Modeling & Analysis
Cell Shape Analysis
Cylindrical
GeoSTAR modeling revealed this shape to be ideal with respect to stress distributions and stress concentration points. Although the stress distribution was ideal, the packing efficiency of cylindrical cells was only approximately 90%. Additionally, due to the contact points between cells being very small, the gluing surface is non-uniform and therefore more complication to attach to adjacent cells. FEA of mesh and stress distributions are shown below.
Hexagonal
This shape proved to be good with respect to stress distributions, but had six stress concentration points, which needed further investigation (see rounded hexagonal). This cell selection packs well and is easily manufactured. FEA of mesh and stress distributions are shown below.
Triangular
This shape found to be inadequate with respect to stress distributions and also contained three large stress concentration points. Although easy to manufacture and excellent packing characteristics, this cell shape is not practical due to high stress concentrations. FEA of mesh and stress distributions are shown below.
Rectangular
The shape is inadequate with respect to stress distributions and also contained four large stress concentration points. FEA of mesh and stress distributions are shown below.
Sinusoidal
The modeling was provided by NASA and was the style of structure SMARF had previously implemented. Very easy to manufacture, but just as cylindrical gluing is an issue. This design is shown below.
Rounded Hexagonal
Shared the same characteristics as the hexagonal cell design, but through the filleting of the sharp edge the stress concentrations were greatly reduced. This design is shown below in a full sheet rendering.
Reinforced Hexagonal
Similar to hexagonal and rounded hexagonal, but contains a sheet between half cells. Has excellent strength characteristics, but is not as volumetrically efficient as hexagonal. This shape is easy to manufacture and quickly adds additional strength to the hexagonal core. This design is shown below in a full sheet rendering.
Full Sheet Analysis
In addition to looking at how the individual cells performed we also used a Computer Aided Drafting (CAD) program, called SolidWorks, to create and analyze the performance of some of the more promising shapes in a full sheet. Drawings of these panels that have not already been shown are below.
