Material models and characteristic value determination for the industrial application of forming and crash simulation, considering the thermal treatments during painting in the process for high-strength materials

Project Background

The ever-increasing demands on the crash safety of automobiles require more precise predictions through crash simulation. In the automotive sector, SMEs mainly act as simulation service providers, suppliers of subcomponents and software developers and must adapt to the increasing requirements of OEMs in order to be competitive. In recent years, simulation in the industrial application of modern steel materials has focused on a continuous mapping of the process chain.

Project Goals

Due to the increasing integration of the results of the forming simulation into the crash simulation, it is necessary to consider a further step of the process chain: The thermal hardening of the paint. In this process, the body is heated to approx. 170° C for approx. 20 minutes. Despite the relatively low temperature, the modern steel materials used undergo changes that influence the mechanical behavior, mainly tempering effects and bake-hardening. The tempering effects occur mainly with the highest strength press hardening steels and lead to a reduction in strength. Bake-hardening occurs in many steel classes and leads to higher strength. 

These effects are to be represented by simple laws which transform the material characteristics in a suitable way when transferring the results of the forming simulation to the crash simulation

  • Substitute model for virtual heat treatment     
  • Transformation module of strain hardening and failure curves
Substitute model for virtual heat treatment

Contributions from Fraunhofer SCAI

  • MpCCI mapper for process chain forming – crash
  • Implementation of transformation module and application to crash model

Project Results

The intended research results on tempering and bake-hardening effects will enable SMEs to keep up with the constantly increasing requirements in terms of calculation and simulation. The corresponding results will increase the prediction accuracy of the simulation of the process chain and thus experimental investigations can be omitted. 

With a more precise prediction of the tolerable loads, the lightweight construction potential can be used even more effectively in the design of new components and assemblies. Thus, resource efficiency can be increased both in production (less material input) and in operation (lower fuel costs due to lightweight construction).

MpCCI mapper for process chain forming – crash

Project Partners

  • TU-Dresden – Institute of Solid Mechanics
  • IWT Bremen – Materials Science
  • Fraunhofer SCAI
  • Arbeitsgruppe „Crashsimulation von umgeformten. Karosserieteilen" des FAT-Arbeitskreises 27 „Finite-Element-Berechnungen"   

Funding Information

This project is funded by the AiF in a program for the promotion of Joint Industrial Research of BMWi.
Project duration: 03/2018 – 12/2021