Felix Kim

Mechanical Engineer

National Institute of Standards and Technology (NIST)

Abstract

Radiation (X-ray and neutron)-based imaging allows observation of morphological characteristics at micrometer length scale inside of a part. These imaging techniques enable scientific investigation of various materials such as geologic materials, powders, metallic materials, and composite materials. Laboratory X-ray computed tomography (CT) systems, for example, allow micrometer-level porosity characterization and failure analysis. At synchrotron imaging facilities, CT scans can be acquired within seconds and four-dimensional (4D) experiments can be carried out. Neutron imaging, on the other hand, provides complementary contrast to X-ray imaging, which can enhance material identification and quantification. In addition to scientific investigation, X-ray CT is becoming a viable industrial inspection tool for advanced manufacturing components. Higher energy (> 225 kV) XCT systems enable industrial non-destructive evaluation (NDE) of larger objects, and linear accelerator-based system (e.g., 9 MeV) also enables inspection of an automobile and a cargo container. In this presentation, basic principles of X-ray and neutron CT will be discussed, and typical measurement workflows and reconstruction processes will be presented. A few previous example applications of lab X-ray, neutron, and synchrotron CT will be presented from the field of granular materials, carbon fiber composite materials, and metal additive manufacturing (AM). Industrial X-ray CT inspection is especially promising for AM parts, and it is important to assess X-ray CT flaw detection reliability for part qualification. Probability of detection (POD) is typically used to assess NDE detection reliability, and our approaches to estimate X-ray CT POD from experiments and by merging with X-ray CT simulations will be discussed. Furthermore, current activities of developing improved X-ray CT flaw phantoms for POD estimation and data sets to evaluate accuracy of automated detection algorithms will be presented.

Biography

Felix Kim is a mechanical engineer at Engineering Laboratory of National Institute of Standards and Technology (NIST). He has been with NIST for 7 years, and he is currently applying X-ray CT techniques to help qualify additive manufacturing parts and processes. He has demonstrated the concept of X-ray CT POD of AM flaws, and he is developing X-ray CT phantoms to assess POD. He is also developing X-ray CT data sets to help evaluated automated detection algorithms. He holds B.S. and Ph.D. in civil engineering from University of Tennessee, Knoxville. He also holds M.S. in structural engineering from Georgia Institute of Technology.