Ultrasonic Inspection for Complex Geometry

复杂几何形状的超声波检测

• 批准号: 2445152
• 金额: --
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2445152
• 关键词: Ultrasonic; Inspection; Complex; Geometry

Phased array ultrasonic testing is a widely used method of sub-surface inspection in NDE, and is able to locate and size defects to a greater degree of confidence and precision than standard ultrasonic testing due to its ability to perform multiple inspections from one location [1]. Data is acquired using Full Matrix Capture (FMC), and an image of the ultrasonic response can be produced using the Total Focussing Method (TFM) [2], providing an indication of flaws in the inspection region. In addition to the direct ultrasonic wave from array to defect, there will be a wave which reflects from a back wall in the inspection material, arriving at the defect later in time. This appears distinct from the direct signal in the FMC data. These reflected waves can be imaged using TFM [3], enabling inspection of the component from multiple angles to increase the rate at which defects are detected, and improve characterisation. Typically, applications of the TFM inspect regions of the component which are either directly below or adjacent to the array [4-7] - in other words, within the array's line-of-sight (LoS). It is common practice in NDE to prioritise inspection of areas most likely to develop defects. In a complex part such as an aircraft engine, it is likely that these areas will not be LoS. This leads to the requirement for disassembly prior to inspection, increasing cost of the inspection process. This research project aims to develop and validate a method which is able to inspect non-line-of-sight (NLoS) areas by reflecting an ultrasonic wave from the geometry of a component. The initial goal is to evaluate how well a phased array can assess these areas using the simple test case shown in figure 1. Subsequent goals are to target the inspection of increasingly complex cases, including abstract part geometry, anisotropic materials or samples whose geometric or material properties are not precisely known. Ultimately, a method capable of inspecting real, industrially relevant samples such that its deployment in an industrial setting will be justified. Work so far has focussed on developing a ray-based model to produce FMC data including reflections of the ultrasonic wave from any individual wall in the component geometry rather than just the back wall, as well as the expected sensitivity of the probe to side-drilled holes (SDH) in these NLoS TFM images. The sensitivity of a 32-element 5MHz probe to a SDH with diameter 0.4mm is shown in figure 2, where multi-mode TFMs are focussed from side wall reflections. These results indicate that there are views which have non-negligible sensitivity to an ideal defect in NLoS areas. While this is a useful tool for determining the expected signal from a defect in ideal conditions, it does not account for random and coherent noise expected from a real system. These results were therefore validated against finite-element simulations by comparing the expected signal response from defects in a range of positions within the geometry. Next steps in the project are investigate how dependent this sensitivity is to the probe location with respect to the geometry, to ensure that defects can be reliably detected, as well as performing validation against experimental results. Following this, the complexity of the models will be increased, as the assumptions of a polygonal isotropic solid are relaxed to include an arbitrary, anisotropic geometry whose dimensions may not be exactly known. Ultimately, it will be a requirement to validate the tools developed against real, industrially relevant samples.

相控阵超声检测是无损检测中广泛使用的一种亚表面检测方法，由于其能够从一个位置执行多个检测，因此能够以比标准超声波检测更高的置信度和精度来定位缺陷并确定缺陷大小[1]。使用全矩阵捕获(FMC)获取数据，并使用全聚焦方法(TFM)[2]产生超声响应的图像，提供检查区域中缺陷的指示。除了从阵列到缺陷的直接超声波外，还会有一种从检测材料的后壁反射的波，稍后到达缺陷。这看起来与FMC数据中的直接信号不同。可以使用TFM[3]对这些反射波进行成像，从而能够从多个角度检查部件，以提高缺陷的检测速度，并改善特性。通常，TFM的应用检查组件的直接下方或邻近阵列[4-7]的区域--换句话说，在阵列的视线(LOS)内。无损检测中的常见做法是优先检查最有可能出现缺陷的区域。在飞机发动机等复杂部件中，这些区域很可能不会丢失。这导致在检查之前要求拆卸，增加了检查过程的成本。该研究项目旨在开发和验证一种能够通过从部件几何形状反射超声波来检测非视距(NLOS)区域的方法。最初的目标是使用图1所示的简单测试用例来评估相控阵对这些区域的评估情况。随后的目标是针对日益复杂的情况进行检查，包括抽象的零件几何形状、各向异性材料或几何或材料属性未知的样本。最终，一种能够检查真实的、与工业相关的样品的方法，使其在工业环境中的部署将是合理的。到目前为止，工作的重点是开发一种基于射线的模型来产生FMC数据，包括超声波从组件几何形状中的任何单个壁而不仅仅是后壁反射的数据，以及探头对这些NLOS TFM图像中侧面钻孔(SDH)的预期灵敏度。32个单元的5 MHz探头对直径为0.4 mm的SDH的灵敏度如图2所示，其中多模TFM通过侧壁反射聚焦。这些结果表明，有些观点对非视距区域的理想缺陷具有不可忽略的敏感性。虽然这是在理想条件下从缺陷中确定预期信号的有用工具，但它不考虑实际系统预期的随机和相干噪声。因此，通过比较几何形状内一定位置缺陷的预期信号响应，这些结果通过有限元模拟得到了验证。该项目的下一步是调查这种敏感性对相对于几何形状的探头位置的依赖程度，以确保可以可靠地检测到缺陷，以及根据实验结果进行验证。在此之后，模型的复杂性将增加，因为多边形各向同性实体的假设被放宽，以包括其尺寸可能不完全已知的任意各向异性几何图形。最终，将需要针对真实的、与行业相关的样本来验证开发的工具。