MBD Simulation on a Piston Assembly

Aim: To model the piston assembly and perform the motion analysis in Solidworks.

Description:

• Piston: A piston is a moving disk enclosed in a cylinder which is made gas-tight by piston rings. The disk moves inside the cylinder as a liquid or gas inside the cylinder expands and contracts. A piston aids in the transformation of heat energy into mechanical work and vice versa.
• Connecting Rod: A connecting rod is an engine component that transfers motion from the piston to the crankshaft and functions as a lever arm. Connecting rods are commonly made from cast aluminum alloy and are designed to withstand dynamic stresses from combustion and piston

• Crank Shaft: A crankshaft is a rotating shaft which (in conjunction with the connecting rods) converts the reciprocating motion of the pistons into rotational motion. Crankshafts are commonly used in internal combustion engines and consist of a series of cranks and crankpins to which the connecting rods are attached.

• Gudgeon Pin: Gudgeon pin connects the piston to the connecting rod, and provides a bearing for the connecting rod to pivot upon as the piston moves.

• End Cap: An End cap is the removable section of a two-piece connecting rod that provides a bearing surface for the crankpin journal.

• Wrist Pin Offset - The position of the wrist pin is going to be varied as followed. But the center of the axis of the piston head and the crank are coincident to each other (i.e) They are on the same plane in all the three cases.

Objective:

• To perform the motion analysis in the following 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

• To obtain the Linear displacement of the Piston Head in all the three cases. Then export the graphs into Excel. Then Superimpose all the three graphs into a single graph.

Figure: Flow of the project.

3D CAD models

• Piston assembly:

• Crank:

• Connecting Rod:

• Endcap:

• Gudgeon Pin:

Steps followed:

• 3D models are created using the drawings provided in the video section of the course.
• Different parts are assembled on the basis of the given information.
• A motor is installed at the crank with given rpm.
• Contacts are established between the parts as per our requirement.
• After running the motion analysis, the required plots are plotted.
• All three different plots are superimposed as per our requirement

Results:

CASE 1

Wrist Pin Offset `	Crank Speed (Rpm)
"0" mm	2000

Maximum Displacement:302mm

Video link: https://drive.google.com/file/d/1h80Wd6wYQET3JIl0KngmugOM4fyE0Sft/view?usp=sharing

CASE 2

Wrist Pin Offset `	Crank Speed (Rpm)
10 mm Positive	2000

Maximum Displacement:302mm

Video link: https://drive.google.com/file/d/1c5fKTBCuRlCCANbTrB3zr8ROs_z8OqsP/view?usp=sharing

CASE 3

Wrist Pin Offset `	Crank Speed (Rpm)
10 mm Negative	2000

Maximum Displacement:302mm

Video link: https://drive.google.com/file/d/1XJ8rLWwCbJiu22Wv6GS5GChRMkcar1hJ/view?usp=sharing

Conclusions:

As we can see that the linear displacement is the same for all three cases, just a slight difference in the plots due to the offsets we have provided during the assembly and design.