“Forming to Crash” Simulation in Full Vehicle Models

Janka Cafolla, Roger W. Hall, David P. Norman, Iain J. McGregor Corus Automotive, UK Corus, France Improving the accuracy of virtual prototypes helps to shorten product development times and reduces the number of physical prototypes required. One way in which the accuracy of crash analysis can be improved is to include the effects of forming in the material properties. Corus has developed a three-step “Forming to Crash” process to account for formed properties in crash analysis during both concept and detailed vehicle design stages. The first step uses a selection procedure to identify the parts most sensitive to the inclusion of formed properties. The second step uses an approximate “Forming to Crash” method to rapidly estimate the formed properties and reduce the time taken to conduct the analysis during concept design. The third step links a detailed forming analysis to a crash analysis to provide a full “Forming to Crash” technique for use during detailed design development. This three-step process is used by Corus to support customers in the application of advanced high strength steels. Introduction The process of forming a component changes the properties of the material being used. This is generally ignored in the design and validation process of automotive structures even though the changes in material strength and thickness may be substantial. Finite Element tools are now able to predict the as-formed material properties and use these in subsequent crash analysis. However, although the forming effects on the performance of individual components have been reported in the literature [1][2][3][4][5][6][7][8], there are few papers reporting the consequence of including formed properties in full vehicle models [9][10]. This paper presents Corus developed procedures, which are used to include the results of forming simulations in the full vehicle crash model. Corus “Forming to Crash” Three-Step Process A vehicle body structure consists of hundreds of formed components. A detailed analysis of the stamping process can take between 5 to 10 days per part to complete. In order to minimise the time taken for vehicle analysis, it is therefore important to understand which components in the vehicle body structure are sensitive to forming and how the formed properties affect the vehicle crash performance. The identification of the key parts in which to include formed properties is the first stage of a “Forming to Crash” (F2C) three-step process, which has been developed by Corus.