Search
Close this search box.
Notifications
Clear all

Stress concentraion in elastomers

5 Posts
2 Users
0 Reactions
402 Views
Posts: 124
Topic starter
(@bw_composite)
Estimable Member
Joined: 17 years ago

Dear All,

I have an issue which I am sure you will be able to help me with.

I modelling an elastomeric component bonded to a sharp - edged metallic component.

I am using a Mooney Rivlin material constituive law.

Due to the sharp corner a very significant stress gradient is calculated.

Indeed, refining the mesh leads to an increase in strain as expected (the sharp corned induces a singularity).

The point is, how to deal with this? A metal would yield, making the singulariy nothing more than an abstract mathematical result which can be by passed using a plastic material law.

But what about a material which does not exhibit yielding?

Is there any guideline, any suggestion, comment you can give us?

Thank you very much

Best Regards

Muzialis

Topic Tags
4 Replies
Posts: 22
(@stusapien)
Eminent Member
Joined: 14 years ago

The Mooney-Rivlin material model would not hold anymore around the singularity (just like the elastic material model doesnt hold). You can use a different material model that hold in that strain range (has some permanent deformation component), or if that area of the model is not of concern you can accept that the results close to the singularity are not accurate.

Topic Tags
4 Replies
Posts: 124
Topic starter
(@bw_composite)
Estimable Member
Joined: 17 years ago

Hi FEGuru,

and thank you for your suggestions.

Just for clarity, are you implying I should switch to some viscoplastic model? (you mention permanent deformations).

And why should that be needed?

I was thimking myself about introducing some time dependancy (as I find physically very unrealistic that such a sharp gradient as the one I am picking would not get relaxed and smeared by rubbers viscosity), but viscoplasticity is a surprise for me.

I would be grateful if you could expand on this.My problem is that results at the singularity are needed (better, results at the location where the singiularity is placed by an incorrect material model)

Thanks

Best Regards

Muzialis

Reply
Posts: 22
(@stusapien)
Eminent Member
Joined: 14 years ago

Hi Muzialis,

Yes I was thinking of a viscoplastic model. I dont think adding viscoelastic effects to rubber would relax a strain singularity.

If you want an accurate solution in the vicinity of the singularity then you should also consider eliminating that mathematical singularity (instead of finding a material model that can handle it). You can do that by replacing sharp corners with non-zero fillet radii, or modeling delamination, etc. This approach however will most probably require a fine mesh in the vicinity of the singularity.

Reply
Posts: 124
Topic starter
(@bw_composite)
Estimable Member
Joined: 17 years ago

FE Guru,

many thanks

Best Regards

Muzialis

Reply
Share: