Challenge

MBD Simulation on a Piston Assembly

MULTI BODY DYNAMICS SIMULATION OF THE PISTON ASSEMBLY

AIM:

To create 3D models of the piston-cylinder assembly according to the provided drawing.
Assemble them according to 3 different configurations and conduct motion analysis to obtain the linear displacement of the piston.

THEORY

The single slider-crank mechanism is the inversion of a four-bar mechanism
It converts the rotary motion of the crank into the reciprocating motion of the slider
It is used in the IC engine, crank as crankshaft, slider as piston and piston and cylinder are connected by connecting rod (with the help of gudgeon pin).
The linear distance traveled by the piston is called the stroke length and it is equal to twice the crank radius.
The offset of connecting rod from the piston center is done to reduce the loss of power and Variation of rpm in the crank.
When there is no offset, the position of the connecting rod is straight when the piston is at TDC and BDC, connecting rod is subjected to huge load due to power stroke, and hence it offers some resistance to smooth rotation of the crank, to overcome that crank spend some energy leading to power loss.
So at the offset position, connecting rod is the inclined position when the piston is at TDC and BDC, hence the load on the connecting rod due to power stroke is comparably less and hence it doesn't offer resistance to the smooth rotation of the crankshaft
Hence there is no power loss, that is why we are examining, whether offset configuration affects the stroke length of the piston or not.

MODELLING AND MOTION ANALYSIS

3D models of the piston, connecting rod, endcap, gudgeon pin and crankshaft is done with the help of given 2d drawings in part module of solidworks
Here the crank radius is 50mm (distance between crank shaft center to end cap centre), therefore stroke length of piston is 100mm
For different assembly configuration, 3 pistons with different gudgeon hole positions are modelled
Assembly is done by keeping the motion analysis in mind and mates are provided according to that, so the correct relative motion between the parts are ensured

Motion analysis is done for all the 3 assembly configuration separately, with input speed of 2000rpm given to crank shaft
Solid contact are provided between the parts with material as dry steel
In motion analysis setting, 1200fps and precise contact is specified to get the linear displacement of piston at each and every second as a result

RESULT

The linear displacement of the piston for 3 different assembly configurations are obtained and compared
By comparison, it is found that all 3 assembly configuration showing the same linear displacement of the piston (stroke length) equal to 100mm (202 to 302) with very little variation
Hence it is confirming that the offset position gudgeon pin has no effect on the stroke length of the piston

Animation

Thank you

Ship work like this
in your own course.