Week 8 Worm Gear Challenge
Objective
To perform a transient structural analysis on a worm gear assembly and to find out the Equivalent stress, Equivalent elastic strain and the total deformation in the model.
Procedure
Preprocessing
The transient analysis of the worm gear is simulated. The model is imported and it is opened in spaceclaim. In spaceclaim, the gear is cut into half by drawing a rectangle over the large gear and pulling it up in the negative direction. Then it is checked for any irregularities. If not, the spaceclaim is closed and the geometry is updated in the model scheme.
The material is usually structural steel material and the geometry is renamed for convenience. Now the contacts are established. A frictionless contact is employed by choosing all the contacting surfaces in the large gear. The contact body is the worm and the target body is the faces of the teeth in the larger gear.
Now the joints are established between the worm and the gear. A revolute ground-worm joint is created by selecting the interior faces of the worm. Another revolute ground-gear is selected by selecting the interior face of the gear.
The meshing of the geometry is carried out. Here the element size is selected as 1.2 mm with a medium smoothing. This element size created a 30827 elements and 17771 nodes which is very less than the 32K elements/nodes limit in student version.
The analysis settings for carrying out this simulation is given below
Step Controls
Number Of Steps 25.
Current Step Number 25.
Step End Time 25. S
Auto Time Stepping On
Define By Time
Carry Over Time Step Off
Initial Time Step 0.2 s
Minimum Time Step 0.2 s
Maximum Time Step 0.5 s
Time Integration On
Solver Controls
Solver Type Program Controlled
Weak Springs Program Controlled
Large Deflection On
Damping Controls
Stiffness Coefficient Define By Direct Input
Stiffness Coefficient 0.
Mass Coefficient 0.
Numerical Damping Program Controlled
Numerical Damping Value 0.1
The rotation of the worm is given in 25 steps with 50 degree increments. The large deflection is turned ON so that the convergence can be achieved easily.
Solution
The simulation is carried out and the results are obtained.
Total Deformation: 14.763 mm Max
Equivalent stress: 1293 MPa Max
Equivalent strain: 0.006275
Conclusion
The worm gear simulation is successfully done and the results are tabulated below
|
Solution |
Output results |
|
Total deformation, mm |
14.763 |
|
Equivalent stress, MPa |
1293 |
|
Equivalent strain, mm/mm |
0.006275 |
It can be seen that the stress is high only at the surfaces of contact.