MBD Simulation on a Piston -Crank Mechanism
Objective:
- To model all the parts and then assemble them in SolidWorks.
- The motion analysis is going to be carried out in three different conditions,
| Sl.No |
Wrist Pin Offset ` |
Crank Speed (Rpm) |
| 1 | "0" mm | 2000 |
| 2 | 10 mm Positive | 2000 |
| 3 | 10 mm Negative | 2000 |
- To plot the Linear displacement of the Piston Head in all the three cases. Then export the graphs into Excel.
- To Superimpose all the three graphs into a single graph.
Piston- Crank Mechanism:
Piston- Crank Mechanism is a demonstration of a simple mechanical system of linkages and motion chains. The objective is to display the working of a piston inside an engine cylinder and how the reciprocating motion of the piston gets converted to rotational motion of the crank.
When the piston is manually pushed and pulled in vertical direction, the connecting rod which connects the piston to the crank transmits the power to the crank wheel which rotates about its crank-shaft axis.
The power/torque of the crank shaft rotation is transmitted to the wheels which drives the vehicle.
3D Modeeling, Assembly and MBD Simulation Setup:
The Piston- Crank Mechanism involves
1. Piston,
2.Connecting rod,
3.End cap of connecting rod,
4. Wrist pin for mounting counting rod to piston, and
5. Crank
Images of the 3D modelled components
1. Piston
2. Connecting rod
3. End cap
4. Wrist pin
5.Crank
Assembly of Piston- Crank Mechanism
MBD Simulation Setup for all the three different conditions.
For the Motion Analysis study, the following conditions to be applied
* Rotating motor is applied to the Crank with 2000 rpm and direction of rotation.
* All contacts are defined between the components of Piston- Crank Mechanism
* Simulation is then run, and results of Linear displacement of the Piston Head in all the three cases are exported to Excel and plotted.
Results and plots:
case1: with 0mm Wrist_pin offset.
Model
Angular velocity(deg/sec) of crank - (Input)
Linear displacement(mm) of piston head w.r.t time - (output)
case4: with +10mm Wrist_pin offset.
Model
Angular velocity(deg/sec) of crank - (Input)
Linear displacement(mm) of piston head w.r.t time - (output)
case3: with -10mm Wrist_pin offset.
Model
Angular velocity(deg/sec) of crank - (Input)
Linear displacement(mm) of piston head w.r.t time - (output)
Observation:
- Even with the offset in wrist_pin position, the linear displacement does not vary significantly
- But the offset in wrist-pin position, helps to reduce the wear and power loss in the system.
- So it is advised to considered the offset in wrist-pin position.
Reference link for 3d models,excel sheets:
https://drive.google.com/drive/folders/1v8PROtqjxF2vVsRhjrBqNHVJlcyB9Occ?usp=sharing