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Evaluation of uncertainties in classical and component (blocked force) transfer path analysis (TPA)

Univ of Salford-Andrew Elliott
Univ. of Salford-Andy Moorhouse, Joshua Meggitt
  • Technical Paper
  • 2019-01-1544
To be published on 2019-06-05 by SAE International in United States
In situ component TPA (originally named in situ source path contribution analysis [Elliott et al. J. Sound Vib., 332 (24) (2013)] has been attracting considerable attention recently. The measurements required with the in situ method are almost identical to conventional TPA but there are two major advantages. First, there is no need to dismantle the vehicle or assembly since all measurements are conducted in situ. Secondly, the forces obtained by matrix inversion are the blocked forces which are an independent property of the source component and are therefore transferrable to different assemblies. The current paper extends this idea of mathematically decoupling components from in situ measurements. The in situ measurement of blocked forces is first considered. A substructure decoupling approach is then described from which independent properties (accelerances) of coupling elements and other components can be extracted from in situ measurements. The independently described components can then in principle be (mathematically) recoupled with other components to build a virtual acoustic prototype. However, the inverse methods used for indirect measurement of blocked forces and for substructure…
 

NVH benefit of the Frunk

Autoneum Management AG-Federico Di Marco, Flavio Pezzani, Andreas Daving, Luca Mazzarella
  • Technical Paper
  • 2019-01-1456
To be published on 2019-06-05 by SAE International in United States
Due to the increasing number of battery electric vehicles (BEVs), the engineering fields regarding driving comfort and NVH issues are becoming more and more challenging: many new factors affect the development of BEVs NVH package. The noise sources related to the powertrain are different from the traditional ones of internal combustion engines, for instance due to the presence of tonal components, strong harmonics and potential whining noise. To satisfy NVH specifications and the need for lightweight solutions to increase driving range, it is important to mask as much as possible the noise coming from the engine bay with materials both lightweight and acoustically performing. Moreover, for electric vehicles new interesting solutions are possible with the introduction of new components, that do not find room under the hood of ICE or hybrid vehicles. These components, if properly designed, could lead to non-negligible NVH benefits. The present paper reports the NVH effects of one of these new components, the frunk, a small compartment inside the engine bay, functionally similar to the trunk. In this paper, the design-by-simulation…
 

Active and Passive Control of torsional vibration in Hybrid Powertrain System

Tongji University-Lijun Zhang, Shijuan Zhang, Dejian Meng, Jie Xu
  • Technical Paper
  • 2019-01-1460
To be published on 2019-06-05 by SAE International in United States
Aiming at the vibration issue in hybrid powertrain system, the torsional vibration mechanical model containing engine,motor and planetary gear subsystems was established. The transient vibration response of typical working condition and modes were analyzed through typical power control strategy ,and the active and passive control of torsional vibration in vehicle hybrid powertrain system was proposed. The active control method of the motor torque was designed and the vehicle shaking vibration was improved. The resonance of the planetary gear system was improved with passive control method by adding the torsional vibration absorbers to the engine and motor. The vehicle shaking vibration and the torsional vibration of the planetary gear system were both improved through the active and passive control.
 

Fast broadband curved Insertion Loss simulation of an inner dash insulator using a cylindrical Transfer Matrix Method spectral approach

Interac-Gerard Borello
Treves-Arnaud Duval, Mickael Goret
  • Technical Paper
  • 2019-01-1583
To be published on 2019-06-05 by SAE International in United States
Middle and high frequency vibro-acoustic simulation of complex shape insulators requires using 3D poroelastic finite elements either for the whole part (up to 2500 Hz maximum) or through singly curved pre-computed Insertion Losses (up to 5000 Hz maximum) to be introduced in large SEA or energy-based models. Indeed, a dependence of the Insertion Loss slopes of noise treatments following the curvature is observed both experimentally and numerically. Beyond frequency range limitations, poroelastic finite elements computations take too much time of typically a few hours each, following all curvatures and thickness 3D maps. A cylindrical Transfer Matrix Method spectral approach allows computing the singly curved Insertion Losses up to 10 kHz in a few minutes only. This is a huge simplification for the SEA modeling effort enabling easier and more precise fully trimmed vehicle middle and high frequency vibro-acoustic simulations. A dash insulator Insertion Loss numerical validation case will be presented comparing all methods with one another.
 

Role of Dynamic Stiffness in Effective Isolation

Deere & Company-Yuzhen Yang
John Deere India Pvt, Ltd.-Balavardhan Reddy Dasabai
  • Technical Paper
  • 2019-01-1495
To be published on 2019-06-05 by SAE International in United States
In any machinery, avoiding noise and vibration completely is a difficult task due to the structural dynamic behaviors of components. To safeguard the operator, it is important to best isolate the operator station from NVH environment. Cabin isolation is an important aspect to minimize structure-borne noise and tactile vibrations to be transferred into the cabin. Isolators are selected based on the isolation system inertial properties at mounting locations in the operating frequency range interested. The most important assumption to select isolators is that the active side and passive side of the isolators are nearly rigid so impedance mismatch is created for effective isolation. This paper describes the importance of dynamic stiffness of the structures on both the active and passive side for better NVH performance. NVH performance of passive side is evaluated analytically and computationally in terms of tactile vibrations and structure-borne noise for various ratios of the dynamic stiffness over isolator stiffness. The isolator selection criterion is also discussed based on rigid body modes, operating frequency range, transmissibility ratio, and kinematic energy distributions.
 

