Learning Forum

[pavan kumar]

this is the type of contact I'm using in the model 

this is the type of input for this simulation

this is second step in the analysis 

 

 

convergence graph

this is the error im getting 

 

[Akshay Maniyar]

Hi Pavan,

Thank you for posting on the forum. I guess you have multiple posts and all the information is scattered. It will be very difficult to understand your issue and help to resolve the issue. I will close all other posts and add the data to this post. Please add some description about your model, so that it will be easy to understand. 

Thanks,

Akshay Maniyar

[peteroznewman]

Thanks Aksay for compiling the multiple posts.  Can you delete those other posts so this is the only post?

Hi Pavan,

It seems the model is not converging in load step 1.  Please show the Step Controls for step 1.  I expect you need to use more initial substeps in step 1.

-Peter

 

[Akshay Maniyar]

 

Hi Peter,

Thanks for checking. I have closed the other posts so no one else can edit or post on them. We can continue with only this compiled post.

Thanks,

Akshay Maniyar

 

[pavan kumar]

Hello,

I want to do structural analysis of oilpan with sealing 

oilpan is plastic material with non linear properties and sealing also rubber material with nonlinear properties

below is the image of components

for ribber 1mm element size is used and for plastic 4mm element size is used  

between the component frictional contact is used below is the image for concact definition

nonlinear adaptive mesh comand is used for rubber part 

below is the image is showing the command for analysis

two step analysis is to be performed 

step one is 0.1MPa internal pressure is applied with gravity 

below is the image for step 1 input

step two is tempature is increased from room temp to 120 degree celcius with gravity 

below is the image for step 2

while running the simulation this is first error i got below is the error image

i got this error after equil iter 2 completed 

after this error bisection 1 occures

model converged some itrations and bisection 2 occures 

after bisection 2 again model got converged i got second error after some time of while running model below is the error image

after this bisections are occures and converged some iterations 

at last i got this error below is the error image

below is the image of step 1 

below is the image of step 2 

please have a look and do the needful 

 

 

Thanks

Pavan kumar  

[peteroznewman]

Hi Pavan,

Delete or disable the Nonlinear Adaptive Region. You don't need that.

Please show the Engineering Data for the rubber material.  Did you use a Hyperelastic material model? You do need that.

Some additional settings are needed to help a hyperelastic material converge. 

Here are my five must do items to achieve convergence in hyperelastic material undergoing large deflection.

https://youtu.be/XCvOyyRJ8rA

 

[pavan kumar]

no i am not using hyperelastic material model 

material data image 

[pavan kumar]

abone is the material data 

please have a look 

 

 

thanks 

Pavan 

[peteroznewman]

You need to fit a Hyperelastic Material Model to the Hyperelastic Experimental Data you have available.

Right now, you only have a Linear Elastic Material model that does not represent the material behavior that you have experimental data for.

I suggest you take some of the free courses in Hyperelasticity.

/courses/index.php/courses/topics-in-hyperelasticity-using-ansys-mechanical/

/courses/index.php/courses/hyperelasticity/

Several other resources are listed here.

[pavan kumar]

Hello Peter,

i gone through the link what you said but still i am getting same type of error here is the error image

before i going throught the link what you said i used the hyperelastic  material here is the image

after gone throught the link what you said i changed the type of material i used 2nd order here is the image

but still i am getting same type of error 

please do the needful 

 

 

Thanks 

Pavan 

[peteroznewman]

Did you create a 1 element unit cube to plot the results from an Ogden 2nd Order model against the Experimental data?  Please show those two curves overlaid.

[pavan kumar]

This is the two curves overlaid  

[pavan kumar]

Hello,

i tried all the possible ways to converge the model but i am not able to do,please have a look and do the needful 

[peteroznewman]

Please rescale the Y axis. The red line goes down so far, while the blue dots look like they are at 0.

[pavan kumar]

Hello Peter,

i am using this above type of rubber material and i tried all the possible ways to converge the model but not able to do 

i am getting same error here is the error image

and after here i attached the convergence graph

and at last i got this type of error here is error image

and here i attached the load step 1 image

i am not understanding where i made mistake can you please have a look and do the needful 

 

 

 

thanks 

pavan

[peteroznewman]

It nearly converged but there were 2 bisections. You should increase the Initial and Minimum Number of steps by a factor of 4.

You should also insert a Command Object in the Model with the command

NEQIT,100

This command tells the solution control logic to keep trying for up to 100 iterations before doing a bisection instead of the default 26 iterations.

I previously gave you a link to a YouTube video with the important Keyopts to use for Hyperelastic Materials. Did you follow that advice?

[pavan kumar]

Hello Peter,

Yes i tried the Keyopt for Hyperelastic Materials but that also not worked, then i tried this above mentioned material properties 

ok i will try this NEQIT,100 

 

 

 

 

Thanks

Pavan