拓扑成像法的分层波导结构内部缺陷检测

摘要

将拓扑成像理论应用于分层波导结构,分析拓扑成像法在分层波导结构缺陷检测方面的应用可行性.首先,对拓扑梯度的表达式进行理论推导,阐述拓扑成像的基础理论和成像原理,对于厚度方向刚性连接的钢-铝双层板,本文结合实际检测需求,提出了优化的拓扑梯度表达式.然后,使用ANSYS有限元软件建立声场计算模型,根据优化的拓扑梯度表达式计算了直接问题和伴随问题两种情况下的声场分布,验证拓扑成像理论的可靠性.结果表明,拓扑成像方法可以准确定位钢-铝双层板中单缺陷和多缺陷,且具有良好的检测分辨率和定位精度,说明拓扑成像法对分层波导结构中的缺陷检测具有可行性.%The aim of this paper is to study the topological imaging theory and to determine whether it is possible to give the locations of all the defects in layered plate. It is considered a two-layered plate consist of aluminum and steel with elastic boundary. First, the formulas of the topological gradient are deduced theoretically, the basic theory and imaging principle are researched, an optimized imaging algorithm is presented for practical detecting. Then, the model building and two kinds of acoustic fields according to the imaging algorithm are all simulated in finite element software ANSYS. It is found that all the defects are located precisely at the detecting results with good resolution, it suggests that topological imaging can be an efficient method to obtain all the defects' locations in layered plate.