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RESEARCH PRODUCT

A critical plane approach based on energy concepts: application to biaxial random tension-compression high-cycle fatigue regime

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Abstract In this paper the energy parameter, defined for random loadings, is analysed. Under uniaxial loading this parameter distinguishes between the strain energy density for tension (positive) and the strain energy density for compression (negative). As a consequence, if there is no mean component in the random loading, we obtain a random history of strain (elastic and plastic) energy density with zero expected value. Under multiaxial loadings the normal strain energy density in the critical plane (i.e. the plane of the maximum damage) is understood as the energy parameter. The history of strain energy density is schematized with use of the rain-flow algorithm. Fatigue damage is accumulated according to Palmgren-Miner hypothesis and the standard fatigue characteristic of the material, rescaled with use of the considered energy parameter. The proposed parameter was verified during fatigue tests of cruciform specimens made of 10HNAP steel, subjected to biaxial non-proportional random tension-compresion. The calculated fatigue lives are included in the scatter band of the experimental data of a factor of 3. Thus, the normal strain energy density in the critical plane seems to be an efficient fatigue parameter under random non-proportional loadings for high-cycle fatigue.