Learning Forum

[Noura Mansour]

the force-displacement curve is linear .. what should i do?

[Akshay Maniyar]

Hi Noura,

Do you have Large deflection ON? 

Thanks,

Akshay Maniyar

[Noura Mansour]

yes

[Noura Mansour]

yes the large deformation was on 

[Akshay Maniyar]

Hi Noura,

Can you try increasing the deformation of the spring and see if it shows nonlinear behavior? Also, I don't see any contact added in your simulation. Any specific reason you have not added contact?

Thanks,

Akshay Maniyar

[Noura Mansour]

Can you tell me how i add contact ?

[Akshay Maniyar]

Hi Noura,

First, right-click on the model in a tree and insert connections. Then you can insert a contact. It will be a self-contact. You can select all the surfaces of the spring for contact and target side.  

Thanks,

Akshay Maniyar

[Erik Kostson]

Hi

We also have a course in contacts that can be of help.

/courses/index.php/courses/contact-mechanics/

All the best

Erik

[Noura Mansour]

 ? ( linearity)

[Erik Kostson]

 

Hi

Please describe more what you want to say – what do you mean with “? linearity”?

If you want help then explain in detail what you mean and want help with otherwise we can not provice any feedback.
Thank you

Erik

 

[Noura Mansour]

Sorry i mean what do you think about this problem (linearity)?

[Erik Kostson]

Hi

Not sure - the important thing is to understand where the nonlinear stiffness comes from in reality in such a spring?

To add, when the coils make contact with each other as the compression increases, the stiffness should change I would imagine.

Hope this helps.
Erik

[Akshay Maniyar]

Hi Noura,

Yes, I agree with Erik. The only non-linearity which is missing is the frictional contact of coils. Also, large deflection is ON so the solver is considering the geometric non-linearity. Please try adding contact and see if it helps.

Thanks,

Akshay Maniyar

[Noura Mansour]

Frictional contact of all geomtry ? 

[Akshay Maniyar]

Yes, you can use frictional or frictionless contact.