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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…
 

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…
 

Noise and Vibration End-of-Line Production Testing and Analysis Challenges

Bruel & Kjaer-Chris Moon
  • Technical Paper
  • 2019-01-1464
To be published on 2019-06-05 by SAE International in United States
Theoretical modeling continues to play a larger role in noise and vibration engineering; however, until products are perfectly made, there will be a need to evaluate their end of line (EOL) performance. Manufacturing production of a wide range of items has classically involved some amount of subjective and/or evolved objective quality testing along the line or at the end of the line. This testing can have goals of determining product safety, durability, functionality, or the vibration/sound quality. A vibration-based measurement approach is often used for many of those goals. Often, many modern products utilize some combination of electric motors, internal combustion engines, and power transmission rotational components. The EOL testing for many of these rotational components is after many years now heavily refined in the measurement and analysis methods, and the separation of good, bad and marginally bad samples may not always be challenging. It is frequently the non-standard types of products, either subcomponents or assemblies, which may provide unique challenges to the typical measurement and analysis methods. Additionally, depending on how new the EOL…
 

Numerical Prediction and Verification of Noise Radiation Characteristics of Diesel Engine Block

Deere & Company-Sanghoon Suh
John Deere Technology Center India-Devendra Mandke, Deepak Ghaisas, Sachin Pawar
  • Technical Paper
  • 2019-01-1591
To be published on 2019-06-05 by SAE International in United States
To assess contribution of structure-borne noise from the engine, it is critical to characterize dynamic and vibro-acoustic properties of the engine components and assembly. In this paper, a component level study of a three-cylinder diesel engine block is presented. Virtual analysis was done to predict natural frequencies and mode shapes of the engine block at the first step. Then, these results were used to decide the optimum test location and an experimental modal test was conducted on the engine block. The initial virtual model was correlated with test using natural frequencies and mode shapes. Then, the virtual model was updated with damping derived from experimental modal test to match vibration frequency response functions. Further, the virtual model was used for prediction of vibro-acoustic transfer functions. The vibro-acoustic transfer functions were also obtained from test. The results of transfer function were correlated with test. In future, we plan to use this approach for prediction of vibration and vibro-acoustic transfer functions for sub-assembly and eventually entire engine assembly to be able to use the models to predict…
 

Development of an Accelerated Laboratory Test to Simulate Real-World Tire Flat-Spotting

Nissan Technical Center North America-Scott Fritz
NissanTechnical Center North America-Farokh Kavarana
  • Technical Paper
  • 2019-01-1509
To be published on 2019-06-05 by SAE International in United States
Tire flat-spotting occurs when tires remain in a loaded condition without rolling for an extended period of time, and can be temporary or permanent depending on the length of storage, vehicle loading and environmental factors. Tire non-uniformity caused due to flat-spots often induce shake and shimmy vibration in vehicles due to increased tire-wheel force variation input into the chassis. This results in increased warranty costs for OEMs / tire suppliers and customer dissatisfaction in third-party quality surveys such as J. D. Power IQS. Flat-spotting is of particular concern for slow-moving vehicle inventory that remains parked for long periods at OEM plants and/or dealership lots. OEMs often stipulate or recommend inventory storage practices for dealers that require physical movement of vehicles every 30 days to reduce the risk of tires developing permanent flat-spots. OEMs also provide component level flat-spotting requirements to tire manufacturers during sourcing and specification timing to secure their internal requirements and targets. The study in this paper initially determined real-world flat-spotting levels on an actual vehicle during the adverse summer months of Arizona.…
 

A Computational Process to Effectively Design Seals for Better Wind Noise Performance

Exa Corporation-Robert Powell, Philippe Moron, Sivapalan Senthooran
Jaguar Land Rover-Nicholas Oettle
  • Technical Paper
  • 2019-01-1472
To be published on 2019-06-05 by SAE International in United States
Ability to assess noise transmitted through seals to cabin interiors early in the design process is very important for automotive manufacturers. When seal design is inadequate, noise transmitted can dominate the interior noise, making the wind noise performance of the vehicle unacceptable. This may cause launch delays costing a great deal of money and loss of sales. Designing seals using conventional experimental processes is challenging, since the location and strength of flow noise sources are not known when the seal design is planned. Making changes to the seal system after the tooling stage is expensive for OEMs, as the supplier must cover tool and redesign costs. Deliberate overdesign by adding multiple layers of seals everywhere reduces profit by raising part and manufacturing costs. There is a strong motivation to use reliable computational capabilities to predict interior noise transmitted through seals early in the design process to address these challenges, designing seals right the first time. The current study presents a computational process that can be used to predict interior noise transmitted through seals early in…
 

