Resonant fatigue test bench for shaft testing

摘要

Shaft fatigue testing involves long test times (～3 months), high energy consumption and high test equipment maintenance costs owing to the high bending and twisting moments required (～1600 Nm), high number of cycles (～10~7 ) and large sample sizes (～30). To reduce testing time, we designed, manufactured and evaluated a resonant plate test bench. Using finite element analysis and topological optimization, we redesigned the traditional resonant flat plates for higher resonant frequency and lower deflection at the plate free ends. We found that the optimal topology is an I-beam; it doubles the frequency of flexion tests, up to 100 Hz, and exhibits 2 mm of deflection under a load of 1 kN. To measure the moments induced on the shaft sample during testing, we measured the surface deflection of the resonant plates. Tests on a calibration axle showed that the induced shaft moment has very high linear correlation (R~2 ＞ 0.99) with the plate's surface deformation. We used our test bench to evaluate fatigue resistance for a type of crankshaft manufactured by a local company. We found that their fatigue resistance limit was 1250 Nm at 10~7 cycles and that their mean useful life was 10 cycles when they are subjected to a 1400 Nm moment. These results agree with previous results on this type of crankshaft using other methods. Highlights 1. Methodology to design high-frequency resonant plates for axle fatigue test 2. Use of finite element analysis and topological optimization 3. Design of resonant plates to induce high flexural or torsional moments 4. Perform crankshafts fatigue tests with 50% reduction in time duration.