16-11-2012, 02:13 PM
Finite Element Analysis of 4-Cylinder Diesel Crankshaft
FEA of 4cylinder disel crank shaft.pdf (Size: 504.85 KB / Downloads: 183)
Abstract—
The stress analysis and modal analysis of a 4-cylinder crankshaft are discussed using finite element method in this paper. Three-dimension models of 480 diesel engine crankshaft and crankthrow were created using Pro/ENGINEER software The finite element analysis (FEM) software ANSYS was used to analyse the vibration modal and the distortion and stress status of the crankthrow.The maximum deformation, maximum stress point and dangerous areas are found by the stress analysis of crankthrow. The relationship between the frequency and the vibration modal is explained by the modal analysis of crankshaft. The results would provide a valuable theoretical foundation for the optimization and improvement of engine design.
INTRODUCTION
Crankshaft is one of the most important moving parts in internal combustion engine [1]. It must be strong enough to take the downward force of the power stroked without excessive bending. So the reliability and life of internal combustion engine depend on the strength of the crankshaft largely. And as the engine runs, the power inpulses hit the crankshaft in one place and then another. The torsional vebration appeas when a power impuls hits a crankpin toward the front of the engine and the power stroke ends. If not controlled, it can break the cuankshaft.
Srength caculation of crankshaft becomes a key factor to ensure the life of engine. Beam and space frame model were used to calculate the stress of crankshaft usually in the past. But the number of node is limited in these models. With the development of computer, more and more design of crankshaft has been utilized finite element method (FME) to calculate the stress of crankshaft. The application of numerical simulation for the designing crankshaft helped engineers to efficiently improve the process development avoiding the cost and limitations of compiling a database of real world parts. Finite element analysis allows an inexpensive study of arbitrary combinations of input parameters
CONCLUSIONS
In this paper, the crankshaft model and crankthrow momal were created by Pro/ENGINEER software. Then the model created by pro/Engineer was imported to ANSYS software.
The maximum deformation appears at the center of crankpin neck surface. The maximum stress appears at the fillets between the crankshaft journal and crank cheeks, and near the central point.journal. The edge of main journal is high stress area.
The crankshaft deformation was mainly bending deformation under the lower frequency. And the maximum deformation was located at the link between main bearing journal and crankpin and crank cheeks. So this area prones to appear the bending fatigue crack. Base on the results, we can forecast the possibility of mutual interference between the crankshaft and other parts. The resonance vibration of system can be avoided effectively by Appropriate structure design The results provide a theoretical basis to optimize the design and fatigue life calculation.