Evaluating fatigue performance of down gauged high strength steel suspension arm

Abstract

The use of high strength steels (HSS) in automotive components is steadily increasing as automotive designers use modern steel grades to improve structural performance, reduce vehicle weight, and enhance crash performance. Weight reduction can be achieved by substituting mild steel with a thinner gauge HSS, however it must be ensured that no deterioration in fatigue performance occurs. Fatigue studies have been carried out to determine the effects various welding processes, gauge, and material strength can have on the fatigue performance of an automotive suspensionarm.Test methodology has also been investigated and the merits of both uniaxial constant amplitude and multiaxial simulation testing have been studied. Results have shown the fatigue performance of welded components to be independent of the strength of the parent material for the steel grades studied. Also, little correlation was found between the fatigue performance of simple welded samples under uniaxial, constant amplitude loading and complex components under biaxial in service loading, road load data. This highlights the care required when estimating component in service performance from small, simplified samples. The work also highlights the need for testing components under in service conditions if optimum use of materials, design, and manufacturing methods is to be achieved.