Accession Number:

ADA230544

Title:

Investigation of Damage Mechanisms in A Cross-Ply Metal Matrix Composite under Thermo-Mechanical Loading

Descriptive Note:

Master's thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH

Personal Author(s):

Report Date:

1990-12-01

Pagination or Media Count:

164.0

Abstract:

Metal matrix composites MMCs are rapidly becoming strong candidates for high temperature and high stiffness structural applications such as the Advanced Tactical Fighter ATF. This study systematically investigated the failure modes and associated damage in a cross-ply, 0902s SCS6Ti-15-3 metal matrix composite under in-phase and out-of-phase thermomechanic fatigue. Initiation and progression of fatigue damage were recorded and correlated to changes in Youngs Modulus of the composite material. Experimental results show an internal stabilization of reaction zone size but degradation and separation from constituent materials under extended cyclic thermal loading. Critical to damage were transverse cracks initiating in the 90 degrees plies, growing and coalescing from fibermatrix interfaces internal to the specimen, progressing outward through the 0 degree plies before failure. Maximum mechanical strain at failure was determined to be approximately 0.0075 mmmm. A correlation was made relating maximum matrix stress to failure life, resulting in a fatigue threshold limit of 280 MPa. An attempt was made to correlate the degradation in Youngs Modulus Damage1-EEo with the applied life cycles from different TMF tests.

Subject Categories:

  • Laminates and Composite Materials

Distribution Statement:

APPROVED FOR PUBLIC RELEASE