水下冲击波作用下大缩比异化模型的数值模拟

以双层加肋圆柱壳结构为模型,采用数值方法对结构在水下爆炸冲击载荷作用下的动响应相似性进行研究,在完全几何相似的条件下,在弹性范围内,应用相似规律可将模型实验的结果推广到原型。但由于所有构件尺寸都按同一比例作几何相似,尤其是大缩比时,将导致某些构件(如型材等)的尺寸过小,模型实际建造难以实现,为此,将相似模型作为基础标准形式,根据实际情况对模型进行一定程度的变异,并分别采用了材料等效法和摊板厚法对相似模型进行变异。研究结果表明:材料等效法能较好地通过变异模型反映相似模型结构振动响应特性,但不适合模拟相似模型结构的应力变化;摊板厚法简单易实施,但由于变异模型局部刚度与真实情况不同,将导致实验结果误差过大。

Numerical Simulation of Reduction Dissimilation Model under Underwater Explosion Shock

In this paper,numerical simulation is used to probe into the similar responses of the prototype and scale double stiffened cylindrical structure when subjected to underwater explosion.The result of the scale model can be spread to that of the prototype within the elastic scope when the geometrical conditions are all similar according to the similarity laws.However,if all the parts are scaled in the same proportion especially in a pretty high reduction proportion,some parts(e.g.section bar,etc.) may be too small to be modeled.Hence,the similar model is considered as a basic standard form,and then model is dissimilated to some extent with material equivalence method and plate thickness sharing method respectively.Results show that the material equivalence method can well reflect the structural vibration response characteristics of similar model while it is not suitable to simulate the stress change of similar model.Plate thickness sharing method is easier to be carried out but the error of the experimental result could be exceedingly big since the stiffness of the dissimilation model is different from that of prototype.This paper aims to provide reference for the similarity research of the nonlinear dynamics of the structures under transient loads.