Dynamic Substructuring for Sources Contributions Analysis in Internal Combustion Engines

Abstract

For vibration and acoustics vehicle development, one of the main challenges is the identification and the analysis of the noise sources, which is required in order to increase the driving comfort and to meet the stringent legislative requirements for the vehicle noise emission. Transfer Path Analysis (TPA) is a fairly well established technique for estimating and ranking individual low-frequency noise or vibration contributions via the different transmission paths. This technique is commonly applied on test measurements, based on prototypes, at the end of the design process. In order to apply such methodology already within the design process, a contribution analysis method based on dynamic substructuring of a multibody system is proposed with the aim of improving the quality of the design process for vehicle NVH assessment and to shorten development time and cost. The methodology here proposed is applied to assess vibrational contributions of an internal combustion engine without considering the corresponding Frequency Response Functions (FRF). Hence, the different excitations of the system (e.g. combustion, piston-liner interaction, bearing contact forces, etc.) are directly applied on the investigated geometry and their contributions are computed through numerical simulation. A comparison of the influence on the overall vibrations of the different excitations acting on an I3 engine will be done for structural vibration paths. The applicability and the accuracy of the methodology is finally discussed with reference to experimental measurements of a V6 engine. Two variants of the engine are investigated: the main differences between the two engine variants, mostly associated with piston-liner interaction forces, are investigated at mid-low frequency main engine orders for the entire speed range at full load condition. The proposed methodology is performed to assess the influence of these differences in terms of acceleration level on the external surface of the numerical model of the engine

Influence of cyclic cylinder pressure variability in the numerical transfer path analysis of multi-body engine

“…In common FMBD systems for industrial applications, the contacts between different bodies are often nonlinear. In order to analyze the dynamics of a substructure considering nonlinear connections at interfaces, a numerical transfer path analysis, based on the sub structuring of a multibody system, was proposed [23,24]. The aim of this methodology is to decompose the original system in order to identify vibro-acoustic sources and noise paths of a vibrating subsystem.…”

“…The transmissibility based method known as Operational TPA, developed to overcome the disadvantage of having individual measures of each single path from a source to a receiver, was developed by Nomura and Yoshida [19]; further reviews and benchmark studies can be found in [20,21].Recent applications combine the TPA methodology with the novelty of numerical simulations. The Hybrid TPA formulation (HTPA) uses simulated excitation forces as input for TPA analysis, where the vibro-acoustic transfer functions are measured [22], while the Numerical TPA (NTPA) proposed in [23,24] is based on the Dynamic Sub structuring (DS) of flexible multi-body systems.…”

Low noise, vibration and harshness solutions for in-line three-cylinder range extender and hybrid electric vehicles

“…Most research has been performed in this area with balance shaft application with four-stroke inline three-cylinder units as the subject engine [6][7][8][9][10]. Two-stroke cycle engines for range extenders or hybrid drive train have been researched by Stan and Personnaz [11], Mattarelli et al [12], Borgi et al [13] and Hooper [14] [15].…”

“…6 Alternatively, the couple can be successfully counteracted by more direct methods via the addition of a contra-rotating balance shaft designed to cancel the action of the couple. This has been considered via the studies by Kim et al, 4 Acri et al, 7 Coltman et al, 8 Suh et al 9 and Heifetz and Marsh. 10…”

“…Most research has been performed in this area with balance shaft application with four-stroke in-line three-cylinder units as the subject engine. 6–10 Two-stroke cycle engines for range extenders or hybrid drive train have been researched by Stan and Personnaz, 11 Mattarelli et al, 12 Borghi et al 13 and Hooper. 14 , 15 Some researchers have considered the in-line three-cylinder two-stroke cycle engine as a suitable candidate as demonstrated by Duret et al, 16 Schlunke, 17 Cantore and Mattarelli, 18 Mattarelli 19 and Mattarelli and Rinaldini, 20 but none of these examples applied a balance shaft.…”