CUSTOM MATERIAL MODELING WITHIN FEA FOR USE IN AUTOFRETTAGE SIMULATION

摘要

Finite Element Analysis (FEA) has been widely adopted. For autofrettage analysis, in order to represent real conditions and materials, it is necessary to properly model end conditions and material behavior, in particular the loss of compressive strength following prior tensile plastic strain, termed the 'Bauschinger Effect'. The latter is a strong function of prior plastic strain and therefore of location; this implies the need to model a different material unloading behavior at each location in the tube. Two possible methods of implementing such a behavior within FEA are examined. These are an 'elastic modulus and Poisson's ratio adjustment procedure' (EMPRAP) and a 'user programmable feature' (UPF). Finally the results are compared to an independent, non-FEA, EMPRAP numerical solution. Close agreement between all three methods is demonstrated. The UPF approach, validated here, is applicable in more complex loading scenarios.