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混凝土结构的无损检测对于桥梁安全来说意义非凡。无损检测技术的基本目的是在不损伤构件的前提下,检测出物体中的缺陷,并确定其位置、大小和性质。在混凝土无损检测中常用的是超声层析成像代数重建技术(ART)。由于ART算法一般采用直线射线追踪,投影矩阵一经确定不再改变,不仅计算精度低,而且在异常体周边单元出现速度远离真值的现象。本文引入了最短路径(SPT)射线追踪,在每次ART迭代之前,利用SPT射线追踪重新计算投影矩阵,再进迭代计算。计算机仿真结果及混凝土试件实验结果表明:SPT射线追踪与ART相结合的算法具有更好的CT重建效果和消噪能力,并提高了计算的精度和图像重建质量。
Non-destructive testing of concrete structures is of extraordinary significance for bridge safety. The basic purpose of NDT technology is to detect defects in an object and determine its position, size and nature without damaging the component. Commonly used in nondestructive testing of concrete is ultrasonic tomography algebraic reconstruction (ART). As the ART algorithm generally uses linear ray tracing, once the projection matrix is determined to no longer change, not only the calculation accuracy is low, but also the phenomenon that the velocity of the surrounding unit in the abnormal body is far away from the true value occurs. In this paper, the shortest path (SPT) ray tracing is introduced. Before each ART iteration, the projection matrix is recalculated using SPT ray tracing and then iteratively calculated. Computer simulation results and experimental results of concrete specimens show that the combination of SPT ray tracing and ART has better CT reconstruction effect and denoising ability, and improves the accuracy of calculation and image reconstruction quality.