含损伤加筋板结构声辐射阻尼变异研究

从能量耗散角度提出了结构声辐射阻尼的有关概念,考虑到辐射阻尼的特性,文章采用结构振动时耗散能量与振动总能量的比来建立辐射阻尼的数学模型,并用数值计算的方法研究简支板结构的声辐射阻尼特性.在研究结构损伤对声辐射阻尼影响的时候,以加筋板结构为例,计算结构不同损伤情况下的声辐射阻尼.基于Mindlin理论,建立描述健康和损伤的四结点有限元板壳单元模型,采用有限元方法计算结构表面动力响应.各向同性损伤单元,采取刚度各向整体弱化的方法分析;对于各向异性损伤单元,采用Kachanov理论,引入了x和y两个方向的弹性损伤折减系数.考虑到不同损伤存在形式,计算分析了损伤对声辐射阻尼的影响.文章建立了一种含损结构的分析方法,通过对一些典型算例分析,在评价损伤对船舶与海洋结构物常用的加筋结构声辐射特性影响方面做出了一定的探索.

A study on the variations of acoustic radiation damping of a damaged stiffened plate

In the framework of energy dissipation theory,radiation damping of structural sound is proposed.Using the ratio between the dissipated energy and the total energy of a vibrating structure to account for the characteristics of radiation damping,a mathematical model for radiation damping is built.Based on the mathematical model,the radiation damping of a simply supported plate is calculated.The radiation damping of a stiffened plate under different damaged conditions is also investigated.Based on Mindlin theory,four-node health and damage shell finite elements are given,and then the finite element method is used to calculate the dynamic surface response of a structure.Isotropic damage elements are built by globally and isotropically weakening the stiffness.Anisotropic damage elements are built by using reduction coefficients for elasticity damages in x and y directions based on Kachanov's theory.Influences of various types of damages on acoustic radiation damping are studied.A computational method is established,aided by some typical examples,to analyze acoustic behavior of a damaged structure.Plates are widely-used in ship and ocean structures.The current method is useful for assessing the influences of the damages present in a stiffened plate on its acoustic radiation properties.