Abstract
In this research, a finite element (FE) technique was used to predict the residual stresses in laser-peened aluminum 5083 at different power densities. A dynamic pressure profile was used to create the pressure wave in an explicit model, and the stress results were extracted once the solution was stabilized. It is shown that as power density increases from 0.5 to 4 GW/cm2, the induced residual stresses develop monotonically deeper from 0.42 to 1.40 mm. However, with an increase in the power density, the maximum magnitude of the sub-surface stresses increases only up to a certain threshold (1 GW/cm2 for aluminum 5083). Above this threshold, a complex interaction of the elastic and plastic waves occurring at peak pressures above ≈2.5 Hugoniot Elastic Limit (HEL) results in decreased surface stresses. The FE results are corroborated with physical experiments and observations.
Highlights
A portable X-ray diffraction (XRD) analyzer, Pulstec μ-X360 (Pulstec Industrial Co., A portable X-ray diffraction (XRD) analyzer, Pulstec μ-X360 (Pulstec Industrial Co., Ltd., Hamamatsu, Japan) using the cosα method using the cosα method was utilized to characterize the surface and in-depth residual described in the SI, Section S2) was utilized to characterize the surface and in-depth stress
The experimental residual stress values were calculated from the whole surface of a peened spot, but the simulated residual stress values were obtained from a line
For aluminum with a relatively low yield strength, XRD measurements might result in even higher errors since the magnitude of the measured stresses are generally low
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. To enhance the accuracy of the model as well as facilitate obtaining a converged plastic strain distribution, a finer mesh was used in and around the pulse area where elements of 0.05 mm × 0.05 mm × 0.03 mm were chosen (Figure 1). While previously a combination of dynamic explicit analysis and static analysis has been typically used in the literature [16,31,32,33], it has been shown that a pure explicit model can be utilized for both steps if the proper solution time is considered for each step [10,21,34,35]. Further information about the calculation of solution times for step one (to ensure the occurrence of all the plastic deformation in the material), and step two (to obtain the equilibrium of stresses in the material) is provided in SI (Section S1.2)
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