A testing method for Young's modulus and Poisson's ratio based on a square plate is provided, which including: obtaining a height, a length, a density, and a quality information of the square plate specimen; measuring the first-order torsional frequencie and the second-order torsional frequencie of the square plate specimen; calculating Poisson's ratio based on the height, the length, the first-order torsional frequency, and the second-order torsional frequency of the square plate specimen; calculating the Young's modulus of the square plate specimen based on the Poisson's ratio and the density. The method establishes a continuous function relationship between the parameter set of the test specimen and the torsional frequency using homotopy method, which can be used to calculate Poisson's ratio. When the material density and Poisson's ratio are known, the Young's modulus can be calculated in conjunction with ANSYS software. The method has advantages in both testing efficiency and accuracy.

A dual piezoelectric wire sensor system and a method for non-destructive testing of a cylindrical structure utilizes a pair of H-shaped calipers attached to the cylindrical structure at radial positions ninety degrees apart. Each H-shaped caliper includes two arms and a crossbar connected to and perpendicular to the two arms. A caliper connecter is attached to the first ends of each arm. A wire connecter is attached to the second ends of each arm, between which a piezoelectric wire is connected and stretched. An electrical terminal connects one wire connector to a two-port signal subtractor, which receives signals from the two H-shaped calipers and generates a difference signal. A measurement unit, connected to the two-port signal subtractor, receives the difference signal, performs a frequency analysis, identifies a resonant frequency of an ovalling mode and identifies a stiffness value of the cylindrical structure.

A test result of a tensile test and a measurement result of a natural frequency are easily associated with each other. A high-speed tensile testing machine 1 is a tensile testing machine that executes a tensile test by applying a test force F to a test target TP. The machine includes: a determination unit 513 that determines a timing at which a striking force FD is applied to a testing machine body 2; a striking structure 60 that applies the striking force FD to the testing machine body 2 at the timing determined by the determination unit 513; a first detection unit 514 that detects a vibration of the testing machine body 2 generated by the striking force FD; a calculation unit 515 that calculates a natural frequency FA of the high-speed tensile testing machine 1 on the basis of a detection result of the first detection unit 514; an execution instruction unit 516 that executes the tensile test; and a recording unit 517 that writes, in a result storage unit 518, information indicating a test result of the tensile test in association with information indicating the natural frequency FA. The timing is included in either before or after the tensile testing machine 1 executes the tensile test.

A structural fatigue life prediction method considering strength degradation effect, wherein the method includes: obtaining strain-time data of the structure under at least one working condition; converting the strain-time data into a stress spectrum; processing the stress spectrum by using a nonlinear cumulative damage model considering strength degradation effect to obtain the residual damage of the structure; calculating the fatigue life of the structure according to the residual damage. The invention modifies the nonlinear cumulative damage model by introducing stress ratio and strength degradation coefficient. The function is mainly expressed in exponential form, which can better reflect the degradation performance of the material. The model form is simple and it can be well applied to practical engineering. This model can be applied to the prediction of fatigue life under multi-level load, which greatly improves the prediction accuracy of structural fatigue life.