This paper discusses the design of a hardened enclosure for high pressure extreme temperature (HPET) pneumatic testing of seals. The seal test fixture is located within a blast-fragment barrier (BFB) in case of a failure of the test fixture. The BFB is located within a hardened test room since the BFB has a 1-in annulus air gap to allow for cabling access to the test fixture, through which shock and gas pressure can propagate out into the room. A 30.5in3 (0.51) volume charged with 15,000psi (1034bar) of compressed nitrogen under a temperature range of −50°F to 400°F was used to produce the worst-case energy release in the event of a catastrophic failure of the seal fixture.

In order to assess the structural capacities of the BFB and test room, an equivalent axisymmetric computational fluid dynamics (CFD) model of the test fixture, BFB, and test room was used to estimate the fragment velocity and applied blast load time histories to the BFB and test room. The BFB was assessed using non-linear dynamic finite element analysis. All of the materials are modeled using a plasticity-based piecewise linear hardening constitutive model, with rate dependency and softening, fit to each material yield, tensile, and elongation limit. The seal fixture generated fragment interactions with the interior surfaces of the BFB model using slideline and pinball contact algorithms.

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