Evolution of faying surface roughness and coefficient of friction around fastener hole in 2024-T3 clad aluminum load transfer specimen
Shrestha, Amul Sudan
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The evolution of surface roughness and friction coefficient on the faying surfaces of 2024-T3 clad aluminum sheets in a fastener joint has been investigated experimentally. The terminal values of the roughness and friction coefficient in fatigue cycled load transfer specimens were measured using a linear reciprocating tribometer. The evolution of surface roughness and friction due to relative sliding of the two sheets was approximated by using a 2024-T3 bare aluminum ball on a 2024-T3 clad aluminum sheet. The repeated frictional/wear loads were applied using the reciprocating tribometer and the friction coefficient, roughness and material wear volume measured as a function of cycle count. The terminal friction values in load transfer specimens were found to exceed unity at locations corresponding to the fretting failure initiation indicating possible localized welding of the two parts. The evolution of friction and surface roughness exhibited similar phases corresponding to the removal of the clad layer and petrification of residual particles between the abrading surfaces. The experimental results indicate that the friction coefficients and wear rates must be included in future fatigue simulations to account for the changes in load transfer mechanisms and the corresponding stress concentrations around the fastener holes.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Aerospace Engineering