Numerical Study of Fatigue Crack Propagation in a Residual Stress Field Induced by Shot Peening
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JMEPEG (2020) 29:5525–5539 https://doi.org/10.1007/s11665-020-05029-9
Numerical Study of Fatigue Crack Propagation in a Residual Stress Field Induced by Shot Peening Cheng Wang
, Guang Wu, Tao He, Yijun Zhou, and Zechen Zhou
(Submitted December 3, 2019; in revised form June 26, 2020; published online August 13, 2020) Shot peening (SP) is a relatively traditional but highly effective mechanical surface treatment that produces a compressive residual stress field in a shot-peened (SPed) surface, which can effectively delay fatigue crack propagation (FCP) and prolong the service life of engineering materials and structures. A multistep analysis method was developed by combining a numerical simulation of the SP process and the LEFM-based (linear elastic fracture mechanics) superposition principle to study FCP behavior in an SP-induced residual stress field. The SP-induced residual stresses were first simulated by a symmetric cell model and then introduced into a finite element model of the CT specimen. The total stress intensity factors and stress ratios with respect to different crack lengths were calculated according to the LEFM-based superposition principle. The influences of external applied load ratios and SP conditions, including one-sided and double-sided SP, on the FCP behavior of the SPed CT specimen were investigated in detail.
Engineering materials and structures that are subjected to variable amplitude loading during service often experience fatigue failure (Ref 1, 2), which consists of three phases: fatigue crack initiation, propagation and fracture. Considering that fatigue cracks mostly initiate on material surfaces, many surface enhancement treatment techniques have emerged to improve the fatigue performance and prolong the service life of engineering components (Ref 3), including SP (Ref 4), deep rolling (DR) (Ref 5) and laser shock processing (LSP) (Ref 6). SP is a relatively traditional but highly effective mechanical surface enhancement treatment technique that is widely used in the aerospace, automotive and power generation industries (Ref 7, 8). As shown in Fig. 1, during the SP process, a large number of small spherical shots are fired at a metal surface, and the resultant impacts produce inhomogeneous elastic–plastic deformation in the SPed materials. As a result, beneficial compressive residual stresses are produced in the surface layer of metallic materials. A large number of experiments have confirmed that SP-induced compressive residual stresses can considerably improve the surface integrity and fatigue resistance of metallic materials (Ref 9, 10).
Numerical simulations with the finite element method (FEM) are inexpensive and easy to perform; moreover, this approach can provide insight into the compressive residual stress strengthening mechanism of SP. For numerical simulations of the SP process, many finite element models have been developed, such as the single-shot impact model (Ref 11), multiple-shot random-impact model (Ref 12, 13), DEM-FEM coupled model (Ref 14), SPH-FEM coupled mode
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