The dynamics of assembled structures are significantly dependent on joints. Joints parameters, owing to be difficultly measured, are always ignored by pure rigid in numerical modeling and it will result in unreliable or even error descriptions. 1∼3 Hz deviations may cause resonance especially in engineering optimization issues; hence it is necessary to identify joints parameters for structural dynamics investigation. In present work, multiobjective optimization algorithms are used to identify joints parameters by approaching actual test results in each series of structure to decrease unreliable or error for numerical modeling. Taking automotive dynamics with seam-welding and spot-welding as examples, the relationship of joints parameters perturbation and structural dynamics is derived to give the selecting reason of parameters' identification. The actual dynamics of an SUV's frame and a thinwalled part in BIW (body in white) are utilized to validate the methodology. Results demonstrate that the validated model has enough accuracy to reflect the dynamics of the actual structure. The methodology provides reliable guarantee for dynamic analysis and the design of structure.

Application of computer simulation techniques in traffic reconstruction will contribute to the sustainable development of protection of pedestrians and driver. In this paper, introducing National Automobile Accident In-Depth Investigation System Nais. The proposed database establishment could handle data while cases accumulate to a certain degree. Based on its strict workflow and thought process, take a collision accident as an example, collecting accident information, using PC-CRASH to reconstruct this accident. Evaluating consistency of simulation results and accident. Finally, in the light of this vehicle, making safe evaluation and analyzing the reason of airbag unexploded. The proposed database provides a powerful and extensible framework that is particularly well suited to analyzing big variety data in traffic accident.