This study aims to identify the effect of road surface to coil spring fatigue life using the strain-life approach. Strain signals were measured by attaching a strain gauge at the critical point of the component. The car was driven on a flat road, as well as uphill, and downhill paths. The results show that the downhill road provided the lowest fatigue life, of 1.5E+4 cycles to failure, which was 53 % lower than that of the uphill and 2,233 % lower than the flat road owing to the braking factor which resulted in a higher stress to the coil spring.

This study examines the fatigue life of the SAE 5160 carbon steel as the material for an automotive coil spring subjected to road strain. The strain signals were acquired by attaching a strain gauge on the component, driving a car up- and down-hill roads. The results of the fatigue life assessment based on the strain-life approach show that the downhill road resulted in a lifespan of 15,000 cycles to failure, which was 53% lower than the uphill road. This value was a result of braking when the vehicle is moving downhill, causing stress to the component leading to shorter fatigue life.