Greetings,
I am a postgraduate student and i would like to study the biomechanics of the knee. I am new to FEBio. I have set a multistep analysis where I want to rotate the femur in the 1st step and then, in the 2nd step to apply an anterior force on tibia. For this, i create cylindrical joints using dummy rigid bodies. In the 1st step i am using prescribed constraints for the tibia rigid body with zero value loadcurves in order to keep it stable. The same goes for the femur and i only keep free the Rx, Ry rotation bc. I apply a loadcurve that descibes the angles that the cylindrical joint consisting of the femur material and dummy material will rotate. Anything until now works as planned.
In the 2nd step , i am using prescribed constraints for the femur rigid body with zero value loadcurves in order to keep it stable and free the tibial x,y translations. Now here come the Negative Jacobians. Whatever i have tried i cant run the simulation. Either i have used a cylindrical joint or i have applied a prescribed force to the y bc of tibia i am always getting a Jacobian error.
I would appreciate any help or ideas.
Thanks in advance,
Kostas
I am a postgraduate student and i would like to study the biomechanics of the knee. I am new to FEBio. I have set a multistep analysis where I want to rotate the femur in the 1st step and then, in the 2nd step to apply an anterior force on tibia. For this, i create cylindrical joints using dummy rigid bodies. In the 1st step i am using prescribed constraints for the tibia rigid body with zero value loadcurves in order to keep it stable. The same goes for the femur and i only keep free the Rx, Ry rotation bc. I apply a loadcurve that descibes the angles that the cylindrical joint consisting of the femur material and dummy material will rotate. Anything until now works as planned.
In the 2nd step , i am using prescribed constraints for the femur rigid body with zero value loadcurves in order to keep it stable and free the tibial x,y translations. Now here come the Negative Jacobians. Whatever i have tried i cant run the simulation. Either i have used a cylindrical joint or i have applied a prescribed force to the y bc of tibia i am always getting a Jacobian error.
I would appreciate any help or ideas.
Thanks in advance,
Kostas
Comment