I have two gears modelled in MES using 2D elements. The smaller gear has a torque applied to it and the larger gear has a prescribed displacement. An initial velocity was applied to both gears. The reaction moment at the second gear is shown in the attached graph. The applied torque is 11435 in-lb and the expected reaction moment is about 37000 in-lb. The analysis rotates the gears through two teeth only.
Can anyone explain to me why the reaction moment is so high and so variable? The average value from the graph would be about right.
Thanks for the help.
Solved! Go to Solution.
Sorry I missed the model image. The connection between the two gears is made using surface contact. The large gear is driven by a prescribed displacement and the smaller gear has a moment applied to it. I applied an initial velocity to each gear at the appropriate rpm. Do I need a prescribed displacement on the small gear also? I don't think so because then the moment would not apply any load to the large gear. The beam on the smaller gear was added so that a moment could be applied to it.
I am not sure if I have the model set up right. I am wanting to determine the stress due to the dynamic loading and impact through a two teeth rotation rather than running it through a full revolution.
The torque applied to the gear train had no ramp on the load curve - all the torque was applied instantaneously. That was the reason for the large cyclic reaction.
At least the centers of the two gears should be fixed to avoid translation. Secondly, you can add more beams to rotate the small gear. Only two lines of beam might result in either large bending deformation of the beams or bad solution (if the constribution of beams on the global matrix system is too large).