Date of Award

12-1991

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Shankar Mall, PhD

Abstract

The objective of this study was to investigate the material behavior of SCS-6/β21-S [0/90]2s in a thermomechanical fatigue environment. Samples of the SCS-6/β21-S composite were subjected to in-phase and out-of-phase cyclic loading; four samples were tested under in-phase conditions and eight samples were tested under out-of-phase conditions. Stress, temperature, and total strain values were acquired during the test sequence and analyzed for indication of possible trends. Experimental results indicated in-phase specimen possessed shorter fatigue lives then their out-of-phase counterparts above the static first ply failure of the matrix. The out-of-phase specimen showed a shorter fatigue life below the first ply failure. The examination of the strain change, modulus change, fractography, and metallography of the in-phase test specimens suggests a fracture mechanism that is fiber dominated. The investigation of these parameters, for the out-of-phase test specimens, indicates the fracture mechanism may be matrix dominated. Additional analysis, using a linear life fraction model and a cumulative damage model, further suggests two parameters govern the fatigue life of SCS-6/β21-S. Both models indicate the maximum stress or strain parameter of the 0° fibers provides reasonable correlation for life prediction and damage accumulation for an in-phase environment. The load range and modulus provide reasonable correlation for the life prediction and damage for out-of-phase test specimen.

AFIT Designator

AFIT-GAE-ENY-91D-9

DTIC Accession Number

ADA243932

Comments

Plain-text title form: Thermomechanical Fatigue of SCS-6/(Beta)21-S (0/90)2s Composite

Additional Files
sf298_HANSON.pdf (112 kB)
SF298 form for thesis of Dana Hanson
Download

Share

COinS