Coupled Vibration Modal Analysis Of Marine Diesel Engine And Testing Platform

Vibration is ubiquitous in the dynamical system; we can say that vibration question is ubiquitous in actual projects. The internal-combustion engine is a kind of widely used power machine; it is one of main vibration source of motive equipment such as diesel locomotives, shipping, automobile, tractor, engineering machinery, etc. The theoretical research indicates that unbalanced mass force and moment on the internal-combustion engine are the main encouragement source of complete machine vibration. Strong vibration will cause the equipment to lose efficiency, and will cause danger to the personal security. During some engine maker make shop test on newly built test platform, engine goes through serious structure vibration, the drama of its vibration is unprecedented. In order to analyses the reason for producing resonance. This paper uses the theory of FEM and ANSYS 7. 0 software in large-scale structure, through setting up the finite element model of large-scale marine diesel and its testing platform, adopt the method of Subspace, calculating and analyzing the dynamic characteristic (namely frequency and vibration deform shape), also it compares calculation results with test modal result. Through this vibration calculation, make resonance source on MBD5S60MC can be clearly present: the engine positioned in new factory of its natural frequency approach the excited frequency, caused violent vibration. When the engine positioned in the old factory no resonance happen anymore, it further indicates that structure of testing platform make important role on vibration, it should never be ignored. With this paper calculation and combined with test result can trace out the reason of resonance during engine running test, excluding the misunderstanding of excessive vibration on diesel engine itself. This paper establishes the coupled finite element analysis modal on marine diesel engine and testing platform can optimize the design proposals for the engine maker. Through the optimized design, may avoid producing similar resonance cases. Thus in the test platform design arrangement stage, improved design can select and match the arrangement for the diesel engine to provide more accurate reference, and has the vital significance on improving production efficiency.