Experimental Study of Micro-Scale Laser Shock Peening on Copper Foils

2011 ◽  
Vol 464 ◽  
pp. 506-509 ◽  
Author(s):  
W. Zhu ◽  
Jian Zhong Zhou ◽  
M Wang ◽  
Shu Huang ◽  
Deng Hui Wei ◽  
...  
Keyword(s):  
Laser Energy ◽  
Mechanical Test ◽  
Test System ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Micro Scale ◽  
Copper Foils ◽  
Typical Experiment ◽  
Shock Peening ◽  
Reliability Performance

Micro-scale laser shock peening (μLSP) is a flexible and precise process that can potentially be applied to metallic structures in micro devices to improve strength and reliability performance. In order to understand the mechanism of μLSP process, a typical experiment was carried out for copper foils specimen with various process parameters. Surface morphology, deformation and hardness of the specimens were observed and characterized by 3D microscope system and situ nano-mechanical test system respectively. It was found that overlapping rate of laser spot has a little effect on microscopic deformation depth which increases slowly with the increasing of laser energy, and micro-hardness of the laser treated specimens was improved significantly.

Numerical Investigation of Opposing Dual Sided Micro Scale Laser Shock Peening

2006 ◽  
Author(s):  
Yajun Fan ◽  
Youneng Wang ◽  
Sinisa Vukelic ◽  
Y. Lawrence Yao
Keyword(s):  
Residual Stress ◽  
Shock Waves ◽  
Laser Shock Peening ◽  
Time Lags ◽  
Laser Shock ◽  
Surface Residual Stress ◽  
Strain Rate Effects ◽  
Micro Scale ◽  
Stress Profiles ◽  
Shock Peening

Laser shock peening (LSP) is an innovative process which imparts compressive residual stresses in the processed surface of metallic parts to significantly improve fatigue life and fatigue strength of this part. In opposing dual sided LSP, the workpiece can be simultaneously irradiated or irradiated with different time lags to create different surface residual stress patterns by virtue of the interaction between the opposing shock waves. In this work, a finite element model, in which the hydrodynamic behavior of the material and the deviatoric behavior including work hardening and strain rate effects were considered was applied to predict residual stress distributions in the processed surface induced under various conditions of the opposing dual sided micro scale laser shock peening. Thus the shock waves from each surface will interact in different ways through the thickness resulting in more complex residual stress profiles. Additionally, when treating a thin section, opposing dual sided peening is expected to avoid harmful effects such as spalling and fracture because the pressures on the opposite surfaces of the target balance one another and prohibit excessive deformation of the target. In order to better understand the wave-wave interactions under different conditions, the residual stress profiles corresponding to various workpiece thicknesses and various irradiation times were evaluated.

scholarly journals Grain boundary response of aluminum bicrystal under micro scale laser shock peening

2009 ◽  
Vol 46 (18-19) ◽  
pp. 3323-3335 ◽  
Author(s):  
Siniša Vukelić ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao
Keyword(s):  
Grain Boundary ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Micro Scale ◽  
Shock Peening

scholarly journals A Novel Micro-Scale Plastic Deformation Feature on a Bulk Metallic Glass Surface under Laser Shock Peening

2013 ◽  
Vol 30 (3) ◽  
pp. 036201 ◽  
Author(s):  
Yan-Peng Wei ◽  
Bing-Chen Wei ◽  
Xi Wang ◽  
Guang-Yue Xu ◽  
Lei Li ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Glass Surface ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Micro Scale ◽  
Deformation Feature ◽  
Shock Peening

Spatially Resolved Characterization of Residual Stress Induced by Micro Scale Laser Shock Peening

2004 ◽  
Vol 126 (2) ◽  
pp. 226-236 ◽  
Author(s):  
Hongqiang Chen ◽  
Y. Lawrence Yao ◽  
Jeffrey W. Kysar
Keyword(s):  
Residual Stress ◽  
Cell Structure ◽  
Fem Analysis ◽  
Dislocation Cell ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
X Ray ◽  
Micro Scale ◽  
Spatially Resolved ◽  
Shock Peening

Single crystal aluminum and copper of (001) and (110) orientation were shock peened using laser beam of 12 micron diameter and observed with X-ray micro-diffraction techniques based on a synchrotron light source. The X-ray micro-diffraction affords micron level resolution as compared with conventional X-ray diffraction which has only mm level resolution. The asymmetric and broadened diffraction profiles registered at each location were analyzed by sub-profiling and explained in terms of the heterogeneous dislocation cell structure. For the first time, the spatial distribution of residual stress induced in micro-scale laser shock peening was experimentally quantified and compared with the simulation result obtained from FEM analysis. Difference in material response and microstructure evolution under shock peening were explained in terms of material property difference in stack fault energy and its relationship with cross slip under plastic deformation. Difference in response caused by different orientations (110 and 001) and active slip systems was also investigated.

