Accession Number:

ADA179264

Title:

Influence of Microstructure and Microdamage Processes on Fracture at High Loading Rates.

Descriptive Note:

Annual rept. no. 1, Feb 86-Jan 87,

Corporate Author:

SRI INTERNATIONAL MENLO PARK CA

Personal Author(s):

Report Date:

1987-02-27

Pagination or Media Count:

21.0

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 SRIs finite element computer codes to compute the stress intensity factor in simulations of the dynamic fracture experiments.

Subject Categories:

  • Properties of Metals and Alloys
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE