The goal of the project is to develop and define new and more accurate methods of analysis for use at the power train (engine to road-wheel) design stage to avoid tiresome and costly rectification programmes during prototype development.
The project addressed two main vibration and noise generation areas, i.e. the engine and the drivetrain. The research was conducted with reference to a typical powertrain of medium class European car and all the methodologies developed were experimentally validated with respect to this powertrain. A multibody software was developed, capable of loading a FE powertrain model with the excitation generated by the combustion and inertia forces, piston secondary motion and valvetrain dynamics loads. The computed results were successfully compared with the measurements carried out on the real engine, suitably instrumented. A Statistical Energy Analysis technique was developed to deal with I.C. engines. A global engine SEA model has been made available and its reliability was demonstrated in predicting averaged vibration and noise levels, so allowing the analytical evaluation of the effect of changes in the engine design parameters.
A non-linear driveline model was developed, showing good correlation with the experimental measurements. A rattle index was developed, and statistical techniques were used to generate optimal indices which relate objective metrics based either on measured data or on data predicted by the driveline model.
The project will address two main vibration and noise generating areas :
-engine structure (Subproject 1 Engine FEM, Subproject 2 Engine SEA)
-drive train (Subproject 3 Gear Rattle).
1. ENGINE FEM : To develop an innovative software package, relying on Finite Element Modelling, capable of predicting the vibrations and noise radiation of the structures up to 2000 Hz.
The focus will be on a more accurate prediction of the excitation forces.
2. ENGINE SEA : To develop a methodology, based on Statistical Energy Analysis techniques, suitable for analysis and prediction of vibration and noise above 500 Hz.
3. GEAR RATTLE : To develop a dynamic model of the drive train capable of predicting the gear rattle phenomenon (audible impact of gear meshes) under transient drive and steady state idle conditions.
An objective performance index of gear rattle will also be defined by correlating subjective responses to a wide range of objective measures.
The generated predictive tools will be the object of a thorough stepwise experimental validation.