MBD Simulation on a Piston Assembly

Aim : To perform motion analysis of Piston assembly

Objective:

1. To create 3-D part of all components of piston assembly and assemble them with proper constraint.
2. To perform motion study and extract useful data from it.
3. Do the analysis of linear displacement of piston for different wrist pin offset

Theoretical Background:

Piston assembly is widely used in engine and pump , It has five major components

1. Piston:

A piston is a component of reciprocating engines, reciprocating pumps, gas commpressor, hydraulic cylinders and pneumatic cylinder, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston ring. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod andor 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. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.

https://drive.google.com/file/d/1kbC0Y7UM6YzM8SOnhtHwsBVi47zZ0PYD/view?usp=sharing

2. Connecting rod:

A connecting rod, also called a con rod, is the part of a piston engine which 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.The predecessor to the connecting rod is a mechanic linkage used by water mills to convert rotating motion of the water wheel into reciprocating motion.The most common usage of connecting rods is in internal combustion engines or on steam engines.

https://drive.google.com/file/d/1aZvx2Yyza24-5yf384eWQQy0TCKp_uWi/view?usp=sharing

3. 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. The arm may be a bent portion of the shaft, or a separate arm or disk attached to it. Attached to the end of the crank by a pivot is a rod, usually called a connecting rod.

https://drive.google.com/file/d/1ob9L1DGsN8q1wfjcyuRjPT-KD0NNS22x/view?usp=sharing

4. Gudgeon pin:

In internal combustion engine, the gudgeon pin (UK, wrist pin or piston pin US) connects the piston to the connecting rod, and provides a bearing for the connecting rod to pivot upon as the piston moves.

https://drive.google.com/file/d/1NNQYPnk5oJtEr6IUO2yWo6Bb796pvAgZ/view?usp=sharing

5. End cap:

https://drive.google.com/file/d/1p8KTrxT2BxcAA8_L4M3gi_AINb7kDzy6/view?usp=sharing

Assembly:

https://drive.google.com/file/d/154NNsuGN6Lpwz79hsoq_SFI1JTSN787M/view?usp=sharing

Problem statement:

Do analysis of linear displacement of piston for three different wrist pin offsets.

Sl.No	Wrist Pin Offset `	Crank Speed (Rpm)
1	"0" mm	2000
2	10 mm Positive	2000
3	10 mm Negative	2000

Procedure followed:

1] Make 3-D model of all part of piston assembly.

2] Assemble all part with appropriate constraint.

3] Check for physical dynamics of piston assembly .

4] Perform motion study and extract some useful information from motion study.

5] Do analysis of linear displacement of piston for different wrist pin offset.

Probelem Encountered

1] before checking for physical dyanamics of assembly check for interferance of matarial , if there is some interferance then physical dyanamics can not be performed and it will give error while performing motion study.This problem can be solved by giving 1mm or some clearance between two mating part.

Plots :

Case-I:

Wrist pin offset – 0 mm

Crank speed -200 Rpm

Case-II:

Wrist pin offset – 10 mm positive

Crank speed -200 Rpm

Case-III:

Wrist pin offset – 10 mm Negative

Crank speed -200 Rpm

Case-IV

superimpose all three cases

Conclusion:

1] Linear displacement of piston varies sinusoidally with repect to time in all three cases.

Result :

Motion study of piston assembly is done successfully .