Manufacturing effects on fatigue strength

© 2019 Elsevier LtdThe fatigue strength of a component is affected by parameters such as geometry, applied loads and material. Although it is theoretically possible to have the same fatigue life in components from the same production lot, there is likely scatter in the measurements of fatigue. The scatter can influence the expected fatigue life, change the S-N curve for the component and adversely impact the stress amplitude axis. In this work, the effect of manufacturing on the fatigue life of a rear axle stabilizer is analysed. The evaluation of the residual stress that results from the manufacturing process suggested that durability was improved, as indicated by the rotation of the S-N curve around the axis, which represents the number of cycles. An optimization of the estimated S-N curve was proposed, it is based on the stresses generated on the manufacturing process, and the slope was increased to account for residual stress. A nonlinear finite element simulation was performed to find a factor that increases the expected fatigue life. The factor depends on the stress generated on the component, both with and without residual stress, and is computed using finite element results. The improvements in the fatigue life can be depicted by rotating the S-N curve and increasing its slope. The error in the fatigue life prediction using the estimated S-N curve was reduced by 22.92% using the factor based on the manufacturing process.