The fatigue crack growth test was carried out in the State Key Laboratory of new metal materials, University of science and technology of Beijing. The test equipment is shown in the figure below, and the model is MTS 810 electro-hydraulic servo fatigue testing machine.

The test system consists of five basic parts: frame, pump station (liquid pressure source), controller, software and all kinds of fixture accessories for clamping specific test pieces. The power of the system comes from the hydraulic silent oil source pressurized by the pump station, which can realize the static loading of the specimen; The maximum load is 100 kn and dynamic load is applied; The maximum load is 100 kn, the loading frequency range is 0.01-50 Hz, and the measurement error of load, displacement, expansion rate and cycle number is not more than 0.5%. When the load exceeds the maximum load of the test system, the test machine stops working due to its own overload protection function. The control system realizes the control of load, displacement, expansion rate and other experimental conditions through closed-loop control.

The testing machine can be used to test and study the tensile fatigue, compression fatigue, fracture toughness, static uniaxial tension and compression and other conventional mechanical properties of various metal and non-metal samples under alternating cyclic load. The loading waveforms include sine wave, oblique wave, square wave, triangle wave, trapezoidal wave, program block wave and so on. The tests involved are all room temperature tests, so they are all completed at 10-25 ℃ at room temperature.