SBIR Phase I: Using Variable Polarization Ultrasonic Shear Waves to Isolate and Quantify the Competing Effects of Microstructure and Stress on the Acoustic Properties of Steel

这个小型企业创新研究(SBIR)第一阶段项目将开发原型设备，以实现对铁磁材料中的声波剪切波的控制，并引入创新技术，使科学家和工程师能够利用可变剪切波极化作为测量和表征材料特性的新工具。这将极大地增强金属的无损检测。为了确定所建议技术的可行性，将使用一种特殊配置的电磁声波换能器(EMAT)来演示剪切波偏振的电子转向。然后，将分析几个不同微观结构的钢样相对于极化角度的声弹关系，目的是建立一种能够准确确定纵向应力的测量方法，而不依赖于样品的微观结构。商业应用既有快速、原位、无损的微观结构评估，也有钢构件的纵向应力测量。具体的例子包括：在钢铁制造和热机械加工的关键阶段进行监测和过程控制；通过及早发现和先发制人地纠正可能导致列车脱轨的极端钢轨应力来改善铁路安全；以及核实桥梁、体育场、工厂和多层钢结构建筑等较旧或受损的钢结构中的正确荷载分配。

This Small Business Innovation Research (SBIR) Phase I project will develop prototype equipment to achieve control of acoustic shearwaves in ferromagnetic materials, and introduce innovative technology to enable scientists and engineers to utilize variable shear wave polarization as a new tool for measuring and characterizing material properties. This will greatly enhance non-destructive testing of metals.To establish the feasibility of the proposed technique, a specially configured Electromagnetic Acoustic Transducer (EMAT) will be used to demonstrate electronic steering of shear wave polarization. Acoustoelastic relationships, relative to polarization angle, will then be analyzed for several steel samples of varying microstructure with the objective of establishing a measurement method capable of accurately determining longitudinal stress, independent of sample microstructure. Commercial applications exist for both rapid, in-situ, nondestructive assessment of microstructure, and for longitudinal stress measurement in steel members. Specific examples include monitoring and process control at critical stages of steel manufacture and thermomechanical processing; improving railroad safety through early detection and preemptive correction of extreme rail stress that can contribute to train derailments; and verification of correct load distribution in older or compromised steel structures such as bridges, stadiums, factories and multi-story steelframe buildings.