Week 8 Worm Gear Challenge

• Objective:-

To simulate the worm-gear assembly, by applying suitable constraints and joint loads for obtaining Equivalent stress, Equivalent elastic strain etc.

• Model Details:-

Given model is big for the academic version, and also due to 1:50 reduction ratio of gears, we are only going to rotate the gear by around 100 deg. So we dont really need the complete gear for our setup. For this purpose, the gear was cut in half and a finer mesh using element size of 2 mm was given as below,

After meshing, the model has 6332 elements and 12610 nodes, which are below the academic version. Also having finer mesh size and higher number of time steps increases the solver time tremendously (sometimes finer mesh even fails to converge if angular rotation per time step is high).

• Loads and Constraints:-

So considering the above constraints to optimise both accuracy and solver time, a suitable mesh is applied along with 45 seconds time steps in the Analysis Settings, with 100 deg rotations per single time steps (that is 100deg/sec or 1.74533 rad/sec angular velocity of worm). Direction of this angular velocity and amount of rotation is carefully kept such that, only the existing half of the gear comes in contact with the worm.

• Results:-

Animation of the Total deformation of the worm-gear assembly:- https://youtu.be/WBiUw3Oynxs

Max. Equivalent stress = 2828.7 MPa

Max. Equivalent elastic strain = 0.01866 mm/mm

Also I have attached the angular velocity plots for worm and gear:-

Ignoring the initial unsteady results for the angular velocity, for both the results the angular velocity stables down to a particular value.

From the plots, angular velocity of worm = -1.7453 rad/sec,

and, angular velocity of gear = -0.035 rad/sec

• Conclusion:-

In summary, we can concluse that the simulation of the Worm-Gear pair has been successful. We have obtianed the Equivalent stress, Equivalent elastic strain and Total deformation plots of the simulation.

Also, we have obtained the values of the angular velocities of the worm (-1.7453 rad/sec) and gear (-0.035 rad/sec). And these match with the input values, the angular velocity ratio (1.7453/0.035 = 49.86 ~50) also confirm with the gear ratio of the assembly, so the gear meshing is correct can be confirmed.