Non-Destructive Testing of Industrial Materials Using Inverse Techniques

使用逆向技术对工业材料进行无损检测

• 批准号: RGPIN-2014-06015
• 负责人: Schajer, Gary
• 金额: $ 2.4万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567534
• 关键词: Non; Destructive; Testing; Industrial; Materials

Industrial quality control testing works straightforwardly when the quantity of interest can be measured independently. However, practical measurements often combine several quantities that then need to be separated. This can be done by using an “inverse” calculation. The “forward” calculation would be to sum all the target quantities, if they were known, to determine the combined measurement that would be made. The inverse calculation separates the various quantities and is much more difficult and mathematically sensitive. The two applications of inverse calculations explored here differ physically but they share substantial mathematical commonality and complementary features. Log Sorting in Sawmills using X-Ray Computed Tomography: To compete effectively in the international market, Canadian sawmills must produce the highest value products from the available raw material. This can be done by examining each log entering a sawmill, and strategically processing it for the highest value product. This sorting must be done well, else substantial wastage will occur either as high-quality material getting used for low-value products, or low-quality material failing to make high-value products. X-ray Computed Tomography (CT) provides a promising way to identify the quality-controlling interior features of logs. CT measurements are well established in the medical field, but are not well suited for industrial use in sawmills because of their complexity, cost and mechanical sensitivity. Work has been ongoing here to develop a simplified, economical and rugged CT scanner design. The key to the approach taken is the observation that the measured logs and their internal features have very specific geometries, for example, logs are cylindrical, heartwood and sapwood are arranged axi-symmetrically, and knots are arranged radially. Thus, a specialized CT inversion scheme can be developed to take advantage of this advance information and thereby reduce the demand on both required measurement accuracy and computational size. Very promising results have been obtained in laboratory tests, and the present proposal is directed towards further functional developments such as spiral scanning and to practical demonstrations. Practical Residual Stress Measurement in Industrial Components: Residual stresses are locked-in stresses that exist in materials without the presence of any external loads. These stresses are important because they significantly affect the dimensional stability and material strength of industrial components. If not detected and controlled in manufacturing processes, substantial material wastage premature product failures can occur. The “hidden” character of residual stresses makes them difficult to measure reliably and requires the use of “inverse” evaluations. Residual stress measurements are typically done by measuring the deformations that occur when some stressed material is removed, for example, by drilling a small hole. Optical techniques such as Digital Image Correlation (DIC) and Electronic Speckle Pattern Interferometry (ESPI) are attractive measurement techniques because they are non-contact, rapid and economical. They provide full-field optical data that allow sophisticated interpretation significantly beyond the more typical minimal data measurement approaches. Traditionally, DIC and ESPI have used monochromatic light. The proposed research is aimed at exploiting the larger data content available in multi-colour optical measurements. This allows 3-D deformation identifications from nominally 2-D data and enables more sophisticated evaluations of residual stresses, including some out-of-plane stress components that are not available with present measurement techniques.

当感兴趣的数量可以独立测量时，工业质量控制测试直接工作。然而，实际测量通常会将几个需要分离的量组合在一起。这可以通过使用“逆”计算来完成。“远期”计算将是把所有已知的目标数量加起来，以确定将进行的综合测量。逆计算将不同的量分开，难度更大，在数学上也更敏感。这里探讨的逆计算的两种应用在物理上有所不同，但它们具有大量的数学共性和互补特征。使用x射线计算机断层扫描在锯木厂进行原木分类：为了在国际市场上有效竞争，加拿大锯木厂必须从可用的原材料中生产出最高价值的产品。这可以通过检查进入锯木厂的每根原木，并有策略地处理它以获得最高价值的产品来实现。这种分类必须做好，否则大量的浪费将会发生，要么是高质量的材料被用于低价值的产品，要么是低质量的材料不能制造高价值的产品。x射线计算机断层扫描（CT）提供了一种很有前途的方法来识别测井资料的质量控制内部特征。CT测量在医疗领域已经很好地建立了，但由于其复杂性，成本和机械灵敏度，不太适合在锯木厂的工业应用。研究人员正在开发一种简化、经济、坚固的CT扫描仪设计。采用这种方法的关键是观察到被测量的原木及其内部特征具有非常特定的几何形状，例如，原木是圆柱形的，心材和边材是轴对称的，结是径向排列的。因此，可以开发一种专门的CT反演方案来利用这些先进的信息，从而减少对所需测量精度和计算尺寸的需求。在实验室测试中获得了非常有希望的结果，目前的建议是针对进一步的功能开发，如螺旋扫描和实际演示。工业部件中实际残余应力测量：残余应力是存在于材料中的闭锁应力，没有任何外部负载的存在。这些应力很重要，因为它们显著影响工业部件的尺寸稳定性和材料强度。如果在制造过程中没有检测和控制，大量的材料浪费，过早的产品故障可能会发生。残余应力的“隐蔽性”使得它们难以可靠地测量，需要使用“逆”评估。残余应力测量通常是通过测量一些受应力材料被移除时发生的变形来完成的，例如，通过钻一个小孔。数字图像相关（DIC）和电子散斑干涉（ESPI）等光学测量技术因其非接触、快速和经济等优点而受到广泛关注。它们提供了全方位的光学数据，使复杂的解释大大超出了更典型的最小数据测量方法。传统上，DIC和ESPI使用单色光。提出的研究旨在利用多色光学测量中可用的更大数据内容。这允许从名义上的二维数据中识别三维变形，并允许对残余应力进行更复杂的评估，包括目前测量技术无法获得的一些面外应力分量。