Analisis Limit Momen Pipa Elbow dengan Beban In-Plane Bending

Pipe bends or elbows are of important component in a piping system. In addition to its function for changing the direction of piping due to layout restriction, an elbow can accomodate expansion becauseit is more flexible than an equivalent straight pipe with the same material and dimension. However, an elbow cannot be analyzed using the engineer's theory of bending,because its cross section become oval under bending. This paper reports a result of finite element study of bending behaviour of a pipe elbow and its influence on limit moment. Limit moment was obtained using nonlinear analysis and Newton-Raphson algorithm was employed. Material behaviour of pipe was treated as large-strain, elastic-perfectly-plastic. The results show that a pipe elbow under in-plane opening bending is stiffer than those under in-plane closing bending, indicated by their limit load - 4.83 times yiels moment for in-plane opening bending, and 1.34 times the yield moment for in-plane closing bending