Finite Element Modeling of Transient Temperatures in a Small-Caliber Projectile

Description

American Journal of Engineering and Applied Sciences 2010, 3 (2), 355-362 pp., ISSN 1941-7020.Future generations of intelligent munition: will use Microelectromechamcal Systems (MEMS) for guidance, fuzing logic and assessment of the battlefield environment. The temperature: fund in a gun system, however, are sufficient to damage some material: used in the fabrication of MEMS. The motivation of this study is to model the dynamic temperature distribution in a typical small-caliber projectile. Approach: An axisymmetric finite-element model of a projectile is developed to simulate temperature: through internal ballistics (the projectile is m the gun barrel) and external ballistics (the projectile travels in a free trajectory towards the target). Accuracy of the simulation is confirmed through comparison to analytical models and to payloads attached to experimental projectiles. In the simulation, the exact value: for one boundary conditions are unknown and or unknowable. A sensitivity analysis determines the effect of these uncertain parameters. Results: The simulation shows that friction at the projectile-gun barrel interface is primarily responsible for elevated temperatures m a gun system. Other factors have much smaller effects. The short duration of the internal ballistics prevents the frictional heat from diffusing into the bulk of the projectile. As a result, the projectile has a shallow, high-temperature zone at its bearing surface a: it leave: the gun barrel. During external ballistics, this heat will diffuse through the projectile, but most of the projectile experience: temperatures of 56°C or lower. Simulation shows that the polymer package around a MEMS device will further attenuate heat flow, limiting temperatures m the device to less than 30°C.Introduction Materials and methods Results Discussion Conclusion