Model Verification of CAE with NVH-test Acting on Downsized Car Engines

Automotive Powertrain CAE NVH-Urban Rönnqvist
NVH-testing Powertrain-Janos Ribarits
  • Technical Paper
  • 2019-01-1550
To be published on 2019-06-05 by SAE International in United States
Today’s trend of downsized internal combustion engine development for cars is characterized with; high torque, low engine speed, low weight, high degree of cyclic irregularity, low excitation frequency due to fewer cylinders active e.g. 4-cylinder or less. Torque output 100 Nm at low engine speed 1000 rpm has become normal. This implies in respect of vibrations that it is important to control engine suspension rigid body modes e.g. roll yaw and pith ones. The rigid body modes frequencies should be low so they cannot be reached and induced by the low exciting harmonics of cylinder pressure and mass forces for low engine speeds or idling. Crucial is the rigid body modes in relation to the excitation forces. It is also important to control the overall flexible vibration modes. Our purpose is to describe the method to optimize the powertrain suspension, beginning with modeling/simulation and ending with verifying the vibration level on a real running engine i.e. a Volvo Cars in-line 4-cylinder VEA diesel engine in a test rig/cell. As a method a mathematical CAE model…
 

Structural Vibration and Acoustic Analysis of a 3-Phase AC Induction Motor

Peyman Poozesh
Kettering Univ-Allan Taylor, Javad Baqersad
  • Technical Paper
  • 2019-01-1458
To be published on 2019-06-05 by SAE International in United States
This paper is aimed at studying the NVH and acoustic performance of a 3-phase AC induction motor in order to find a way to reduce the magnetic component of noise from an electric motor in an electric vehicle (EV). The method suggested here is to reduce the magnetic component of sound from the motor by making modifications to the end bracket of the motor housing. EVs are being considered the future of mobility mainly owing to the fact that they are environment-friendly. With a lot of companies already investing heavily in this technology, electric drives are set to become extremely popular in the years to come. The heart of an EV is its motor. Modern electric vehicles are quiet and with the lack of an IC engine to mask most sounds from other components, the sound from the electric motor and other auxiliary parts become more prominent. This paper lays down a process to analyze the sound radiated from the electric motor in three broad steps. First, to model the motor in an electromagnetic platform,…
 

New acoustic material for vehicle applications and measurement techniques to determine absorption coefficient for small size test samples

Mikromasch Eesti Ltd-Anna Kozmenkova
Tallinn University of Technology-Jüri Lavrentjev, Hans Rämmal
  • Technical Paper
  • 2019-01-1585
To be published on 2019-06-05 by SAE International in United States
A new sound absorbing material for vehicle applications is presented and acoustic properties are investigated in this paper. The material is made of natural leather collagen and inhibits unique characteristics of genuine leather. Production technology uses the residues of leather industry, is ecofriendly and allows fabrication of the parts of any shape. The price is competitive to synthetic polymers. Absorption coefficient is one of the most commonly used parameters to characterize acoustic properties of materials. There are two main techniques to experimentally determine the absorption coefficient: the impedance tube transfer function method and reverberant room method. In the second case the absorption coefficient is determined at random incident sound field while in the impedance tube only direct incident field is considered. The main advantage of the first method however is the small size of samples. Therefore the impedance tube method was preferred in this investigation, since in the developing process of new material only small samples were available. The standard reverberation room method is limited to minimum size of samples of 10m2. In the paper…
 

Design & Development of Partial Engine Encapsulation for Interior Noise Reduction in Commercial Vehicles

VE Commercial Vehicles Ltd-Sourabh Jadhav
VE Commercial Vehicles Ltd.-Yadhu S. Aswan
  • Technical Paper
  • 2019-01-1589
To be published on 2019-06-05 by SAE International in United States
This paper focuses on partial encapsulation technique for reducing air-borne noise from the rocker cover of a commercial vehicle diesel engine. Due to increasing awareness, customers demand for improvised NVH-Noise Vibration and Harshness performance in modern day vehicles. Better NVH performance implies better comfort for passengers as well as vehicle operator. This further increases the driver up time due to reduced driver fatigue. In order to improve NVH performance of existing vehicle and observe different noise and vibration zones, detailed noise and vibration mapping was carried out on one of our vehicle platform. It is observed that engine noise is one of the major contributors for interior noise, apart from road inputs etc. There are well established methods to reduce the inherent noise of the engine, but the same might affect other performance parameters including fuel efficiency and exhaust emissions, which are pain areas of major automotive industries due to stringent homologation norms. Engine top area partial encapsulation with barrier cover is designed considering various integration as well as heat load constraints at vehicle level.…
 

Developing a Custom Data Acquisition Software Package for a Self-contained Acoustic Testing Facility

Kolano and Saha Engineers Inc-Sagar Patil, Pranab Saha
Kolano and Saha Engineers Inc.-Richard Kolano
  • Technical Paper
  • 2019-01-1501
To be published on 2019-06-05 by SAE International in United States
This paper provides an overview of custom software developed for the sound generation, control and data acquisition of a self-contained acoustic testing facility system used for conducting random incidence sound absorption tests and sound transmission loss tests on small samples in accordance with SAE J2883 and J1400 standards, respectively. The paper discusses the thoughts behind developing user friendly algorithms and graphical user interfaces (GUI) for sound generation, control, data acquisition, and signal processing to obtain good data and precautions should there be any anomalies in the data.