Hi everyone!
I'm currently modeling a wooden tower for a wind turbine as part of a project. I have loads from the rotor blades and so on that I'd like to apply to the top of the tower. I wanted to try using the load transfer surface feature, but as soon as I add it, I get the error message "Jacobian matrix not positive definite," which I wasn't getting before. Does anyone have any ideas? Otherwise, I'd have to convert the loads into line loads, which would be very time-consuming.
Best,
Ariane
How exactly did you define it? The surface always needs something it can transfer the load to cleanly. It also makes a difference how you distribute the load.
Could the FE mesh also be too coarse?
Does it really need to be a load transfer surface?
Regards,
Robert
Hello Robert,
when I refine the FE mesh, I get this message instead: The stiffness matrix is singular | The structure is unstable. I defined the load distribution area as a plane with the stiffness set to load distribution area, and then set the direction to FE-isotropic. But it doesn't have to be a load distribution area; it just would have been convenient.
Best,
Ariane
I just tried it out:
You can model the wing as a pure load-transfer surface and, if necessary, connect it to just a single node. However, you won't get any bending moments or anything like that.
But that doesn't explain why the stiffness matrix is now becoming singular.
That would need to be considered separately and is probably not dependent on the transfer surface.