Simulation Error

Good Afternoon, I am trying to simulate a 3D model in ANSYS workbench. The model is a Tibia bone with a fracture and i am using 2 fixer e 12 screw. First, I got the mechanical properties of the bodies (screw, fixer and tibia).

Bone- Using a orthotropic material 

Screw and fixer- material from ansys library

Before that using the  mechanical  i select the contact , for two situation (frictional- bone/bone – 0,4)

(frictional – bone/steel- 0,6)

Mesh /bone

I applyed two forces and fixed support in the bottom,

Results

I have a similar study where the difference is the type of fracture and the deformation is around 2mm in the bone.

I would like know how can i do a ligament between tibia and fibula to restrict the movement and represent the  variation of Young’s Modulus (Tibia) 

Thank you.

Link Google Drive - https://drive.google.com/drive/folders/1w6mul-aWBdtpE3W_fy_8yFg0bJuuMuQD?usp=sharing

Answers

  • peteroznewmanpeteroznewman Member
    edited September 11

    Hello Evandro, welcome to the Forum!

    I accessed your Google Drive Link. For future posts, please put one archive in the link because you have too many folders. I downloaded TCC2.wbpz from the wbpz folder. This is the correct way to share projects. Don't upload the files you put in the Analysis folder.

    When I opened the archive, there are three analysis systems. Please limit the Project to one system. I opened system B, but there was only a bone in there. Delete that since there are no questions on that system. When I opened system C, it looks like what you wrote about above.

    In system C, Plac-Convc-SF, I see you have solved using ANSYS 18.1. I have access to ANSYS 2020 R1. Can you upgrade to that version?

    I see that you have a 6-core computer, but you only solved on 2 cores. On ANSYS 18.1, you must click on the Solve Process Settings, and under the Advanced Tab, you can type in 6 for the number of Processors and instead of taking 15 minutes to solve, it might take less time. Also, check the box that says Distributed.

    I see you have 55 automatically generated Bonded Contacts. I don't think it is accurate to use bonded contact between the head of the screw and the hole in the steel plate. It would be more accurate to use frictional contact. There are 12 screws. I think these 12 contacts between the head and the hole should be frictional.

    Contact 55 has bone bonded to the steel plate, is that accurate?

    Contact 54 has bone bonded to the steel plate, is that accurate?

    Contact 53 has bone bonded to the steel plate, is that accurate?

    Contact 21 has two screws bonded to each other, that is wrong.

    You might want to look into Bolt Pretension. That allows the screw heads to pull down toward the threads by having ANSYS automatically split the screw shank between the head and the threads and apply a pretension force in Step 1 of a 2-step analysis. Once all the screws are tightened, the loads are applied to the bone in Step 2.

  • EvandroEvandro Member
    edited September 11

    Thank you Mr Peter, first of all i have to apologize for the confusion that i made in the link and i change to Ansys 2020R1. In the archive you saw three analysis systems, actually the system A was the system in question. I will delete the system B, but the system C is a comparation that i will have to do with system A. However i will change everything you said about system C.

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