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Nonlinear Ultrasonic Measurement of the Remaining Life of Engineering Structures

工程结构剩余寿命的非线性超声测量

基本信息

批准号：
2424000
负责人：
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：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-2424000
关键词：
Nonlinear Ultrasonic Measurement Remaining Life

项目摘要

One of the grand challenges in non-destructive testing (NDT) is the measurement of the remaining life of a structure. Up to now, most NDT methods aims to detect and characterise relatively large defects which occur at the end of the life of a structure using linear ultrasound. Recently, potential use of non-linear ultrasound has been demonstrated in the literature to be sensitive to early formation of defects such as microcracks. This occurs because as material ages or become defective, they become increasingly non-linear. Different techniques have been developed, namely second harmonic generation, wave mixing, and diffuse field method. However, signals from non-linearity are relatively small compared to linear ultrasound, and hence can be easily masked by noise or other non-linearities. As a result, these techniques have not been fully exploited yet, due to them not having reached the required sensitivity to image the build-up of material non-linearity. The project aims to develop the required modelling tool to fully understand the measurement scenario to exploit non-linear techniques, understand its limitations and potentially extract (or image) material non-linearity. The technique I have been exploiting is the wave mixing technique. In this method, two primary waves (blue and green) are made to interact, and under some specific conditions, they will produce an additional wavefield, termed as the resonant wave (red). This wave can be related to the material non-linearity at the point of interaction, hence having the potential of spatial localisation. Until now, a 2D numerical model has been successfully developed, and validated against theory for non-linear wave mixing. It has been used for the 1D mapping of non-linearity within material, showing that a correction factor has to be included to the equation from the literature relating the amplitude of the resonant wave to material non-linearity. The next step is to explore the potential of arrays for wave mixing.

无损检测(NDT)中最大的挑战之一是结构剩余寿命的测量。到目前为止，大多数无损检测方法的目的是利用线超声来检测和表征结构在寿命结束时出现的相对较大的缺陷。最近，非线性超声的潜在用途在文献中已被证明对诸如微裂纹等缺陷的早期形成敏感。这是因为随着材料老化或变得有缺陷，它们变得越来越非线性。已经发展了不同的技术，即二次谐波产生法、混波法和扩散场法。然而，与线性超声相比，来自非线性的信号相对较小，因此很容易被噪声或其他非线性所掩盖。因此，这些技术还没有被充分利用，因为它们还没有达到成像材料非线性建立所需的灵敏度。该项目旨在开发所需的建模工具，以充分了解测量情景，以利用非线性技术，了解其局限性，并潜在地提取(或成像)材料非线性。我一直在开发的技术是混波技术。在这种方法中，两个主波(蓝色和绿色)相互作用，在某些特定条件下，它们将产生一个额外的波场，称为共振波(红色)。这种波可以与相互作用点处的材料非线性有关，因此具有空间局部化的潜力。到目前为止，已经成功地建立了二维数值模型，并与非线性混频的理论进行了验证。它已被用于材料内非线性的一维映射，表明必须在文献中将共振波的幅度与材料非线性联系起来的方程中包括一个修正因子。下一步是探索阵列用于混波的潜力。