Simulation models for cranktrains of combustion engines
Tutor / director / evaluatorCodina, Ramon
Document typeMaster thesis
Rights accessOpen Access
The avoidance of excessive free forces and torsional vibration at cranktrains is essential for a long lifetime and silent operation of internal combustion engines. Hence numerical simulations of these properties play an important role in their design. Commonly the design is divided into two stages. In the first conceptual stage numerous design variants have to be simulated by simple methods with low computational cost. The analytical kinetostatic model has been dominating the conceptual simulation of cranktrains for decades. During the following layout stage detailed simulations are carried out. A large number of advanced commercial simulation software packages based on MBS and FEM are available for these complex models. But this software is not effective in fast simulating strongly simplified models how it is required in the conceptual stage. From the recent trend of growing power density in modern car engines emerged a demand for simulation software that fills the gap between these two groups of simulation tools. This master’s thesis compared numerical methods for the computation of free forces, free moments and torsional vibrations at a fundamental level. The aim was to evaluate the prospects of numerical methods such as multibody simulations (MBS) in fast conceptual cranktrain simulations. Multibody models of cranktrains were implemented and compared with the established kinetostatic model. This included a crankshaft that was discretized by beam elements. One of the central questions was whether numerical methods like MBS can gain significant improvements in precision and range of validity when they are applied in conceptual simulations. On the other hand disadvantages of numerical methods such as higher computational cost were assessed.