Conical Acrylic Windows Under Long Term Hydrostatic Pressure of 20,000 Psi

Abstract

Conical acrylic windows with cone angles 30 deg ≤ α ≤ 150 deg have been subjected to sustained hydrostatic pressure of 20,000 psi for up to 1,000 hr duration. The thickness to minor diameter ratio (t/D) of the more than 200 windows varied from 0.750 to 2.000. Model scale windows served as the bulk of test specimens, and the majority of the tests were conducted at room temperature. Test findings indicate that only windows with t/D > 1 and cone angle α ≥ 60 deg will not fail in less than 1,000 hr of sustained hydrostatic loading although considerable cracking will take place. For optically acceptable service of 1000 hr duration under 20,000 psi hydrostatic pressure, the windows must have t/D ≥ 2 and a cone angle α ≥ 90 deg. The axial displacements of such windows after 1000 hr of hydrostatic loading at 20,000 psi, are approximately 0.1 times their minor diameter, with approximately 50 percent of this displacement taking place during the first hour of pressure application.