I have been working on a simulink model for attitude control of a solar sail spacecraft. I am now trying to study how the structural properties of the sail (its flexibility) impacts the dynamics and control. A solar sail is combosed of 4 thin support booms in X configuration, on which a thin mylar membrane (3e-6 m thickness) is mounted to harvest the kinetic energy of solar radiation. A generic solar sail model (40x40m in dimensions) is illustrated below.
I tried to use Simscape Multibody to model one quadrant of this system. I used a cylindrical flexible beam for the booms and a reduced order flexible solid for the membrane. I generated the geometry in Ansys, exported it in an STL file and imported it in MATALB. At first I tried following this tutorial to obtain the mass and stiffness matrices required, however the meshing obtained here did not look right, probably because my model was too thin for a "modal-solid" analysis. The mesh obtained is illustrated below. Nevertheless, I generated matrices out of it and fed them into the reduced order flexible solid to see what happens, and as expected I got an error.
At this point I thought the issue was the improper generation of K and M and so I performed the entire modal analysis and matrix generation in Ansys. I loaded them into MATLAB and ran the model again, but came across the same warning and error. I read this post which explains the warning I received, so I thought maybe the interface frames defined in the Origins field are in the wrong order. Since there are only 3 interface nodes (the 3 points of the triangle), I was able to try all the possible combinations and found the "correct" order of frames that does not throw the warning anymore. However, the error is still there, and I am unable to simulate my model. I also do not know how to debug this further, or how to find a workaround and make it work. Can the thickness of my "solid" be considered as an extreme value in its geometry? If I cannot use the Reduced Order Flexible Solid, is there anything else I can use to model my system? Please advise.
All the files required to reproduce the error can be found here. Thank you,
Irina
