Optimization of crashworthiness of the thin shell structure composed from polycrystal metals by crystal shear banding

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For a ductile metal, localized shear banding appears as the preceding phenonemenon to the fracture. Initiation and developing of the shear band significantly influenced on the crystarograhic structure of the polycrystal materials and on loading paths. The puropose of the research project is to develop the method of optimization of crashworthiness of shock absorbing components by controlling the initiation and the developing of shear banding the obtained results are as follows.1. For FCC crystals, the mathematical model of the criterion to the initiation of shear band is established. Introducing the hypothetical 13th slip system defined by the proposed criterion into the finite element polycrystal model, numerical simulator which can be applied to the problem of weakning of crystals caused by developing of shear banding is established.2.Results of the numerical simulation and the experiment for plane strain compression of the FCC polycrystal shows that the shear banding penetrates or not according to the relative configuration of crystarographic orientation between ajacent crystal grain. The result suggests the possibily of the optimization of crashworthiness of the shock absorbing component made of polycrystal metals by controlling crystarographic texture of them.3. Numerical simulater for impact problems of a beam and of a cylindrical shell is developed. It is clarified that strain rate sensitivety of a material slightly improve the crashworthiness of a beam and a thin shell structure.