失效准则在船舶碰撞破坏中的应用研究

An application research on failure criteria of collision damage in ship structures

船舶结构冲击破坏一直都是学者们研究的重点,而碰撞破坏是船舶结构在生命周期内最有可能遭受的冲击破坏形式。因为船舶惯性质量大,在很低的速度下,碰撞也会造成船舶损毁的严重后果。作为判定结构是否失效的关键依据,失效准则对碰撞仿真分析结果的准确性有着至关重要的影响。本文针对典型的船体双层壳结构,结合试验数据,对比尖刀型撞头碰撞仿真下双层壳结构的塑性变形,对碰撞有限元模型及材料本构参数进行验证。在此基础之上重点研究GL、RTCL和JC工程上3种常用金属延性失效准则在碰撞破坏仿真分析中的应用。结果显示:板壳结构在碰撞载荷下,撞击中心的应力三轴度在0.3~0.6之间,考虑应力三轴度的RTCL和JC失效准则更能真实反应板的撞击破坏。而船舶碰撞多属于低速碰撞,应变率效应影响较小。

Failure of the ship structure attracts more and more attention recently. Collision is considered to be one of the most common damage for the structure and can sharply shorten its lifespan. Since the weight of the ship is sometimes very large, serious damage can still happen even with a low impact velocity. In order to know whether the failure occurs on a structure or not during the simulation, the failure criteria is always used and affects the analysis a lot. The present paper compares the effect of three different types of failure criterion on numerical results. Firstly, suitable parameters in the finite element method are chosen and validated by comparing with experimental data in modelling the typical double shell collision model. After that, the application of three types of failure criterion, namely the GL, RTCL, and JC models, are discussed. Results show that the triaxiality greatly affect the accuracy of the simulation, while the strain rate has much less effect especially under low impact velocity.