to transmit the failure of the coupons outside the corrosion environment and across a wall or other boundary surface without requiring a power supply.

Abstract: A method for detecting cracks in a honeycomb structure includes the steps of: placing the honeycomb structure on the upper face of a first plate with the two end faces of the honeycomb structure facing up and down, respectively; applying to the honeycomb structure impact load adequately heavy to make powdery substance fall off the cracked portions of the honeycomb structure; and detecting the powdery substance having fallen off the cracked portions. The method enables the detection of cracks in the honeycomb structure to be simpler and easier and the honeycomb structure to be hardly damaged.

Abstract: A wear gauge for determining excessive wear of the notches and lugs of an aircraft fueling nozzle adapter to expeditiously sense wear which might result in leakage of fuel during an aircraft refueling operation.

Abstract: A damage evaluation method and apparatus of a metal material which is capable of determining whether a flaw in the metal sample is originated by the creep damage or in the manufacturing process, and also capable of estimating a remaining life of the metal component. The damage evaluation method of a metal material by the present invention is a method for evaluating a flaw in the metal sample comprising the steps of mounting onto a metal surface including an internal flaw and on both sides of the flaw a transmitting probe for transmitting an ultrasonic waves and a receiving probe for receiving the ultrasonic waves, transmitting the ultrasonic waves towards the internal flaw and receiving the diffracted wave from the flaw for determining whether or not a flaw is present in the metal, based on the analysis of the distribution of the diffracted waves and an analysis of the sample as to whether voids (creep voids) are present and, if present, the distribution of the voids.

Abstract: A support for facilitating the bending test of flexible substrates is disclosed. The support includes a plastic or adhesive plastic applied on the substrate to keep the shards together after breakage, thereby eliminating the process of collecting the shards and fitting them back together for failure analysis.

Abstract: It is disclosed a method of detecting and quantifying subsurface defects (10) in an article (1) made of high strength non magnetisable materials after the use in a high temperature environment. A crack (8) or gap on a surface (7) of the article (1) is brazed and after the brazing operation the crack (8) or any remaining braze defect or subsurface crack (10) is detected and quantified by means of a multifrequency eddy current system.

Abstract: A magnetostrictive strain sensor includes a Hall effect sensor for measuring the change in magnetic flux a magnetic circuit including a magnetostrictive element. A strain sensing apparatus includes one or more magnetic elements defining a magnetic circuit having a gap, and including a magnetostrictive element adapted to receive a load force. A Hall effect sensor is disposed within the gap for sensing a change in magnetic flux in the magnetic circuit. The Hall effect sensor may include a programmable circuit for zeroing and calibrating the sensing apparatus, and for providing temperature compensation. The magnetostrictive element may be magnetized to form the magnetized element, and may be formed from material known as TERFENOL-D.

Abstract: A system 10 for continuously monitoring the integrity of a structure 14 includes a sensor pad 16 having a surface 18. The surface 18 is provided with a set of first channels 22 and interspersed second channels 24. Surface 18 is sealed onto the surface 12 of structure 14 so that the channels 22, 24 together with surface 12 form respective sets of first and second cavities 26 and 28. The first cavities 26 are placed in fluid communication with a vacuum source 101 via a third channel 30. The second cavities 28 are vented to the atmosphere via a fourth channel 34, through hole 35, and conduit 36. A high impedance 102 is placed in series between the vacuum source 101 and the first cavities 26. A differential pressure transducer 103 is connected across the high impedance 102 and monitors for change in vacuum condition between the vacuum source 101 and the vacuum in the cavities 26.

Abstract: A leakage inspection method for a sealed container in which a liquid of a non-electrolyte is contained for judging whether a defect exists in the container, the method comprising the steps of applying an inspection AC voltage through electrodes from an inspection power source unit; detecting an AC current flowing through the container and the contained liquid by means of a current detector; obtaining a digital value corresponding to an absolute value of the instantaneous value of the detected AC current; successively totaling the digital values during a totaling period having a specific relation to the waveform of the AC current whereby the total value of the digital values corresponding to the absolute values of the respective instantaneous values of the AC current is arithmetically operated and judging that the defect exists in the container when the total value as the value to be judged is larger than a setting value.

Abstract: A method for detecting cracks in a honeycomb structure includes the steps of: placing the honeycomb structure on the upper face of a first plate with the two end faces of the honeycomb structure facing up and down, respectively; applying to the honeycomb structure impact load adequately heavy to make powdery substance fall off the cracked portions of the honeycomb structure; and detecting the powdery substance having fallen off the cracked portions. The method enables the detection of cracks in the honeycomb structure to be simpler and easier and the honeycomb structure to be hardly damaged.

Abstract: A multiaxial strain cycle (32, 72) is received that is described by a strain tensor that is a function of time. A hyperelastic constitutive model (34, 74) corresponding to the material is received. A fatigue crack growth curve (36, 76) is obtained. A cracking energy density is calculated (50, 90) based on the constitutive model (34, 74) and the multiaxial strain cycle (32, 72). The cracking energy density is a function of material plane (44, 84) and indicates the portion of the total elastic strain energy density that is available to be released on a selected material plane (48, 88). A cracking plane is determined (54, 98) based upon the cracking energy density. A fatigue life is estimated (60, 100) based on the cracking plane and the fatigue crack growth curve (36, 76).

