MBD simulation on a piston assembly
Aim:
To model the various parts that are needed to make the piston assembly. To analyse the modelled piston assembly in various aspects.
Objectives:
- To model the various parts in piston assembly in solidworks.
- To analyse the multibody dynamics of the piston assembly in various aspects.
- To obtain the plots of linear displacement of the piston head in different cases.
Various cases of simulation:
The MBD simulation of the piston assembly is done with 3 different case studies. The different case studies are done by changing the wrist pin offset.
| Sl.No |
Wrist Pin Offset ` |
Crank Speed (Rpm) |
| 1 | "0" mm | 2000 |
| 2 | 10 mm Positive | 2000 |
| 3 | 10 mm Negative | 2000 |
IC engine:
The internal combustion engine plays a vital role in the automobile field. The invention of IC engines has a huge role in the development of the world. The engine turns the reciprocating motion into rotating motion. One of the major component in the engine assembly is piston assembly. There are two types of IC engines. They are, 1) two stroke engine and 2) four stroke engine. The four major processes were done inside the engine. They are a) intake, b) compression, c) power and d) exhaust.
Based on the number of strokes taken by the engine to complete all the four stages, they are classified into two stroke and four stroke engines.
Piston assembly:
One of the major component in the IC engine is piston assembly. Moreover, piston assembly done a maximum role in the engine. The piston assembly converts the reciprocating motion of the piston into rotating motion by using crank.
There are various components in the piston assembly and are demonstrated on the above image.
Modelling of piston assembly:
The five major components in the piston assembly is modelled and assembled to do the motion analysis.
1) Piston head
2) Connecting rod
3) End cap of the connecting rod
4) Wrist pin
5) Crank
The piston head is modelled with the rings. In the piston head, simple projections are made for placing the wrist pin.
Piston head:
Connecting rod:
End cap of the connecting rod:
Wrist pin:
Crank:
Then all the parts are assembled in such a way that the piston moves in a reciprocating motion where the crank and the connecting rod moves in a rotating motion.
Motion analysis:
The motion analysis was carried out by three different cases based on the given parameters.
Case 1:
Initially, the motion analysis was done with 0mm wrist pin offset. The crank is provided with motor of 2000rpm speed and the linear displacement of the piston is plotted. 8000 fps was set to get the smooth curve. The motion animation was also obtained from the analysis.
The midpoint of the wrist pin and the origin has 0mm offset.
The plot for the linear displacement of the piston is shown below,
Case 2:
The next analysis was done with a positive offset of 10mm in the wrist pin. The linear displacement of the piston was plotted.
The midpoint of the wrist pin and the origin has an offset of 10mm in the positive direction.
The plot for the linear displacement of the piston is shown below,
Case 3:
The next analysis was done with a negative offset of 10mm in the wrist pin. The linear displacement of the piston was plotted.
The midpoint of the wrist pin and the origin has an offset of 10mm in the negative direction.
The plot for the linear displacement of the piston is shown below,
Superimposed plot:
The superimposed plot that contains all the plots of three cases were drawn and shown below,
Result and discussion:
From the linear displacement plot of the different case studies, the Top Dead Centre (TDC) and the Bottom Dead Centre (BDC) of the piston was obtained. From this, lot of informations are obtained regarding the modelling of a piston for required output. The superimposed graph correctly meshed with case 2 and case 3. The case 1 plot has a slight differ at the starting range but it ends with smooth mesh. Thus, it explains that the TDC and BDC of the three different case studies didn't differs very much.
Animation video:
The youtube link for the animation of various case studies are provided below,
Case 1:
Case 2:
Case 3:
Part and assembly model:
The CAD model of the ic engine assembly parts and assembly was compressed and the google drive link is provided below.
https://drive.google.com/file/
Conclusion:
Thus, the engine assembly parts are made and assembled. The motion analysis was done with three different parameters.