Representation of Rigid body to point mass- In FEM 2

[elogesh]

Hai,

I have heavy rigid body of approximately 25Kg.The natural frequencies is definitely too high.

This rigid mass is supported by three springs.The other end of the spring is attached to a base plate.

I want to construct equivalent FE model.

I represented the rigid model as an equivelent point mass located at the centre of gravity of the rigid body.

Then I calculated mass moment of inretia of the rigid body and applied to the point mass.Apart from this whether I have to give any more properties.

Looking forward for your comments.

Regards,
elogesh

 

[OhMyGoodness]

Additionally, three joints at an offset to the center of mass should be defined where each spring is connected to the mass. Each joint then is connected to the central joint (mass) by weightless rigid elemenets. This will simulate the rotational action of the 25kg mass in a dynamic simulation.

 

[GregLocock]

You may also need to define all 6 stiffnesses (3 roattional and 3 translational) of each of your springs.

Also make sure that you have correctly aligned the principal axes for the inertia. If you don't know what this means check out a dynamics textbook.

Cheers

Greg Locock