Corrosion and biaxial fatigue of welded structures

The aim of this research is to develop an experimental approach for corrosion fatigue behaviour of welded structures subjected to simultaneous biaxial, rotating-bending and torsional loading, results of which could be used in railway bridges, ship, offshore structures, ground vehicles etc. The experimental program developed here considers stress field information due to the variations of applied stress conditions, surface treatments and corrosive environment using simulated heat-affected-zone (HAZ) and base materials. This is aimed at providing a procedure for improved design of new welded structures subjected to biaxial loading. The experimental data have been collected and compared with standard theoretical “stress–life” curves generated by earlier researchers (Juvinall, Shigley and Collin’s method). Experimental data in dry and corrosive environment (3.5% NaCl solutions) for rotating-bending–torsional thrust have been collected. This initial investigation suggests that the effects of secondary thrust is more severe than the effects due to corrosive environment, as it accelerates the initiation of the cracks; and consequently, the fatigue life reduces significantly. Design-engineers must consider reducing the effects of secondary thrust and minimising the environmental effect to improve on crack initiation properties of the structures.