Modeling and characterization of recompressed damaged materials

Becker, R ; Cazamias, J U ; Kalantar, D H ; LeBlanc, M M ; Springer, H K

Lawrence Livermore National Laboratory

关键词: 37 Inorganic, Organic, Physical And Analytical Chemistry;    Electron Microscopy;    Strain Rate;    Ablation;    Simulation;   

DOI  :  10.2172/15009779
RP-ID  :  UCRL-TR-202345
RP-ID  :  W-7405-ENG-48
RP-ID  :  15009779

美国|英语

来源: UNT Digital Library

【 摘 要 】

Experiments have been performed to explore conditions under which spall damage is recompressed with the ultimate goal of developing a predictive model. Spall is introduced through traditional gas gun techniques or with laser ablation. Recompression techniques producing a uniaxial stress state, such as a Hopkinson bar, do not create sufficient confinement to close the porosity. Higher stress triaxialities achieved through a gas gun or laser recompression can close the spall. Characterization of the recompressed samples by optical metallography and electron microscopy reveal a narrow, highly deformed process zone. At the higher pressures achieved in the gas gun, little evidence of spall remains other than differentially etched features in the optical micrographs. With the very high strain rates achieved with laser techniques there is jetting from voids and other signs of turbulent metal flow. Simulations of spall and recompression on micromechanical models containing a single void suggest that it might be possible to represent the recompression using models similar to those employed for void growth. Calculations using multiple, randomly distributed voids are needed to determine if such models will yield the proper behavior for more realistic microstructures.