ELASTIC- PLASTIC ANALYSIS FOR SQUARE SHELL TUBES DURING PURE BENDING USING FINITE ELEMENT

An analytical model with sufficiently non linear kinematics to capture the development in engineering applications to resist  bending  stress for thin walled elastic-plastic steel tubes which used as structural members. The results indicate that collapse of such tubes is imperfection sensitive for tubes with height to thickness ratio (h/t), but the sensitivity decreases as the ratio decreases. Experimentally, the tubes collapse due a limit moment instability which is followed by the formation of a kink on the compression flange of the tubes. The present research removes the limitation in the pre- bifurcation analysis and concentrates on the numerical prediction ANSYS -11 program of the response with stress and strain distribution on thin walled tubes of square cross section.  The numerical, analytical and experimental results are converges to each other, by simulating the response of square tubes subjected to static and dynamic axial bending loading .The finite element models  used for this work are featured by the geo-metric and material characteristics of square tubes and comparison of the computed bending response to the results and findings of the experimental works shows that the finite element models described here, approached the actual bending response of the square tubes to a satisfactory degree both in terms of collapse modes and main bending characteristics such as  bending stress and strain and deformation displacement