Estudo da absorção de energia em diferentes geometrias de estruturas de paredes finas em aço DP600 submetidas a compressão progressiva dinâmica para uso na indústria automobilística

Abstract

Thin-walled structures are widely used in the automobile industry for body construction. During a collision, they are responsible for absorbing the impact mechanical energy by its deformation, minimizing the load transferred to the occupants, a concept known as crashworthiness. The geometry of the structures, materials used and construction methods have an influence on the way it behaves. To assess the influence of the pieces’ geometry, this study was divided into three different stages. The first one aims at the correct characterization of the material and its mechanical, chemical and microstructural properties. The second, provides a theoretical basis indicating the difference in strength of the structure due to geometry, calculated analytically with concepts of column and plate buckling. Finally, in the third, strain rates are obtained and the characteristics of dynamic progressive buckling are measured using a rigid mobile barrier, accelerometers and high-speed cameras. The thin-walled structures were all based on the same initial concept and the same construction method. The base part has corrugations, deformation initiators along its length and eccentric loading. The second part brings additional deformation initiators and also eccentric loading. The third part has an increase in thickness, shorter in length and a change in its end in order to obtain an axial loading. The tested parts were manufactured in DP600, and the structures that were axially loaded did not show a tendency to global buckling, resulting in greater reaction force and being able to absorb all the energy of the proposed impact in less time. It was also concluded that it is possible to reduce the influence of eccentric loading by the correct positioning of deformation initiators. These results indicate important points for the design of such structures, enabling mass and costs reductions and increased protection for final consumers.