Hi all,
I am a master student at the University of Twente and I am developing a distal radius fracture model in AnyBody. I have a question regarding my modelling approach and validation results.
To model the fracture, I split the radius into RadiusProximal (~90%) and RadiusDistal (~10%). To preserve AMMR anatomy, I kept the original segment Seg.Radius as a massless, inertia-free ghost segment:
• no muscles or joints attached
• rigidly welded to RadiusProximal
• used only as a kinematic reference for anatomical nodes (sRel/ARel)
All muscles, joints, and wrapping surfaces were reassigned to the new fracture segments. The two fracture parts are connected using a rigid kinematic coupling to preserve overall consistency with the intact model.
With this setup:
• muscle forces and joint reaction forces match the intact AMMR model
• ghost segment contributes Fout = 0
I compared the force output of the fracture driver between the two segments with a reference model using AnyForceMomentMeasure2 applied to the intact AMMR model with:
• cutsystem = On (CutSystemNormal = y: long bone axis pointing towards elbow)
• cut at the same fracture plane
• including original radius, all muscles connected to radius, and joint reaction forces on proximal side of the fracture plane
My final goal is to extend this model to force-dependent kinematics (FDK) to simulate motion of fracture fragments under static loading conditions.
Questions
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Is this ghost-segment + rigid coupling approach a valid way to preserve intact-model mechanics in AnyBody?
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Or should all dependencies on the original Seg.Radius be fully removed (including mirrored nodes and anatomical references)?
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Is AnyForceMomentMeasure2 with a cut system a valid way to verify equivalence between the intact and fracture models? Should both approaches theoretically yield identical force results?