复合粘接结构脱粘缺陷全聚焦成像模拟及算法优化研究

Total focusing imaging simulation and algorithm optimization of debonding defect of composite bonding structure

针对材料声学参数差异较大的复合粘接结构脱粘缺陷检测困难的问题,研究了复合粘接结构的检测原理及难点,分析了脱粘尺寸对回波幅值的影响,提出了将全聚焦算法应用于复合粘接结构的成像检测方法。分别建立了复合粘接结构的常规PA成像检测和全聚焦算法成像检测的有限元检测模型,提出了基于指向性理论的分序列局部全聚焦加速算法,通过设定角度阈值筛选有效阵元序列来提高计算效率。研究结果表明:对于复合粘接结构脱粘缺陷的检测,全聚焦算法成像检测相对常规PA成像检测具有更高的检测精度;应用加速算法后,对于32阵元的相控阵探头,[-4 mm,4 mm]和[4 mm,8 mm]之间矩形目标区域的全聚焦成像检测,计算量降低了34.7%,且未降低成像质量。

Aiming at the problem that it is difficulty to detect the debonding defects of composite bonded structures with large differences in material acoustic parameters, the detection principle and difficulties of such structures were studied, the influence of the size of the debonding on the amplitude of echo was analyzed. The finite element detection model of conventional PA imaging detection and total focusing method imaging detection for composite bonding structure was established respectively, a partial-sequence local total focusing acceleration method based on directivity theory was proposed. The effective array element sequence was selected by setting the angle threshold to improve the imaging efficiency. The simulation results indicate that the total focusing imaging method has superiority over the conventional PA imaging detection for the detection of such composite bonding structures. After the algorithm is improved, for the 32-element phased array probe, the calcu-lation time of imaging detection of the rectangular area between [-4mm, 4mm] and [4mm, 8mm] by the acceleration method is reduced by 34.7%,without reducing the imaging quality.