First of all, I'm so sorry that I can’t share the model due to some constraints. But I can provide the coordinates and mass of each body in my model.
I think my problem is similar to the example below. At first, I built a model based on the dimensions and load from the jib boom crane example. MotionView gave almost the same results as the hand calculation using force balance throughout the process of lifting the membrane (I ran it with quasi-static), with only about 0.04% error.
Next, I built a my model using the coordinates and masses shown in the figure below. I used a Motion on the translational joint to simulate the lifting process with the following step function:
STEP(TIME,0,0,3,0) + STEP(TIME,3,0,12,-565) + STEP(TIME,12,0,22,565)
The simulation results show that, during the first 3 seconds, F_lift = 7.52×10³ N, which corresponds to about a 4% error between the theoretical and simulation results. The error then increases as the cylinder extends, until it reaches its maximum stroke (That’s about a 12.75% error, with 15,333.68 N (theory) and 13,380 N (simulation).
I’m wondering:
Why does the error increase as the cylinder extends, even though I’m using quasi-static analysis?
Could this be due to how the force/moment arm is computed internally in MotionSolve?
Or is there something I might be missing in my modeling setup?
Any suggestions would be really appreciated. Thanks!
