箱形梁在水下近距非接触爆炸作用下的整体毁伤研究

Study on integral damage modes of box-like beam subjected to underwater closely located non-contact explosion

为了研究舰船在水下近场爆炸作用下的整体毁伤模式,根据相似原则设计了两种箱形梁模型,将TNT炸药置于模型中部正下方爆炸,通过改变爆距和药量来研究试验模型在不同爆炸工况下的整体运动特性,并利用高速摄影仪观察模型的动态响应过程.试验研究发现:在梁模型一阶湿频率与气泡脉动频率相近的条件下,气泡脉动会激起结构明显的整体弯曲运动;当爆距与最大气泡半径之比为1～1.5时,梁结构会发生中垂破坏,形成一个或两个塑性绞;当爆距与最大气泡半径之比为2～4时,梁结构会发生鞭状运动响应;水下爆炸气泡对水面结构的整体毁伤作用大于初始冲击波。

In order to study the damage modes of warships subjected to underwater blast loading,two experimentally used box-like beams were designed based on similarity criterion.Dynamic responses of the beams floating on water subjected to underwater explosion were investigated by changing the distance from explosion source and the amount of explosive with TNT charge located closely under the mid-span of the models.In tests,high-speed photography was applied to obtain the whole process how the objects react against blast loading.The experimental results show that explosion bubble pulses will activate beam to bend severely as a whole when the first wet frequency of beam approximates to the frequency of bubble pulses.If the ratio of explosive distance to maximum bubble radius ranges from 1 to 1.5,the beam will be damaged in sag state with one or two plasticity hinges,and if it ranges from 2 to 4,the beam will produce whipping motion.To sum up,explosion bubble pulses play a greater role in making the integral damage of beams than initial shock wave.