A fault propagation path identification method for A320 air conditioning system based on improved Bayesian network

Accurately evaluating the continuous effect of penetration and moving charge explosion of earth penetrating weapons is the premise of reliable design of shield on the protective structure. Firstly, a three-stage integrated projectile penetration and moving charge explosion finite element analysis method was proposed based on the technologies of volume filling of explosive and the two-step coupling in penetration and explosion processes. By conducting the numerical simulations of the existing tests of moving charge explosion, penetration and static charge explosion of normal strength concrete (NSC) and ultra-high performance concrete (UHPC) targets, the accuracy of the proposed method in describing the propagation of explosive waves, peak stress, cracking behavior and damage evolution of target under the penetration and explosion was fully verified. Besides, for the scenario of an NSC target against a 105 mm-caliber scaled projectile, the differences of target damage predicted by the proposed finite element analysis method and traditional penetration and static charge explosion method were compared. Meanwhile, the superimposed effect of the penetration and explosion stress field and the influence of shell constraint and fracture fragment were analyzed. Based on the damage characteristics of targets at different detonation time instants of explosive, the most unfavorable detonation time instant of the warhead was determined. Finally, numerical simulations were conducted for the scenarios of three prototype warheads: SDB, WDU-43/B and BLU-109/B. The destructive depths of NSC and UHPC shields subjected to the penetration and moving charge explosion loadings are 1.33, 2.70, 2.35 m and 0.79, 1.76, 1.70 m, respectively. The corresponding scabbing and perforation limits of shields were further given. The results show that the destructive depths, scabbing limits and perforation limits calculated by the finite element analysis method with considering integrated penetration and moving charge explosion are about 5%–30% higher than those calculated by the traditional penetration and static charge explosion method.