FRF direct/modal - variable acceleration

Altair Forum User

Hi guys,

 

I am reading the book 'OptiStruct for Linear Dynamics' from Altair and trying to run direct and modal FRF analysis.

If I apply a variable load all is good but I don't understand how to apply a variable displacement, velocity or acceleration. 

 

I defined the unit load as SPCD but I don't really understand the sentence on page 51 (see picture attached). It seems that I have to put a constraint on the node and direction that I want to excite. Can you help me?

 

 

 

 

Altair Forum User

@dracu777 

 

That means if you applied the displacement at the node for dof1 in type SPCD.

 

You need use the SPC to constraint the same node for dof1.

Altair Forum User

Thank you for the answer LKZ, yes it works like you said.