Influence of Microstructure and Microdamage Processes on Fracture at High Loading Rates.
Abstract
The optimal use of advanced beta and near-beta titanium alloys, in situations involving dynamic or shock loading, requires an understanding of how both microstructure and loading rate influence the fracture behavior. To address this need, SRI is performing dynamic crack initiation and propagation experiments on Ti-10V-2Fe-3A1 in three microstructural conditions, varying the loading rate to establish the rate-dependence of the fractire toughness. A new experimental method, developed in a previous Air Force Office of Scientific Research program (the one-point-bend impact test) and advanced instrumentation techniques (optical and Hall effect displacement transducors) are used to measure the dynamic initiation and propagation toughness. The Fracture Surface Topography Analysis (FRASTS) technique, a novel quantitative fractography technique, is applied to the fractured specimens to elucidate the microstructural failure mechanisms contolling fracture in each of the investigated microstructures. This report summarizes the progress made during the first year of the program. A metallurgical investigation has been completed to determine the appropriate heat treatments to produce three microstructures with 0%, 12%, and 40% of primary alpha phase, and with a strength level of about 1300 MPa. An optical technique to measure crack opening displacements (COD) during dynamic fracture experiments has been developed. Numerical algorithms have been implemented in SRI's finite element computer codes to compute the stress intensity factor in simulations of the dynamic fracture experiments.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 27, 1987
- Accession Number
- ADA179264
Entities
People
- D. A. Shockey
- J. H. Giovanola
Organizations
- SRI International