Study on Characteristics of Stress and Parameters Influence in Microscale Laser Shock Peening

2011 ◽  
Vol 464 ◽  
pp. 336-339 ◽  
Author(s):  
Yu Jie Fan ◽  
Jian Zhong Zhou ◽  
Shu Huang ◽  
W. Wang ◽  
Deng Hui Wei ◽  
...  
Keyword(s):  
Residual Stress ◽  
Shape Factor ◽  
Influence Factor ◽  
Laser Energy ◽  
Laser Shock Peening ◽  
Beam Diameter ◽  
Laser Shock ◽  
Asymmetrical Distribution ◽  
Shock Peening ◽  
Distribution Of Stress

Microscale laser shock peening (μLSP) can generate beneficial compressive stress distribution in the targets, as the used beam diameter in μLSP is at the order of micron equivalent with grain size, the treated material must be considered as anisotropic and inhomogeneous, this causes an asymmetrical distribution of residual stress. In this paper, shape factor σSF was introduced and defined to characterize the asymmetrical distribution of stress, optimum conditions of factors and the influence degree were explored based on Taguchi design with the optimal object of stress characterization values. The results show that shape factor is a significant characteristic of residual stress induced by μLSP, crystal orientation is the most important influence factor, but laser energy and peening number have significant influence on stress characterization values.

scholarly journals Effect of Laser Shock Peening on Fatigue Stress Concentration of Polyester Reinforced by Al-Micro Powder Composites

2020 ◽  
Vol 38 (3A) ◽  
pp. 325-334
Author(s):  
Ahmed N. Al- Khazraji ◽  
Ammar A. Mutasher
Keyword(s):  
Stress Concentration ◽  
Aluminum Powder ◽  
Volume Fraction ◽  
Laser Energy ◽  
Unsaturated Polyester ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Fatigue Stress ◽  
Endurance Strength ◽  
Shock Peening

Laser shock peening is a widely common process for materials treatment and typically used for fatigue strength enhancement especially for metals. In this paper, its effect on polymeric composite materials studied experimentally. Unsaturated polyester was used as a matrix in order to composites preparation and Aluminum powder as fillers. A Hand lay-up technique has been used for composites making. Composites with three volume fractions of Aluminum powder were prepared (2.5%, 5%, and 7.5%). Fatigue specimens as a standard and with (1mm) semi-circular notch are prepared for testing. The fatigue test was performed at room temperature and stress ratio (R=-1). Laser shock peening with two levels of energy have been applied (1Joule, and 2Joule). The results showed an increase in the endurance strength of the notch for 7.5% volume fraction especially at 1J laser energy by about 26.7056% compared with the un-treatment notched state, which in turn reduced the fatigue stress concentration by about 21.0508% compared with standard fatigue stress concentration. On the other hand, the presence of notch effect on endurance strength was increased after laser treatment of composites with 2.5% volume fraction and the reduced was by about 39.698% at 2J laser energy.

Spatially Resolved Characterization of Geometrically Necessary Dislocation Dependent Deformation in Micro-Scale Laser Shock Peening

2008 ◽  
Author(s):  
Youneng Wang ◽  
Sinisa Vukelic ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao
Keyword(s):  
Scale Effects ◽  
Fem Simulation ◽  
Target Material ◽  
Material Point ◽  
Laser Shock Peening ◽  
Lattice Rotation ◽  
Length Scale ◽  
Laser Shock ◽  
Micro Scale ◽  
Shock Peening

As the laser spot size in micro-scale laser shock peening is in the order of magnitude of several microns, the anisotropic response of grains will have a dominant influence on its mechanical behavior of the target material. Furthermore, conventional plasticity theory employed in previous studies needs to be reexamined due to the length scale effect. In the present work, the length scale effects in microscale laser shock peening have been investigated. The crystal lattice rotation underneath the shocked surface was determined via Electron Backscatter Diffraction (EBSD). From these measurements, the geometrically necessary dislocations (GND) density that the material contains has been estimated. The yield strength increment was then calculated from the GND distribution by using Taylor model and integrated into each material point of the FEM simulation. Finite element simulations, based on single crystal plasticity, were performed of the process for both with and without considering the GND hardening and the comparison has been conducted.

scholarly journals Simulation and Experimental Study on Residual Stress Distribution in Titanium Alloy Treated by Laser Shock Peening with Flat-Top and Gaussian Laser Beams

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1343 ◽  
Author(s):  
Xiang Li ◽  
Weifeng He ◽  
Sihai Luo ◽  
Xiangfan Nie ◽  
Le Tian ◽  
...  
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Stress Distribution ◽  
Energy Distribution ◽  
Laser Energy ◽  
Residual Stress Distribution ◽  
Laser Shock Peening ◽  
Laser Beams ◽  
Laser Shock ◽  
Shock Peening

The residual stress introduced by laser shock peening (LSP) is one of the most important factors in improving metallic fatigue life. The shock wave pressure has considerable influence on residual stress distribution, which is affected by the distribution of laser energy. In this work, a titanium alloy is treated by LSP with flat-top and Gaussian laser beams, and the effects of spatial energy distribution on residual stress are investigated. Firstly, a 3D finite element model (FEM) is developed to predict residual stress with different spatial energy distribution, and the predicted residual stress is validated by experimental data. Secondly, three kinds of pulse energies, 3 J, 4 J and 5 J, are chosen to study the difference of residual stress introduced by flat-top and Gaussian laser beams. Lastly, the effect mechanism of spatial energy distribution on residual stress is revealed.

Sign in / Sign up

Export Citation Format

Share Document