MBD Simulation on a Piston Assembly

MBD SIMULATION ON PISTON ASSEMBLY

1)INTRODUCTION :

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, and pneumatic cylinders, among other similar mechanisms. 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. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder.

AIM -To design and simulate the piston assembly in Solidworks and to obtain various plots for the conditions given.

2)OBJECTIVE:

In this, the main objective is to do motion analysis of piston assembly by Designing different Parts of the Piston Assembly and Assemble them in SolidWorks. The various conditions are;

S. NO.	Wrist Pin Offset	Crank Speed (RPM)
1.	0 mm	2000
2.	10 mm Positive	2000
3.	10 mm Negative	2000

3)PROCEDURE:

The piston assembly- motion analysis begins with the individual part design which is then assembled and then simulated.

• Part Design:

PISTON DESIGN:

The piston is the primary mechanical component which transfers power from combusting fuel to the crank with the help of a connecting rod.

GUDGEON PIN:

In internal combustion engines, the gudgeon pin connects the piston to the connecting rod and provides a bearing for the connecting rod to pivot upon as the piston moves.

CONNECTING ROD:

A connecting rod is the part of a piston engine that connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the crankshaft. The connecting rod is required to transmit the compressive and tensile forces from the piston, and rotate at both ends.

END CAP:

The end cap is the extended part (can be assembled with a connecting rod by threaded bolts) of the connecting rod and it can be designed with the connecting rod dimensions.

CRANK:

A crank is an arm attached at a right angle to a rotating shaft by which circular motion is imparted to or received from the shaft. When combined with a connecting rod, it can be used to convert circular motion into reciprocating motion, or vice versa.

ASSEMBLY:

The assembly has done by mating each part individually to the planes of assembly and the mate between the parts is done. The crank is inserted first and then, the end cap, connecting rod, gudgeon pin, and the piston are imported and they are mated.

4)SIMULATION & ANALYSIS:-

In our study, we are going to analyze the assembly by offsetting the wrist pin in three different ways, and then its effect on the linear displacement of the piston will be analyzed.

Wrist Pin Offset: The position of the wrist pin is going to be varied but the piston and crank plane need to be similar in all three cases(i.e., the plane of piston and crank are in coincident )

• RPM-2000 & FRAMES/ SECOND= 7200(with precise contact) => this condition has to be maintained in all three cases

CASE 1- 0 mm offset

• The wrist pin and axis of rotation of crank coincides with each other

PLOT-

In the plot, the linear displacement of piston starts between the 200 &300. The smooth constant curve indicates that the constant linear displacement of piston with respect to time.

CASE 2 – 10 mm offset (positive)

• The wrist pin and the axis of rotation of crank are at 10mm distance (positive offset)

PLOT-

In the plot, the linear displacement of the piston starts from 200 due to the positive offset. The smooth constant curve indicates that the constant linear displacement of piston with respect to time.

CASE 3- 10 mm offset (negative)

• The wrist pin and the axis of rotation of crank are at 10mm distance (negative offset)

PLOT-

In the plot, the linear displacement of piston starts near 300 and then proceeding downwards due to the negative offset. The smooth constant curve indicates that the constant linear displacement of piston with respect to time.

MERGED PLOTS – From the above three plots, the superimposed plot has been created which is used to compare the three case study and their reactions.

5)CONCLUSION:

From the above plots, it was clear that the linear displacement was almost the same for all the plots but there will be slight variation due to the offset provided.

The offset was provided in order to vary the stress acting on the connecting rod which was stressed under various loads acting on the piston. without offsetting the line of action of power transmission is caused impact load on the assembly which is harmful during operation.

6) ANIMATION VIDEO:

CASE 1(ZERO OFFSET)-https://youtu.be/zOz5qeFt-y0

CASE 2(POSITIVE OFFSET)-https://youtu.be/gNekhoQ_1TE

CASE 3(NEGATIVE OFFSET)-https://youtu.be/deYDbyJ9t7Q

7)GOOGLE DRIVE -FILES

https://drive.google.com/drive/folders/1Gy7fjNP2F-UulNA-46zfRpVoJOFwRka8?usp=sharing