Modeling of Microstructural Effects on Fracture Processes at High Loading Rates
Abstract
We extended classical dynamic fracture mechanics to a class of new commercially useful titanium microstructures and demonstrated that their dynamic fracture behavior differs significantly from that of previously studied model materials. By combining continuum measurements (obtained using the torsion split Hopkinson bar and one-point-bend fracture test methods) and fractogaphic measurements (obtained using fracture surface topography analysis, FRASTA), we generated a complete data base on static and dynamic strength and fracture toughness for various microstructures of the alloy Ti-IOV-2Fe-3AI. We determined effects of microstructural features on microfailure behavior and we modeled some of the observed microfailure processes using finite element analysis. Whereas the dynamic initiation toughness was only moderately higher than the static initiation toughness (at most 20%), a very strong rise was found in the crack propagation toughness with crack extension (as much as a 100% increase) for velocities as low as 100 m/s. This rate dependent resistance curve effect is an intrinsic material property (in contrast to a structural effect) and a strong function of microstructure. We demonstrated that the formation of shear lips is also a strongly rate dependent phenomenon and that shear lips, when they develop, make only a modest contribution to the propagation toughness (on the order of 20% for the case studied here). Our results also showed that, in general, there is not a direct correlation between the dynamic initiation and propagation toughnesses.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1992
- Accession Number
- ADA255684
Entities
People
- D. A. Shockey
- Jacques H. Giovanola
- Richard W. Klopp
Organizations
- SRI International