Fatigue Testing Machine

Under rated axle load, maximum deformation per meter wheelbase shall not exceed 3mm.

Under rated axle load, maximum deformation per meter wheelbase is 2.14mm.

Minimum fatigue life shall not be less than 50×10⁴ cycles, and average fatigue life shall not be less than 80×10⁴ cycles.

Test load: 0.25 to 2.5 times rated axle load. The sample did not show fracture or severe plastic deformation failure after reaching 81.0×10⁴ cycles.

1. The air spring suspension assembly adjusts the full-load equilibrium position through the height valve for inflation and deflation: the working height of left and right air springs shall be as per design requirement (315mm), and the difference in working height between left and right air suspension springs shall be ≤5mm; the actuator is loaded to the design load (5625kg) at full-load equilibrium position.
2. Test procedure:
At the working height of 315mm for left and right air springs, inflate to reach the design load of 5625kg, slowly pull up and press down by 10mm, and record the actuator load and stroke in real time.
3. Test data processing:
1) Subtract 1/2 of the non-suspension mass from the single actuator load to obtain the vertical load of the air spring; calculate the deformation of the air spring through the actuator stroke;
2) Calculate the average value of the vertical load and deformation of the single-side air spring for each test;
3) Perform quadratic function fitting on the vertical load-deformation to obtain the vertical stiffness curve of the air suspension. The quadratic function fitting expression is as follows: y=ax²+bx+c。

The test is carried out as per the standard requirements. The left air spring stiffness is 536.9N/mm, and the right air spring stiffness is 556.4N/mm. The test curve is shown in Appendix B.

The test is carried out at a frequency of 0.75Hz for 95,000 cycles, and no macro-cracks are found in the sample.