Modeling and Parameter Design of a Laser Shock Peening Process

Laser shock peening (LSP) is a surface treatment technique that has been applied to improve fatigue and corrosion properties of metals. The ability to use a high energy laser pulse to generate shock waves, inducing a compressive residual stress field in metallic materials, has applications in multiple fields such as turbomachinery, airframe structures, and medical appliances. In the past, researchers have investigated the effect of LSP parameters experimentally [1 Clauer, A. H., Fairand, B. P. and Wilcox, B. A. 1977. Laser Shock Hardening of Weld Zones in Aluminum Alloys. Metallurgical Transactions A, 8A: 1871–1876. [Crossref], [Web of Science ®] , [Google Scholar], 2 Fairand, B. P., Clauer, A. H., Jung, R. G. and Wilcox, B. A. 1974. Quantitive Assessment of Laser Induced Stress Waves Generated at Confined Surfaces. Applied Physics Letters, 25(8): 431–433. [Crossref], [Web of Science ®] , [Google Scholar], 3 Fairand, B. P. and Clauer, A. H. 1979. Laser Generated Stress Waves: Their Characteristics and Their Effects to Materials. Laser-Solid Interactions and Laser Processing, 50: 27–42. [Google Scholar], 4 Peyre, P., Fabbro, R., Merrien, P. and Lieurade, H. P. 1996. Laser Shock Processing of Aluminium Alloys. Application to High Cycle Fatigue Behavior. Material Science and Engineering, A210: 102–113. [Crossref], [Web of Science ®] , [Google Scholar], 5 Peyre, P., Berthe, L., Scherpereel, X. and Fabbro, R. 1998. Laser-shcok Processing of Aluminium-coated 55C1 Steel in Water-confinement Regime, Characterization and Application to High-cycle Fatigue Behavior. Journal of Material Science, 33: 1421–1429. [Crossref], [Web of Science ®] , [Google Scholar]] and performed a limited number of simulations on simple geometries [6 Braisted, W. and Brockman, R. August 1999. Finite Element Simulation of Laser Shock Peening. International Journal of Fatigue, 21(7): 719–724. [Crossref], [Web of Science ®] , [Google Scholar], 7 Nam, T. 2002. Finite Element Analysis of Residual Stress Field Induced by Laser Shock Peening, Columbus, Columbus: Ohio State University. Ph.D. Dissertation [Google Scholar], 8 Ding, K. and Ye, L. 2006. Laser Shock Peening Performance and Process Simulation, Cambridge, Cambridge: Woodhead Publishing Limited. [Crossref] , [Google Scholar], 9 Warren, A. W., Guo, Y. B. and Chen, S. C. 2008. Massive Parallel Laser Shock Peening: Simulation, Analysis and Validation. International Journal of Fatigue, 30: 188–197. [Crossref], [Web of Science ®] , [Google Scholar]]. However, monitoring the dynamic, intricate relationship of peened material experimentally is expensive and challenging. With an increasing number of applications on complex geometries, these limited experimental and simulations capabilities are not sufficient for LSP process design. A computational mechanics procedure is required that can perform simulations of multiple treatments of LSP at the same location, sequential LSP at multiple locations, different overlapping configurations of LSP locations, and complex geometries. With increased computer speed as well as increased sophistication in non-linear finite element (FE) analysis software, it is now possible to develop a simulation-based design investigation approach for an effective LSP process design. In this paper, the process parameters are identified and a three-dimensional simulation is adopted and validated. This simulation is then used in sensitivity analysis of performance metrics of residual stress for variations in the LSP parameters such as pressure pulse magnitude and shape, spot shape and size, component thickness, number of shots, layout of shots, and multiple shot sequences.