This conference paper was submitted for presentation at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

Predicting structural failure in automotive engineering remains a significant challenge in the area of virtual vehicle development, gaining further importance in the context of "Virtual Certification." The increasing use of modern lightweight materials, ultra-high-strength steels, and new innovative joining techniques contributes to heightened material diversity and complexity in vehicle bodies. Traditional resistance spotwelds are now complemented by growing use of self piercing rivets, line welds, and flow drill screws among other techniques. The failure of these connections is of particular concern in crash scenarios, as it significantly impacts vehicle safety. Therefore, robust and industry-applicable computational methods are essential for dealing with the complexity of vehicle structures and delivering reliable predictive results. In this seminar, the L2-Tool, a modular failure assessment framework, which was developed at the Virtual Vehicle Research Center in a joint research project with Volkswagen AG and Audi AG will be presented. The key element of this framework is the assessment of the failure with special surrogate models, which guarantee a high prediction quality despite a low additional computing time. Particularly high-strength lightweight materials have an increased risk of crack initiation under plane tensile load, for example due to the heat input in the welding process or due to the notch effect on rivets and flow drill screws. A key element of this method is that these two types of failure can be distinguished and assessed using a non-local approach. For the parameterization of the failure models, a combination of real and virtual testing with detailed, small-scale specimens is used, which will be briefly outlined in the presentation. After the development phase, the failure models are integrated into the product development process in a multi-stage integration process, starting with implementation via user interfaces, followed by an comprehensive test phase and the final industrialization by the crash solver provider. In the conclusion of the presentation, illustrative results of the L2-Tool applied to vehicle substructures are presented. The framework within the standardized calculation process is also described, with emphasis on the pre- and post-processing phases. The predictive accuracy of the method is addressed, and finally, potential applications are shown.