How to model spring?

You can make use of CBUSH element for your requirement.

Using this element you can specify stiffness in all the 3 translational & 3 rotational directions. Attaching the CBUSH card info FYR.
But when you define more than one stiffness value for BUSH element, you would need to create a local coordinate system for other directional stiffness.
In order to do this create a local system and then card edit the BUSH element > toggle on CONT > pick the local system under CID field, attaching the image FYR.
Hope this helps.Refer Optistruct user guide for detailed information.
 

<?xml version="1.0" encoding="UTF-8"?>

Unable to find an attachment - read this blog

Thank you very much for your reply Rahul

I Have the following spring and I have meshed it with tetra element. Then I defined PBUSh property and assigned that to the component. Is that correct?

Spring CBush is 1D element & spring property could be defined via PBush element.If you are interested in Spring failure then it would be good to model spring with tetrahedral element.If you want to use spring just to transfer load & moment then 1d approach would be good.Let me check if i have same file for 1d Cbush element.

<?xml version="1.0" encoding="UTF-8"?>

Spring CBush is 1D element & spring property could be defined via PBush element.If you are interested in Spring failure then it would be good to model spring with tetrahedral element.If you want to use spring just to transfer load & moment then 1d approach would be good.Let me check if i have same file for 1d Cbush element.

<?xml version="1.0" encoding="UTF-8"?>

How can we model the spring as 3d.. I want to see stresses on the spring.. What type of material should be used for spring?

 

 

How can we model the spring as 3d.. I want to see stresses on the spring.. What type of material should be used for spring?

In this case, CBUSH element does't work. You have to design a 3D CAD for the spring and then run a static analysis or non linear static analysis ....