Optimizing High-Value Components with CT Scanning and Computer Simulation

Posted on 4 March 2019 by Kerim Genc

Parts used in high-value applications often require optimization to save weight, costs and improve performance. Virtual inspection and modeling of components is particularly valuable in this process for understanding design problems at an early stage, potentially saving costs later on.

We recently worked with North Star Imaging (NSI) and ANSYS on a workflow solution streamlining the often complex process of going from 3D computed tomography (CT) data to mechanical simulation. Simpleware industrial CT software was used to bridge the gap between imaging data and simulation to analyze the differences between as-designed and as-manufactured parts from Additive Manufacturing (AM).

The key questions here were about whether there were any design differences present between the two parts and how the differences between them may affect real world performance.


Workflow Step 1: Capturing the Part Geometry

This workflow started with a project of Prof Albert To’s team at the University of Pittsburgh using ANSYS to re-design a bracket geometry with a weight-saving lattice. An EOS direct metal laser sintering (DMLS) printer created titanium and aluminum models, which were then scanned at NSI’s lab to obtain high-quality images of the models in less than 2 hours.

Additively manufactured titanium alloy bracket built for the University of Pittsburgh, and stack of CT image data generated by NSI

Workflow Step 2: CT Data Processing with Simpleware Software

The CT data was imported to Simpleware software for image processing and high-quality model generation, taking advantage of the software’s ability to reproduce the ‘as-manufactured’ geometry of the part. The volume meshes from Simpleware software are guaranteed to be ready for simulation, cutting down on the time-consuming workflow associated with having to re-mesh segmented image data in a Finite Element (FE) solver.

High-quality mesh generated in Simpleware software

Workflow Step 3: Comparing CAD and CT-based Models

Simpleware software was also used to compare the deviation between the scanned part and the original, idealized CAD design. Landmark and automatic registration tools, as well as a deviation analysis tool, enabled understanding of fine differences between the parts. This included defects likely introduced during additive manufacturing.

Deviation analysis in Simpleware software between original CAD geometry and image-based STL using color mapping

Workflow Step 4: Inspection and Simulation

The volume mesh from Simpleware software was directly imported to ANSYS Mechanical to carry out structural simulation. Results demonstrated that the AM component still performed well compared to the CAD model, despite the differences identified in the deviation analysis. The method was therefore successful at understanding how identifying defects at the design stage can help increase confidence in manufacturing decisions.

Comparison of stress in CAD model (A) and scan model (B) in ANSYS Mechanical

Case Study: Moog, Inc.

This workflow has been used by Moog, Inc. for part inspection. Moog optimized the design of an impulse pressure manifold for a specific material and hydraulic fluid configuration. The AM manifold was CT scanned by NSI and the 3D images processed in Simpleware software. Inspection revealed pores, cracks, and other defects in the AM part compared to the original CAD design. FE simulation in ANSYS Mechanical then detected stress deviations that allowed Moog to re-evaluate their original CAD design and quantify fitness-for-purpose.

Visualization and processing of CT data and deviation analysis between CAD and CT data in Simpleware software

Paul Badding, Mechanical Design Section Head at Moog, commented:

“The Simpleware model reconstruction provides an essential solution to assess the usability of an AM produced part. The effect of a defect or geometry deviation in a critical location can be quantified. Based on a comparison to the nominal CAD geometry the impact on structural integrity and fatigue life can be evaluated. This workflow provides a key solution to determine the disposition of an AM produced part with deviations from the nominal design.”

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Watch the whole workflow and ask questions. Join Synopsys, NSI and ANSYS on April 25, 2019:

Any Questions?

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