ME345: Modeling and SimulationProfessor Frank Fisher

Stevens Institute of Technology 

Last updated: June 25, 2009 

Software versions used in the tutorial:SolidWorks 2007 SP4.0

Bevel Gear Exercise

Table of Contents:

Part 1: BackgroundPart 2: Preparing the SimulationPart 3: Running the SimulationPart 4: Summary

Part 1: Background

This analysis is primarily an exploration of the uses for Joint Couplers in COSMOSMotion

An explanation of Joint Couplers:

Joint couplers allow the motion of a revolute, cylindrical, or translational joint to be coupled to the motion of another revolute, cylindrical or translational joint. The two coupled joints may be of the same or different types; for example, a revolute joint may be coupled to a translational joint. The coupled motion may also be of the same or different type. For example, the rotary motion of a revolute joint may be coupled to the rotary motion of a cylindrical joint, or the translational motion of a translational joint may be coupled to the rotary motion of a cylindrical joint. Coupler joints are used here to produce motion between objects of complex geometry where a simple mate will not suffice. In this case the objects are bevel gears

You will remember from ME 361 (Design of Machine Components) in the sections concerning gear trains that speed ratios between gears can be determined with the equation:

Where:

n = gear speed

N = number of teeth

d = pitch diameter

Remember to keep in mind that the velocity changes direction between each gear.

When applying the joint couplers the most important things to know are:

• How the gear ratio will affect the output motion of the connecting gear.

This will need to be calculated yourself and entered when defining the joint coupler properties. In this case the calculation is simple as the parts used in the assembly: 20bevel4 and 20bevel5 both contain 20 teeth and the part 40bevel1 contains 40 teeth.

• The direction of the output gear velocity relative to that of the input gear.

Normally this is as simple as changing the sign of the output motion when defining the joint coupler but you need to be careful what parts you assign as the input and output gears.

Bevel Gear ExercisePart 2: Preparing the Simulation

• Open “Bevel_Gears_For_ppt.sldasm”

• When asked to “Automatically add new Parts to Grounded or Moving Parts?” Select “No”

Bevel Gear Exercise

Bevel_Gears_For_ppt.sldasm

Define Moving and Ground Parts

(There are no ground parts in this model)

Bevel Gear ExerciseAdd Revolute Joint

1

Select Gear as 1st Part

2

Select Ground as 2nd Part

3

Select Edge for Location

Bevel Gear ExerciseAdd Revolute Joint

1

Select Gear as 1st Part

2

Select Ground as 2nd Part

3

Select Edge for Location

Bevel Gear ExerciseAdd Revolute Joint

1

Select Gear as 1st Part

2

Select Ground as 2nd Part

3

Select Edge for Location

Bevel Gear ExerciseAdd Joint Motion on 20Bevel5

Bevel Gear Exercise

• Define Joint Coupler between 20Bevel5 and 40 Bevel1 (Joint 1 and Joint 3)

• Define Joint Coupler between 40 Bevel1 and 20Bevel4 (Joint 3 and Joint 2)

• Enter Values as shown below

Add Joint Coupler

Bevel Gear ExercisePart 3: Running Simulation

•Set frames to 250

•Press calculator button to run simulation

Part 4:Summary

Couplers allow the proportional movement of one joint with respect to another.

Couplers can link:Rotational - RotationalRotational - TranslationalTranslational - Translational

Available for combinations of Revolute, Cylindrical, and Translational joints

One joint can be linked to multiple joints provided they do not conflict with motion generators or other couplers

Couplers are primarily used for representing gears without taking into account losses