Comparison of Non-Destructive Evaluation Techniques for Damage Detection in Fibre-Reinforced Composites

纤维增强复合材料损伤检测无损评估技术的比较

• 批准号: 1969404
• 金额: --
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1969404
• 关键词: Comparison; Non; Destructive; Evaluation; Techniques

Context:Fibre-reinforced composite materials are used across a wide range of industries, including aerospace and military, as their high strength and low weight offer an advantage over other materials. Defects in composite materials (e.g. cracks, debonding, delaminations) are caused by stress, fatigue or impact events. These defects affect the structural integrity of the composite plates, potentially leading to the complete failure of the material. The detection and characterisation of such defects are thus of primary importance in predicting the composite's health and performance capabilities. Non-Destructive Evaluation (NDE) or Testing (NDT) aims to identify and characterise damage in a given structure, both internally and externally, while conserving its structural integrity. Such evaluation is conducted using different imaging techniques (e.g. radiography, ultrasonic testing, thermography, infrared testing, etc.). Ultrasonic testing enables the detection and localisation of defects, as well as the characterisation and sizing of these defects, and is widely used for NDE of composite structures for damage detection. Ultrasonic testing presents several advantages, including relatively high resolution and the ability to detect internal defects and inconsistencies in materials, both homogeneous and inhomogeneous. However, in the case of immersion ultrasonic imaging, it is harder to set up, requires the full immersion the sample, and results in longer acquisition times in order to achieve high accuracy. Conventional radiography was first applied on metals and alloys to study their structural integrity and look for manufacturing defects. Later on this technique was applied to the study of composite materials and impact damage, and is widely used today for the detection of defects. X-ray computed tomography (CT) results in the production of a 3D cross-section image of the sample, and enables the detection of defects such as delaminations, porosity, or cracks, which are not visible in 2D radiography. X-ray CT images are usually compared with more established NDE techniques, mainly ultrasonic C-scan imaging. However, as the nature of the components used for the manufacturing of composite plates tend to have similar absorption coefficients, or, alternatively, if defects are smaller in size and cannot lead to a clear variation in intensity, damage cannot always be resolved. This is usually the case for carbon fibre/epoxy resin composite plates, which are widely used in the aerospace industry.Aims of project and methodology:Edge-Illumination Phase Contrast X-ray imaging (EI XPCi) is an X-ray imaging technique which uses phase shift effects induced in an X-ray beam when going through an object to create contrast. This resolves the problem of the poor contrast resulting from similar absorption coefficients or smaller defects, and thus results in better contrast.This project aims to benchmark EI XPCi as a viable non-destructive evaluation technique for damage detection and characterisation in fibre-reinforced composite plates. This will be achieved by comparing EI XPCi with established ultrasonic testing techniques, foremostly immersion C-scan ultrasonic imaging, both qualitatively and quantitatively. The two imaging techniques' capability of detecting, localising and characterising different types of defects induced in composite plates during service, as well as common manufacturing defects will be studied and quantified. Several types of samples will be used, ranging from artificial defects induced in simple materials to simulate the damage in composite plates, to varying degrees of damage induced in composite plates with different structural complexity. By doing this, a new interpretation of damage detection using ultrasonic C-scan imaging can be obtained, complemented by EI XPCi, as well as a better understanding of the detection capabilities and limitations of each imaging technique.

背景：纤维增强复合材料由于其高强度和低重量比其他材料具有优势，被广泛应用于航空航天和军事等行业。复合材料中的缺陷（如裂纹、脱粘、分层）是由应力、疲劳或冲击事件引起的。这些缺陷会影响复合板的结构完整性，可能导致材料的完全失效。因此，这些缺陷的检测和表征对于预测复合材料的健康状况和性能能力至关重要。无损评估（NDE）或检测（NDT）旨在识别和表征给定结构的内部和外部损伤，同时保持其结构完整性。这种评价是使用不同的成像技术进行的（如放射照相、超声波检测、热成像、红外检测等）。超声检测能够检测和定位缺陷，以及这些缺陷的特征和尺寸，广泛用于复合材料结构的无损检测，用于损伤检测。超声检测有几个优点，包括相对较高的分辨率和检测材料内部缺陷和不一致的能力，无论是均匀的还是不均匀的。然而，在浸入式超声成像的情况下，它更难设置，需要充分浸泡样品，并导致较长的采集时间，以达到高精度。传统的射线照相技术首次应用于金属和合金，用于研究其结构完整性和寻找制造缺陷。后来，该技术被应用于复合材料和冲击损伤的研究，并在今天广泛用于缺陷的检测。x射线计算机断层扫描（CT）产生样品的3D横截面图像，并能够检测诸如分层、孔隙或裂纹等缺陷，这些缺陷在2D射线照相中是不可见的。x线CT图像通常与更成熟的濒死体验技术进行比较，主要是超声c扫描成像。然而，由于用于制造复合板的部件的性质往往具有相似的吸收系数，或者，如果缺陷尺寸较小并且不能导致强度的明显变化，则不能总是解决损坏。在航空航天工业中广泛使用的碳纤维/环氧树脂复合板通常就是这种情况。项目目标和方法：边缘照明相衬x射线成像（EI XPCi）是一种x射线成像技术，它利用x射线束在穿过物体时引起的相移效应来产生对比度。这解决了由于吸收系数相似或缺陷较小而导致对比度差的问题，从而获得了更好的对比度。该项目旨在将EI XPCi作为一种可行的无损评估技术，用于纤维增强复合材料板的损伤检测和表征。这将通过将EI XPCi与现有的超声检测技术（主要是浸入式c扫描超声成像）进行定性和定量比较来实现。两种成像技术的检测、定位和表征复合材料板在使用过程中引起的不同类型缺陷的能力，以及常见的制造缺陷将被研究和量化。将使用几种类型的样品，从简单材料中引起的人工缺陷模拟复合材料板的损伤，到不同结构复杂性的复合材料板的不同程度的损伤。通过这样做，可以获得使用超声c扫描成像进行损伤检测的新解释，并辅以EI XPCi，以及更好地了解每种成像技术的检测能力和局限性。