Parthi, Have a look at this video http://www.3dmojo.com/2012/09/06/todcast-10-faking-geometry-deformations-tips-and-tricks/. I would apply a similar approach to this gasket. Create a series of deformation configurations of the gasket. From there use File|Open with the "Merge into new document" option selected for the top level assembly. Then use File|Open with "Merge into current document" selected for each of the separate gasket configurations. This will allow you to show|hide these models separately and equally update the assembly at a later date.
thanks for your video., in solidworks animation i did like that only..
i thought in 3D via is there anyother method to do easily..
And i have another one doubt Mr.Earl
In that video i seen 2 hands are Putting gasket in falnge.
how to create like that (how did u insert that hand) ???
For the hands, you might search for them on 3DVIA.com or on 3D Content Central or GrabCAD or the like. I would use the "Merge into current" option to bring the hands into the scene.