XCT Study of Cone Crack Damage in Multilayered Transparent Panel Structures and Comparison to Modeling

Report No. ARL-TR-6082
Authors: William H. Green; Raymond E. Brennan; Costas F. Fountzoulas
Date/Pages: August 2012; 26 pages
Abstract: Transparent and opaque materials are used by the U.S. Army in protective systems for enhancing survivability of ground vehicles, air vehicles, and personnel. Transparent materials are utilized for face shields, riot gear, and vehicle windows, in addition to other applications for sensor protection, including radomes and electromagnetic windows. Fracture from low-velocity impacts limits visibility and impairs continued vehicle operations. Transparent protective systems typically consist of glass, polymeric, and ceramic materials. Impact damage in different multilayered transparent panel structure types was investigated using a number of nondestructive evaluation methods, including phased array ultrasonic testing and x-ray computed tomography (XCT). Some of the damaged specimens exhibited multiple cone cracks in the second glass layer in front of the backing plate. The spatial characteristics of cone cracks were analyzed using geometric data from the XCT scans (images). Quantitative calculations on the extent of the cone spans were performed. Physical cone attributes (e.g., cone angle) were compared to crack damage geometries generated by theoretical simulations of impact damage.
Distribution: Approved for public release
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Last Update / Reviewed: August 1, 2012