Calculation of Lankford coefficient from orientation distribution function and modelling of forming limit diagram using Marcniak-Kuczynski hypothesis of geometric instability

Abstract

Complex stampings are developed with the aid of data obtained from laboratory tensile test and average plastic strain ratio that enables the press formability of sheet metals to be reliably predicted. Formability is best assessed by Hecker’s method of punch stretching and drawing the forming limit diagrams. Analytically, the forming limit diagrams are modeled by geometric instability analyses based on Marciniak & Kuczynski with a high degree of accuracy. Also, texture analysis is used to get average plastic anisotropic ratio input parameter to the above model. In the present research, texture is determined by measuring four incomplete pole figures of the planes {110}, {200}, {112} and {103} using Schulze back reflection technique. This analysis provided orientation distribution function which is in turn used to calculate average plastic anisotropic ratio. The data from texture and others experiments, such as tensile test, roughness measurement and density measurement are used in the analytical model to get forming limit diagrams. The theoretical forming limit diagrams obtained show significant departure from the experimentally evaluated ones only in plain strain condition.