Development of Improved Dynamic Failure Models.
Final technical rept. 10 Jan 81-30 Sep 84,
SRI INTERNATIONAL MENLO PARK CA
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Improved computational models were developed for dynamic failure by shear banding and ductile fracture. The research effort involved theory, experiments and numerical analyses. A high performance split Hopkinson torsion bar was constructed and used to measure flow stress, failure strain, and shear band instability strains in VAR 4340 steel at strain rates ranging between 800 and 6000 s-1. Taylor-type rod impact tests were performed to measure the dynamic flow curve as a function of temperature to 947 C and initial hardness. The fracture surface topography of tensile bars was quantitatively analyzed to ascertain details of the ductile fracture processs and seek their dependence on microstructure. Observations and data from the experiments guided the modifications to the failure models. Viability of the models was verified and their usefulness in ordnance design was demonstrated by incorporating the models into the C-HEMP finite difference code and simulating various armor penetration scenarios. Keywords Shear band model Ductile fracture model Taylor test.
- *SHEAR PROPERTIES
- MATHEMATICAL MODELS
- NUMERICAL ANALYSIS
- STRAIN RATE
- FINITE DIFFERENCE THEORY
- TORSION BARS