Accession Number:

ADA230220

Title:

Characterization of Mechanical Damage Mechanisms in Ceramic and Polymeric Matrix Composite Materials

Descriptive Note:

Technical rept. Oct 1989-Oct 1990

Corporate Author:

SOUTHWEST RESEARCH INST SAN ANTONIO TX

Personal Author(s):

Report Date:

1990-10-01

Pagination or Media Count:

64.0

Abstract:

The principal objective of the program has been to establish the loading rate dependence of compressive deformation and fracture mechanisms in whisker and fiber-reinforced ceramic matrix composites, and in fiber-reinforced polymeric matrix composites. Work during the last year has emphasized several types of composite Silicon Carbide fiber and Silicon Carbide whisker-reinforced pyroceram, and graphite fiber-reinforced thermoplastic. The behavior of a unidirectional carbon fiber-reinforced thermoplastic matrix composite subject to compressive loading at strain rates ranging from 10 to the minus 5 sec t the minus 1 to 5000 sec to the minus 1 is reported. Damage mechanisms are identified, and discussed in terms of matrix microstructure and fiber interactions. In particular, it is found that under quasi-static conditions, two absolutely critical factors control the life of the composite, i.e., the ability of the polymeric matrix to resist shear and thereby inhibit fiber flexure, and the ability of individual fibers to resist the nucleation of compressive plastic shear bands during flexure. It also is shown that at very high rates of strain approx. 5000s to the minus 1, the strength suddenly begins to increase with strain rate in an extremely robust fashion. The measured strength-strain rate dependence in this range is shown to be consistent with the kinetics of kink band propagation.

Subject Categories:

  • Ceramics, Refractories and Glass
  • Laminates and Composite Materials

Distribution Statement:

APPROVED FOR PUBLIC RELEASE