Simulysis Blog

Engineering Challenge:

Crank shaft is a large component with a complex geometry in the I.C engine, which converts the reciprocating displacement of the piston to a rotary motion. Crankshaft consisting of shaft parts, two journal bearings and one crank pin bearing. The Shaft parts which revolve in the main bearings, the crank pins to which the big end of the connecting rod are connected, the crank arms or webs which connect the crank pins and shaft parts. The design of modern engines is required to make noise and vibration as light as possible. In order to successfully control the noise and vibration, the vibration of  crankshaft which  can cause vibration and noise of the engine, and some even can destroy crankshaft bearing and crankshaft itself must be estimated and analyzed. So early in design stage, computations  of natural frequencies and mode shapes of crankshaft system are indispensable.

A crankshaft  system vibration is a complex three-dimensional coupled vibration under running conditions, including the torsional, longitudinal and lateral vibrations. So a detailed modal analysis is to performed to determine the fundamental vibration mode shapes and corresponding frequencies.

The objective is to perform a modal analysis of a crank shaft to determine its mode shape and its natural frequency. A three-dimension models of crankshaft was modeled and meshed (Pre-Processing). The mesh file is then imported to a solver and different material property required for solving has to be specified. The necessary boundary conditions should also be given. The solving is then carried out and different mode shapes are then viewed in a Post-Processor. The maximum deformation, maximum stress point and dangerous areas are found by the stress analysis.


First mode Displacement:

Fifth mode Displacement:

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