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Fatigue Life of Materials Strengthened by Laser Shock Processing
摘要： The influence of the thickness of 03Х22Н6М2 stainless steel samples strengthened by laser shock processing on their fatigue life is investigated by finite-element modeling. This technology is found to increase the fatigue life of thin (2 mm) samples more than threefold.
关键词： finite-element modeling,fatigue life,residual stress,laser shock processing
更新于2025-09-23 15:19:57
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Investigation of novel laser shock hydroforming method on micro tube bulging
摘要： Tubular components are indispensable in manufacturing industry, but when its size decreases to micro level, the formability of micro tube will become undesirable. To improve the formability of micro tube, this study suggested a novel laser shock hydroforming method. This method used laser-induced shock wave as energy source and liquid as medium to transmit pressure wave. It was the pressure wave that forced the material of micro tube to ?ow into the die cavity and replicated the shape of that. The dynamic forming process of micro tube was ?rst studied by numerical means, and the numerical results agreed with experimental ones. Then, the middle section thickness of formed micro tube was researched experimentally. The results shown that the uniformity of thickness distribution was improved compared to that in quasi-static condition, and the improvement of that was analyzed by numerical means. In addition, the reason for the increase of formability was investigated in the aspect of contact stress, and numerical results con?rmed that the impact of the material of micro tube on the die caused the increase in compressive stress, a phenomenon bene?cial to the formability enhancement. Finally, the paper compared the deformation behaviors —deformation velocity and strain rate —with and without a die, proving that the die was one factor that contributed to the formability improvement.
关键词： Square-section die,Formability,Fluid–solid interaction,Laser shock hydroforming,Micro tube
更新于2025-09-23 15:19:57
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Characterization of the ballistic properties of ejecta from laser shock-loaded samples using high resolution picosecond laser imaging
摘要： A high resolution picosecond laser imaging diagnostic has been developed for making high-resolution spatial measurements of ejecta particles moving at high velocities (a few km/s). Preliminary results obtained with both visible (532 nm) and UV (355 nm) lighting are presented for laser shock-driven tin ejecta experiments performed with different kind of surface defects. These results are compared with those obtained at LANL under high explosive loading using ultraviolet in-line Fraunhofer holography, and also with molecular dynamics (MD) simulations performed at lower space and time scales.
关键词： Microjetting,ps laser imaging,Ejecta,Laser shock
更新于2025-09-19 17:13:59
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Effect of laser shock peening on high cycle fatigue characteristics of 316LN stainless steel
摘要： The influence of ‘laser shock peening’ (LSP) on fatigue behavior of 316LN stainless steel has been studied at 298 K by conducting fully reversed stress controlled fatigue tests in the range 200–300 MPa. A triangular wave form with a constant frequency of 5 Hz was employed for all the tests conducted below 107 cycles on the virgin and laser shock peened samples. The run out tests at 107 cycles were performed at a frequency of 60 Hz. The studies have clearly revealed that the fatigue life is dependent on surface condition of the material and stress amplitude employed. A comparison is made of cyclic stress-strain hysteresis loops and fatigue lives between virgin and peened material. The peened material showed better fatigue strength and life at low stress amplitudes pertaining to high cycle fatigue regime, and exhibited lower density of surface microcracks. The improved fatigue resistance of peened material is attributed to the presence of residual compressive stresses to a depth of ~100 μm from the surface. The beneficial effect of compressive stresses is perceived both in the reduction in number density of Stage-I microcracks and retarded stage-II crack growth in the initial stages (that revealed striations with lesser spacing compared to un-peened samples).
关键词： Laser shock peening,Stainless steel,High cycle fatigue,Compressive residual stresses
更新于2025-09-19 17:13:59
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Thermal Relaxation Features of Residual Stresses Arising upon Laser Shock Processing of Heat-Resistant Materials
摘要： In this paper, we study the thermal relaxation features of compressive residual stresses generated during laser-shock wave processing in high-alloyed heat-resistant Iron GH2036 alloy. A finite element modeling of thermal relaxation of the generated compressive residual stresses was performed. The features of the thermal effects on the redistribution of the compressive residual stresses in the temperature range from 200 to 650°C are studied. Based on comparative analysis, the results of the finite element modeling correlated well with the experimental data known in the literature.
关键词： residual stresses,thermal relaxation,finite element modeling,laser-shock wave treatment
更新于2025-09-19 17:13:59
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Local deformation and macro distortion of TC4 titanium alloy during laser shock processing
摘要： Experimental investigation has been carried out to understand the local deformation, macro distortion, and residual stress distribution of TC4 titanium alloy thin plate with different thickness during laser peening processing. The results show that the geometry distortions generate different profile directions depending on the laser shock processing condition. The deformation coefficient λ based on laser power density and sheet thickness is used to predict the macro deformation mode. When λ < 0.212, no macro distortion is produced; when 0.212 < λ < 0.58, volume is transferred along the top surface, the geometric distortion direction is away the laser beam, compressive residual stress is induced on the surface, and convex deformation is produced; when 0.65 < λ, volume is transferred along the bottom surface, the macro distortion direction is toward the laser beam, tensile residual stress is induced on the surface, and concave deformation is produced; the threshold of concave and convex deformation is about 0.62. The deformation coefficient λ and the threshold of concave and convex deformation can be adopted to predict and control the geometry distortion of TC4 titanium alloy thin plate during laser shock processing.
