Simulation on computed tomography
Quality assessment of 3D printed lattice structures

Why would you want to assess the effects of defects in 3D printed structures?

Additive manufacturing (AM) allows the production of highly complex structures. However, due to the complexity of the underlying physics, geometrical deviations of the as-manufactured geometry from the as-designed one can occur. These deviations are often referred to as process-induced defects. The defects, in turn, also affect the mechanical behavior of the printed parts. Of course, the question is what is the effect of process-induced defects? Can the printed structure still withstand the designed load? How different is the performance of an as-manufactured structure compared to an as-designed one? To find this out, a common approach is to perform a finite element analysis to study different loading scenarios. This allows for quality control of printed parts.

What is the problem?

The first challenge is to acquire the geometrical model of the as-manufactured structure. A preferred choice is to record the shapes of the printed parts via computed tomography (CT). The second challenge is that the CT data is not directly suited for finite element modeling. Prior to the analysis, a 3D model reconstruction should be performed, which requires a lot of manual effort. When the geometry is highly complex with multiple small-scale features, this process becomes computationally very costly and can be even simply impossible.

DirectFEM provides a unique solution

DirectFEM’s solution offers a faster and easier way: our software can compute directly on the CT scans. This approach neither requires a 3D model reconstruction, nor mesh generation. In comparison to the high manual and computational costs of simulating lattice structures conventionally, our solution delivers fully automatic simulation results in less than an hour!

Comparison of as-designed and as-manufactured structures made easy

As the CT scans are directly embedded into the simulation pipeline, it becomes very easy to estimate the effects of defects on the mechanical behavior of as-manufactured structures. It allows to compare the designed and achieved performance of 3D printed structures.

More application areas are possible

The use of CT-based simulation to perform the quality assessment of 3D parts in the early design stage is not the only application area. DirectFEM’s technology enables the simulation of CT geometries in a very wide range of applications:

  • Biomechanical application
  • AM product quality assessment
  • Simulation-driven metrological assessment
Microarchitectured lattice simulation. Project with Siemens AG

The project is performed in a collaboration with Computational Mechanics and Advanced Material group at the University of Pavia, Italy and Department of Civil Engineering at the Aalto University, Finland

The comparison of CT scan models and the figures displaying the stress distribution and as-designed and as-manufactured lattices are reprinted from
Korshunova, N., Alaimo, G., Hosseini, S.B., Carraturo, M., Reali, A., Niiranen, J., Auricchio, F., Rank, E., & Kollmannsberger, S. (2021). Bending behavior of octet-truss lattice structures: modelling options, numerical characterization and experimental validation. Materials & Design, 2021. Use permitted under the Creative Commons Attribution License CC BY 4.0.

Das Projekt DirectFEM wird im Rahmen des EXIST-Programms durch das Bundesministerium für Wirtschaft und Energie und den Europäischen Sozialfonds gefördert.

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