Residual stress field of ballised holes

• Published in: Journal of mechanical science and technology 2012, 26(5), , pp.1555-1565
• Main Authors: Lai, Man On, He, Zhimin
• Format: Article
• Language: English
• Subjects: Applied sciences; Boundaries; Cold working; Compressive properties; Control; Dynamical Systems; Elasticity. Plasticity; Engineering; Exact sciences and technology; Forming; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Industrial and Production Engineering; Inelasticity (thermoplasticity, viscoplasticity...); Interference; Mechanical Engineering; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Nondestructive testing; Physics; Production techniques; Pushing; Residual stress; Simplification; Solid mechanics; Structural and continuum mechanics; Vibration; 기계공학
• ISSN: 1738-494X; 1976-3824
• DOI: 10.1007/s12206-012-0326-6

Ballising, involving pushing a slightly over-sized ball made of hard material through a hole, is a kind of cold working process. Applying ballising process to fastener holes produces compressive residual stress on the edge of the holes, and therefore increases the fatigue life of the components or structures. Quantification of the residual stress field is critical to define and precede the ballising process. In this article, the ballised holes are modeled as cold-expanded holes. Elastic-perfectly plastic theory is employed to analyze the holes with cold expansion process. For theoretical simplification, an axially symmetrical thin plate with a cold expanded hole is assumed. The elasticplastic boundaries and residual stress distribution surrounding the cold expanded hole are derived. With the analysis, the residual stress field can be obtained together with actual cold expansion process in which only the diameters of hole before and after cold expansion need to be measured. As it is a non-destructive method, it provides a convenient way to estimate the elastic-plastic boundaries and residual stresses of cold worked holes. The approach is later extended to the case involving two cold-worked holes. A ballised hole is looked upon as a cold expanded hole and therefore is investigated by the approach. Specimens ballised with different interference levels are investigated. The effects of interference levels and specimen size on residual stresses are studied. The overall residual stresses of plates with two ballised holes are obtained by superposing the residual stresses induced on a single ballised hole. The effects of distance between the centers of the two holes with different interference levels on the residual stress field are revealed.