A Novel Spot Weld Failure Prediction Methodology in Safety Simulations

Abstract

Translate Article

<div class="section abstract"><div class="htmlview paragraph">Spot-weld joinery plays a major role in maintaining structural integrity of vehicle during an accident scenario. Robust failure definitions are important for accurate prediction of spot-weld failure in crash safety simulations. Spot welds have a complex metallurgical structure, consisting of fusion and heat affected zones. Identifying material failure definitions for huge number of spot-weld joint combinations in a typical Body in White (BIW) of a vehicle is highly challenging.</div><div class="htmlview paragraph">In conventional LS-DYNA-MAT100 material model, spot-weld failure prediction accuracy is limited under complex crash loading scenarios, especially angular and bending load conditions. In order to enhance the failure predictions, a novel mathematical failure model is developed by considering instantaneous resultant loading along with bending moment as a key failure parameter to determine spot weld joint failure. A three dimensional failure surface is constructed by incorporating physical test data of tensile, shear, angular and bending load conditions at different strain rates. This user defined failure criteria is capable of predicting spot-weld failure more accurately, considering typical crash loading scenarios.</div><div class="htmlview paragraph">Significant amount of physical tests are carried out for spot weld joint combinations and an empirical basis is formulated using regression analysis to generalize the failure surface for a given material and thickness combination. Comprehensive failure database formulation using this approach has avoided extensive number of spot-weld joint physical tests, which are ideally required to cover all the possible joint combinations at full vehicle level. This methodology is one of its kind and addresses the complex challenges in spot-weld failure prediction in crash CAE simulations. This paper talks about the developed failure criteria, approach for global database creation, component and vehicle level test and CAE correlation aspects.</div></div>