Martinez-Marchese A, Esmaeilizadeh R, Toyserkani E
Multi-Scale Additive Manufacturing (MSAM) Lab, Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave W, Waterloo, Ontario, N2L 3G1, Canada.
Multi-Scale Additive Manufacturing (MSAM) Lab, Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave W, Waterloo, Ontario, N2L 3G1, Canada.
Ultrasonics. 2024 May;140:107296. doi: 10.1016/j.ultras.2024.107296. Epub 2024 Mar 22.
Laser ultrasonics (LU) is a non-contact and non-destructive method with a high data acquisition rate, making it a promising candidate for in-situ monitoring of defects in different additive manufacturing (AM) processes, including laser powder bed fusion (LPBF) and directed energy deposition, as well as final part inspection. In order to see the effect of various artificial defect types on an LU sub-surface reconstruction, AlSi10Mg samples with side through-holes, as well as Ti6Al4V samples with bottom blind holes and trapped powder were printed using LPBF, and then ultrasound B-scans of the samples were obtained using an LU system. The resulting scan data was processed using a custom frequency domain phase shift migration (PSM) algorithm, to reconstruct the defects and their locations. Novel ways of pre-processing the B-scan, used as an input to PSM, and taking advantage of its frequency representation, are demonstrated. Newton's method was used to find a stationary phase approximation, used to account in the frequency domain for the fixed offset emitter-receiver arrangement within the PSM calculation. The Newton's method calculation time was reduced by 33%, by using an approximation of the phase function to find an initial guess. The smallest defects that were detected using this method were in the size range between 200 to 300μm for the bottom hole defects, using an 8 ns laser pulse duration. The effect of the laser on the surface of a part being built, and the challenges and further work needed to integrate LU in a LPBF machine for in-situ inspection are discussed.
激光超声（LU）是一种非接触、无损且数据采集速率高的方法，使其成为原位监测不同增材制造（AM）工艺（包括激光粉末床熔融（LPBF）和定向能量沉积）中的缺陷以及最终零件检测的一个有前景的候选方法。为了研究各种人工缺陷类型对LU亚表面重建的影响，使用LPBF打印了带有侧面通孔的AlSi10Mg样品以及带有底部盲孔和 trapped powder的Ti6Al4V样品，然后使用LU系统对样品进行超声B扫描。使用定制的频域相移偏移（PSM）算法处理所得的扫描数据，以重建缺陷及其位置。展示了对用作PSM输入的B扫描进行预处理并利用其频率表示的新方法。使用牛顿法找到平稳相位近似值，用于在频域中考虑PSM计算内固定偏移发射 - 接收装置。通过使用相位函数的近似值来找到初始猜测，牛顿法的计算时间减少了33%。使用此方法检测到的最小缺陷对于底部孔缺陷，在200至300μm的尺寸范围内，使用8 ns激光脉冲持续时间。讨论了激光对正在构建的零件表面的影响，以及将LU集成到LPBF机器中进行原位检测所需面对的挑战和进一步的工作。
