1. 제 목 : Predictive Thermal Explosion Models for Energetic Materials





2. 연 사 : Dr. Jack J. Yoh


University of California


Lawrence Livermore National Laboratory


USA








3. 일 시 : 2004년 8월 30일 월요일 오후 4시~





4. 장 소 : 301동 1512호 세미나실





5. 요 약





In thermal explosions, time scales for behavior can range from days to microseconds. During the relatively slow heating phase, the response of an energetic materials system is paced by thermal diffusion and chemical decomposition, while the mechanical response is essentially a quasi-static process. As the decomposition reactions accelerate, heat is generated faster than it can diffuse. Product gases are formed and rising pressure accelerates the energetic and containment material. The resulting violence can range from a pressure rupture to a detonation.





We have performed multi-dimensional numerical simulations of slow thermal explosion of confined high explosives (HE). The pre- and the post-ignition stages of the process is modeled by an Arbitrarily Lagrangian-Eulerian code that can handle a wide range of time scales that varies from a structural to a dynamic hydro time scale. During the pre-ignition stage, quasi-static mechanics and diffusive thermal transfer from a heat source to the HE are coupled with the finite chemical reactions that include both endothermic and exothermic processes. Once the ignition is detected, that is an onset of stage two, a hydro dynamic calculation is performed along with a level-set treatment of the propagating burn front. The predictions are made on the time-to-explosion, the rate of confinement wall expansion, and the fracture of a metal container. The experimental measurements are used to validate the predictions.





6. 문 의 : 기계항공공학부 정석호 교수(880-7114)