Abstract: A system for inspecting the joint of a composite structure includes a transmitting transceiver and a receiving transceiver, as well as a processing element. Typically, the composite structure includes first and second panels that are connected to define the joint, with the second panel extending outwardly from the first panel of the joint. Moreover, the composite structure includes a filler disposed at the joint. The transmitting transducer is disposed proximate an input side of the second panel and can transmit an ultrasonic signal into the second panel such that at least a portion of the signal reflects off of the first panel at the joint and exits an output side of the second panel. A receiving transducer disposed proximate the output side of the second panel can receive a reflected portion of the ultrasonic signal. And a processing element is capable of identifying a defect in the composite structure.

Abstract: A damage evaluation method and apparatus of a metal material which is capable of determining whether a flaw in the metal sample is originated by the creep damage or in the manufacturing process, and also capable of estimating a remaining life of the metal component. The damage evaluation method of a metal material by the present invention is a method for evaluating a flaw in the metal sample comprising the steps of mounting onto a metal surface including an internal flaw and on both sides of the flaw a transmitting probe for transmitting an ultrasonic waves and a receiving probe for receiving the ultrasonic waves, transmitting the ultrasonic waves towards the internal flaw and receiving the diffracted wave from the flaw for determining whether or not a flaw is present in the metal, based on the analysis of the distribution of the diffracted waves and an analysis of the sample as to whether voids (creep voids) are present and, if present, the distribution of the voids.

Abstract: A method for determining fracture toughness KIC of materials ranging from metallic alloys, brittle ceramics and their composites, and weldments. A cylindrical specimen having a helical V-groove with a 45° pitch is subjected to pure torsion. This loading configuration creates a uniform tensile-stress crack-opening mode, and a transverse plane-strain state along the helical groove. The full length of the spiral groove is equivalent to the thickness of a conventional compact-type specimen. KIC values are determined from the fracture torque and crack length measured from the test specimen using a 3-D finite element program (TOR3D-KIC) developed for the purpose. In addition, a mixed mode (combined tensile and shear stress mode) fracture toughness value can be determined by varying the pitch of the helical groove. Since the key information needed for determining the KIC value is condensed in the vicinity of the crack tip, the specimen can be significantly miniaturized without the loss of generality.

Abstract: The invention relates to a method of measuring the biaxial shaping behaviour of metal materials, more particularly sheet metal. In the measuring method a flow locus curve comprehensively describing the shaping behaviour of the material is determined by determining the flow limits under tensile and compressive loading of secondary samples of a primary sample previously subjected to at least tensile, but preferably also to compressive loading. Preferably a number of flow locus curves of different preliminary loading of the primary sample are determined for each material. These flow locus curves, completely ascertained by tests, provide the further processor with a reliable ancillary means of selecting a material required for the particular shaping operation.

Abstract: The onset of rolling contact fatigue in an object may be detected by measuring the residual stresses in the surface of the object, and monitoring changes in their magnitude or their direction. The values of residual stresses in the surface are those averaged over a depth that may be in the range say 0.1 mm to 8.0 mm, for example about 2.5 mm. For ferromagnetic objects such as rails, the method may utilise an electromagnetic probe. Prior to rolling contact fatigue the surface stresses are compressive, and the onset of rolling contact fatigue may be characterised by a marked decrease of the stress in the generally transverse direction.

Abstract: The present invention provides a method of designing a high fatigue strength in high tensile strength steel, comprising: obtaining values of tensile strength &sgr;B (unit thereof is MPa) and Vickers hardness Hv of the steel; measuring a flaw area of an inclusion, when a fracture origin is located only at a surface of the steel; and estimating, in designing the high fatigue strength steel, that a fatigue limit &sgr;w (unit thereof is MPa) of the steel satisfies either &sgr;w≧0.5 &sgr;B or &sgr;w≧1.6 Hv, when a square root of the flaw area, (area)½ (unit thereof is m), contained in the steel is no larger than 45.8/&sgr;B2 or 4.47/Hv2. According to the present invention, a method of evaluating high fatigue strength in high tensile strength steel, in which method a relationship between a flaw dimension (area) of ODA and the fatigue strength is considered, and a high fatigue strength material can be provided.

Abstract: Focusing on the application of a predetermined relationship between the length of a fatigue damage detection sensor having a width of a specified shape and a required sensitivity or sensing accuracy (crack propagation rate), the present invention provides a fatigue damage detection sensor for structural materials and mounting method thereof, wherein when the length between a pair of fixing portions for fixing to a surface of a structural material M, both ends of a sensor body (2) sandwiching a notched portion (5) is defined as 2H, the length of a crack C that can propagate from a tip (5A) of the notched portion (5) is defined as (a), the number of times that a working load acts on the material is defined as N, and the crack propagation rate is defined as da/dN, the length 2H between said fixing portions is set so as to obtain a required sensitivity with which da/dN is proportional to H0.5m (m is a constant determined by a material).