## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### Meshing issue (disorted elements at some nodes)

• Suresh Varma
Subscriber

Hello there,

I am performing a cold bend thin glass in static structural analysis where I need to bend thin glass onto a rigid structure.

so here are the images for each setup.

I took body sizing of 25mm for both bodies.

The top body is the contact and the lower body is the target in the contact setting with a frictionless and adjust-to-touch treatment.

the analysis settings are shown below with a lower body having a rigid setup and the upper body having pressure on the lower surface.

the body has a symmetry on two sides as shown in below pictures

now the problem is when the analysis is performed the top body tries to move towards the lower body but the elements at the edge are getting distorted and are unable to find the target location to converge in the below images i shown the reference

So i need a solution where the mesh of the top body have a gradient mesh or a adaptive mesh so i used this Nonlinear adaptive region i got a converged solution but the stress are 3-4x times the actual value.

so can some one suggest how i can refine a gradient mesh ??

Thank you

Suresh Varma.

• Erik Kostson
Ansys Employee

Hi

4 things.

Use surface bodies and thus shell elements (happens automatic when meshing a surface) instead of 3D parts as you have now (as these are thin structures – no need for 3D parts).

Analyse the whole model – so no symmetry is then needed.

Add a small restrain in one vertex in X or use weak springs (https://featips.com/2020/05/14/weak-springs-yes-or-no/).

Finally one does not need adaptive meshing region if you do as per the above suggestions (so take that away).

All the best

Erik

• Suresh Varma
Subscriber

Hey erik,

thank you for the suggestion. two question one should i use shell elements for both the bodies and second one where shoul use a weak springs in my case a example would really helpful

thank you

Suresh Varma.

• Erik Kostson
Ansys Employee

Yes.

See the post I added for weak springs and how to activate them – you can also search online for more info on how to activate it.
https://featips.com/2020/05/14/weak-springs-yes-or-no/

All the best

Erik

• Suresh Varma
Subscriber

Hello Erik,

I have applied thin shell elements in SpaceClaim using mid surface and used the upper body bottom layer and lower body top layer as shown.

I am not able to converge the solution with the above settings with weak springs on. could you please have a look and suggest me the way forward

thank you

Suresh Varma.

• Erik Kostson
Ansys Employee

See what I said before and go through the post – : Analyse the whole model – so no symmetry is then needed.

you still have half the model and is not correctly restrained – mirror it on the yx plane to get the full model we said as shown below for instance that is what you should have.

You might then need to change the contact settings – see this video for that.

Also the force is too high like 2 MPa on glass – try something like some kPa perhaps or use many more substeps (see this for sub steps – https://www.ansystips.com/2018/06/non-linear-convergence.html – search the internet for more info)

With this you should be able to solve this. All the best. Erik

• Suresh Varma
Subscriber

hello erik,

I will work on it now and update here .

• Suresh Varma
Subscriber

hello erik,

My setup with frictionless contact and behaviour of asymmetric and rest values to program controlled is running when i have both the bodies with the same material which is structural steel and i am obtaining results but when i input glass the analysis goes on but doesn't give me results.

I have tried using increasing stiffness to higher values when i look into solver output it shows too much penetration at xx elements.

Any suggestion on this problem.

Thank you

Suresh varma.

• Erik Kostson
Ansys Employee

Hi

See these videos for convergence and contacts.