How to solve problems at a nonlinear quasi-static contact problem?

Altair Forum User
Altair Forum User
Altair Employee
edited May 2021 in Community Q&A

I tried to create a very simple example for an nonlinear quasi-static contact problem (see 'model_contact1.jpg' and 'Ausgangsmodell.hm').

There are two cuboids. The red one is fixed (all 6 DOF) by contraints. The upper blue cuboid is loaded with a very small Force (0.01N). I used solid elements and the mesh size is the same for both solids. The contact is established via contact surfaces. You can find the contact properties in the attachment ('contact_properties.jpg').

To analyse the contact pressure I activated the control card 'CONTF' ('see control_cards.jpg').

 

After I created a loadstep for an non-linear quasi-static analysis, I executet the analysis.

 

I got some results, but I don´t really know how to read/understand them (see the attachments). There are no contact forces or contact pressures but there are Element stresses and displacements in both parts.

 

I deleted the whole contact but I got the same results. That means the definition of my contact isn´t correct.

I already changed the contact setting and increased the number of increments, without any general influence to the results.

 

Furthermore I merged the 2 solids together as one cube. I meshed it with elements of the same size as before and run a linear static analysis. I got the same stress distribution with nearly the same values.

 

Can you help me to solve my problems, please? Or how can I approach to find my mistake?

<?xml version="1.0" encoding="UTF-8"?>model_Contact1.JPG

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

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

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

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

Unable to find an attachment - read this blog

Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2017

    Hi,

     

    The reason is both the components are nodally connected. Remove the nodal connection and introduce contact between them and try again 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2017

    That make sense... The cube was one solid and I splitted it into 2 cuboids and moved each of them in another component. I was not aware about this connection. :o/emoticons/default_ohmy.png' srcset='/emoticons/ohmy@2x.png 2x' title=':o' width='20' />

    Where in the model can I find the nodal connection or how can I delete this connection?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2017

    @ddwgw2017

     

    You can use Equivalence panel (Shift + F3) the check connectivity. 

     

    Use 3D page>> Detach>> ELements from elements

  • SAI VIJAY CHANDRA GAJULA
    SAI VIJAY CHANDRA GAJULA Altair Community Member
    edited May 2021

    @ddwgw2017

     

    You can use Equivalence panel (Shift + F3) the check connectivity. 

     

    Use 3D page>> Detach>> ELements from elements

    image