Study On Multiaxial Stress–Strain Curve Of Notched Bar With Three-Dimensional Approximate Method

When a notch rod specimen is conducted under tension combined torsion load, the notch root point is under a multiaxial plane stress condition. The relationship of the point's stress and strain is nonlinear when the point is under plastic state. So it is difficult to pridict the stress and strain, and it is important for the pridiction of the notch rod specimen'life. It is reported that the issue is approached through the two-dimensional (2D) Neuber approximate method. However, the results are not reasonable, especially for the circumferential stress-strain curve.Based on the 2D approximate method, three-dimensional (3D) approximate method is proceeded, which combined the Armstrong-Frederick (A-F) cyclic plastic theory and the incremental Neuber method. The 3D approximate method is that the incremental plastic stress and strain distributions can be determined through solving six incremental constitutive equations and six incremental Neuber equations after each incremental loading step. The stress-strain hysteresis loop can be obtained in the final. It is noticed that the results from 3D approach can improve the circumferential stress-strain curve, as well as obtain the stress and strain distributions not only under plane-stress condition, in which cannot be approached by 2D method.