Minutes of meeting – Sigraflex 1st June 2022

Participants:

NTNU: Antonio Alvaro, Emanuele Solfiti

CERN: Nicola Solieri, Pablo Munoz

NTNU presentation:

• one particle was separated by scotch taping and cut by FIB/SEM. The section showed both aligned and misaligned regions,
• FIB/SEM cross-section shown in the previous meeting was increased in size,
• There is no criterion to detect the particles boundary in the section image,
• The micro-structure will be considered as foam in the next steps,
• Two types of regions were visually identified: 1. Packed regions, denser and with aligned micro-sheets, 2. Loose regions, with randomly oriented micro-sheets,
• One modelling approach is the rule of mixture assuming different moduli and variable volume fraction for each type of regions,
• Another modelling approach is the direct re-construction of the micro-structure in the FE, but this needs to be simpler than the one showed in the ppt.
• In the last case, the material properties for FE model can be chosen as that of graphite single crystal or pyrolytic graphite. These properties are anisotropic (in-plane and out-of-plane) hence the geometry should be meshed on this purpose,
• The pore size, shape, and orientation together with volume ratio of aligned-to-misaligned regions are of primary importance for any type of modeling. This involves robust image processing (i.e., it takes time),
• N₂ flows in Sigraflex by Knudsen diffusion: gas flow in Sigraflex is under investigation.

Next meeting:

• Masterclass of Nicola about beam-matter interaction, 14^th June 17.30