MBD Simulation on a Piston Assembly
MULTI BODY DYNAMICS SIMULATION ON A PISTON ASSEMBLY
AIM:
- Model all the parts of the piston 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 |
The position of the wrist pin is going to be varied as followed. But the center of the axis of the piston head and the crank are coincident to each other.
- 0 mm Offset - Run a simulation.
- 10 mm Positive Offset - If the crank rotation is in the clockwise direction.
- 10 mm Negative Offset - If the crank rotation is in the clockwise direction.
- Obtain the Linear displacement of the Piston Head in all the three cases. Then export the graphs into Excel. Then Superimpose all the three graphs into a single graph.
INTRODUCTION:
Piston assembly consists of a piston, piston rings, and piston pin known as a gudgeon pin. As the piston is connected to the small end of the connecting rod with the help of a gudgeon pin. It transmits gas force generated during combustion to the connecting rod and crankshaft.
THEORY:
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod.
Piston Rings:
There are two types of piston rings: compression and oil control ring. Piston rings are generally made up of rectangular section.
Gudgeon pin:
Gudgeon pin is the main load-carrying part in piston assembly. The small end of the connecting rod is connected to the piston with the help of a gudgeon pin.
Connecting Rod:
The main function of a connecting rod is to form a link between a piston and crankshaft. A small end of the connecting rod is connected to the piston with a gudgeon pin and the big end is separated into two parts for ease of assembly with a crankpin. The two parts of the big end are bearing cap and big end housing. Both are being bolted together. This is done for ease of assembly of connecting rod with a crankpin.
Crankshaft:
The crankshaft is the final link in the slider-crank mechanism. The linear motion of a piston is converted into a rotary motion of a crankshaft. The energy is generated into the combustion chamber by transforming the reciprocating motion of a piston into rotary motion of a crankshaft.
PARTS OF 3D MODELLING IN PISTON ASSEMBLY:
3D model of the piston:
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings.
3D model of the connecting rod:
The main function of a connecting rod is to form a link between a piston and crankshaft. A small end of the connecting rod is connected to the piston with a gudgeon pin and the big end is separated into two parts for ease of assembly with a crankpin.
3D model of the crank:
The crankshaft is the final link in the slider-crank mechanism. The linear motion of a piston is converted into a rotary motion of a crankshaft.
3D model of the gudgeon pin:
Gudgeon pin is the main load-carrying part in piston assembly. The small end of the connecting rod is connected to the piston with the help of a gudgeon pin.
3D model of the end cap:
The two parts of the big end are bearing cap and big end housing. Both are being bolted together. This is done for ease of assembly of connecting rod with a crankpin.
FINAL ASSEMBLY:
Piston assembly consists of a piston, piston rings, and piston pin known as a gudgeon pin. As the piston is connected to the small end of the connecting rod with the help of a gudgeon pin. It transmits gas force generated during combustion to the connecting rod and crankshaft.
MOTION ANALYSIS STUDY:
In the motion study the following steps are performed:
- Select the motion analysis in the drop-down menu.
- The motor is placed to the crank at the speed of 2000 RPM.
- Frames per second are given as 12000 with precise contact.
- Contact is given between
- Endpin and Crank.
- Crank and Connecting rod.
- Connecting rod and Wrist pin.
- Wrist pin and Piston.
5. Gravity in the y-direction.
The calculation is performed for the motion analysis for about 1 second. The linear displacement of the piston head with respect to time is obtained.
The three cases are:
| Sl.No |
Wrist Pin Offset ` |
Crank Speed (Rpm) |
| 1 | "0" mm | 2000 |
| 2 | 10 mm Positive | 2000 |
| 3 | 10 mm Negative | 2000 |
Wrist Pin Offset - The position of the wrist pin is going to be varied as followed. But the centre of the axis of the piston head and the crank are coincident to each other (i.e) They are on the same plane in all the three cases.
Case 1: 0mm offset - The crank rotation is in the clockwise direction.
Linear Displacement Graph
Case 2: 10 mm Positive Offset - If the crank rotation is in the clockwise direction.
Linear Displacement Graph
Case 3: 10 mm Negative Offset - If the crank rotation is in the clockwise direction.
Linear Displacement Graph
SUPERIMPOSED GRAPH:
Here the linear displacement graph from each case is exported to excel and then superimposed it.
ANIMATION LINK OF MOTION ANALYSIS OF MBD SIMULATION OF A PISTON ASSEMBLY:
https://youtu.be/HkyQhjKFynk