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Lecture

Simulating the mechanical properties of complex cellular microstructures using CT data

Friday (09.10.2020)
09:40 - 10:00 Room 1

Whether foam structures in materials science or granular materials in soil science – estimating the mechanical properties of complex arbitrary microstructures is of high interest to numerous research fields. Frequently used structures are, e.g., metallic foams in lightweight sandwich structures. To predict the mechanical properties of the entire composite, precise models of the constituents are needed. A common approach to solve this problem is to use microstructural data such as relative density, pore size and average beam thickness for analytical models like those introduced by Gibson and Ashby [Gibson 1999]. These approaches allow to estimate mechanical properties of a given structure on a mean field. But realistic cellular structures are often not perfectly regular and can thus lead to significant deviations between model and reality. For this reason, numerical simulation is needed.

 

Within this contribution, analysis tools for both approaches are presented: Either to derive statistical information about the microstructure or to determine the mechanical properties directly from volumetric images of the structure by applying mechanical models. The latter approach allows also to take irregularities like variations of the local material thickness and anisotropic behavior resulting from a geometrically oriented microstructure into account.

The surface of a foam structure is determined using a locally adaptive subvoxel-accurate surface determination. Subsequently, microstructural statistics are derived. The relative density is calculated as well as the cell diameter, beam thickness and principal orientation of the cells. This data is used for evaluating the analytical model by Gibson and Ashby. Modeling of the full structure is carried out by an FE simulation based on the immersed boundary method and enables to observe stress and strain distributions on the microscale directly on CT scans without the need of meshing.

 

Results show that the structure mechanical simulation leads to an anisotropic stiffness with different Young’s Modulus depending on the loading direction where the analytical approach by Gibson and Ashby can only predict isotropic material behavior because it does not take the local microstructure into account. Nevertheless, global microstructure information is derived from the CT-dataset which can be used for future analytical models.

Speaker:
Dr.-Ing. Pascal Pinter
Volume Graphics GmbH
Additional Authors:
  • Dr. Karl-Michael Nigge
    Volume Graphics GmbH
  • Dr. Stefan Dietrich
    Karlsruhe Institute of Technology (KIT)

Dateien

Category Short file description File description File Size
Poster Foam Analysis An image of the open foam analyzed within our contribution 2 MB Download