MBD Simulation on a Piston Assembly

AIM: Run a motion analysis for Piston Assembly.

OBJECTIVES:

• Create 3D models for all the components.
• Assemble all the parts.
• Perform motion analysis by rotating the crank at 2000 rpm for 3 different conditions.
• Obtain the Linear displacement of the Piston Head in all the three cases.
• Superimpose all the three graphs into a single graph in Excel.

ENGINE PISTON ASSEMBLY

Piston assembly is important part of the engine because an engine converts the reciprocating motion of the piston created by the force of combustion gases into rotary motion of the crankshaft which is useful for the motion on the vehicle.

DIFFERENT CONDITIONS

STEP-WISE PROCEDURE:

• First, we have to create piston, wrist pin, connecting rod, end cap and crank with dimension in front plane.

• Now we have to assemble all the components with appropriate constrain in front plane.

• Then go to motion analysis and give the contact between crank and end-cap, crank and connecting rod, connecting rod and wrist pin, wrist pin and piston.
• Give the motor to crank and set the speed 2000 rpm.
• To capture every crank angle position set the frames per second to 12000.
• Then calculate the motion data and plot the graph for the linear displacement of piston.
• Now We give the 10 mm offset between crank axis and wrist pin axis in another motion study.
• Then we give the 10 mm offset between crank axis and wrist pin axis in opposite direction from above case in another motion study.
• Then export the data of all studies to excel and make plot there.

OUTPUT PLOTS

Case 1: Perform motion analysis for 0 mm offset

Linear Displacement of Piston

Case 2: Perform motion analysis for 10 mm positive offset

Linear Displacement of Piston

Case 3: Perform motion analysis for 10 mm negative offset

Linear Displacement of Piston

Comparison of 0 mm and 10 mm positive case

Comparison of 0 mm and 10 mm negative case

Superimpose of all the three graphs

CONCLUSION

There are main two side of piston which is major thrust side and minor thrust side.

If the crankshaft rotates clockwise, the major thrust face will be on the left-hand side of the piston and opposite side id minor thrust side. So, during the compression stroke minor thrust side is contact with piston.

During the power stroke the force of combustion is high, some of that force pushes the piston against the cylinder wall. So, we can say that this is friction forces which is actually energy loss. Due to this push forces piston is in contact with major thrust side and noise of piston slap is occurred. So, there will be a more thrust during power stroke and wear of this side is also high.

So, for reducing the wear and noise wrist pin offset is given towards the major side thrust.

Google drive link for Part and Assembly

https://drive.google.com/drive/folders/14MAWxA4hY840Ei7Id2m_y37SW-7MwFft?usp=sharing