Multibody Dynamics using Solidworks-MBD Simulation on a Piston Assembly

Introduction

The purpose of this project is to simulate the dynamics of a piston assembly in Solidworks. We will be simulating the dynamics of in 3 cases.

Case 1:Piston at neutral position with regards to crankshaft.

Case 2: Piston at 10 mm positive offset with regards to crankshaft

Case 3: Piston at 10 mm negative offset with regards to crankshaft.

The primary graph we will be considering will be that of linear displacement of the piston.

The motor wil be rotating at 2000rpm clockwise and the number of frames capture will be 12000 per second to ensure a smooth graph.

Procedure

Model the different components of the assembly .

Assemble the different components and make sure that the required rotational freedom for the crankshaft as well as linear motion for the piston is present.

In the solidworks motion add-on add a 2000 rpm rotary motor to the crankshaft.

Give contact between differnet components of the assembly with all materials being steel(dry)

In settings give the frames per second as 12000 and enable precise contact.

Run the simulation for a short time,ideally for 3 or 4 full crankshaft rotations.

Create the graph with linear displacemnet of piston and make sure that it is smoth.

Create the graph for angular velocity of crankshaft and make sure that it is the same rpm that we gave.

For cases 2 and 3:

Adjust the mates of the right plane of the piston with that of the assembly for 10mm forward or backward and run the simulation as before.

Results

Case 1:

Case 2:

Case 3:

Superimposed Graph for comaprison

Conclusions

As expected there is only differene in the time between which the piston reached TDC and BDC when positive or negative offset is given to the piston.

The positive offset piston reaches TDC and BDC faster than the other two with the negative offset piston lagging behind the other two.