In a material testing machine including a load actuator including a shaft configured to make a linear motion, and configured to apply a load to a test piece through the linear motion of the shaft, the load actuator includes a bearing configured to support the shaft, and the bearing serves as an air bearing.

A high-speed tensile testing machine conducts a tensile test on a test piece by applying a test force to the test piece. The high-speed tensile testing machine includes a detection unit configured to detect a test period indicating a time from when the test piece starts to deform under action of the test force to when the test piece breaks, and a determination unit configured to determine validity of a test result of the tensile test, on the basis of the test period and natural vibration of the high-speed tensile testing machine. Specifically, in the case where the test period is a predetermined multiple or more of a specific cycle indicating a cycle of the natural vibration of the high-speed tensile testing machine, the determination unit determines that the test result of the tensile test is valid.

The present invention relates to a device for measuring residual stress and hardness. Residual stress remaining in a metallic material due to deformation, thermal stress, or the like is a cause of various problems including degradation of mechanical properties such as fatigue strength and fracture properties and difficulty in post-processing. It is very difficult to derive a calibration curve when measuring stress by an existing non-destructive Barkhausen noise measurement method. When cross points of Barkhausen noise measurements for three or more stresses are not at one position, calibrated curves can be easily found by scaling the Barkhausen noise measurements by using calibration equations of the present invention to collect the cross points at a unique position, thereby providing a practical method of easily measuring stress of a metal by a Barkhausen noise measurement method. Therefore, according to the present invention, it is found that the internal microstructure and surface residual stress of a metal cause crossing points not to be at a unique position in a conventional Barkhausen noise measurement experiment. In addition, basic physical properties and surface residual stress of a metallic material may be measured using the above-mentioned physical feature.

According to one embodiment, a diagnostic method includes changing a position of a mechanical structure to be diagnosed with a drive unit based on an acceleration command, the acceleration command being generated based on a log swept sine (LOGSS) signal, calculating an impulse response based on the acceleration command and measured acceleration of the mechanical structure, the measured acceleration being measured by an accelerometer, analyzing at least one of a linear characteristic and a nonlinear characteristic relating to the mechanical structure based on the impulse response, and diagnosing the mechanical structure based on the at least one of the linear characteristic and the nonlinear characteristic relating to the mechanical structure.

The invention relates to a traction or friction measuring apparatus and method of calibration. The apparatus comprising a flat disc traction surface; a spherical ball traction surface constructed and arranged to, in use, contact said disc traction surface; a support structure constructed and arranged to support said disc and ball traction surfaces with respect to one another whilst allowing relative rotational movement therebetween; about an axis, the disc drive means and ball drive operable to effect the relative movement between said disc and ball traction surfaces and include disc speed measuring means and ball speed measuring means, and thereby to generate a traction or friction force therebetween; and force measuring means associated with at least said disc and ball traction surfaces to provide a force measurement arising from said traction or friction force and that measurement of the ball speed and the disc speed can be made at a point of pure rolling between the ball and disc in order to accurately determine the disc track radius based on the known ball track radius. The method comprises the following steps: a. steadily increasing the disc speed and reduce the ball speed (or vice versa) in such a way as to ensure that at some point the speeds pass through a point where the disc and ball are in pure rolling, b. plotting traction force against the slide/roll ratio (SRR), c. observing and recording the values of the motor speeds that correspond to the point of transition from positive to negative (or negative to positive) traction force as the contact passes through pure rolling contact, and, d. determining the disc track radius (DTR) based on the formula: DTR=Ball speed×ball track radius/Disc speed.

A calibration method for brittle fracture assessment parameters for pressure vessel materials based on the Beremin model includes selecting at least two types of specimens of different constraints, and calculating the fracture toughness values K.sub.0 corresponding to 63.2% failure probability for each type of specimens at a same calibration temperature by using the respective fracture toughness data. The method proceeds by obtaining the stress-strain curve of the material at the calibration temperature, generating finite element models for each type of specimens, and calculating the maximum principal stress and element volume of every element at K=K.sub.0 in each model. A series of values of m are assumed to compute a group of σ.sub.u values for each type of specimens, and then m˜σ.sub.u curves are plotted for each type of specimens. Brittle fracture assessment parameters are then determined for the material according to the coordinates of the intersection of the m˜σ.sub.u curves.

An error compensation system and method may include applying a mechanical load to a reference sample to obtain a load measurement signal from the load sensor and a displacement measurement signal from the displacement sensor, calculating a transfer function to create a load filter and a displacement filter to be applied to the load measurement signal and the displacement measurement signal, respectively, applying the load filter to the load measurement signal to calculate a load compensation value, and applying the displacement filter to the displacement measurement signal to calculate a displacement compensation value, and determining the compensated value by comparing the load compensation value with the displacement compensation value, wherein the compensated value is determined prior to testing a specimen so that the compensated value is used to automatically correct a measured deflection of the specimen to arrive at an actual specimen deflection.

A tensile testing machine includes: a processing filter that removes a noise component included in a test force measurement signal output from a load cell; and an adjustment unit that adjusts a frequency characteristic of the processing filter.

An amplitude detecting method and a material tester are provided. As functional blocks of a program that is installed in a personal computer and is stored in a memory, a measurement noise eliminating part that eliminates measurement noise, a vibration noise eliminating part that eliminates vibration noise assumed to be caused by an inertial force according to a natural vibration according to reach of an impact of breakage or destruction of a test piece at the entire tester, an amplitude detecting part that detects the amplitude of a natural vibration superimposed in the data period used for evaluating material characteristics, and a display control part that controls display of an amplitude value of the natural vibration and a test result on the display device are included.

A method for searching for statistics correlated with a strength of a pillar-shaped honeycomb formed body after firing having predetermined design specifications including a step of measuring two or more parameters for 90% or more of the polygonal cells excluding partial cells at the outermost periphery, and calculating two or more statistics for each parameter measured; a step of firing each of the plurality of pillar-shaped honeycomb formed bodies before firing under predetermined conditions to prepare a plurality of pillar-shaped honeycomb formed bodies after firing; a step of evaluating a correlation between the two or more statistics and the strength of the plurality of pillar-shaped honeycomb formed bodies after firing; and a step of determining a statistic having the highest correlation with the strength of the pillar-shaped honeycomb formed bodies after firing having the predetermined design specifications from among the two or more statistics.