Study on Cyclic Stressª²Strain Relation Under Tension-Torsion   Complex Loading
Shang Deguang  Yao Weixing   Wang Dejun
(Department of Aircraft Engineering Nanjing University of Aeronautics and Astronautics 210016)(Shenyang Northeastern University 110006)

Abstract: In this paper, the tension-torsion specimens were used as researching subjects.The cyclic stress-strain relation under multiaxial proportional and nonproportional loading was studied according to the characteristic of the stress and strain on the multiaxial critical plane and the researching results of multiaxial critical plane principle. A multiaxial cyclic constitutive relation model under proportional loading was first derived based on the uniaxial cyclic stress-strainrelation, and then a multiaxial cyclic constitutive relation under nonproportional loading was obtained by the varying behaviour of the normal strain and the maximum shear strain on the critical plane. The experiments of tension-torsion proportional and nonproportional cyclic loading were conducted to verify the model. The prediction of the model agrees with the experimental results reasonably well.
Keywords: proportional cyclic loading, nonproportional cyclic loading, multiaxial fatigue, cyclic stress-strain relation.