This presentation was held at the 2020 NAFEMS UK Conference "Inspiring Innovation through Engineering Simulation". The conference covered topics ranging from traditional FEA and CFD, to new and emerging areas including artificial intelligence, machine learning and EDA.

Resource Abstract

Metal Additive Manufacturing (AM) can be used to produce topologically complex designs, which are difficult or impossible to engineer using traditional manufacturing techniques. Non-destructive inspection and testing of such structures can be challenging due to internal or inaccessible features. Inability to find and correct for defects in built parts can lead to increased performance testing, potentially more failures and therefore more scrappage of parts; wasting precious time and resources.
Here a “hot box” heat exchanger is presented as an industrial example of how X-ray Computer Tomography (CT) can be used as part of a non-destructive testing process to inspect complex structures.

From the CT scan, an image-based model was be built to identify and analyse defects and deviations from the original design. At this stage the part could be deemed fit for use if any deviations fall within allowed tolerances or inspected further using image-based simulation. Inspection at this stage also means changes can be made to the manufacturing process for future manufacturing runs (such as a design change for trapped powder extraction).

Image-based simulation allows virtual performance testing of the “real” part (as opposed to a CAD idealisation). This includes any defects, pores, warping etc. which could have occurred during the manufacturing process.

In the “hot box” heat exchanger example, defects in the structure were identified. This was mainly in the form of trapped powder in narrow channels, and some deviation to the lattice structure. An image-based simulation of the “as-built” structure was undertaken to show the impact of these deviations from the “as-designed” structure. This simulation focuses on the thermal performance of key areas of the “hot box”.
The ability to perform dimensional, integrity and surface inspection in a single workflow proved to be highly beneficial for the current production process of the “hot box”. It has the potential to reduce inspection time and remove the need for additional inspection equipment, therefore reducing costs, cycle times and potential increasing workable floorspace.