# Simscape Flexible Multibody simulation using Finite element import method

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Goutham Sajja on 8 Apr 2021
Answered: Steve Miller on 4 Jun 2021
Dear All,
I have modeled a component as a flexible body in Simscape multibody using Finite element import method. Finite element analysis was performed on MSC Nastran.
I am happy to achieve the flexibilty of the component. I am able to visualise its flexibilty using external force applied at one of the boundary nodes/interface frames.
My question is how can I achieve the flexibile movement of the component by means of motion of another neighbouring component?
The below figure explains the model in 2D. The pivot arm (green component) rotates about an axis that is going into the screen in the counter clockwise direction. As it rotates by an angle, it contacts the flexible component and bends it so that it undergoes elastic deformation.
I have placed frames on each of the components at the appropriate locations and a revolute joint for the arm. I planned to use rigid transform block, but that will not help as the transformation between the frames will reduce as the arm moves towards the flexible component.
It would be really nice if you could advice me on how I could proceed with the simulation and achieve the result.
Thanks and Regards,
Goutham Sajja
Yifeng Tang on 2 May 2021
Simscape Multibody support contact modeling using the spatial contact force block. Haven't used it together with flexible body before so I am not sure if you can do both together. Also the contact body needs to be convex hull, so depending on your geometry, you may need to do a bit extra work to isolate the part that may touch the other object.
Another idea to consider: looks like the contact force in this case is set by the flexibility of that dark part and you already have some simulation applying force to it and observing the bending. I think it's possible to translate that bending to the position of the pivot arm (in rotation angle probably), which will give you a lookup table from pivot arm position to reaction force from the flexible part. This way you may be able to apply that force to both the pivot arm and the flexible part and simulate the EFFECT of contact force and bending.

Steve Miller on 4 Jun 2021
Hi Goutham,
If you know which surfaces will touch one another, I recommend attaching rigid, massless geometries to each part at an interface frame defined on the two bodies and putting a Spatial Contact Force block between those two geometries. For example, a sphere on one part and a brick on the other. This approximation will work when the points that touch are only minimally affected by the deflection of the parts.
--Steve

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