Hi,
I'm using a knee model to simulate the 10NM valgus torque with prestrain. I defined one FEBio step from 0 to 3 sec, including the prestrain application step(from 0 to 1s), flexion step(from 1 to 2s), and loading step(from 2 to 3s). For boundary conditions, the femur and tibia are rigid bodies, the tibia is fixed, and the femur is free except the flexion rotation. The analysis type in control section is "static," and it's the "full-Newton" method. When the flexion angle is 0deg/30deg/60deg, the simulations work well, and results look good to me. However, when the flexion angle is 90 deg, the simulation keeps running for more than 2 days (the computer has 4 cores/8 threads, 16GB RAM) and only finished 90% of the flexion step after 2 days(still running, no error termination). It had more than 600 iterations in each time step. So I tried to change the analysis type from "static" to "dynamic." Then, the simulation results look weird after using the dynamic type: the fiber stretch of the end of the ligaments attached to the femur is super large, which is approximate 5 times than usual. Two ends of the ligaments use "rigid nodes" attached to the femur and tibia, respectively. I was wondering why this happened? How can I solve it? Should I use other analysis types instead of the dynamic? Or should I use the Tied contact to define the lig-bone-lig?
Any suggestions/help, I will appreciate it a lot!!
Best,
Yidan
I'm using a knee model to simulate the 10NM valgus torque with prestrain. I defined one FEBio step from 0 to 3 sec, including the prestrain application step(from 0 to 1s), flexion step(from 1 to 2s), and loading step(from 2 to 3s). For boundary conditions, the femur and tibia are rigid bodies, the tibia is fixed, and the femur is free except the flexion rotation. The analysis type in control section is "static," and it's the "full-Newton" method. When the flexion angle is 0deg/30deg/60deg, the simulations work well, and results look good to me. However, when the flexion angle is 90 deg, the simulation keeps running for more than 2 days (the computer has 4 cores/8 threads, 16GB RAM) and only finished 90% of the flexion step after 2 days(still running, no error termination). It had more than 600 iterations in each time step. So I tried to change the analysis type from "static" to "dynamic." Then, the simulation results look weird after using the dynamic type: the fiber stretch of the end of the ligaments attached to the femur is super large, which is approximate 5 times than usual. Two ends of the ligaments use "rigid nodes" attached to the femur and tibia, respectively. I was wondering why this happened? How can I solve it? Should I use other analysis types instead of the dynamic? Or should I use the Tied contact to define the lig-bone-lig?
Any suggestions/help, I will appreciate it a lot!!
Best,
Yidan
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