• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.43-50
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• 2012

The effects of parameters related to the finite element simulation of the laser shock peening(LSP) process on the residual stresses of Inconel alloy 600 steel are discussed. In particular, we focus on the maximum pressure, pressure pulse duration, laser spot size, and number of shots. It is found that certain ranges of the maximum pressure and pulse duration can produce the maximum compressive residual stresses near the surface, and thus proper choices of these parameters are important. The residual stresses are not affected by the laser spot size, provided it is larger than a certain size. The magnitudes of the compressive residual stresses and the plastically affected depths are found to increase with an increasing number of shots, but this effect is less pronounced for more shots.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.3
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• pp.290-296
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• 2005

The contour method is based on the elastic superposition principle, and relies on deformations that occur when a residually stressed part is cut along a plane. During the cut, the part is constrained at a location along the cut so that deformations are restrained as much as possible. The displacement is applied to an elastic FE model of the half. When plasticity is involved in the relaxation process, the superposition principle is no longer valid, and stress error in the resulting measurement of residual stress would be caused. Residual stress states in a laser peened Ti-6Al-4V strip were taken for the FE simulation.

• Structural Engineering and Mechanics
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• v.62 no.6
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• pp.739-748
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• 2017

Notches such as slots are typical geometric features on mechanical components that promote fatigue crack initiation. Unlike for components with open hole type notches, there are no conventional treatments to enhance fatigue behavior of components with slots. In this work we evaluate the viability of applying laser shock peening (LSP) to extend the fatigue life of 6061-T6 aluminum components with slots. The feasibility of using LSP is evaluated not only on damage free notched specimens, but also on samples with previous fatigue damage. For the LSP treatment a convergent lens was used to deliver 0.85 J and 6 ns laser pulses 1.5 mm in diameter by a Q-switch Nd: YAG laser, operating at 10 Hz with 1064 nm of wavelength. Residual stress distribution was assessed by the hole drilling method. A fatigue analysis of the notched specimens was conducted using the commercial code FE-Safe and different multiaxial fatigue criteria to predict fatigue lives of samples with and without LSP. The residual stress field produced by the LSP process was estimated by a finite element simulation of the process. A good comparison of the predicted and experimental fatigue lives was observed. The beneficial effect of LSP in extending fatigue life of notched components with and without previous damage is demonstrated.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1250-1264
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• 2023

This paper presents approximate in-depth residual stress and plastic strain profiles for laser-peened alloy 600 surface via FE analysis. In approximations, effects of the initial welding residual stress and the number of shots are quantified. Based on FE analysis results, residual stress profiles are quantified by two variables; the maximum difference in stress before and after LSP, and the depth up to which the compressive residual stress exists. Plastic strain profiles are quantified by one variable, the maximum equivalent plastic strain at the surface. The proposed profiles are validated by comparing with published LSP experimental results for welded plates. Effects of the initial welding residual stress and the number of shots on these variables are discussed. The proposed profile can be directly applied to predict the mitigation effect of LSP on PWSCC and to efficiently perform structural integrity assessment of laser peened nuclear components.