scholarly journals Shock recompaction of spall damage

2020 ◽  
Vol 127 (24) ◽  
pp. 245901 ◽  
Author(s):  
D. R. Jones ◽  
S. J. Fensin ◽  
B. M. Morrow ◽  
D. T. Martinez ◽  
R. S. Hixson
Keyword(s):  
Spall Damage

Characterization of Incipient Spall Damage in Shocked Copper Multicrystals

2008 ◽  
Vol 18 (4) ◽  
pp. 393-413 ◽  
Author(s):  
P. Peralta ◽  
S. DiGiacomo ◽  
S. Hashemian ◽  
S.-N. Luo ◽  
D. Paisley ◽  
...  
Keyword(s):  
Spall Damage

3-D Characterization of Global and Local Microstructural Effects on Spall Damage in Shock Loaded FCC Metals: Experimental and Modeling

2013 ◽  
Author(s):  
A. Brown ◽  
K. Krishnan ◽  
L. Wayne ◽  
P. Peralta ◽  
S. N. Luo ◽  
...  
Keyword(s):  
Weak Link ◽  
Heat Treatments ◽  
Taylor Factor ◽  
Weak Links ◽  
Spall Damage ◽  
Heat Treated ◽  
Microstructural Effects ◽  
Global And Local ◽  
Low Pressures

Global and local microstructural weak links for spall damage were investigated using 3-D characterization in polycrystalline (PC) and multicrystalline (MC) copper samples, respectively. All samples were shocked via flyer-target plate experiments using a laser drive at low pressures (2–6 GPa). The flyer plates measured approximately 500 μm thick and 8 mm in diameter and the target plates measured approximately 1000 μm thick and 10 mm in diameter. Electron Backscattering Diffraction (EBSD) and optical microscopy were used to determine to presence of voids and relate them to the surrounding microstructure. Statistics on the strength of grain boundaries (GBs) was conducted by analyzing PC samples and collecting the misorientation across GBs with damage present, and it was found that a misorientation range of 25–50° is favorable for damage. Statistics were also taken of copper PC samples that had undergone different heat treatments and it was found that although the 25–50° range is less dominant, it is still favorable for damage nucleation. Removal of initial plastic strain via heat treatments and an increase in Σ3 CSL boundaries, indicative of strong annealing twins, also led to an increased amount of transgranular damage. 3-D X-ray tomography data were used to investigate the shape of the voids present in untreated, as received and heat treated samples. It was found that the as received sample contained a higher amount of “disk”, or, “sheet-like” voids indicative of intergranular damage, whereas the heat treated samples had a higher fraction of spherical shaped voids, indicative of transgranular damage. MC samples were used to study microstructural weak links for spall damage because the overall grain size is much larger than the average void size, making it possible to determine which GBs nucleated damage. Simulations and experimental analysis of damage sites with large volumes indicate that high Taylor factor mismatches with respect to the crystallographic grain GB normal is the primary cause for the nucleation of damage at a GB interface and a low Taylor factor along the shock direction in either grain drives void growth perpendicular to the GB. Cases where experimental results show damage and simulation results show no damage are attributed to the presence of an intrinsic microstructural weak link, such as an incoherent twin boundary.

Spall damage of a mild carbon steel: Effects of peak stress, strain rate and pulse duration

2016 ◽  
Vol 660 ◽  
pp. 139-147 ◽  
Author(s):  
C. Li ◽  
B. Li ◽  
J.Y. Huang ◽  
H.H. Ma ◽  
M.H. Zhu ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Strain Rate ◽  
Pulse Duration ◽  
Peak Stress ◽  
Stress Strain ◽  
Mild Carbon Steel ◽  
Spall Damage

Numerical Simulations of the Spall Damage of the Target Material Induced by Laser Driven Flyer Impacting

2010 ◽  
Vol 156-157 ◽  
pp. 1305-1312
Author(s):  
He Jun Wang ◽  
Hui Xia Liu ◽  
Zong Bao Shen ◽  
Wei Li ◽  
Yuan Yuan Zheng ◽  
...  
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Target Material ◽  
Surface Velocity ◽  
Free Surface Velocity ◽  
Damage Distribution ◽  
Spall Damage ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Simulation Results ◽  
Constant Interest

The spall phenomenon has been a subject of constant interest for many years, and it is still widely investigated in various ways including the experiment. This paper uses the method of smoothed particle hydrodynamics and the model of Johnson-Cook tensile cumulative damage to simulate the process of spall induced by the laser-driven flyer loading. Using this method, some numerical simulation results can be obtained, like the different time of the 2D image of damage distribution and the rear free surface velocity histories of target material. These results could offer some useful messages for the study on spall damage.

scholarly journals Ultrasonic detection of spall damage induced by low-velocity repeated impact

2012 ◽  
Vol 2 (4) ◽  
Author(s):  
Naoya Nishimura ◽  
Katsuhiko Murase ◽  
Toshihiro Ito ◽  
Takeru Watanabe ◽  
Roman Nowak
Keyword(s):  
Medium Carbon Steel ◽  
Impact Testing ◽  
Acoustic Microscopy ◽  
Tensile Failure ◽  
Ductile Material ◽  
Low Velocity ◽  
Damage Development ◽  
Repeated Impact ◽  
Spall Damage ◽  
The Impact

AbstractThis paper address the examination of spall damage in medium carbon steel subjected to a repeated impact testing. The experiments were performed well below the threshold spall-stress of 2.6 GPa and the damage introduced in the subsurface volume was investigated using the low frequency scanning acoustic microscopy. Based on B- and C-scan images (the images taken along and perpendicular to the impact surface) we made a qualitative and semi-quantitative evaluation of the damage type (voids in a ductile material or cracks in a brittle one) and its distribution. We found the spall damage development dependent on the amplitude and the duration of the stress pulses. In particular, we proved that the high, long stress pulses induce damage that resembles tensile failure of material, in which voids or cracks nucleate along the spall plane to form macro-cracks. This explains why spall-damage is not seen when the first impact is below the characteristic threshold spall-stress. However, when the tests consist of more than four impacts the spall damage is produced already under stress below the threshold-value.

scholarly journals Spall damage in aluminum alloy

1995 ◽  
Vol 32 (8-9) ◽  
pp. 1135-1148 ◽  
Author(s):  
Jian Zheng ◽  
Ze-Ping Wang
Keyword(s):  
Aluminum Alloy ◽  
Spall Damage
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