Resonant fatigue test bench for shaft testing

Abstract

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 (~107) 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 (R2 > 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 107 cycles and that their mean useful life was 104 cycles when they are subjected to a 1400 Nm moment. These results agree with previous results on this type of crankshaft using other methods.

Numerical modelling of deep rolling influence over crankshaft bending and correlation with fatigue behaviour

“…Fatigue tests were performed with a custom-made crankshaft test rig developed by Cantisano. 33 The rig uses the system's resonance frequency to employ elevated sinusoidal loads to the crankshaft with minimum energy input, similar to the bench developed by Huertas et al 34 A single crank throw is fixed between two suspended inertia arms, one of which is driven by an electrodynamic shaker. The control system developed by Cunha et al 35 is capable of identifying the rig's natural frequency through impulse excitation and Fast Fourier Transform (FFT) calculation.…”

Crack propagation mapping at component‐level fatigue testing by means of natural frequency tracking control

“…Rigs dedicated to crankshaft testing often employ similar concepts to impose sufficient bending or torsional fatigue loads 8 . Park et al, 9 Williams and Fatemi, 10 and Çevik and Gürbüz 11 used adapted universal machine servo‐hydraulic actuator setups.…”

“…Inertia blocks are used to fine‐tune the system's natural frequency and facilitate excitation in the vibration mode of interest. However, the induced loads can be challenging to control 8 . Ko et al 12 ran a crankshaft staircase campaign at 50 Hz using a commercial electromagnet machine setup.…”

“…The authors did not share any detail on the embedded controller, most likely treated as a black box. Yang et al 13 and Huertas et al 8 also obtained crankshaft bending fatigue strength through a customized resonance machine employing own‐designed machines. The authors, however, did not unveil the controller equipment or its logic.…”

“…7 Rigs dedicated to crankshaft testing often employ similar concepts to impose sufficient bending or torsional fatigue loads. 8 Park et al, 9 Williams and Fatemi, 10 and Çevik and Gürbüz 11 used adapted universal machine servo-hydraulic actuator setups. However, this option simplifies the control scheme and does not contribute to the overall celerity of the process, with a maximum loading frequency between 25 and 35 Hz.…”