Spatially Resolved Characterization of Geometrically Necessary Dislocation Dependent Deformation in Microscale Laser Shock Peening

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Youneng Wang ◽  
Jeffrey W. Kysar ◽  
Sinisa Vukelic ◽  
Y. Lawrence Yao
Keyword(s):  
Finite Element ◽  
Scale Effects ◽  
Target Material ◽  
Material Point ◽  
Laser Shock Peening ◽  
Lattice Rotation ◽  
Length Scale ◽  
Laser Shock ◽  
Geometrically Necessary Dislocation ◽  
Shock Peening

As the laser spot size in microscale 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 re-examined 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. From these measurements, the geometrically necessary dislocation (GND) density that the material contains has been estimated. The yield strength increment was then calculated from the GND distribution by using the Taylor model and integrated into each material point of the finite element method (FEM) simulation. Finite element simulations, based on single crystal plasticity, were performed for the process both with and without considering the GND hardening, and the comparison has been conducted.

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.

Dynamic Material Response of Aluminum Single Crystal Under Microscale Laser Shock Peening

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Sinisa Vukelic ◽  
Youneng Wang ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao
Keyword(s):  
Residual Stresses ◽  
Single Crystals ◽  
Electron Backscatter Diffraction ◽  
Target Material ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Laser Target ◽  
Aluminum Single Crystal ◽  
Anisotropic Mechanical Properties ◽  
Shock Peening

The process of laser shock peening induces compressive residual stresses in a material to improve material fatigue life. For micron sized laser beams, the size of the laser-target interaction zone is of the same order of magnitude as the target material grains, and thus the target material must be considered as being anisotropic and inhomogeneous. Single crystals are chosen to study the effects of the anisotropic mechanical properties. It is also of interest to investigate the response of symmetric and asymmetric slip systems with respect to the shocked surface. In the present study, numerical and experimental aspects of laser shock peening on two different crystal surfaces (110) and (11¯4) of aluminum single crystals are studied. Lattice rotations on the top surface and cross section are measured using electron backscatter diffraction, while residual stress is characterized using X-ray microdiffraction. A numerical model has been developed that takes into account anisotropy as well as inertial terms to predict the size and nature of the deformation and residual stresses. Obtained results were compared with the experimental finding for validation purpose.

Characterization of Plastic Deformation Induced by Microscale Laser Shock Peening

2004 ◽  
Vol 71 (5) ◽  
pp. 713-723 ◽  
Author(s):  
Hongqiang Chen ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Crystal Lattice ◽  
Electron Backscatter Diffraction ◽  
Fem Analysis ◽  
Copper Sample ◽  
Laser Shock Peening ◽  
Lattice Rotation ◽  
Laser Shock ◽  
Shock Peening

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.

Parametric Study on Single Shot and Overlapping Laser Shock Peening on Various Metals via Modeling and Experiments

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Yunfeng Cao ◽  
Yung C. Shin ◽  
Benxin Wu
Keyword(s):  
Experimental Data ◽  
Residual Stress ◽  
Finite Element ◽  
Element Model ◽  
Substrate Material ◽  
Laser Shock Peening ◽  
Single Shot ◽  
Laser Shock ◽  
3D Finite Element ◽  
Shock Peening

Laser shock peening (LSP) under water confinement regime involves several complicated physical phenomena. Among these phenomena, the interaction between laser and coating material during LSP is very important to the laser-induced residual stress, which has an important effect on the fatigue and corrosion properties of the substrate material. To gain a better understanding of this interaction, a series of experiments, including single shot, single-track overlapping, and multitrack overlapping LSP, has been carried out on various metals with different coatings. A 3D finite element model has also been developed to simulate the LSP process. Combining this with a previously developed confined plasma model, which has been verified by the experimental data from literature, the 3D finite element model is used to predict the residual stresses induced in the substrate material as well as the indentation profile on the substrate surface. The model prediction of indentation profiles is compared with the experimental data. The residual stresses in the depth direction are also validated against the X-ray diffraction measurement data for 4140 steel and Ti–6Al–4V, and good agreements are obtained for both predictions. The effect of process parameters on the residual stress is also investigated both experimentally and theoretically.

scholarly journals Finite Element Analysis of Laser Peening of Thin Aluminum Structures

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 93 ◽  
Author(s):  
Kristina Langer ◽  
Thomas J. Spradlin ◽  
Michael E. Fitzpatrick
Keyword(s):  
Finite Element ◽  
High Strength ◽  
Laser Shock Peening ◽  
Laser Peening ◽  
Laser Shock ◽  
Element Analysis ◽  
Thin Sections ◽  
Thin Aluminum ◽  
Shock Peening ◽  
Selection Of

Laser shock peening has become a commonly applied industrial surface treatment, particularly for high-strength steel and titanium components. Effective application to aluminum alloys, especially in the thin sections common in aerospace structures, has proved more challenging. Previous work has shown that some peening conditions can introduce at-surface tensile residual stress in thin Al sections. In this study, we employ finite element modeling to identify the conditions that cause this to occur, and show how these adverse effects can be mitigated through selection of peen parameters and patterning.

Sign in / Sign up

Export Citation Format

Share Document