考虑静水压力的加筋圆柱壳体径向碰撞机理研究

水下碰撞是水下结构物的主要事故形式之一,而深水静压载荷环境下的碰撞、触礁等问题是深水静压和碰撞联合载荷作用下的结构响应问题,是最为危险的碰撞环境.采用MSC/Dytran大型非线性动力有限元程序,建立数值有限元模型,考虑深水静压和外物撞击的联合作用,进行深水静压环境、无水压力环境下以及不同撞击载荷多工况碰撞环境和撞击历程的数值分析,对加筋圆柱壳体碰撞载荷作用下的变形、失效机理和变形历程进行比较,分析了不同速度、质量撞击物撞击载荷作用下撞击强度、深水压力载荷等对碰撞历程的影响和加筋圆柱壳体深水碰撞环境下的动态响应特性和碰撞机理.结果显示:由于准静压载荷的附连联合作用,撞击形变将不可避免地带来准静压载荷的做功,其能量将直接由结构吸收,从而将导致加筋圆柱壳体结构的防撞能力急剧下降.同时,随着静水压力的增大,撞击初始阶段所产生的小变形将导致圆柱壳体的整体环向失稳,从而导致壳体整体迅速压溃,因此,深水环境下结构碰撞问题的研究主要是结构的初始稳定性问题的研究.圆柱壳体通过横向平台的加强后将有效提高壳体结构的横向失稳临界应力,从而能够明显地改善加筋圆柱壳体结构的径向耐撞能力.

Collision mechanism analysis for rib-stiffened cylinder under water pressure condition

The collision is one of the frequent accidents for ocean structure underwater, such as submarines, and the problem of collision underwater is the coupling of collision and high water pressure,which is the most dangerous collision condition for submarines. Firstly, the MSC/Dytran and MSC/Nastran were used to analyze the static water pressure state with circumferential stress and longitudinal displacement,and the numerical simulation models were built in this paper.Then the coupling collision mechanism was studied by the MSC/Dytran.The multi-calculation cases were carried out, which include the collision with or without considering water pressure, the striker with different mass and initial velocity, etc. By those calculations, the deformation and energy absorbing characteristics of rib-stiffened cylinder under water pressure, the effect of pressure, the effect of collision initial velocity and the striker mass were discussed. The results show that the collision resistance capability of submarine will be down sharply, owing to the work done by water pressure even if little flexibility occurs by initial contact. And with the pressure increased, more and more distortion energy will occur by water pressure, and the structure will crush rapidly. So it can be said that the major research problem for underwater collision is the study for initial stability of structure in initial contact phase.