【摘要】 在普通超声波检测的基础上引入层析成像技术,形成新的超声波层析成像探伤系统,可以有效克服普通超声波检测定位困难的缺点,能准确检测铸体中缺陷的大小、形状和位置。本文重点对超声波层析成像探伤系统的工作原理和阻尼LSQR算法(DLSQR算法)进行研究,经过数据采集、正演模拟、建立走时方程、反演求解等过程,实现了基于DLSQR算法的图像重建方法。实验表明,DLSQR算法具有良好的稳定性、较小的存储容量和计算量,适合病态问题求解。更多还原

【Abstract】 Inspection of casting flaw with ultrasonic technology is a useful method. However, it is difficult to inspect casting flaw with common ultrasonic method for bad permeance in the castings caused by coarse crystal particle, incompact and asymmetric method metallographic structure. Furthermore, cylindrical crystal particles of the castings will result in the diffraction of ultrasonic wave, which make it difficult to orientation for inspection. The shortcoming of common ultrasonic inspection could be overcome by the introduction of tomography technology to common ultrasonic inspecting system. The application of damping LSQR algorithm to ultrasonic tomography inspecting system is researched. A new image reconstruction algorithm base on DLSQR algorithm is accomplished , which is composed of data acquisition, forward imitation, travel-time equation, and inversion calculation. The result show DLSQR algorithm has a good stability, need less memory capacity and calculation amount. The DLSQR algorithm is fit for the solution of ill problem.更多还原