中文摘要：

受曲界面影响,超声波在曲面构件中传播时声束聚焦、散射特性增强,声能量出现汇聚与分散现象,造成缺陷定量困难.针对试块对比法等传统手段检测成本高及适应性较弱的问题,研究了基于超声测量模型的曲面构件缺陷定量方法.以脉冲激励方式下的超声波多元高斯声束模型和缺陷散射模型为基础,建立了曲面构件水浸超声测量模型,并对凸、凹两种曲面试块内的缺陷回波进行了模型有效性验证.以平底孔缺陷为例,基于该模型建立了曲面构件缺陷定量表征曲线,通过仿真研究了声束在曲面构件中的聚焦和散射特性,分析了相对缺陷波高随曲率半径、缺陷深度和缺陷尺寸的变化规律,并通过预测相对缺陷波高进行缺陷定量.以钢制曲面试块水浸超声检测为例进行了缺陷定量应用实验,模型预测与实验结果比较,相对缺陷波高预测误差小于1.2 dB,缺陷大小定量误差不大于8.7％,表明这种方法可行,为曲面构件水浸超声检测时的缺陷定量提供了一种简便有效的途径.

英文摘要：

With the influence of curved surface,ultrasonic beam scattering and focusing will be enhanced during the propagation in curved components.So the acoustic energy is strengthened or weakened,resulting in difficulties of defect quantification.To overcome the disadvantage of high cost and low adaptability of traditional methods such as reference block,a defect quantification method based on ultrasonic measurement model for curved components with immersion ultrasonic testing is studied.Based on multi-Gaussian ultrasonic beam models and defect scattering models under the way of pulse excitation,an immersion ultrasonic measurement model for curved components is proposed.The model is verified by measuring the defect echo waves of a convex specimen and a concave specimen.Taking a flat bottom hole as an example,the defect quantification characterizing curves are established based on the ultrasonic measurement model.The characteristics of ultrasonic beam scattering and focusing in curved components are studied by simulation.Moreover,the relations between the relative defect wave amplitude and the curvature,as well as the defect depth and the defect quantification are analyzed.Therefore,the defects can be quantified by predicting the relative defect wave amplitude.As an example of the application,a steel curved component is studied during its immersion ultrasonic inspection,and the comparisons of the model predictions with experimental results show that the prediction deviation of the relative defect wave amplitudes is less than 1.2 dB,and the quantization error of the defect quantification is not more than 8.7 ％.So the proposed method is feasible,which can be conveniently and effectively applied to curved components with immersion ultrasonic testing.