scholarly journals Comparative study of symmetric and asymmetric deformation of Al single crystal under micro scale laser shock peening

Author(s):  
Sinisa Vukelic ◽  
Youneng Wang ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao
2006 ◽  
Vol 129 (3) ◽  
pp. 485-496 ◽  
Author(s):  
Youneng Wang ◽  
Hongqiang Chen ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao

Micro-scale laser shock peening (μLSP) can potentially be applied to metallic structures in microdevices to improve fatigue and reliability performance. Copper thin films on a single-crystal silicon substrate are treated by using μLSP and characterized using techniques of X-ray microdiffraction and electron backscatter diffraction (EBSD). Strain field, dislocation density, and microstructure changes including crystallographic texture, grain size and subgrain structure are determined and analyzed. Further, shock peened single crystal silicon was experimentally characterized to better understand its effects on thin films response to μLSP. The experimental result is favorably compared with finite element method simulation based on single-crystal plasticity.


2004 ◽  
Vol 71 (5) ◽  
pp. 713-723 ◽  
Author(s):  
Hongqiang Chen ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao

Electron backscatter diffraction (EBSD) is used to investigate crystal lattice rotation caused by plastic deformation during high-strain rate laser shock peening in single crystal aluminum and copper sample on 110¯ and (001) surfaces. New experimental methodologies are employed which enable measurement of the in-plane lattice rotation under approximate plane-strain conditions. Crystal lattice rotation on and below the microscale laser shock peened sample surface was measured and compared with the simulation result obtained from FEM analysis, which account for single crystal plasticity. The lattice rotation measurements directly complement measurements of residual strain/stress with X-ray micro-diffraction using synchrotron light source and it also gives an indication of the extent of the plastic deformation induced by the microscale laser shock peening.


Author(s):  
Yajun Fan ◽  
Youneng Wang ◽  
Sinisa Vukelic ◽  
Y. Lawrence Yao

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.


2009 ◽  
Vol 46 (18-19) ◽  
pp. 3323-3335 ◽  
Author(s):  
Siniša Vukelić ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao

2013 ◽  
Vol 30 (3) ◽  
pp. 036201 ◽  
Author(s):  
Yan-Peng Wei ◽  
Bing-Chen Wei ◽  
Xi Wang ◽  
Guang-Yue Xu ◽  
Lei Li ◽  
...  

2004 ◽  
Vol 126 (2) ◽  
pp. 226-236 ◽  
Author(s):  
Hongqiang Chen ◽  
Y. Lawrence Yao ◽  
Jeffrey W. Kysar

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.


2007 ◽  
Vol 101 (2) ◽  
pp. 024904 ◽  
Author(s):  
Hongqiang Chen ◽  
Youneng Wang ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao

2011 ◽  
Vol 464 ◽  
pp. 506-509 ◽  
Author(s):  
W. Zhu ◽  
Jian Zhong Zhou ◽  
M Wang ◽  
Shu Huang ◽  
Deng Hui Wei ◽  
...  

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.


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