Eddy Current Sensor Arrays for Stress and Damage Mapping

虽然涡流方法在工业中广泛用于裂纹定位，但在英国很少有工作来开发其作为感测应力的廉价且便携的方式的潜力。由于电磁与物质相互作用的复杂性，涡流信号很难解释，目前无法明确区分它们对应力、微观结构和缺陷的敏感性。应对这一挑战需要多学科的方法;将仪器仪表，信号处理与材料科学结合在一起。这两个团队能够很好地开发必要的硬件，并开始建立涡流信号、残余应力、缺陷、表面几何形状和微观结构之间的近似关系。这种理解将有助于我们开发低成本，非破坏性的涡流方法的残余应力，主动缺陷检测，并提供指导的结构完整性工程师关于残余应力载荷下的缺陷评估。为此，我们将开发一套参考样本，量化的压力和损害水平，技术将得到验证和完善。我们将开发和评估应力/微观结构/缺陷成像从近表面到20毫米的深度，使用新型脉冲涡流传感器阵列沿着与先进的信号分析，特别是近表面高达200微米的深度应力分布。哈德斯菲尔德将设计和开发脉冲涡流传感器，而曼彻斯特拥有必要的材料知识和补充应力和损伤测量技术，以验证和评估不同传感器设计和信号分析程序的成功。虽然一个通用的明确的工具，同时测量应力和损伤的发展还有一段路要走，我们希望范围的灵敏度范围的便携式原型涡流能力，提供廉价的，非破坏性的信息，在特定情况下的应力和损伤水平。

While eddy current methods are widely used in industry for crack location, very little work has been undertaken in the UK to exploit their potential as a cheap and portable way of sensing stress. Due to the complex nature of electromagnetic interactions with matter, eddy current signals are difficult to interpret and it is currently not possible to unambiguously separate their sensitivities to stress, microstructure and defects. Meeting this challenge requires a multidisciplinary approach; bringing together instrumentation, signal processing with materials science. The 2 teams are well placed to develop the necessary hardware and to begin to establish approximate relationships between the eddy current signature, residual stress, defects, surface geometry and microstructure. This understanding will help us to develop low cost, non destructive eddy current methods for residual stress, active defect detection, and provide guidance for structural integrity engineers regarding the assessment of defects under residual stress loading. To this end we will develop a set of reference samples with quantified levels of stress and damage upon which the techniques will be validated and refined. We will develop and evaluate stress/microstructure/defect imaging from near the surface up to 20mm depth using novel pulsed eddy current sensor arrays along with advanced signal analysis, particularly up to 200 micrometer depth stress distribution of near surface. Huddersfield will design and develop the pulsed eddy current sensors while Manchester has the necessary materials knowledge and complementary stress and damage measurement techniques to validate and evaluate the success of different sensor designs and signal analysis procedures. While the development of a general unambiguous tool for simultaneous stress and damage measurement is some way off, we hope to scope the range of sensitivity of portable prototype eddy current capability to provide cheap, non destructive information about stress and damage levels in specific cases.