Today, a car model consists of up to 1200000 Finite Elements with 5-15 mm per element edge. Considering the over-all car simulation, the FE-model is relative fine, but in comparison to the dimension of the individual joints, e.g. mechanically fastened joints, this discretisation is rather coarse. The crash behaviour of modern car structures is highly influenced by the behaviour (stiffness, strength) of the joints. In order to meet the increasing requirements regarding the precision of the calculated failure behaviour of cars in a complex car crash scenario, it is absolutely essential to consider the connection points in the simulation process. In the consequence, a detailed modelling technique with many elements for each joint cannot be used. Instead, there is a need for a simplified joint model. This FE-model has to cover the experimental results as good as possible while still fulfilling the modelling restrictions in a full car crash simulation. Mechanical joining is becoming more and more important in modern car designs because it is suitable for joining dissimilar materials as well as coated and pre-painted materials. The paper presents a mesh independent FE-model for mechanically fastened joints which is suitable for full car crash simulations. This FE-model includes a failure criterion which is based on both forces and plastic deformation. The numerical study has been done using the FEM program Abaqus/Explicit. The input data for the FE-model was determined by experiments. The paper shows a strategy to identify the relevant parameters from experimental data. The study presents a testing setup and an experimental procedure to define the strain rate dependent behaviour of mechanically fastened joints under combined axial and shear loading conditions. Experimental results of mechanically fastened joints at quasi-static and crash conditions are part of the paper.
Modelling of mechanically fastened connections for full car simulations
Modellierung von mechanischen Verbindungen für eine vollständige Fahrzeugsimulation
2008
13 Seiten, 16 Bilder, 1 Tabelle, 11 Quellen
Conference paper
English
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