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Mechanical Behavior Of Cracked Panels Repaired With Bonded Composite Patch, Michael A. Hansen
Mechanical Behavior Of Cracked Panels Repaired With Bonded Composite Patch, Michael A. Hansen
Theses and Dissertations
This research focuses on investigating the mechanical behavior of cracked aluminum panels repaired with bonded boron/epoxy composite patches. The effects of crack initiation and growth on the residual strength of the repaired panels are characterized. This research establishes a correlation between damage modes, residual strength and evolution of strain within as well as outside the patch. Monotonic tensile tests on specimens with a perfectly bonded patch were used to determine the base line strength. Likewise, fatigue tests on specimens with a perfectly bonded patch served to establish baseline fatigue life. In addition, several specimens with a perfectly bonded patch were …
Internal Damage Detection And Assessment In Beams Using Experimental Natural Frequencies, Frances K. Durham
Internal Damage Detection And Assessment In Beams Using Experimental Natural Frequencies, Frances K. Durham
Theses and Dissertations
This study investigated the frequency response of a cantilever beam with the intent of establishing a reliable nondestructive method of damage detection. The test specimens were 12 aluminum 2024 T3 beams, each identical except for a unique, eccentrically located notch, and one reference notchless beam. The machined notches varied in length and location to simulate varying degrees of damage. Laser doppler vibrometry enabled the data acquisition. The changes in natural frequencies were correlated to notch length and notch location. A comparison of eccentric and centered notch influence on the natural frequencies also is discussed.
Tensile Stress Rupture Behavior Of A Woven Ceramic Matrix Composite In Humid Environments At Intermediate Temperature, Kevin J. Larochelle
Tensile Stress Rupture Behavior Of A Woven Ceramic Matrix Composite In Humid Environments At Intermediate Temperature, Kevin J. Larochelle
Theses and Dissertations
Stress rupture tests on the SylramicTM fiber with an in-situ layer of boron nitride, boron nitride interphase, and SiC matrix ceramic matrix composite were performed at 550°C and 750°C with 0.0, 0.2, or 0.6 atm partial pressure of water vapor, pH2O. The 550°C, 100-hr strengths were 75%, 65% and 51% of the monotonic room temperature tensile strength, respectively. At 750°C, the strengths were 67%, 51%, and 49%, respectively. Field Emission Scanning Electron Microscopy analysis estimated the total embrittlement times for 550°C with 0.0, 0.2, and 0.6 atm pH2O were >63 hrs, >38 hrs, and between …