MBD Simulation on a Piston Assembly

MBD Simulation of a Piston Assembly:-

                                                         It's an MBD simulation of a single-cylinder piston assembly. The main components are piston, connecting rod, wrist pin, end cap, and crank. All the components and assembly files are attached to this report. 

                     The wrist pin is assembled inside piston slots which connect the piston with the connecting rod. Connecting rod then mounted over the crankshaft. 

Simulation Setup:-

                     The initial input is provided to crank and output is achieved as linear displacement of the piston. 

                                  Input angular velocity = 2*3.14*2000/60

                                                                   = 209.33 rad/sec

                                                                   = 12000 deg/sec

                     No of frames per second = 7200

                     Precise contact selection = On

Case 01 (0 mm offset):-

                      In this case, the right plane of the piston is in line with the right plane of the crank. It means their axes are on the same plane as shown below-

We are providing constant rpm to the crank so its movement will remain the same throughout the process.

                                 The linear displacement of piston is shown below-

Explanation:-

              We observe that the displacement has harmonic motion which we can understand by the fact that the shadow of vertical circular motion is nothing but a harmonic motion. The maximum displacement is around 303 mm. 

Case 02 (10 mm positive offset):-

              The piston is in a slightly offset position from the crank axis.

The linear displacement of the piston is given as-

The resulting pattern is again the same for the displacement for the same reason. The highest point reaches slightly sooner than the 0 mm offset case because- the highest displacement occurs when the crank is slightly in left than the vertical axis (because it's offset on the left side). 

Case 03 (negative offset):- 

                         The offset is given on the opposite side as-

The linear displacement of piston is found as-

The maximum displacement is the same as the previous case of positive offset. In this case, the highest point reaches slightly late than case 02 because its highest point occurs when the crank reaches slightly on the right side than the vertical axis.

Summary:-

             The three individual cases can be combined together as-

* (1). series 1 (green line) is of case 01

   (2). series 2 (red line) is of case 03

   (3). series 3 (green line) is of case 02