非线性超声检测系统检测分辨力和灵敏度的确定方法

A method to determine the testing resolution and sensitivity of nonlinear ultrasonic testing systems

为了提高非线性超声技术的检测能力并优化试验设置,提出了一种非线性超声检测系统的检测分辨力及检测灵敏度的确定方法,并根据该方法搭建了试验系统。对同一材料不同厚度的试件进行相同条件下的非线性超声二次谐波法检测,之后将测得的相对非线性系数与试件厚度进行线性拟合。拟合直线的斜率截距之比可表征该检测系统的检测分辨力,拟合直线的斜率可表征检测灵敏度。结果表明,该方法可去除非线性超声检测中的系统非线性,使测量数据具有更高对比度,利于基于非线性超声技术的材料损伤程度判定、微观组织演化评定等工作的高效展开。

In order to improve the detection capability of nonlinear ultrasonic technology and optimize the experimental settings,a method to determine the testing resolution and sensitivity of nonlinear ultrasonic testing systems was proposed,and the experimental system was set up according to this method.The nonlinear ultrasonic measurements based on the method of second harmonic generation were carried out for several specimens which had same material but different thicknesses.Then,the relative nonlinear parameters of the specimens were linear fitted with the specimen thicknesses.It was found that the ratios of the slopes and intercepts of the fitting curves could be used to quantify the testing resolution of the testing system,and the slopes can be used to characterize the testing sensitivity.The results showed that the instrument nonlinearity introduced by nonlinear ultrasonic testing systems can be removed by using this method,which enhanced the contrast ratio of the measurement data.Therefore,the evaluation of material damage degree and microstructure evolution based on nonlinear ultrasonic technology can be carried out more efficiently.