红外CT模拟在混凝土板内部缺陷探测中的应用

红外成像技术采用非接触式检测方法,对结构内部缺陷进行实时、快速大面积扫描探测,作为无损检测领域一项新的技术在土木工程中得到越来越广泛的应用。但是,这种技术的主要缺点是只能通过成像技术显示缺陷表面状况,却无法获知缺陷深度和厚度。本文以一维有缺陷混凝土板为研究对象,采用有限差分法对混凝土板进行热传导数值模拟分析,获得每一点物体表面温度差与缺陷深度及其厚度的非线性对应关系。在此基础上,采用人工神经网络算法,实现对混凝土板内部缺陷的三维重构,即红外CT模拟。本文提出的方法可以同时获得缺陷深度和厚度,并适用于任意形状的缺陷。

Application of infrared CT simulation on damage detection of concrete slabs

For the concrete structure,a key question is that how to adopt effective methods to detect the property,size and location of the interior defects in the field of the engineering construction.The increasingly recognized applicability of infrared thermography has caused developments of non-destructive testing and diagnoses for civil engineering fields.A significant adwantage of this technique is that invisible defects can be safely and rapidly diagnosed by visualizing the temperature fields on its surface.However,the main limitation of this technique is unable to determine the depth and thickness of the defect.In this paper,the finite difference method of one-dimensional heat conduction numerical simulation is introduced in order to acquire nonlinear relationship between superficial temperature contrast and depth and thickness of the damage taking one-dimensional damaged concrete slab as an example.The artificial neural network algorithm is utilized to realize three-dimensional reconstruction of defects.The new developing technology is called infrared CT.The simulated examples show that the technology can not only effectively deal with the any irregular shape of defects,but also figure out the depth and thickness of defects simultaneously.