SBIR Phase I: Using Ultrasonic Shear Polarization Contrast to Locate and Size Defects

这个小型企业创新研究(SBIR)第一阶段项目将确定一种新的超声波无损方法用于检测和表征金属中的疲劳裂纹等缺陷的可行性。现有的超声波方法很难在管道、压力容器、储罐和其他钢板和梁结构上发现典型表面点蚀的情况下检测裂纹，特别是在进入内表面或外表面有限或昂贵的情况下。提出的剪切极化对比度(SPC)方法使用专有的换能器来产生和分析具有任意极化的横波，这些横波在一个表面上产生并从远表面反射回换能器，以区分高度极化敏感的特征，如裂纹(高度各向异性)和对极化不太敏感(相对各向同性)的良性点蚀和腐蚀。在第一阶段，将分析在存在不同程度点蚀的情况下缺陷方向和尺寸的各种组合的极化敏感性，以开发和验证裂纹检测阈值和尺寸精度的预测模型。在第二阶段原型开发之后，预期的第三阶段实验室和现场仪器将允许对部件和结构(包括内部和两个表面)进行彻底的非破坏性评估，同时只需要接触一个表面。该项目的更广泛影响/商业潜力将是提高关键民用、能源、石化和工业基础设施的资本投资的安全性和保护。该项目将采用电子控制声波偏振的新技术，以分析和表征它们与工程材料的物理、内部微结构的相互作用，为无损检测、材料分析和法医工程提供新的分析能力。例如，可以检查老化关键基础设施(如桥梁)中无法接触到的板和梁组件的内表面是否有裂缝，估计这些结构的剩余使用寿命，并实施加固、更换或拆除计划。到目前为止，这种能力还不存在。由此产生的商业设备将是一个可现场部署的系统，集成了专有的电磁声波换能器(EMAT)、专门的电子设备和软件。EMAT只需要最少的测试表面准备，即使是高温工艺也允许生产继续进行，减少或可能消除生产损失和清空容器的不便。该系统？S的竞争优势是独一无二的能力，能够测试和表征内部体积和两个表面上的裂缝，以及对位于凹坑和粗糙区域下方和内部的裂缝进行分类，只需接触一个表面。

This Small Business Innovation Research (SBIR) Phase I project will determine the feasibility of a novel ultrasonic non-destructive method for detecting and characterizing defects such as fatigue cracks in metals. Existing ultrasonic methods have difficulty detecting cracks in the presence of the typical surface pitting found on pipes, pressure vessels, storage tanks and other steel plate and beam structures, particularly if access to the inner or outer surface is limited or costly. The proposed method, Shear Polarization Contrast (SPC), uses a proprietary transducer to generate and analyze shear waves with arbitrary polarization, generated on one surface and reflected from the far surface back to the transducer, to distinguish highly polarization-sensitive features such as cracks (highly anisotropic) from benign pitting and corrosion that are less polarization-sensitive (relatively isotropic). In Phase I, polarization sensitivity will be analyzed for various combinations of defect orientation and size in the presence of varying degrees of pitting to develop and validate a predictive model for crack detection threshold and sizing accuracy. After Phase II prototype development, the anticipated Phase III laboratory and field instruments will allow thorough non-destructive evaluation of components and structures, including the interior and both surfaces, while only requiring access to one surface.The broader impact/commercial potential of this project will be improved safety and protection of capital investment in critical civil, energy, petrochemical and industrial infrastructure. This project will incorporate novel techniques to electronically steer the polarization of acoustic shear waves to analyze and characterize their interaction with the physical, internal micro-structure of engineering materials, providing new analytical capabilities for Non-Destructive Testing, materials analysis and forensic engineering. For example, inaccessible inner surfaces of plate and beam components in aging critical infrastructure such as bridges could be inspected for cracks, the remaining useful life of these structures estimated, and a plan for reinforcement, replacement or demolition could be implemented. Until now, this capability did not exist. Resultant commercial equipment will be a field-deployable system integrating a proprietary Electromagnetic Acoustic Transducer (EMAT), specialized electronics and software. EMATs require minimal test surface preparation, allowing production to continue for even high temperature processes, reducing or possibly eliminating loss of production and the inconvenience of emptying vessels. The system?s competitive advantage is the unique ability to test and characterize cracks in the interior volume and on both surfaces, as well as classify cracks located under and within pitted and rough areas, only requiring access to one surface.