Abstrakt

It goes without saying that numerical simulations play important role in the modern engineering practice. Contemporary CAD environments combined with FEM solvers, along with computer power of modern processors, give the engineer fast and efficient tool. Ultimately, however it is the user alone who is responsible for the correctness of the results. As long as the FEM calculations remain in the sphere of academic exercise, the inevitable errors/mistakes resulting from improper use of FEM systems may postpone scientific development of some ideas. This is not the case however when industry application of FEM is considered as it usually involves substantial financial or other responsibility. In particular, we may mention these applications when human safety is a key factor. In this area Ls-Dyna has its special position as a tool for simulation of car collisions. Apart from car manufacturers the code is used also by the producers of safety barriers who must adhere to the specifications of specific standards. In Europe, as of March 2017, the current state of affairs is given by EN1317-2010 standard. These include, among others, precise definitions of initial conditions for car and the placement of the car relative to the analyzed restraint system. While such precision is necessary to allow comparing different barriers it is not sufficient to cover the abundance of the real-life situations. As a part of the research project jointly funded by National Centre for Research and Development (NCBiR) and General Director for National Roads and Motorways, Poland the present authors are responsible for numerical simulations of various real-life scenarios that do not conform to those of EN1317-2010 standard. To model the barrier-car collision we use car models that are freely available, correcting them when necessary however. The major effort is put on the correct recreation of barrier geometry along with proper boundary conditions and connections between barrier parts. As far as spatial discretization is concerned the majority of car’s and barrier’s parts are modeled with shell elements. In this report we study the influence of some Ls-Dyna control cards that affect the behavior of shell elements used in FEM simulations of crash tests.

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