Casula O, Poidevin C, Cattiaux G, Dumas Ph
Commissariat à l'Energie Atomique. CEA Saclay, Bat 611, 91191 Gif sur Yvette, France.
Ultrasonics. 2006 Dec 22;44 Suppl 1:e647-51. doi: 10.1016/j.ultras.2006.05.122. Epub 2006 Jun 6.
The inspection is mainly performed in contact with ultrasonic wedge transducers; However, the shape cannot fit the changing geometries of components (butt weld, nozzle, elbow). The variable thickness of the coupling layer, between the wedge and the local surface, leads to beam distortions and losses of sensitivity. Previous studies have shown that these two phenomena contribute to reduce the inspection performances leading to shadow area, split beam.... Flexible phased arrays have been developed to fit the complex profile and improve such controls. The radiating surface is composed with independent piezoelectric elements mechanically assembled and a profilometer, embedded in the transducer, measures the local distortion. The computed shape is used by an algorithm to compute in real-time the adapted delay laws compensating the distortions of 2D or 3D profiles. Those delay laws are transferred to the real-time UT acquisition system, which applies them to the piezoelectric elements. This self-adaptive process preserves, during the scanning, the features of the focused beam (orientation and focal depth) in the specimen. To validate the concept of the Smart Flexible Phased Array Transducer, prototypes have been integrated to detect flaws machined in mock-ups with realistic irregular 2D and 3D shapes. Inspections have been carried out on samples showing the enhancement performances of the "Smart Flexible Phased Array" and validating the mechanical and acoustical behaviors of these probes.
检测主要通过与超声楔换能器接触来进行；然而，其形状无法适应部件（对接焊缝、接管、弯头）不断变化的几何形状。楔块与局部表面之间耦合层厚度的变化会导致波束畸变和灵敏度损失。先前的研究表明，这两种现象会降低检测性能，导致阴影区域、波束分裂……已经开发出柔性相控阵来适应复杂轮廓并改进此类检测。辐射面由机械组装的独立压电元件组成，并且换能器中嵌入的轮廓仪可测量局部畸变。算法利用计算出的形状实时计算出适配的延迟定律，以补偿二维或三维轮廓的畸变。这些延迟定律被传输到实时超声检测采集系统，该系统将其应用于压电元件。这种自适应过程在扫描过程中保留了样品中聚焦波束的特征（方向和焦深）。为了验证智能柔性相控阵换能器的概念，已将原型集成到对具有逼真不规则二维和三维形状的模拟件中加工的缺陷进行检测。已对样品进行检测，结果显示了“智能柔性相控阵”的增强性能，并验证了这些探头的机械和声学性能。
