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LASER-Based Manufacturing as a Green Manufacturing Process
Published in R. Ganesh Narayanan, Jay S. Gunasekera, Sustainable Material Forming and Joining, 2019
Ashish K. Nath, Sagar Sarkar, Gopinath Muvvala, Debapriya Patra Karmakar, Shitanshu S. Chakraborty, Suvradip Mullick, Yuvraj K. Madhukar
Significant reduction of fatigue crack propagation in aluminum alloy specimens have been reported (Kashaev et al. 2017; Peyre et al. 1996). Figure 15.45 (Brar et al. 2000) shows the fatigue crack growth behavior of as received, shot peened, and laser-peened specimens. Laser peening dramatically improved the fatigue life with clear differences in the early and later stages of crack growth. The difference in behavior between laser peening and shot peening is attributed to surface embrittlement and surface roughening due to the shot peening process which creates sites at which cracks develop rapidly and tends to reduce the beneficial effects of the compressive residual stresses.
Computer simulation as an aid to predict fundamental frequency of a sandwich system via discrete singular convolution method
Published in Mechanics Based Design of Structures and Machines, 2021
Haidong Jiang, Yonggui Chen, Guofa Zhang, Xiaoyong Peng
Initial stresses may be considered as the kind of tensions persevere in the body of solids subsequent to vanishing the chief root of the loads. The mentioned form of stress may be instigated by various causes such as severe thermal alteration (Arsenault and Taya 1987), plastic deformity (Kholdi et al. 2020) or phase transition (Kumar and Bag 2019). It must be noticed that sometimes the initial stress exert helpful influences to the operation of the mechanisms (Luzin, Spencer, and Zhang 2011). As a high-tech instance, laser peening applies beneficial compression to metallic parts of turbine blades (Fameso and Desai 2020). In frames of theory of elasticity, Liu et al. (2018) recorded a survey on function of solo-oriented initial stress on the vibrational response and static stability of an FG-GNPR nanocomposite closed cylindrical shells versus various cases of applied boundaries.
Laser shock peening: a promising tool for enhancing the aeroengine materials’ surface properties
Published in Surface Engineering, 2023
K. Praveenkumar, S. Sudhagara Rajan, S. Swaroop, Geetha Manivasagam
The mechanical properties of the materials can be tailored through the development of the required microstructure [102]. Fatigue and wear resistance predominantly depend on the materials’ microstructure [103]. Materials experience noticeable microstructural change due to larger plastic deformation induced by high-pressure shock waves during the laser peening process. These microstructural changes can be observed using an optical microscope, SEM, TEM and EBSD techniques.
Microstructure-crystallographic texture and substructure evolution in unpeened and laser shock peened HSLA steel upon ratcheting deformation
Published in Philosophical Magazine, 2023
Pushpendra Kumar Dwivedi, R. Vinjamuri, Krishna Dutta
In this study, the microstructure and micro-texture evolution of unpeened and laser-peened HSLA steel subjected to uniaxial ratcheting fatigue was investigated using an EBSD-based methodology. The detailed analyses of the deformation mechanism at different loading conditions led to draw the following major conclusions: Laser-peened ratcheted specimen clearly exhibited less deformation than unpeened ratcheted specimen at the same loading condition – dominance of the grains in the <001 > and <101 > orientations on the surface and cross-section, respectively, were noticed.The as-received/unpeened condition showed a {011} < 211 > texture component, which was transformed into a highly intense {011} < 111 > texture component after LSP. It was the result of severe plastic deformation caused by high strain rate and high-pressure shock wave interaction during laser peening. Ratcheting deformation of unpeened specimen generated rotated Cube {001} < 110 > texture component while the laser-peened specimen produced weak rotated Goss {011} < 011 > texture component after ratcheting. After ratcheting, the texture intensity for the unpeened specimen was slightly increased from 3.364 to 3.655 m.r.d. while that drastically reduced from 4.265 to 2.744 m.r.d. for the laser-peened specimen. Such variation in texture intensity enables the peened specimens to sustain for more fatigue cycles.The grain alteration mechanism for unpeened specimens was found to be of the continuous dynamic recovery and recrystallisation (CDRR) type, which involved the gradual transformation of VLAGB to LAGB and then to HAGB to form new grains. In contrast, the marginal grain size increment in the laser-peened specimen could be correlated with a continuous dynamic recrystallisation (CDRX) mechanism.Substructure generation during laser peening indicated pre-mature dislocation cell formation due to the multiplication of dislocations. As the ratcheting deformation accumulated in the specimens, well-defined dislocation sub-cell formations were noticed which had changed their morphology with increasing strain. Dislocation patterns change gradually from dislocation lines and tangles to dislocation walls and sub-cells with higher ratcheting strain accumulation. The laser-peened sample had a larger substructure size than the unpeened one at the same stress condition, which was attributed to the release of stored energy during ratcheting.