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WAVE PROPAGATION IN HEAD ON BONNET IMPACT: MATERIAL AND DESIGN ISSUES
Edmondo Di Pasquale,Daniel Coutellier 한국자동차공학회 2017 International journal of automotive technology Vol.18 No.4
Head on bonnet impact is becoming more and more important in automotive design as regulations on pedestrian safety become more demanding. Despite the relatively low amount of energy involved, these impacts are truly dynamic phenomena as the event duration is comparable with the traveling time of the different wavefronts generated by the impact. In this paper, we show that we can build up a simplified model for the impact based on wave propagation analysis. Using this model, we can analyze head acceleration on existing bonnets or predict it on new ones. Head acceleration in a bonnet impact can thus be estimated over the whole area of the bonnet with a few minutes of CPU.
Hakim Naceur,Jun Lin,Daniel Coutellier,Abdel Laksimi 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5
In the present investigation, a new modified smoothed particle hydrodynamics (SPH) method particularly adapted for the analysis ofplanar structures undergoing geometric nonlinearities is introduced and discussed. The problem of inconsistency which is often encounteredin the classical SPH method is alleviated by introducing modifications of the kernel function and its derivatives using an explicitpolynomial feature representation based on the Taylor series expansion. Tensile instabilities arising in the Eulerian-based SPH formulationwhich appear due to large deformations are attenuated by the introduction of a total Lagrangian formulation which is robust for largedisplacements/rotations. The resulting nonlinear problem is solved using the explicit dynamics time integration scheme. The validity ofthe proposed approach is demonstrated through two numerical applications involving geometrical nonlinearities, where the obtainedresults are compared to those obtained using the standard finite element method.