ANALYSIS OF BOLT JOINT USING THE FINITE ELEMENT METHOD

A numerical analysis of the initially clamped bolt joint subject to the working pressure is presented in the paper. Special, hexahedral 21- and 28-node isoparametric finite elements have been employed to model the contact zone. In this model, one takes into account loading due to the working pressure in the gap between the gasket and the flange arising as an effect of the progressing joint opening, what has not been considered in recent papers. Nonlinear stiffness characteristics of the bolt and the flange with the gasket are developed. Working pressure corresponding to the critical bolt force resulting in the joint leakage (complete opening between the gasket and the flange) is determined. FE computational results are compared with the available experimental results. The numerical results are presented using the authors ’ own graphical postprocessor. 1. Subject of analysis Flange joints are commonly used, e.g. in pipeline connections. Various aspects concerning approximate analytical calculations in a one-dimensional form, properties and servicing of the bolt joints are described in [1,2,3]. Osgood [4], Motosh [5], Shigly and Mischke [6] discussed in their works the flange connections in which the contact surfaces, which include the area between the flanges and the gasket, are assumed to be constant and without friction between the flange and the gasket. The nonlinear force-deflection behaviour of the connection was presented in Junker [7] and Bickford [8]. In the papers by Zahavi and others [9,10,11], one can find numerical analyses based on the finite element method that make use of commercial finite ele