Scozzafave, C., Ericsson, L., Wildmann, U., and Spinelli, D., "Development of a Fatigue Analysis Methodology Using the Software FEMFAT Strain®," SAE Technical Paper 2013-36-0359, 2013, doi:10.4271/2013-36-0359.
The aim of this paper is to present a methodology for approval of component that is applied when the first version is tested on a durability track with closed circuit and fails without meeting the approval criteria previously established. This approach was applied in suspension support on commercial vehicles.The full commercial vehicle was modeled in finite element for stress analysis in frame torsional loading. By presenting stress regions near the material's limit, tests were made on durability track with deformation measurement at the main critical spots. The component has failed in one of the measured spot without reaching the established number of laps for component approval on track.With the deformation measurement signal for one lap at the failure spot, a fatigue analysis using the software FEMFAT strain ® has been made, correlating the obtained damage with the number of laps on track until component failure.An improving proposal for the front stabilizer bar support was modeled in Finite Elements and again torsional loading in the frame was analyzed. With these two stress results, (the one with failure and the new version) it was possible to create a proportionality factor between the stresses verified in the two versions.To exclude the second round of testing in the component design, it was proposed a fatigue analysis with the measurement signal of the failed version corrected by the proportionality factor between the two versions. It is believed that, because of the similarities between geometries, and using the same vehicle for testing, strains found in the second round of testing would be proportional smaller.The fatigue analysis was performed with the one lap deformation signal (corrected by the proportionality factor) and the damage obtained was correlated with the number of laps on the track until new version failure. As the number of laps meets the criteria previously established, the new version was approved.In summary, this paper proposes a component approval methodology using FEMFAT strain ® that requires less testing time on durability track, providing reduction of time and cost in the commercial vehicles development.