SYMPOSIA PAPER Published: 01 January 1994

Methodology for Predicting Canopy Fracturing Patterns During Ejection


A computer program for the prediction of crack propagation in aircraft transpar encies is described. The program, PACE (program for automated crack extension), provides an analyst with an automated means to update continually an initial finite element model to account for the propagation and branching of cracks resulting from the use of detonating cord and mechanical breakers to fragilize the transparency. The time frames of action for both the exploding detonating cord and fast fracture of the polymer transparency are short with respect to any gross movement of the canopy; hence, the primary focus of the research is the determination of the initial fracture or breakout pattern of the canopy. Relatively simple fracture mechanics expressions are used to estimate crack propagation direction and the number of branches. Experimental work and correlations to predictions made by PACE are described. An overview of the computational process is provided.

Author Information

Arnold, RR
Anamet Laboratories, Hayward, CA
Collins, PS
Anamet Laboratories, Hayward, CA
Ayoub, PS
Naval Air Warfare Ctr., Aircraft Division, Warminster, PA
Tung, R
Naval Air Warfare Ctr., Aircraft Division, Warminster, PA
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Developed by Committee: E08
Pages: 766–777
DOI: 10.1520/STP13737S
ISBN-EB: 978-0-8031-5270-0
ISBN-13: 978-0-8031-1990-1