Spatially resolved characterization of residual stress induced by micro scale laser shock Peening

2003 ◽  
Author(s):  
Hongqiang Chen ◽  
Y. Lawrence Yao ◽  
Jeffrey W. Kysar
Keyword(s):  
Residual Stress ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Micro Scale ◽  
Spatially Resolved ◽  
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.

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 Characterization of Heterogeneous Response of Al Bicrystal Subject to Micro Scale Laser Shock Peening

2010 ◽  
Vol 51 (5) ◽  
pp. 793-796 ◽  
Author(s):  
S. Vukelic ◽  
I. C. Noyan ◽  
J. W. Kysar ◽  
Y. L. Yao
Keyword(s):  
Laser Shock Peening ◽  
Laser Shock ◽  
Micro Scale ◽  
Shock Peening

Fabrication and Characterization of Micro Dent Arrays by Laser Shock Peening on Ti-6Al-4V Surfaces

2009 ◽  
Author(s):  
R. Caslaru ◽  
Y. B. Guo ◽  
M. P. Sealy
Keyword(s):  
Residual Stress ◽  
Friction And Wear ◽  
Rolling Contact ◽  
Laser Shock Peening ◽  
Alternative Methods ◽  
Laser Shock ◽  
Shock Peening ◽  
Enhanced Surface ◽  
Center Area

Surface micro dents may act as lubricant reservoirs to reduce friction and wear in sliding and rolling contact applications. Surface patterning has become a valuable technique for fabricating micro dents. Alternative methods such as micromachining present obvious limitations in comparison with laser shock peening (LSP). In this paper, the use of LSP along with an automatic X-Y table proves to be an attractive and reliable method for producing micro dent arrays with enhanced surface integrity and free of cracks. Surface topography, residual stress, and microhardness of the fabricated micro dent arrays on polished Ti-6A1-4V have been characterized. It has shown that LSP is capable of efficiently fabricating mass micro dent arrays with controllable size. The center area of the peened dents has highest hardness. In addition, high compressive residual stress can also be created.

Fatigue Life Recovery via Laser Shock Peening in Mechanically Damaged Aluminium Sheet; Experiments and Prediction Models

2014 ◽  
Vol 891-892 ◽  
pp. 980-985 ◽  
Author(s):  
Niall Smyth ◽  
Philip E. Irving
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Prediction Models ◽  
Load Cycle ◽  
Laser Shock Peening ◽  
Stress Fields ◽  
Hole Drilling ◽  
Laser Shock ◽  
Aluminium Sheet ◽  
Shock Peening

This paper reports the effectiveness of residual stress fields induced by laser shock peening (LSP) to recover pristine fatigue life. Scratches 50 and 150 μm deep with 5 μm root radii were introduced into samples of 2024-T351 aluminium sheet 2 mm thick using a diamond tipped tool. LSP was applied along the scratch in a band 5 mm wide. Residual stress fields induced were measured using incremental hole drilling. Compressive residual stress at the surface was-78 MPa increasing to-204 MPa at a depth of 220 μm. Fatigue tests were performed on peened, unpeened, pristine and scribed samples. Scratches reduced fatigue lives by factors up to 22 and LSP restored 74% of pristine life. Unpeened samples fractured at the scratches however peened samples did not fracture at the scratches but instead on the untreated rear face of the samples. Crack initiation still occurred at the root of the scribes on or close to the first load cycle in both peened and unpeened samples. In peened samples the crack at the root of the scribe did not progress to failure, suggesting that residual stress did not affect initiation behaviour but instead FCGR. A residual stress model is presented to predict crack behaviour in peened samples.

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