Now i am learning the example of membrane1.py. I have read these codes as followed,
for n in S.dem.nodes:
I am confused about the definition of inertia here. I am not good at the rotation inertia. When i referred to some knowledge, i found that rotation inertia a tensor and it can be transformed to a digonal tensor with three priciple axis. Here the definition of the node's inertia is a vector. So i am wondering if the three value is the three components of principle rotational inertia tensor?
The second is that in the engine of IntraForce, there is a functor named In2_Sphere_ElasMat(). I refered to the definition of this functor, but still not understand. Since the sphere has only one node, it does not generate internal force. Why it is applied a internal force using this functor? How does this force come? The relative code is following,