Polymeric Material Study for the D-Fuze Windshield.

摘要

Pursuant to a previous report, an effort has been made to continue to find higher performance materials for the design of windshields. A product that the U.S. Army Research Laboratory provides the test and evaluation community is a yawsonde, now termed 'diagnostic fuze' or 'D-fuze'. This device is capable of sensing the inertial environment of a cannon-launched projectile and telemetering the live data to a ground station. In order to telemeter data in flight, the antenna has to radiate through a protective windshield. This windshield is not only transparent to radio frequency radiation but is also a means of ballistic and thermal protection. A recent flight experiment with a prototype artillery projectile revealed a weakness of the nylon 66 windshields to 'blow-by' gases. The windshields were designed to survive aero-pressures attributable to Mach 3 launch and flight with a significant safety factor. However, blow-by effects were never considered. A cursory study has been performed on selected extruded bar stock polymers, which are readily available without our having to consult a compounding source, for machining windshields for D-fuzes of various geometries. Ultem 2300 appears to provide the best mechanical, thermal, and electrical properties of the studied polymer materials. However, depending on the thickness of the geometry, a designer may want to reconsider using unfilled Ultem 1000. The cross section of the geometry reduces to a range near 0.03125 inch; there may not be enough glass fiber to reinforce the polyetherimide matrix. Further literature research indicated that the ogive of the M762 fuze is made from injected molded polyetherimide with 30% glass filler.