抛锚撞击水下管汇的数值模拟研究

Numerical simulation of anchor impacting submarine manifold

船舶抛锚撞击水下管汇会影响到管汇的正常作业,基于ANSYS/LS-DYNA动力学分析软件,建立锚-水下管汇-海床土体的三维有限元模型,对抛锚碰撞水下管汇的过程进行数值仿真。通过求解水下管汇受碰撞后的等效应力、应变的时间历程及受撞击部位的凹陷损伤深度,发现最大等效应力点出现在管汇与锚接触位置处,管汇的碰撞部位最终发生凹痕变形。同时讨论锚与管汇接触面的形状以及海床土体对水下管汇损伤程度的影响,当冲击能量相同时,锚与水下管汇的碰撞接触面积越小,水下管汇的损伤深度就越大;当锚与管汇接触的接触面积相同时,冲击能量越大,水下管汇的损伤变形越大。海床土体的剪切弹性模量对管汇的凹陷损伤深度以及最大等效应力影响与冲击能量有关,海床土体的内摩擦角对管汇的碰撞影响较小。

The impact of the ship＇s anchor on the submarine manifold will affect the normal operation of a manifold. Based on ANSYS /LS-DYNA—the dynamics analysis software,and by establishing a 3D finite element model of anchor,submarine manifold and seabed soil,the process of a submarine manifold impacted by anchor is simulated. By computing the time history of equivalent stress and strain and the dent depths of the impacted elements of submarine manifold,it is found that the maximum equivalent stress appears in the contact position between the manifold and the anchor,eventually the collision part of manifold will have dent deformation. At the same time,the effect of the interface＇s shape between anchor and manifold,and the seabed soil are discussed. When the impact energy is identical,the smaller the contact area between anchor and submarine manifold,the greater the damage depth of the submarine manifold; when the contact area between anchor and submarine manifold is definite,the greater the impact energy,the larger the damage deformation the submarine manifold will suffer. The effect of the shear modulus of seabed soil on the depression damage depth of a manifold and the maximum equivalent stress is related to the impact energy,and the internal friction angle of the seabed soil has little effect on the impact of the manifold.