INTERNAL GENEVA MECHANISM USING MULTI-BODY DYNAMICS IN SOLIDWORKS

INTRODUCTION :

The Geneva Mechanism or Maltese cross is a gear mechanism that translates a continuous rotation movement into intermittent rotary motion. The rotating drive wheel is usually equipped with a pin that reaches into a slot located in the other wheel ( driven wheel ) that advances it by one step at a time.

OBJECTIVE :

The aim of this challenge is to design an internal geneva mechanism which converts a constant rotational motion into intermittent rotational motion and discuss major results of the system.

PROCEDURE

STEP 1: CAD model for the given Driver wheel and Driven Wheel

1. Driver Wheel

2. Driven Wheel

3. ASSEMBLY OF INTERNAL GENEVA MECHANISM

STEP 2 : MBD SIMULATION WITH AND WITHOUT PRECISE SETTING AT 10RPM FOR THE SYSTEM

• Simulate the MBD system using the Motion add-on in Solidoworks
• Take a constant speed motor rotating clockwise with 10 rpm on the driving wheel.
• Set the contact solids and material to run the simulation.
• Evaluate all the required results and run the next simulation with Precise contacts 'on'.
• Run the same simulation a again and obtain the required results. Set FPS at 60.
• Repeat the above steps for 20 rpm and 120 fps and evaluate the results.

PRECISE SETTING TABLE

RESULTS

EXCEL PLOTS FOR CASE 1 a : Motor Angular speed =10 RPM, Precise Contact= 'ON', 60 FPS, Simulation time = 30s

1. Contact Forces vs Time

2. Angular Displacement(shown in orange) of the Driven Wheel vs Time

EXCEL PLOTS FOR CASE 1 b : Motor Angular speed =10 RPM, Precise Contact= 'OFF', 60 FPS, Simulation time = 30s

1. Contact Forces vs Time

2. Angular Displacement of the Driven Wheel vs Time

COMPARISION PLOT : Contact Forces With and Without Precise Contact for above two cases (Motor Angular speed =10 RPM, 60 FPS, Simulation time = 30s )

EXCEL PLOTS FOR CASE 3 : Motor Angular speed =10 RPM, 60 FPS, Simulation time = 30s

1. Angular velocity (blue) vs Time

EXCEL PLOTS FOR CASE 2 a : Motor Angular speed =20 RPM, Precise Contact= 'ON', 120 FPS, Simulation time = 30s

1. Contact Forces vs Time

2. Angular Displacement of the Driven Wheel vs Time

EXCEL PLOTS FOR CASE 2 b : Motor Angular speed =20 RPM, Precise Contact= 'OFF', 120 FPS, Simulation time = 30s

1. Contact Forces vs Time

2. Angular Displacement of the Driven Wheel vs Time

COMPARISION PLOT : Contact Forces With and Without Precise Contact for above two cases (Motor Angular speed =20 RPM, 120 FPS, Simulation time = 30s )

EXCEL PLOTS FOR CASE 3 : Motor Angular speed =20 RPM, 120 FPS, Simulation time = 30s

1. Angular velocity vs Time

CONCLUSION :

• It is observed that when the precise contact setting is 'ON' there is a delay observe during mating of Driver and Driven part but when the precise contact setting is 'OFF' there is a no Backlash error is observe in motion.

• In case of Precise contact, the contact forces are high and irregular (varies) whereas in case of without precise contact the contact forces are less and constant.

• The Angular velocity for driver wheel is linearly increasing in both cases.

• There is not much vaariation observe in Angular displacement when precise contact setting changes.

Note : From my previous course experiences it is given in problem to attach video link, I didn't attach the video link here since in the question it is not mention to attach that.