Crankshaft Optimization Based on Experimental Design and Response Surface Method

To improve the applicable performance of the engine and accomplish the determination of optimization, the crankshaft, as one of its essential components, is optimized based on experimental design and response surface method (RSM). First, the static analysis of the crankshaft is carried out. Over the solution, the maximum equivalent stress and deformation distribution of the crankshaft and the area with the most concentrated stress are obtained to provide the direction for subsequent optimization. Then the modal analysis is carried out to define the portions with large amplitude to prevent resonance. At the same time, based on the modal analysis results, the harmonic response of the crankshaft is examined to ensure that the crankshaft can avoid resonance and fatigue caused by forced vibration at different engine speeds. It also provides a theoretical basis for the further optimization design of the crankshaft. Then, through the experimental design and response surface optimization analysis, the optimization purpose of reducing the maximum equivalent stress, maximum deformation, and lightweight of the crankshaft is accomplished. Through the design expert software, the response surface model and fitting equation of the crankshaft are solved by the RSM, which provides a reference basis for optimizing the crankshaft. Finally, according to the optimization scheme, the crankshaft is reconstructed, and the optimized crankshaft model is compared with the original model. After optimization, the maximum equivalent stress is reduced by 9.43%, the maximum deformation is reduced by 3.68%, and the mass is reduced by 1.30%. At the same time, the first three natural frequencies are reduced by 10.28, 10.28, and 10.34%, which achieves the purpose of optimizing the crankshaft design. The research results provide effective theory and evidence for the structural design of the crankshaft.