High Cycle Fatigue Testing and Analysis Using Car Standard Sequence

An original computer software package for controlling a servo-hydraulic machine was used to carry out uniaxial and biaxial variable amplitude loading tests on a high strength steel. Tension-compression and torsion uniaxial tests, as well as combined proportional tension-torsion tests were performed under the car loading sequence CARLOS used for fatigue strength investigations of car wheel suspension components. The number of sequences to crack nucleation was estimated by means of a crack front marking technique using very small amplitude cycles to generate marker bands on the fracture surface. The experimental data obtained from these tests were compared to the predictions of the fatigue life prediction method proposed by Morel and based on a microplasticity analysis. It was shown that all the predictions, though non-conservative, were within an acceptable scatter band.