The purpose of this project was to show the design process for a crankshaft with known physical loading. This crankshaft services a single cylinder four-stroke diesel engine. The engine has some known dimensions, such as the crank length, the piston weight, and other simple factors. The diameter of the crankshaft, the fillet radius, and the crankshaft material was originally unknown.
This is the given schematic for the crankshaft.
This report is meant to serve as a guide in the design of the critical features previously unknown paired with the full analysis of the known criteria. The methodology behind this report is such that it is broken down into two parts. The first part consists of the kinematics of the mechanism as well as the forces acting on the crankshaft.
These are the determined stress pressures at various positions of the cycle for the first plane.
These are the determined stress pressures at various positions of the cycle for the second plane.
The second part details how the stresses were analyzed, the critical dimensions were determined, and the factors of safety were realized.The results from this analysis came in many forms. The mean and alternating stresses gave information related to the factors of safety, which were in turn used to evaluate the performance of a specific material with a specific diameter shaft for each iteration. This process involved multiple iterations where many different materials and diameters were selected. Eventually, the diameter of the crankshaft and rod journal was determined to be 25mm, and the material was determined to be AISI 1060 Q&T 650 Steel and the surface to be grounded. In addition, the fillet radius was found to be 0.2mm. It should be noted that the rod journal diameter and the crank journal diameter were set equal to assist in the manufacturing of the crankshaft. These results came from many different trial and error experiments which resulted in the lowest cost material with the largest diameter available while still supplying a firm factor of safety.
The factor of Safety using various methods in plane 1.
The factor of Safety using various methods in plane 2.
Want more? Shown below is the full report and Matlab code for this project.
Crankshaft Design Project Matlab Code
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