三层复合结构热无损检测的建模与有限元仿真

Modeling and Simulation of Thermal NDT of Three-layered Structures by Finite Element Method

论述三层复合结构板热无损检测(TNDT)的建模和基于有限元法的计算机仿真。在柱坐标系下建立三层复合结构板TNDT的数学模型;讨论用有限元法求解轴对称结构的瞬态热传导问题。利用有限元分析软件ANSYS模拟了热无损检测信息参数随缺陷大小和深度的变化,深入地分析缺陷参数(如大小和深度)与信息参数(如最大温差和最大对比度)的基本关系。结果显示,在缺陷深度一定时,最大温差与缺陷半径成正比,最大对比度与缺陷半径成正斜率的线性关系;而在缺陷半径一定时,最大温差和最大对比度与缺陷深度分别成一定的非线性函数关系。其研究结果为制定飞机上铝胶接结构板的热无损检测方案提供了有益的参考。

Modeling and computer simulation of thermal nondestructive testing （TNDT） of three-layered structures are studied based on the finite element method （FEM）. The TNDT mathematical model of three-layered structures is constructed in cylindrical coordinates, and the application of FEM to solving transient heat conduction problems in the cylindrical geometry is discussed. The evolutions of TNDT informative parameters versus defect size and depth are simulated by using the FEM analysis software ANSYS. The basic relationships between defect parameters, such as radius and depth, and chosen informative parameters, such as maximum differential temperature and maximum running contrast, are thoroughly explored to obtain some simple regression expressions. It is shown that, at a fixed defect depth, maximum differential temperature is directly proportional to defect radius, and maximum running contrast is linear to defect radius. However, if defect radius is fixed, both informative parameters become non-linear functions of defect depth. It is believed that obtained results may help engineers in developing a TNDT strategy for aviation bonded aluminum panels.