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One of the issues in stamping of advanced high strength steels (AHSS) is the stretch bending fracture on a sharp radius (commonly referred to as shear fracture). Shear fracture typically occurs at a strain level below the conventional forming limit curve (FLC). Therefore it is difficult to predict in computer simulations using the FLC as the failure criterion. A modified Mohr-Coulomb (M-C) fracture criterion has been developed to predict shear fracture. The model parameters for several AHSS have been calibrated using various tests including the butter-fly shaped shear test. In this paper, validation simulations are conducted using the modified (M-C) fracture criterion for a dual phase (DP) 780 steel to predict fracture in the stretch forming simulator (SFS) test and the bending under tension (BUT) test. Various deformation fracture modes are analyzed, and the range of usability of the criterion is identified.

Battery packs for Hybrids, Plug-in Hybrids, and Electric Vehicles are assembled from a system of modules (sheets) with a tight sheet metal casing around them. Each module consists of an array of individual cells which vary in the composition of electrodes and separator from one manufacturer to another. In this paper a general procedure is outlined on the development of a constitutive and computational model of a cylindrical cell. Particular emphasis is placed on correct prediction of initiation and propagation of a tearing fracture of the steel can. The computational model correctly predicts rupture of the steel can which could release aggressive chemicals, fumes, or spread the ignited fire to the neighboring cells. The initiation site of skin fracture depends on many factors such as the ductility of the casing material, constitutive behavior of the system of electrodes, and type of loading.

CRASH-CAD is a commercially available computer aided design package that specifically addresses design problems of components and sub-assemblies of automotive bodies subjected to crash loading. The program is fully interactive and leads an engineer in several steps towards an improved crashworthy design. The objective of the present paper is to give a theoretical foundation of this new computer program and demonstrate its various capabilities. CRASH-CAD enjoys unparalleled modelling simplicity. It requires only basic cross-sectional dimensions of a given member and a discretization into Superfolding Elements is done automatically. The current version of CRASH-CAD is applicable to prismatic members subjected to predominantly axial compressive loads.

The crushing behavior of axially compressed short thin-walled open-section columns was studied. Results of model tests on 0.1 mm thick aluminum foil specimens have shown that the panels collapsing in the symmetric and asymmetric deformation mode provide respectively, upper and lower bound for the energy absorbed in any other buckling mode. In both cases, the crush response of the panel was predicted theoretically with a reasonable accuracy. Attempts were made to introduce beneficial geometric imperfections of a specified magnitude so that the structure will be forced to collapse in the most energy efficient deformation mode.

The crushing process of thin platic shells is formulated as a problem of isometric transformation of surfaces. In terms of mechanics isometric transformation means inextensible deformation of the shell middle surface. In order to identify the mechanism of the formation of folds tests were performed on axially compressed P.V.C. cylindrical panels. A simple method was then developed for predicting the force-shortening characteristics and mean crushing strength of compressed members.

Static and dynamic strength of thin-walled mild steel box columns subjected to axial loading is studied both theoretically and experimentally. A series of impact tests was made using a pendulum hammer experimental facility. The computed dynamic crushing force was always higher than the corresponding static value and the ratio of the two forces /dynamic correction factor/ was shown to be an increasing function of the initial impact velocity. A simple theory is used to predict the average force level and energy absorption of dynamically crushed columns. A good agreement between the theory and present experimental results as well as those of other authors was obtained. A significance of an averaging procedure for a proper interpretation of test results is emphasized. The results obtained are applicable in the preliminary design of energy absorbing members of crushworthy buses and trucks.

As opposed to slender columns, tubular members used in the automobile industry are quite “stocky” so that the shear rigidity is comparable to the bending rigidity. It has been conjunctured that appreciable shear forces developed in the process of progressive crushing might be responsible for a loss of stability and a global collapse of compressive members. This problem is studied here using a simple model of the tube undergoing finite rotations and local crushing. It was found that the shear forces are caused by redistribution of stresses at the crushed zones and tube ends and by the associated finite changes of the geometry of the tube. An essential mechanism which triggers these events is the unsymmetric local folding, described by Abramowicz and Jones. A simple estimate is given on the maximum magnitude of shear forces both in the positive and negative direction.

Ground impact caused by road debris can result in very severe fire accident of Electric Vehicles (EV). In order to study the ground impact accidents, a Finite Element model of the battery pack structure is carefully set up according to the practical designs of EVs. Based on this model, the sequence of the deformation process is studied, and the contribution of each component is clarified. Subsequently, four designs, including three enhanced shield plates and one enhanced housing box, are investigated. Results show that the BRAS (Blast Resistant Adaptive Sandwich) shield plate is the most effective structure to decrease the deformation of the battery cells. Compared with the baseline case, which adopts a 6.35-mm-thick aluminum sheet as the shield plate, the BRAS can reduce the shortening of cells by more than 50%. Another type of sandwich structure, the NavTruss, can also improve the safety of battery pack, but not as effectively as the BRAS.