CONCEPT DESIGN FOR FATIGUE RESISTANCE

Extensive work has been carried out by the fatigue research community into the nature of fatigue failure using computational and experimental methods, leading to a 'toolkit' for fatigue design. However, these techniques rely on detailed knowledge of the component geometry, materials and service loading and are more suited to the final stages of the design process. The concept design phase is where there is most scope for improvement, because if the conceptual design can be nearly right first time then iteration at the design analysis stage can be reduced. The proposed work will develop a method for rapid quantitative comparisons of concept designs that will allow a cost-effective approach to design improvement with attendant reductions in prototyping, manufacturing and service failure costs. The overall goal is to devise new risk based metrics for concept design evaluation and selection that reflect actual fatigue performance in service. The metrics devised will be correlated to case histories from the automotive, aerospace and industrial sectors, to show that, in the simplest sense: low risk = survival; medium risk = fatigue failure in extreme operating conditions; high risk = likelihood of fatigue fracture under normal operating conditions. The research is timely since many organisations are trying to move to a culture of right first time design coupled with design simulation rather than expensive and time consuming prototype testing.