MBD Simulation on a Piston Assembly

PISTON ASSEMBLY SIMULATION

Aim: To model and assemble the parts of the piston assembly and run the motion analysis simulation.

Introduction: Piston assembly is used in engineering applications to convert rotatory motion to translatory motion or vice versa. It consists of the following parts-

1. Piston
2. Connecting Rod
3. Crank
4. End Cap
5. Wrist Pin

Problem specification:

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

Models:

1) Piston:

The piston is a component that slides back and forth due to the rotation of the crank. The model of the piston is created using the following geometry

To create a 3D model of following steps have been taken

1. Making the sketch on the plane.
2. Adding the features like Revolve, Cut revolve, cut extrude, Boss extrude, Fillet.

2) Connecting Rod: A connecting rod also called a con 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.

Geometry:

Model:

Using the given geometry the model has been created by making the sketch on the planes and then adding features like Boss extrude and Cut extrude. A suitable fillet is provided.

3) Crank: A crank is an arm attached at a right angle to a rotating shaft by which a 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.

Model:

Using the given geometry the model has been created by making the sketch on the planes and then adding features like Boss extrude and Cut extrude and mirror. A suitable fillet is provided.

4) End Cap: It is used to close the connecting rod end.

Geometry:

Model:

5)Wrist Pin: A wrist pin is a pin through the skirt of a piston in an internal-combustion engine, to which the little end of the connecting rod is attached.

Geometry:

Model:

Assembly: After making the models assembly is created using suitable mates.

1 0 offset

10 mm positive offset

10 mm negative offset

Motion Analysis Simulation:

1. Provided motor into crank of 2000 RPM
2. Contact is solid body contact between the surfaces and material is dry steel
3. Gravity is in Y direction
4. 8400 frames per second and precise contact is used.

Result and plots: Linear displacement of piston is plotted in three different given comdition.

1) 0 mm offset

2) 10 mm positive offset

3) 10 mm negative offset

Conclusions:

1. There is only a slight difference between the plots.
2. Having an offset pin relieves the stress that is caused in the rod when it reaches the top or bottom dead center
3. the plot is between linear displacement vs time.
4. In all the plots 311 mm is the starting point.

Animations:

1 https://drive.google.com/file/d/1vEmHbl0S8MjAY57oL0VaHR9YbxaccXPK/view?usp=sharing

2 https://drive.google.com/file/d/1NhPKqNVQlQXC_LquhY9YTvuP_qaozZwM/view?usp=sharing

3 https://drive.google.com/file/d/1eElU5bA_sIamlsvT0KnO9AVTdHSxSHNM/view?usp=sharing

FILES:

https://drive.google.com/drive/folders/1rrJ4GhNW8rJgZNIT2f1cm04HjhvZ8uTw?usp=sharing