Developing an analytical model for a marine diesel engine test stand

This article aims to develop an analytical model for designing the foundation of engine test stands. The whole system was modelled by including the harmonic variation of the dynamic forces, the magnitudes of the forces, the constant and the moving parts of the engine and the dynamometer, foundation lower slab and upper slab, concrete properties of the foundation, the springs between the foundation slabs, location of the engine and dynamometer on the foundation, gravity centers etc. This study consists of four main steps. At first, the engine foundation is focused, and its general characteristics, dimensions, sectional views, concrete properties, gravity centers, ground characteristics and soil properties are evaluated. So a static endurance capability and strength calculations are overcome. Secondly, the dynamical forces (maximum gas pressure inside the combustion bowl and acting onto the piston crown area) and dynamical loads (fixed and moveable parts of the engine, their masses, inertia, rotating and linear moving mass forces) are evaluated. At further step, analytical model was formed. The test stand is then modelled by a pair of spring and mass system. Vibrations model is utilized by two degrees of freedom. At final step, solution of the mathematical model about the test stand (foundation + engine + dynamometer) is discussed and concluded.