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An Analytical Investigation of the Crankshaft-Flywheel Bending Vibrations for a V6 Engine
ISSN: 0148-7191, e-ISSN: 2688-3627
Published May 01, 1995 by SAE International in United States
Annotation ability available
High vibration levels at the rear bearing cap and oil pump were observed in dyno tests for a particular design of a V6 engine at a rated speed of 4800 r/min. It was found experimentally that the crankshaft-flywheel assembly had a bending resonance at 240 Hz which was excited at around 4800 r/min by 3rd order forces on the crankshaft.
A newly developed crankshaft system model (CRANKSYM) was used to analytically verify the above finding and propose possible solutions to the problem. CRANKSYM can perform a coupled analysis among the crankshaft structural dynamics, main bearing hydrodynamics and engine block flexibility. It considers the flywheel dynamics (including the gyroscopic effect), belt loads, crankshaft “bent” and block misboring, and the anisotropy of the block flexibility as seen from a rotating crankshaft. It can also calculate the dynamic stresses on the crankshaft throughout the whole engine cycle. A brief description of CRANKSYM is given in the paper.
It was found using CRANKSYM, that internal balancing of the crankshaft and reduced flywheel inertia reduced the flywheel vibration and the dynamic load on the rear main bearing considerably. On the contrary, stiffening of the rear main bearing cap did not decrease the flywheel vibration or the rear main bearing dynamic load.
CitationMourelatos, Z., "An Analytical Investigation of the Crankshaft-Flywheel Bending Vibrations for a V6 Engine," SAE Technical Paper 951276, 1995, https://doi.org/10.4271/951276.
- Wilson, E. L Yuan, M. W. Dickens, J. M. “Dynamic Analysis by Direct Superposition of Ritz Vectors,” Earthquake Engineering and Structural Dynamics 10 813 821 1982
- Arnold, R. R. Citerley, R. L. Chagrin, M. Galant, D. “Application of Ritz Vectors for Dynamic Analysis of Large Structures,” Computers and Structures 21 461 467 1985
- Wilson, E. L. Bayo, E. P. “Use of Special Ritz Vectors in Dynamic Substructure Analysis,” Journal of Structural Engineering 112 8 1944 1954 1986
- Mourelatos, Z. P. “A Three-Dimensional Crankshaft Structural Analysis Using Dynamic Substructuring with Ritz Vectors,” Journal of Sound and Vibration December 1994
- Gockel, M. A. “MSC/NASTRAN: Handbook for Dynamic Analysis,” The MacNeal-Schwendler Corporation 1983
- Bella, D. Reymond, M. “MSC/NASTRAN: DMAP Module Dictionary,” The MacNeal-Schwendler Corporation 1994