A new approach on necking constitutive relationships of ductile materials at elevated temperatures

A new method is presented to determine the full-range, uniaxial constitutive relationship of materials by tensile tests on funnel specimens with small curvature radius and finite element analysis (FEA). An iteration method using FEA APDL (ANSYS parametric design language) programming has been developed to approach the necking constitutive relationship of materials. Test results from SAE 304 stainless steel at room temperature show that simulated load vs displacement curve, diameter at funnel root vs displacement curve, and funnel deformation contours are close to modeled results. Due to this new method, full-range constitutive relationships and true stress and effective true strain at failure are found for 316L stainless steel, TA17 titanium alloy and A508-III stainless steel at room temperature, and 316L stainless steel at various elevated temperatures.