Developing a Transient Finite Element Model to Simulate the Launch Environment of the 155-mm SADARM Projectile

摘要

Projectiles like SADARM, with delicate electronic components, need robust designs that are able to survive high 'g' accelerations and spin rates. Unfortunately, the packaging of these components and their space requirements reduce the design's safety margin. Therefore, considerable care must be used in analyzing the structural package. Conventional projectiles are typically analyzed using a quasi-static, axisymmetric, finite-element approach that balances the peak propellant pressure on the base of the projectile with an equivalent acceleration. In most circumstances, the robustness of the design makes this approach more than sufficient for identifying problem areas in the structure. However, the internal components used in SADARM are sensitive to off- axis loading such as that caused by spin rate or the rapid unloading of the projectile's base that occurs at muzzle exit. Additionally, stress waves caused by balloting and impedance mismatching within the stack design only serve to further reduce the design margin. To compensate for the reduced design margin and the increased source of potentially damaging loads, more sophisticated finite-element techniques need to be employed. The techniques presented here represent a modern approach to analyzing the projectile's launch loading conditions over traditional techniques.