Surface roughness effect to fatigue strength of 7075-T6 aluminum alloy

The effect of surface roughness on fatigue life of 7075-T6 Aluminum Alloy was widely studied. A function of fatigue life in terms of surface roughness was obtained. As the surface roughness increases, fatigue life decreases and vice versa. The objective of this present study is to build a practical tool for predicting the fatigue life of 7075-T6 Aluminum Alloy due to various surface roughness parameters Ra. The tool is indicated by surface correction factor Cs, which will be used to do correction of fatigue life obtained from simulation, which is commonly performed in ideal surface roughness condition, Cs=1. Various value of surface roughness parameter Ra was obtained from the various variable of the machining process. First, an estimated surface correction factor was obtained as the fatigue life ratio of the specimen with a certain Ra value to that of the specimen having an ideal surface condition. Then, a function of surface correction factor defined as Cs versus Ra was generated. A fatigue simulation was conducted using commercial software to predict fatigue life at the ideal surface condition. Finally, fatigue life for various values of Ra can be estimated using the obtained correction factors. It was concluded that the proposed surface correction factor Ra was applicable to estimate the fatigue life during simulation.