Abstract
Electronics packages in precision guided munitions are used in guidance and control units, mission computers, and fuze-safe-and-arm devices. They are subjected to highg-loads during gun launch, pyrotechnic shocks during flight, and highg-loads upon impact with hard targets. To enhance survivability, many electronics packages are potted after assembly. The purpose of the potting is to provide additional structural support and shock damping. Researchers at the US Army recently completed a series of dynamic mechanical tests on a urethane-based potting material to assess its behavior in an electronics assembly during gun launch and under varying thermal launch conditions. This paper will discuss the thermomechanical properties of the potting material as well as simulation efforts to determine the suitability of this potting compound for gun launched electronics. Simulation results will compare stresses and displacements for a simplified electronics package with and without full potting. An evaluation of the advantages and consequences of potting electronics in munitions systems will also be discussed.
Highlights
E weapons community currently has a strong need to design and eld reliable electronics for precision munitions. ese electronic systems and subsystems are used in guidance and control units, mission computers, sensors, and fuzesafe-and-arm devices
While modern technology has evolved to produce high-precision and highly reliable electronic systems, they are not constructed to survive the harsh environments of gun launch. e current issues faced are high vibratory loads, high-g-accelerations, pyrotechnic shocks during ight, and high-impact loads through hard targets
In an effort to mitigate the severity of these loads, electronic components are o en potted to enhance structural support, dampen large dynamic vibrations due to gun launch [1]
Summary
E weapons community currently has a strong need to design and eld reliable electronics for precision munitions. ese electronic systems and subsystems are used in guidance and control units, mission computers, sensors, and fuzesafe-and-arm devices. Projectile live- re testing is customarily used to build reliability and optimize design This testing is costly and, in many cases, impractical for de ning gunlaunch-induced stresses on many organic materials used in subassemblies. For this reason, structural analysts employ nite element analyses (FEAs) to predict the impact of gun launch on these subassemblies and components. Dynamic FEA helps to build reliability and provides signi cant insight into systems survivability for munitions designers It saves programs millions of dollars in testing, as multiple designs and materials can be simulated in a matter of days and for a fraction of the cost of live- re testing. Similar comparisons are made at temperature extremes to assess differences with the potting in the glassy and rubbery phase. is study assumes that the potting adheres to the chips, the board, and the can
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