Evaluation on Spot Weld Models in Structural Dynamic Analysis of Automotive Body in White

Spot weld models are widely used in finite element analysis（FEA） of automotive body in white（BIW） to predict static,dynamic,durability and other characteristics of automotive BIW.However,few researches are done on evaluation of the validity of these spot weld models in structural dynamic analysis of BIW.To evaluate the validity and accuracy of spot weld models in structural dynamic analysis of BIW,two object functions,error function and deviation function,are introduced innovatively.Modal analysis of Two-panel and Double-hat structures,which are the dominated structures in BIW,is conducted,and the values of these two object functions are obtained.Based on the values of object functions,the validity of these spot weld models are evaluated.It is found that the area contact method（ACM2） and weld element connection（CWELD） can give more precise prediction in modal analysis of these two classical structures,thus are more applicable to structural dynamic analysis of automotive BIW.Modal analysis of a classical BIW is performed,which further confirms this evaluation.The error function and deviation function proposed in this research can give guidance on the adaptability of spot weld models in structural dynamic analysis of BIW.And this evaluation method can also be adopted in evaluation of other finite element models in static,dynamic and other kinds of analysis for automotive structures.

Crashworthiness Analysis of a Minibus Body in White Through Reverse Engineering

To investigate the crashworthiness of a minibus body in white (BIW) and create a digital model for further analysis and improvement, the crash behavior of the BIW was quantitatively analyzed using re-verse engineering. Each part of the BIW was identified and digitalized to conduct a finite element model. A frontal crash was simulated numerically using the explicit finite element analysis software LS-DYNA. BIW crash tests were conducted to validate the finite element model. The computational results agree well with the test data, not only for the collapse mode, but also in the force-time and acceleration-time correlation curves. The methods used to create the finite element model can be used to further improve or develop safer vehicles.

Lightweight design of an electric bus body structure with analytical target cascading

Lightweight designs of new-energy vehicles can reduce energy consumption,thereby improving driving mileage.In this study,a lightweight design of a newly developed multi-material electric bus body structure is examined in combination with analytical target cascading(ATC).By proposing an ATC-based two-level optimization strategy,the original lightweight design problem is decomposed into the system level and three subsystem levels.The system-level optimization model is related to mass minimization with all the structural modal frequency constraints,while each subsystem-level optimization model is related to the sub-structural performance objective with sub-structure mass constraints.To enhance the interaction between two-level systems,each subsystem-level objective is reformulated as a penalty-based function coordinated with the system-level objective.To guarantee the accuracy of the model-based analysis,a finite element model is validated through experimental modal test.A sequential quadratic programming algorithm is used to address the defined optimization problem for effective convergence.Compared with the initial design,the total mass is reduced by 49 kg,and the torsional stiffness is increased by 17.5%.In addition,the obtained design is also validated through strength analysis.