关键词： Thin plate,Residual stress,Geometry distortion,Laser shock peening
更新于2025-09-19 17:13:59
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Fatigue Life Behavior of Laser Shock Peened Duplex Stainless Steel with Different Samples Geometry
摘要： Two different stress raiser geometries (fillet and notched) were treated by laser shock peening (LSP) in order to analyze the effect of sample geometry on fatigue behavior of 2205 duplex stainless steel (DSS). The LSP treatment was carried through Nd:YAG pulsed laser with 1064 nm wavelength, 10 Hz frequency, and 0.85 J/pulse. Experimental and MEF simulation results of residual stress distribution after LSP were assessed by hole drilling method and ABAQUS/EXPLICIT software, respectively. The fatigue tests (tensile-tensile axial stress) were realized with stress ratio of R = 0.1 and 20 Hz. A good comparison of residual stress simulation and experimental data was observed. The results reveal that the fatigue life is increased by LSP treatment in the notched samples, while it decreases in the fillet samples. This is related to the residual stress distribution after LSP that is generated in each geometry type. In addition, the fatigue crack growth direction is changed according to geometry type. Both the propagation direction of fatigue crack and the anisotropy of this steel results detrimental in fillet samples, decreasing the number of cycles to the fatigue crack initiation. It is demonstrated that the LSP effect on fatigue performance is influenced by the specimen geometry.
关键词： laser shock peening,residual stress,duplex stainless steel,fatigue life,sample geometry
更新于2025-09-19 17:13:59
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Healing cracks in selective laser melting by 3D laser shock peening
摘要： Selective Laser Melting (SLM) of Ni-based superalloys such as CM247LC is prone to weld-cracking. This paper investigates how to suppress cracks by repeatedly applying Laser Shock Peening (LSP) during the building phase of SLM. Samples made of CM247LC were processed with different LSP parameters, and the influence on bulk crack density has been quantified. It was observed that for all chosen conditions, a significant decrease of up to 95% could be achieved, demonstrating the potential of the new hybrid 3D LSP method in improving SLM processability of alloys sensitive to cracking.
关键词： Ni-based superalloy,CM247LC,Selective laser melting,Crack density,Laser shock peening,3D laser shock peening
更新于2025-09-16 10:30:52
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On the Effectiveness of Different Surface Finishing Techniques on A357.0 Parts Produced by Laser-Based Powder Bed Fusion: Surface Roughness and Fatigue Strength
摘要： Laser-based powder bed fusion (L-PBF) is an additive manufacturing (AM) technique that uses a computer-controlled laser beam as the energy source to consolidate a metal powder according to a layer-upon-layer strategy in order to manufacture a three dimensional part. This opens the way for an unprecedented freedom in geometry, but the layer-wise build-up strategy typically results in a very poor surface ?nish, which is a?ected by the staircase e?ect and by the presence of partially molten particles. Surface ?nishing treatments are therefore necessary to obtain an adequate surface ?nish, to improve the fatigue behavior and to meet mechanical and aesthetic needs. The present contribution systematically compares numerous surface ?nishing techniques, including laser shock processing, plastic media blasting, sand blasting, ceramic shot peening and metal shot peening with steel particles of di?erent sizes (φ = 0.2 mm and φ = 0.4 mm). The results show that all the proposed methods improve the surface quality and the fatigue life of A357.0 L-PBF parts. However, the achievement of the lowest surface roughness does not necessarily correspond to the best fatigue performance, thus suggesting that multiple mechanisms may be active and that besides surface roughness also residual stresses contribute to increase the fatigue strength.
关键词： laser shock processing,additive manufacturing,fatigue,shot peening,surface ?nishing,plastic media blasting,sand blasting,surface roughness,A357.0,laser-based powder bed fusion
更新于2025-09-16 10:30:52
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Effect of Laser Shock Peening on Fatigue Life at Stress Raiser Regions of a High-Speed Micro Gas Turbine Shaft: A Simulation Based Study
摘要： Fatigue failure due to stress raiser regions on critical rotating components in gas turbine engines, such as the shaft, is a crucial aspect. Methods to reduce these stresses and improve fatigue life are a source of ongoing research. Laser shock peening is a method where compressive residual stresses are imparted on the stress raisers of such components. However, numerical based studies on multiple laser shock peening applied to stress raisers is under-researched. Hence, this study will attempt to predict the fatigue life at fillet radii step induced stress raiser regions on a high-speed gas turbine engine shaft by utilization of laser shock peening. The objective of this study was achieved by developing a more computational efficient finite element model to mimic the laser shock peening process on the fillet radii step induced stress raiser regions of a shaft. A modified laser shock peening simulation method for effective prediction of the residual stress field was introduced. Furthermore, the fatigue life improvement due to laser shock peening was predicted by employing Fe-safe fatigue software. From the results, the modified laser shock peening simulation method provided accurate prediction of the residual stress field with a reduced computational time of over 68% compared to conventional methods. The fatigue life revealed an improvement of 553% due to laser shock peening, which is comparable to similar findings in the literature. Hence, from the findings and results achieved, the developed finite element model can be an appropriate tool to assist in the fatigue life estimation of laser shock peening applied to stress raisers.
关键词： Fatigue,laser shock peening,Fe-safe software,stress raiser regions,finite element model
更新于2025-09-16 10:30:52