Contact force from simulation is higher by about 2000 N

Chandresh Zinzuwadia_21606

Hello, 

I am working on a simulation of Rivet installation. Everything is modeled with solid elements. The rivet is with Elform 14 and rest of the parts are with Elform 24. I am comparing results to experimental data. I am comparing to load versus deflection curve. I am getting the same shape curve but the load is 2000 N more from simulation. 

I tried contact type 7, Type 19 and Type 25. In all cases I get the same result. (CONTACT PARAMS ARE BASED ON RECOMMENDED VALUES)

The simulation was also run with LS-DYNA (in the same published paper) and they obtained the same result as experiment. 

Please see attached result of my simulation.

Any suggestions and help is appreciated.

Thanks! 

Adriano A. Koga

There are a lot of aspecta that might impact correlation with experimental data.

It will be hard to give an hint here, without further details, and images. Maybe also sharing tha paper that you've mentioned, or at least more details.

Chandresh Zinzuwadia_21606

Sure, here are further details.

Paper --> https://www.researchgate.net/profile/Rene-Alderliesten/publication/240027145_Riveting_Process_Induced_Residual_Stresses_Around_Solid_Rivets_in_Mechanical_Joints/links/5de8d71a4585159aa462ddbe/Riveting-Process-Induced-Residual-Stresses-Around-Solid-Rivets-in-Mechanical-Joints.pdf

Model --> See attached image. 

Plates and rivet are aluminum. The punch is modeled with steel material properties but is rigid. I am extracting contact force between the punch and rivet and comparing it to the punch force vs deflection from paper.

Thanks! 

PaulAltair

Chandresh Zinzuwadia_21606 said:

Sure, here are further details.

Paper --> https://www.researchgate.net/profile/Rene-Alderliesten/publication/240027145_Riveting_Process_Induced_Residual_Stresses_Around_Solid_Rivets_in_Mechanical_Joints/links/5de8d71a4585159aa462ddbe/Riveting-Process-Induced-Residual-Stresses-Around-Solid-Rivets-in-Mechanical-Joints.pdf

Model --> See attached image. 

Plates and rivet are aluminum. The punch is modeled with steel material properties but is rigid. I am extracting contact force between the punch and rivet and comparing it to the punch force vs deflection from paper.

Thanks! 

With dissimilar material stiffnesses in contact (aluminium, steel), The setting used for 'Istf' in the contact may be relevant here, you may try Istf=4 (lower stiffness of main/secondary is used to derive contact stiffness) if you are not using it already

If you can share the model I can take a look.

If you have a DYNA input for the model, you may also try running that directly in Radioss (use 2022.2 if you can)

Paul

Chandresh Zinzuwadia_21606

Paul Sharp_21301 said:

With dissimilar material stiffnesses in contact (aluminium, steel), The setting used for 'Istf' in the contact may be relevant here, you may try Istf=4 (lower stiffness of main/secondary is used to derive contact stiffness) if you are not using it already

If you can share the model I can take a look.

If you have a DYNA input for the model, you may also try running that directly in Radioss (use 2022.2 if you can)

Paul

Hi Paul, 

Thanks for the response. I have tried Istf 4 and it produced the same results. I don't have the LS-DYNA input model. 

I didn't know the best way to share the model so I created a case and attached the model files to it. Case # CS0418407

Looking forward to hearing from you.

Chandresh