Power Transmisison Torsional Analysis for a Tilting Test Stand

Abstract

An engine tilting test stand is still in the design process at VTP Roztoky. During this design process, a model has been suggested that starts with the engine, and ends with a dynamometer. Throughout this thesis, first an analytical, and then a dynamic model has been built in the necessary software to examine and evaluate mass properties of rotating parts of a flexible power transmission between a combustion engine and a dynamometer. The natural resonant frequencies of the system have been assessed, and the behavior of the system during the resonant frequencies have been evaluated. Using the dynamic model, the dynamic torques between the relevant parts have been examined, and in some cases converted to other variables to monitor the safety, and possibly failure, of the relevant parts in question. Transient behavior for engine start and engine stop has also been assessed, and monitored for possible critical conditions, and finally, design suggestions have been made to get the system to create alternative options for the parts in question, and possible make the system more efficient and safe.

An engine tilting test stand is still in the design process at VTP Roztoky. During this design process, a model has been suggested that starts with the engine, and ends with a dynamometer. Throughout this thesis, first an analytical, and then a dynamic model has been built in the necessary software to examine and evaluate mass properties of rotating parts of a flexible power transmission between a combustion engine and a dynamometer. The natural resonant frequencies of the system have been assessed, and the behavior of the system during the resonant frequencies have been evaluated. Using the dynamic model, the dynamic torques between the relevant parts have been examined, and in some cases converted to other variables to monitor the safety, and possibly failure, of the relevant parts in question. Transient behavior for engine start and engine stop has also been assessed, and monitored for possible critical conditions, and finally, design suggestions have been made to get the system to create alternative options for the parts in question, and possible make the system more efficient and safe. The analytical model and the dynamic model show the same natural frequencies, which justifies that the system model was properly built in the software GT-Suite. The dynamic variables have been evaluated and it has been found out that both the dual mass flywheel and the hydro motor are safe to use, as long as the resonant frequencies are passed in a short period of time without letting the resonant peak torques build up. The critical dynamic torque value for the dual mass flywheel 480 Nm, and the critical pressure value for the hydro elements 360 bars are both not exceeded. In both cases the simulation results show that the values do not even exceed 200. The frequency analysis shows that the critical areas are between 0-100 RPM and 800-900 RPM, where the resonant frequencies cross with the engine RPM and create high torque and rotational speed amplitudes. Finally, the future steps regarding the project are discussed, where a suggestion has been made to improve the analytical model by adding extra masses and torsional stiffness, while it is stated that its possible and needed to build a full engine model in 1-D to be able to properly evaluate the transient engine starting and stopping conditions.