Date of Award
Master of Science
Department of Aeronautics and Astronautics
Marina B. Ruggles-Wrenn, PhD.
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 [± 45°] 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 2x105 cycles.
DTIC Accession Number
Wilkinson, Michael P., "Mechanical Properties and Fatigue Behavior of Unitized Composite Airframe Structures at Elevated Temperature" (2014). Theses and Dissertations. 759.