Investigation of laser shock induced ductile damage at ultra-high strain rate by using large scale MD simulations

2012 ◽  
Author(s):  
Jean-Paul Cuq-Lelandais ◽  
Michel Boustie ◽  
Laurent Soulard ◽  
Laurent Berthe ◽  
Joelle Bontaz-Carion ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Large Scale ◽  
High Strain ◽  
Md Simulations ◽  
Ductile Damage ◽  
Laser Shock

Characterizations on Microscale Laser Dynamic Forming of Metal Foil

2006 ◽  
Author(s):  
Gary J. Cheng ◽  
Daniel Pirzada
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Electron Backscatter Diffraction ◽  
Laser Forming ◽  
Metal Foil ◽  
Laser Shock ◽  
Forming Process ◽  
High Shock ◽  
Shock Peening

Laser dynamic forming (LDF) is a unique hybrid forming process, combining the advantages of laser shock peening, laser forming and metal forming, with an ultra high strain rate forming utilizing laser shock waves. In this paper, a hybrid forming technique based on laser dynamic forming will be demonstrated. The feasibility of laser dynamic forming will be discussed through experiments. The mechanical and microstructure of the formed 3D structures will be characterized. The grain microstructure and misorientation will be investigated quantitatively with Electron backscatter diffraction (EBSD). The residual stress distributions are measured using X-ray diffraction. We will describe the important factors that lead to improved micro-formability at high strain rate induced by high shock pressure. It is concluded that with further development, this may be an important microforming technology for various materials. LDF has great potential for meso-, micro- and nano scale forming since the laser provides high precision, highly-localized heating intensity, high repeatability, fast setup and superb flexibility.

Molecular Dynamics Simulations of the Shear Bands Formation of Single Crystal Bulk Copper during the High Strain Rate Compressive Process

2018 ◽  
Vol 934 ◽  
pp. 30-34
Author(s):  
Yuan Ching Lin ◽  
Chung Jun Shen
Keyword(s):  
Molecular Dynamics ◽  
High Strain Rate ◽  
Strain Rate ◽  
Single Crystal ◽  
High Strain ◽  
Shear Bands ◽  
Md Simulations ◽  
Localized Deformation ◽  
Narrow Region ◽  
Crystal Bulk

In this work, the high strain rate compressive process of single crystal bulk copper was studied by molecular dynamics (MD) simulations. The simulated result indicated that the localized deformation caused the formation of shear bands (SBs). It was found that the formation of shear bands in single crystal was owing to a plenty of the plastic deformations that caused by dislocations slippage or twinning concentrated in a narrow region [1], and the temperature at the shear bands region was rising more quickly than the others.

scholarly journals Large scale high strain-rate tests of concrete

2012 ◽  
Vol 26 ◽  
pp. 01030 ◽  
Author(s):  
M. Peroni ◽  
G. Solomos ◽  
B. Viaccoz ◽  
G. Magonette ◽  
R. Kiefer
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Large Scale ◽  
High Strain

Numerical Simulation of Laser Shock Peening in Presence of Weld for Fatigue Life Design

2014 ◽  
Author(s):  
Emricka Julan ◽  
Said Taheri ◽  
Claude Stolz ◽  
Patrice Peyre ◽  
Philippe Gilles
Keyword(s):  
Numerical Simulation ◽  
Stress Field ◽  
Residual Stresses ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Laser Shock Peening ◽  
Initial Stresses ◽  
Laser Shock ◽  
Shock Peening

Laser shock peening (LSP) is a surface mitigation technique that can be applied to improve the life of a metallic component through the generation of a compressive surface stress field induced by high-power laser pulses. Numerical simulation of LSP (produced residual stresses) in presence of an initial stress field similar to those obtained under welding has been carried out in nonlinear dynamic by coupling an explicit code (Europlexus) and an implicit one (Code_Aster). In the first step, an axisymetrical model has been validated by comparison with an analytical solution considering an elastic-perfectly plastic behavior law. Then, comparisons with Abaqus calculations have been carried out in terms of displacements and residual stresses using the Johnson-Cook high strain rate constitutive law to validate multi-impact 3D modeling. High strain rate parameter of Johnson-Cook law has been identified using LSP on thin plates. Validations of the simulations are then performed by comparing with experimental determined deformations caused by LSP on thick plates. For 25 overlapped shots, LSP induced residual stresses calculated with and without initial residual stresses similar to those obtain under welding have been compared to adress the effect of initial stresses on final residual fields.

Ductile Damage Assessment Using Continuum Damage Mechanics and Methodology for High Strain-Rate Damage Analysis

2017 ◽  
Author(s):  
Alexander Sancho ◽  
Paul A. Hooper ◽  
Catrin M. Davies
Keyword(s):  
Plastic Deformation ◽  
High Strain Rate ◽  
Strain Rate ◽  
Damage Assessment ◽  
Damage Mechanics ◽  
High Strain ◽  
Continuum Damage Mechanics ◽  
Ductile Damage ◽  
Continuum Damage ◽  
Static Conditions

The interest of this research is to assess the experimental techniques used for ductile damage measurement both in quasistatic and high strain-rate conditions. The results can later be used for the calibration of Continuum Damage Mechanics (CDM) models. A procedure for the evaluation of damage accumulation in quasi-static conditions is presented. The technique used to measure damage is based on the elastic modulus calculation from unloading and reloading cycles performed at different stages of plastic deformation. Tests have been performed in a continuous manner and the strain variations have been recorded using a small gauge extensometer. This methodology includes a second experiment in which the geometry of the specimen is monitored, allowing to extract the true stress-strain behaviour of the material even after necking phenomenon starts. The proposed methodology has been applied to stainless steel 304L. Regarding the high strain-rate conditions, a continuous test cannot be performed due to physical as well as practical difficulties. Therefore, an interrupted methodology has been devised in which the plastic deformation is applied at high strain-rate and the damage measurement is performed separately in quasi-static conditions. An experimental rig has been developed to interrupt high-speed tensile tests at strain-rates up to 103s−1. Its design and preliminary calibration are analysed and its future use for damage assessment discussed.

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