Investigating the Effect of Low Plasticity Burnishing (LPB) Process on Fatigue life of Rotating Notched Shaft

One of the most appropriate methods for providing compressive residual stresses in the surface layer of parts is low plasticity burnishing that can increase fatigue life of metals. Low plasticity burnishing reduces or completely eliminates surface tensile stresses, without optimizing the environment, materials or design components. During this process, a free-rolling ball with proper vertical load is moved on the work-piece in order to create plastic deformation and compressive residual stress. In this study, finite element modeling of the process on Aluminum Alloy 7075-T6 shaft is presented in two conditions, single and double ball. Effect of the process on residual stresses and fatigue life of work-piece by strain-based approach is investigated. Results show that, using double ball instead of single ball in this process can increase axial and radial compressive residual stresses up to 1.5. Also, residual stress depth in double ball condition is higher than single ball condition. The fatigue strength in the work-piece with double ball LPB against without LPB and single ball is increased 3 and 2 times, respectively.