Crash Analysis of Automotive Chassis Structure Considering the Strain Hardening Effect

TLDR: In this article, the effect of forming process on crash response of typical Sports Utility Vehicles (SUV) was analyzed using Hyperform and LS Dyna, and a significant change in energy absorption, peak force and stroke of the front rail was predicted.

Abstract: The work hardening during the forming process is generally ignored in crash analysis. This paper presents computational details of the effect of forming process on crash response of typical Sports Utility Vehicles (SUV). Forming results for front panels of a medium‐sized SUV were calculated using Hyperform and LS Dyna. These were imported into the crash model and crash results compared with and without the forming effects. Time taken to generate the forming data by a variety of methods is quantified and the trade‐off between time taken and accuracy is examined. LS‐DYNA was used for both forming and crash simulations. The effect of thickness, work hardening and residual stresses on the crashworthiness results is measured; crash response is seen to be significantly affected when the effects of forming are included. The paper proposes a systematic method to transfer data from the forming analysis to crashworthiness analysis (both using LS‐DYNA), allowing thickness, residual stress and plastic strain data selectively or in combination to be used to initialise the crash model. The relative effect of each of these forming parameters has been examined and the importance of, work hardening on the crash response of the stamping front rail has been identified. A significant change in energy absorption, peak force and stroke of the front rail was predicted, indicating a far stiffer response in the formed rail than would be expected based on the nominal material properties. Therefore, forming effects should be accounted for in vehicle crashworthiness predictions.