A combination of destructive and nondestructive testing methods was utilized to evaluate the impact velocity and energy conditions that caused fracture in alumina structural ceramics. Incremental damage was produced in aluminum-backed Al_2O_3 tiles using drop tower testing for low velocity impact with a high mass indenter. Under these test conditions, a damage threshold range was determined below which there was no impact damage and above which fracture occurred. The majority of damage in the fractured samples consisted of radial and cone cracking. The samples were nondestructively evaluated using digital radiography, X-ray computed tomography, and ultrasound C-scan imaging. Bulk damage detected by these techniques was compared to surface damage observed by visual inspection. Qualitative evaluation of surface and bulk cracks and quantitative percent damage assessment were used to compare the integrity of the nondestructive techniques. While all three methods were able to detect surface cracks, C-scan imaging was more effective at detecting internal damage in the alumina samples while X-ray computed tomography was more effective at producing three-dimensional images of the crack patterns.
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