Optimisation of the bending process of High Strength Low Alloy sheet metal: numerical and experimental approach

Abstract

Anchorage parts for automobile safety belts and other safety parts must resist shock loadings without breaking. They are typically made from High Strength Low Alloy sheet metal and fabricated by blanking and bending operations. The study of their behaviour during fabrication and their resulting mechanical properties has been conducted experimentally and numerically. The experimental results were used to validate the numerical simulation. The resulting material damage is taken into account by a user subroutine in the Abaqus Standard Finite Element code. Damage is one of the objective functions intervening in the forming process of safety parts as well as in the prediction of unbending and shock loads. This study is based on the use of “the design of experiments technique” and the approximated representation by response surfaces. For unbending operations representative of dynamic shock loading conditions, the objective functions represent the maximum unbending load and maximum damage. The parameters that represent the die radius Rd and the sheet/die clearance C are optimised in order to obtain the most resistant safety part possible.