Papers by Author: T. Dirgantara

Abstract: In this paper, the prediction and comparison of the behavior of thin-walled prismatic structures (square tube, top-hat and double-hat sections) in absorbing energy using theoretical and numerical analysis are presented. Equations to predict crushing length and dynamic mean crushing force of top-hat and double-hat sections were applied for material mild steel St37 and the effect of spot weld positions are also figured out. For comparison, an explicit non-linear commercial finite element code LS-DYNA was used to predict the response of the structures subjected to axial crushing. It was found that results of numerical methods and theoretical prediction have good agreement. Assuming that the failure of spot-weld is neglected, mean dynamic crushing force of double-hat section is 90% higher compared to that of square tube.

Abstract: This paper presents the geometrically nonlinear analysis of cracked plates by the dual boundary element method. Extrapolation of displacements on the crack surfaces is used to compute the stress intensity factors. The normalized stress intensity factors for the cracked square plate with fully clamped and simply supported boundary conditions are presented.

Abstract: In this paper, buckling analysis of cylindrical shells with a circumferential crack is presented. The analyses were performed both numerically using FEM and experimentally. The numerical analyses and experiments were conducted for several crack lengths and radius of curvature, and two different boundary conditions were applied, i.e. simply support and clamp in all sides. The results show the effect of the presence of crack to the critical buckling load of the shells. There are good agreements between experimental and numerical results.

Abstract: The presence of cracks or similar imperfections can considerably reduce the buckling load of a shell structure. In this paper, buckling analysis of cylindrical shells with a longitudinal crack is presented. Numerical buckling analyses of cylindrical shells were performed using FEM, and verified by experiment. The numerical analyses and experiments were conducted for several crack lengths and radius of curvature, and two different boundary conditions were applied, i.e. simply support and clamp in all sides. The results show the effect of the presence of crack to the critical buckling load of the shells. There are good agreements between experimental and numerical results.