Development of Lightweight Commercial Aircraft Windshields with New High Strength Glasses,
PPG INDUSTRIES INC PITTSBURGH PA GLASS RESEARCH CENTER
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To evaluate the effect of increased surface compression on failure resistance, it was necessary to test instrumented windshields and measure surface stress versus velocity for different designs. A resulting test program included 164 bird impacts against 28 full-size, flat windshields incorporating different interlayers and glass plies of varying thicknesses at varying locations and temperature conditions. This paper presents the results of the program in the form of stress-velocity curves and pass-fail results for different designs. It also shows the evolution of a design which features a thick high strength thermally tempered core for load carrying and a thin chemically strengthened inboard ply to enhance fail-safe yet survive the stresses which occur during impact. The thickthin high strength glass windshield met all bird impact qualification tests at Boeing and subsequent thermal-pressure certification. This design concept was also employed for lighter weight retrofit applications for other commercial aircraft windshields.