Date of Award

3-14-2014

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Marina B. Ruggles-Wrenn, PhD.

Abstract

The tension-tension fatigue behavior of newly developed polymer matrix composites (PMCs) and that of a unitized composite was studied. The PMCs investigated in this effort consisted of an NRPE (a high-temperature polyimide) matrix reinforced with carbon fibers. Two PMCs consisting of the aforementioned matrix with different fiber architectures were studied: one reinforced with a 2D woven fiber fabric and another reinforced with a non-crimp 3D orthogonal woven fiber fabric. The unitized composite consisted of a PMC co-cured with a ceramic matrix composite (CMC) layer, which acts as a thermal barrier. The PMC portion of the unitized composite had the same constituent properties and weave as the aforementioned 2D PMC. The CMC layer consisted of a zirconia-based matrix reinforced with a 2D woven quartz fiber fabric. For all three material systems (3D PMC, 2D PMC, and unitized composite), material properties were investigated for both on-axis [0/90 deg] and off-axis [plus-minus 45 deg] fiber orientations. Tensile properties were evaluated at (1) room temperature and (2) with one side of the specimen at 329 C and the other side exposed to ambient air. Tension-tension fatigue tests were conducted at elevated temperature at a frequency of 1.0 Hz with a ratio of minimum stress to maximum stress of R= 0.05. Fatigue run-out for this effort was defined as 2x10 (5) cycles.

AFIT Designator

AFIT-ENY-14-M-5

DTIC Accession Number

ADA610904

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