For the establishment of bone model, besides considering the bone density, elastic modulus, poisson's ratio, yield stress and yield strain, should the damage caused by bone being cut by screws be considered? I don't know whether you have made a similar model, could you give me some experience? If you have specific data, that's the best.
Dear Luo,
There is no limit in FEM when it comes to details. Since there is a trade-off between the complexity and accuracy, the model should ideally be just detailed enough to capture the essential mechanics.
Bones have a directional structure. Therefore, assuming isotropic properties by simply using two elastic constants (elastic modulus and Poisson's ratio) may not be an accurate approach in the first place. Due to this anisotropy and layered structure, as the screw is tightened, longitudinal bone cracks can form in reality (similar to layer delamination in the composite structures). Those cracks can be prevented with proper drilling but I am not sure about your case. To simulate any cracks or thread cuts in the bone, proper damage models should certainly be used. Applying correct contact and friction models is also important to capture the fundamental effects regarding tightening.
I hope this helps!
Best wishes,
Gokhan
Gokhan Serhat
Dear Gokhan,
Thank you very much for having time to answer my questions! Currently my FEA model is bone drilling and screws need to be screwed into the tunnel. As for the longitudinal cutting of bone you mentioned, an appropriate damage model should be used. Could you please give me an idea of which model to use? Thank you very much!
Dear Luo,
I think it is better to apply Johnson-cook damage model. you may refer the following article.
Ayip Rosidi, Turnad Lenggo Ginta and Ahmad Majdi Bin Abdul Rani
"Optimization of bone drilling parameters using Taguchi method based on finite element analysis"
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