Determination of the limiting surface pressure of component materials used in bolted joints on ring-shaped specimens at elevated temperature up to 300 °C

Abstract

Within the focus of lightweight engineering the evaluation of the surface pressure in compressively loaded contact faces of bolted joints is challenging the designer in order to exploit the full material potential for weight reduction in an optimum way. Despite usually given ambient temperature conditions during assembly an altered compressive strength for bolted components subjected to thermal loading in service has to be considered. In contrast to tensile strength only restricted information about values for compressive strength at elevated temperature is existing. Furthermore values are largely determined on cylindrical specimens, not on specimens with clearance hole, thus not close to component structures of bolted joints. Therefore conservative guide values or assumptions are used. An extension of both testing methods referenced in guideline 2230 part 1, edition November 2015 of the association of German engineers (VDI) for determination of the limiting surface pressure up to 300 °C is presented. Results for two steel and one aluminium alloy depending on the test temperature are displayed. In addition, investigations with variation of test speed in continuous runs and tests for the investigation of the material behaviour in discontinuous trials with hold times are accomplished at elevated temperature.