The Research On Strength Performance And Structure Optimization For Diesel Engine Crankshaft

In recent years, the study of re-manufacture of engine components become one of the central issues inside automobile industry. Crankshaft, loaded complicatedly, always has strength problems such as fracture phenomenon. Therefore, crankshaft become the most important component in the re-manufacture study.This study aims to enhance the intensity of crankshaft and reduce the probability of fatigue failure. FEA software was used to analysis the static stress of crankshaft. After summary and analysis of this result, the danger of the study crankshaft was predicted. Two kinds of optimization method of the fillet structure were proposed. Compared analysis were carried out between crankshafts with different fillet structures by static analysis and dynamic analysis with FEA software ANSYS.UG software was used to create 3D model of crankshaft. The relationship between cylinder pressure and crankshaft angle was obtained theoretically from dynamic analysis of engine and the relationship between connecting rod force and crankshaft angle was obtained theoretically from mechanical analysis of crank-connecting rod mechanism. Theoretical analysis apply boundary condition information for finite element analysis.ANSYS software was used to analyze both the static stress and dynamic stress of crankshafts. The principle of stress, deformation and their distribution were introduced comprehensively, include the stress principle both during one working cycle and in every dangerous condition.After summary the result of FEM analysis, the danger of the study crankshaft was predicted. Two kinds of optimization method of the fillet structure were proposed. One is the cutting fillet structure and the other one is the stepped fillet structure. Modified the model with two different fillet structures and carried out static stress again by using ANSYS. The best size assemble of new structure was got from parametric study by using APDL language. The structure with the best size can both reduce the magnitude of the maximum stress and make the maximum stress well-distribution on the whole crankshaft.This study not only focus on the magnitude of stress, also on the distribution of stress and study was carried out by the combination of static analysis and dynamic analysis, which made this study more comprehensive. A study process of crankshaft including crankshaft stress analysis, parametric design, structure optimization and verification of optimization method was concluded from this study.