Local stress based fatigue assessment of multiaxially stressed automotive antiroll bars

Abstract Using a high-strength, cold formed and shot peened antiroll bar for heavy duty truck axles subject to multiaxial-proportional bending and torsion as an example, the paper shows a stress based fatigue life assessment procedure applicable in the early design phase of such high-performance suspension components with pronounced surface treatment. Finite element simulations reveal the component’s failure-critical locations and the multiaxial stress state acting there under the applied operational load. Strain gage measurements on prototype antiroll bars verifiy the accuracy of the simulations. Theoretical design S-N curves have been derived using the FKM-guideline recomendations regarding the material fatigue properties and correction factors accouting for the surface treatment (shot peening), in conjunction with the FEM results. The paper gives insight and explains the theoretical approach to local stress-based multiaxial fatigue analysis. Fatigue tests under fully reversed costant amplitude loading verify the theoretically determined S-N curves. The good agreement betrween experimental and theoretical fatigue lives pinpoints the great potential of the stress-based procedure described within the FKM guideline for treating multiaxial-proportional loading and life influencing effects resulting from the surface treatment in full-scale industrial components.