Abstract
A method of performing torsional low cycle fatigue tests on thin-walled tubular specimens is described. Shear strains are measured and controlled using an internally mounted rotary variable differential transducer (RVDT). Test results for a 1045 hot-rolled and normalized steel are discussed. As in the case of uniaxial fatigue analysis, power law relationships are assumed in the elastic strain-life, plastic strain-life, and stress-plastic strain functions. From this analysis, the fatigue strength and ductility exponents and coefficients in torsion are determined, as well as the cyclic strain hardening exponent and strength coefficient in torsion. These properties are compared to those obtained in uniaxial fatigue tests of the same steel. The question of whether the cyclic strain hardening, fatigue strength, and fatigue ductility exponents are stress state dependent is specifically addressed. This is one of the fundamental issues that must be resolved if uniaxial fatigue properties are to be used to analytically predict multiaxial fatigue behavior.
Published Version
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