# How to see effect of Point mass on Structure

Manoj55
Member

in Structures

If Structure is holding one Body with point mass of 'x'

How we can analyze this condition of Point mass is resting on few surfaces and we want to see stresses in structure.

## Comments

Under Geometry, Insert Point Mass, select a face on structure to transfer the load to.

In Static Structural, is the load Gravity? You could also evaluate the effect on the natural frequency in Modal.

You can duplicate the Static Structural system and in the copy, select a different face in the model to support the mass.

Note that a "spider" of Constraint Equations will spread the support over the entire face.

If you want just a portion of the face to support the mass, you need to divide the face in the CAD system.

Yes, I got it.

I found in internet we need to give two times acceleration in upward direction.. Is this right ?

1. Insert point mass on faces

2. Give fixed support

3. Apply acceleration 2g in upward direction

4. Solve

What you think on this sequence is it give result that what we want ?

Please paste into your reply the URL of the webpage where you found the 2G acceleration. I hadn't heard of that one.

If you want the effect on stress of adding a point mass to a structure fixed to ground, I would provide Standard Earth Gravity -Y direction to the model and solve. Duplicate that system and add the point mass to the structure on the copy, then Solve the copy. Now you have the stress before and after adding the point mass and can put the images side-by-side.

If the structure is on wheels or on rocket accelerating into space, or is mobile and could be dropped, then different acceleration loads apply than Standard Earth Gravity.