R. Schmidt

Shock wave-loaded plates

Abstract The present paper reports on modeling, numerical simulation, and experimental investigation of plates subjected to impulsive loading. The kinematical hypothesis used for the theoretical description of the transient response includes transverse shear deformations, rotary inertia, and geometrical nonlinear effects. The material modeling accounts for elastic–plastic behavior, isotropic and kinematical hardening, and strain rate sensitivity. The numerical simulation of the transient inelastic vibrations is performed using isoparametric finite elements. Both the Chaboche and the Bodner–Partom viscoplastic constitutive laws are used to trace the evolution of the material characteristics in the framework of a layered shell model. The theoretical and numerical developments are checked by experimental investigations of thin steel plates subjected to shock waves. These experiments are performed in a shock tube with various impact periods and loading histories. The topics addressed in this report include (a) the correlation of experimental and simulated transient inelastic response using the Chaboche and Bodner–Partom models, (b) the sensitivity of the predicted structural response to variations of the material parameters identified on the basis of uniaxial tension tests, (c) the effect of the transverse shear stress distribution on the local evolution of the material behavior and on the global dynamic response, (d) the evolution of deflections, stresses, and plastic zones under blast loading conditions.

Shock tube experiments and Fe-simulation of the structural and material non-linear transient response of plates subjected to blast loading

This paper deals with the experimental investigation, modelling, and finite element simulation of structures exposed to shock-type blast loading conditions taking into account the structural and material non-linear effects. First- and thirdorder transverse shear deformation theories of plates and shells serve as basis of a finite element algorithm for the simulation of the transient, geometrically nonlinear elastic-viscoplastic response. Isoparametric Lagrangian 9-node shell finite elements and the central difference method for the time integration of the nonlinear equations of motion are used. Experiments are performed on thin clamped circular aluminium and steel plates in shock tubes. The main advantage of this experimental technique is that the front wave impinging on the structure is plane and yields a uniformly distributed pressure pulse. Consequently, in contrast to other experimental methods reported in literature, the time history of the shocktype loading can be modelled easily during the FE analysis. Comparative numerical simulations using first- or third-order transverse shear deformation plate theory, respectively, show a very good agreement with the experimental results. The best correlation with the experimentally observed transient response and permanent deflection is obtained by the refined, third-order transverse shear deformation model.

Vibrations Of Viscoplastic Under Impact Load

In the present paper theoretical and experimental investigations are made to verify viscoplastic theories applied to thin-walled structures. The vibrations of plates are studied under the assumption of small strains and moderate rotations theoretically and numerically by using constitutive models of Chaboche and Bodner-Partom. The numerical results are compared with experiments.