Many commonly used infrared window materials, such as zinc sulfide and zinc selenide, are subject to structural failure due to stress-corrosion induced cracking. This failure mechanism is of critical importance in applications in which the window experiences high static pressure loading for prolonged periods in humid atmospheres, conditions typical of airborne optical windows. The most effective means of screening windows against failure due to this mechanism is by use of overpressure proof testing. In this paper, the design of overpressure proof tests for large airborne infrared windows is discussed. The underlying physical phenomena and governing mathematical relationships are presented. A hypothetical proof test design for a large infrared window to be employed in a man-rated aircraft is developed to illustrate the application of the analytical methodology; Practical considerations in the execution of large infrared window overpressure proof tests are also discussed.
Charles J. Pruszynski,
"Overpressure proof testing of large infrared windows for aircraft applications", Proc. SPIE 1498, Tactical Infrared Systems, (1 October 1991); doi: 10.1117/12.46811; https://doi.org/10.1117/12.46811