The present disclosure provides a dynamic true triaxial electromagnetic Hopkinson bar system and testing method, the method including: firstly, before applying a static prestress and an impact load, recording and storing complete ultrasonic signals in the directions X, Y, and Z without application of the static prestress and the impact load; secondly, applying the static prestress; thirdly, recording and storing complete ultrasonic signals in the directions X, Y, and Z under the static prestress; fourthly, applying the impact load, and utilizing an triaxial and six-directional synchronous-coordinated-control electromagnetic loading system to apply a dynamic impact load to a test specimen; and fifthly, after completing the dynamic impact loading test, recording and storing once again complete ultrasonic signals in the directions X, Y, and Z without releasing the static prestress after application of the static prestress and the dynamic impact load.

The hardness of a rail after the rail having a temperature equal to or higher than an austenite region temperature is forcibly cooled in a cooling facility is predicted. A plurality of sets of data for learning composed of a cooling condition data set and output data of hardness are acquired using a model that performs computing by using a cooling condition data set having at least a surface temperature of the rail before the start of cooling and the operating conditions of the cooling facility as input data and the hardness inside the rail after the forced cooling as output data.

To provide a three-dimensional hardness distribution measurement method with better measurement accuracy. The method is a three-dimensional hardness distribution measurement method including and repeating: cutting evenly a surface of a member to be measured; imaging the surface having been cut; and pushing an indenter for a hardness test into a plurality of points on the surface having been imaged. In the method, a cutting depth of the surface is controlled, in the cutting, to a predetermined constant amount, and indentation depths of the indenter at the plurality of points are controlled, in the pushing, to a predetermined constant amount.

Provided is an inorganic composition having excellent mechanical strength and the like.

Disclosed is an inorganic composition and the like, wherein the flexural strength of the inorganic composition is 300 MPa or greater, and the fluorescence intensity based on JIS K 0120, is 3,000 RFU or less.

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.

A method for preparing a SiC ingot includes: disposing a raw material and a SiC seed crystal facing each other in a reactor having an internal space; subliming the raw material by controlling a temperature, a pressure, and an atmosphere of the internal space; growing the SiC ingot on the seed crystal; and collecting the SiC ingot after cooling the reactor. The wafer prepared from the ingot, which is prepared from the method, generates cracks when an impact is applied to a surface of the wafer, the impact is applied by an external impact source having mechanical energy, and a minimum value of the mechanical energy is 0.194 J to 0.475 J per unit area (cm.sup.2).

A system for measuring loading on a test specimen. The system includes the test specimen arranged between a first loading bar and a second loading bar. The system further includes a first loading unit and a second loading unit configured to apply a first load and a second load to the first and second loading bars, respectively. The system further includes a first clamp and a second clamp configured to hold the first and second loading bars against the first and second loads, respectively. The system further includes a clamp actuating unit configured to selectively release at least the first clamp. The clamp actuating unit further includes a controller configured to electrically actuate at least one first electromechanical transducer from a retained state to a released state to release the first clamp, such that the first loading bar applies a first loading wave to the test specimen.

A Bauschinger effect test fixture that cooperates with a test machine for stretching and compressing materials to perform a Bauschinger effect test on a test piece having a symmetrical configuration with two wide ends and a narrow middle part. The fixture includes two identical split bodies, where each split body has a base provided, longitudinally from a central part to one end of the base, with a limiting groove corresponding to a half of the profile of the test piece. Two sides of the groove are arranged symmetrically with a plurality of threaded through holes and a cover is provided along its central axis with two threaded through holes with which the test piece is pressed tightly by bolts. An end of the cover corresponding to a notch of the limiting groove is provided with a through groove configured for placing a stress ultrasonic detection probe on the test piece.

A compressive load is exerted with a test apparatus across a rock sample that has a specified length-to-diameter ratio. A strain on the rock sample is measured during the compressive loading with a strain gauge. A mechanical property of the rock sample is determined based at least in part on the compressive load. An elastic property of the rock sample is determined based at least in part on the measured strain and the compressive load.

An output member for a Direct Impact Hopkinson pressure bar includes an elongate tube portion and a disc-shaped cap portion. The tube portion has a first end and an opposite second end, while the cap portion includes a first face and an opposite second face. A circular stub protrudes from a center of the first face, and a circular cavity is formed in the second face. Each of the stub and the cavity is concentric with the cap portion, with a diameter of the cavity being greater than a diameter of the stub. The second face of the cap portion is positioned in intimate contact with the first end of the tube portion, with the cap portion being concentric with the tube portion.