New models for depicting corrosion fatigue behaviour and calendar life of metallic structural component

New S - N - t surface model is proposed for depicting corrosion fatigue behaviour and novel formulae are derived to estimate the parameters of proposed model by best fitting from a minimal experimental dataset of corrosion fatigue tests. From the Palmgren-Miner rule, a cumulative damage model for the alternation between corrosion and fatigue is developed to evaluate calendar life of metallic structural component. Corrosion tests are conducted on unnotched and notched specimens from LD10CS aluminium alloy and 15CrMnMoVA alloy steel in artificial corrosion environments. Fatigue tests are also performed on corroded specimens subjected to constant amplitude loading and the interaction mechanisms between corrosion and fatigue are deduced from fractographic studies. The applicability of the new models has been shown for experimental datasets for depicting corrosion fatigue behaviour and for evaluating calendar life of motor brace rod in helicopter.