Elastic Interaction Between Fasteners in Gasketed Bolted Joints

An experimental study is presented in order to determine the effect of several parameters on the elastic interaction between various fasteners in a gasketed joint. Parameters include the gasket thickness, bolt spacing, tightening sequence, fastener grip length, and the level of fastener preload. The joint is made of two steel flanges with a Styrene Butadiene Rubber gasket of various thicknesses. The joint is fastened together using 1/2” - 13 SAE Grade 8 fasteners that are specially instrumented to measure the initial preload and the residual tension in each fastener. Four different gasket thicknesses are considered, namely, 1/16”, 1/8”, 3/16”, and 1/4”. For the same bolt circle of the flange, bolt spacing is varied by using different number of bolts; spacing that corresponds to using three, five, or seven bolts are considered in this study. The effect of the tightening sequence is studied by using sequential bolt tightening, star pattern, and simultaneous tightening. Bolt tightening is accomplished by using either an electric digital torque wrench with various control options, or a production-size multiple spindle fastening system that is capable of simultaneous tightening of all fasteners using torque, torque-turn, or torque-to-yield control of each fastener.