I used SolidWorks to design a piston, rod, and crankshaft and conduct motion studies. My goal was to create well-defined motion studies with sufficient temporal resolution, reasonable friction and specification of load bearing faces. I used the results of the motion study to identify the two parts of the cycle that have the maximum reaction forces. I conducted Finite Element Analysis (with mesh refinement) of the stresses, displacements, and factor of safety for the model at times of maximum positive and negative reaction forces.

Re-Design for 3D Printing

I then modified my engine assembly so that a miniature version of it could be printed on a Markforged Mark Two 3D printer. My goal was to produce a model that showed the movement of the piston and connecting rod when the crankshaft is turned. In order for this to work, I modeled the crankcase as well as the cylinder and main bearing. I included some cutaways so that the motion would be visible from the outside. I also included tolerances between the moving parts so that they would be able to move with respect to each other after they were printed.cI used an angle tolerance of 5 degrees and the maximum possible tolerance that SolidWorks allowed when saving as an STL (0.018102in). Finally, I printed the parts individually and put together my assembly.

Initial Design: Files for parts, assemblies, and simulations .