Transient Structural Analysis of a Double Universal Joint

Transient Structural Analysis of a Double Universal Joint

Overview:

Structural analysis was performed on a double universal joint with a spring of different materials considering the effects of inertia and damping to evaluate the Equivalent stress and total deformation of the spring.

Geometry:

Two rotating shafts are connected by a couple of spiders with a double cardan in between them such that the rotation motion can be transferred from one shaft to the other. The geometry is shown in the following figure,

General Setup:

Since the spring attached to the shaft is the point of interest, there is no need for evaluating the stress and deformation in the spider or the cardan. Hence the contact regions are not specified. This could reduce the computation time.

Joints:

A revolute joint attached to the ground was defined for the shaft which is in contact with the gear and also for the shaft that is in contact with the spring. A fixed joint was defined for the face of the spring shown in the figure below. Also, revolute joints of body-body connection are defined for all the contacts between spider and cardan.

Analysis Settings:

The analysis is carried out in 5 steps with the same setup for all the steps. Large deflection is enabled and weak spring has opted as program controlled to provide stability during the analysis.

Rotation of 30 degrees in each time step was given to the revolute joint that is in contact with the gear.

Results:

Results obtained from the simulation for the different materials are tabulated below. It could be observed that the Equivalent stress is maximum in the spring that is made up of structural steel and it is least when the spring is made up of Titanium alloy. Generally, when titanium is alloyed with aluminium or vanadium, its strength increases tremendously than any of the low or medium grades steel. Due to this, stress induced in the material is low. Hence, these results stand out as a piece of evidence for the above claim.

Materials	Equivalent Stress- Max (MPa)	Total Deformation (mm) - Max
Structural Steel	1509.8	23.858
Stainless Steel	1462.6	23.203
Titanium Alloy	744.17	23.825

The following figures show the results obtained for the case of titanium alloy.

Animation:

https://drive.google.com/drive/u/0/folders/1ljKx4qqCnjO87ga5JN9y1QjiFXKANrtn