含损伤加筋板结构声辐射模态变异研究

本文采用声辐射模态的有关理论,用结构的声辐射模态参数来表征结构本身的固有声辐射特性.以加筋板结构为例,计算不同加筋情况和结构不同损伤情况下的声辐射模态.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K8chanov理论,引人了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,计算分析了损伤对振动频率、模态以及声辐射模态的影响.文章建立了一种含损伤结构的分析方法,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 variations of acoustic radiation modes of a damaged stiffened panel

In the framework of linear sound theory,the inherence acoustic radiation properties of a structure are fully described by its acoustic radiation modes.In this paper,the radiation modes of a stiffened panel under different damaged conditions are 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 natural frequencies,vibration and acoustic radiation modes are studied.A computational method is given,aided by some typical examples,to analyze acoustic behavior of a damaged structure.Panels are widely-used ship and ocean structures.The current method is useful for assessing the influences of the damages present in a stiffened panel on its acoustic radiation properties.