Authors: Houchun Xia, David Y. Xue
Addresses: Vehicle Synthesis, Analysis and Simulation Process Center, North American Operation Design and Engineering Centers, General Motors Corporation, 30200 Mound Road, Warren, Michigan 48090, USA. ' Analytical Services & Materials Inc., 107 Research Drive, Hampton, Virginia 23666, USA
Abstract: The large deflection-induced geometric nonlinearity of vehicle body panels under road shipping condition is investigated. The example structure presented is the door outer panel of a passenger car. Studies include nonlinear finite element analysis of displacements, stresses and normal modes, and fracture mechanics analysis for crack growth rate and fatigue life prediction involving large deflections. The modified Newton-Raphson method is employed for the nonlinear analysis, and the fracture mechanics analysis is based on the virtual crack closure technique to compute the structural energy release rate, G. Results show that although the panel transverse deflection is large, i.e. close to panel thickness at the container design loading level, the difference between linear and nonlinear solutions is not significant. The reason is that the panel midplane is not stretched excessively due to the nature of the constraints provided by the container. This situation exists for most vehicle body panels under shipping environments. Therefore, the linear analysis strategy currently used in automotive industry for shipping container design is feasible. The results of the fracture mechanics analysis indicate that the dominant failure mode for the assumed panel fatigue cracking is the opening mode or Mode-I and the panel fatigue life can be greatly improved by properly designing the shipping container.
Keywords: fracture mechanics; nonlinear analysis; vehicle design; vehicle structures; structural analysis; vehicle body panels; passenger cars; vehicle doors; door panels; road shipping; finite element analysis; FEA; displacement; stress; crack growth rate; fatigue life prediction; large deflections.
International Journal of Vehicle Design, 1997 Vol.18 No.5, pp.533 - 547
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