The Utilization of Onboard Sensor Measurements for Estimating Driveline Damping

Michigan Technological Univ-Jason Blough, DARRELL Robinette
Michigan Technological Univ.-Jon Furlich
  • Technical Paper
  • 2019-01-1529
To be published on 2019-06-05 by SAE International in United States
The proliferation of small silicon micro-chips has led to a large assortment of low cost transducers for data acquisition. Production vehicles on average exploit more than 60 on board sensors and that number is projected to increase beyond 200 by 2020 per vehicle. Such a large increase in sensors is leading the fourth industrial revolution of connectivity and autonomy. One major downfall to installing many sensors is compromises in their accuracy and processing power due to cost limitations for high volume production. The same common errors in data acquisition such as sampling, quantization, and multiplexing on the CAN bus must be accounted for when utilizing an entire array of vehicle sensors. A huge advantage of onboard sensors is the ability to calculate vehicle parameters during a daily drive cycle to update ECU calibration factors in real-time. One such parameter is driveline damping that changes with gear state and drive mode. A damping value is desired for every gear state and recent years has seen an increasing number of forward gear ratio’s ranging from 8-10 in…
 

Structure-borne prediction on a tire-suspension assembly using experimental invariant spindle forces.

Siemens Industry Software NV-Jesús Ortega Almirón, Fabio Bianciardi, Patrick Corbeels
  • Technical Paper
  • 2019-01-1541
To be published on 2019-06-05 by SAE International in United States
Road induced noise is getting more and more significant in context of the electrification of the powertrain. The automotive industry is seeking for technologies to predict the contribution of vehicle components upfront, early in the development process. Classical Transfer Path Analysis (TPA) is a well-established technique that successfully identifies the transmission paths of noise and vibration from different excitation sources to the target responses, but has some drawbacks, such as that it requires the physical availability of the vehicle. To achieve shorter development cycles, avoid costly and time-consuming design iterations, and due to the limited availability of prototypes, engineers derived a method that addresses these requirements. Component-based TPA is a relatively new TPA approach that allows to characterize the source excitation by a set of equivalent loads (blocked forces) independently from the receiver structure and to predict its behavior when coupled to different receivers. FBS is applied in order to obtain the coupled assembly. However, there are a number of challenges affecting its applicability, such as the proper modelling of the coupling degrees of freedom…
 

Early Research on Additively Manufactured Sound Absorbers

Univ of Kentucky-David Herrin
Univ. of Kentucky-Weiyun Liu
  • Technical Paper
  • 2019-01-1576
To be published on 2019-06-05 by SAE International in United States
Additive manufacturing is slowly changing how components are developed and manufactured. As the technology evolves, it is anticipated that industry will begin 3D printing sound absorbers. In many cases, these are components that may be difficult to manufacture in another way. Several designs were 3D printed and positioned in an impedance tube for testing. Absorbers including long perforations, lightweight panels, and Helmholtz resonators with corkscrew configured necks are considered. Simulation is performed using plane wave methods and acoustic finite element analysis.
 

Aluminum Foil Perforation Impact on Acoustic and Thermal Performance of Automotive Sound Absorbers

General Motors-Gang Glenn Yin, Alan Parrett, Timothy J. Roggenkamp
General Motors De Mexico S de R L de CV-Felipe G. Salazar Prieto
  • Technical Paper
  • 2019-01-1580
To be published on 2019-06-05 by SAE International in United States
Adding aluminum foil on sound absorber surface has broad application in automotive industry. The foil layer offers thermal insulation for the parts close to exhaust pipes, turbo charge and other heat sources in engine compartment, it also adds physical protection in tough water-splashing/stone-impinging environment at vehicle exterior. It is known that adding impermeable plain foil will impact the sound absorption negatively, so micro perforated aluminum foil is widely used based on micro perforated absorption principle[]. Analytical results of sound absorption from micro-perforated panel or panel with fibrous substrate materials matches very well with measurement when perforation is well controlled in lab environment. However, for industry mass production perforated aluminum foil, it is found that hole size and shape, which are two important parameters of perforation pattern, are not precisely controlled as the samples for lab research, flimsy foil with thickness in between (0.02-0.25mm) is not behaving exactly like elastic panel. In addition, the adhesive film applied on foil back and hot molding process add more uncertainties to part final performance, moreover perforation pattern also might…