有限要素解析による管フランジ締結体のボルト締付け過程の評価:うず巻形ガスケットを用いた場合

抄録

In multi-bolt system, the scatter in bolt tension is largely dependent on the method of tightening operation and elastic interaction due to the successive tightening of bolts. In this study, focuses are placed on effects of elastic interaction and a new bolt-up strategy using three-dimensional finite element analysis, in which a gasket is modeled as a nonlinear one-dimensional gasket element, is proposed. Two types of numerical procedures are presented here. One is to predict the final scatter in bolt tension when tightening all bolts one by one in arbitray order with target preload. The other is to predict the amounts of initial bolt loads needed to create uniform final preloads with one pass operation of bolt tightening. The effectiveness of the numerical approach proposed here is substantiated by comparing numerical results with experimental ones. Contact pressure distributions on the gasket bearing surface, which significantly affect the sealing performance of flange connections, are also evaluated. The objective connection is composed of bolts, pipe flanges and a spiral wound gasket with inner and outer rings.