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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Assessment of a Hybrid Patch Transfer-Green Functions Method for Predicting the Vibroacoustic Response of Curved Systems with Attached Noise Control Treatments</title>
      <link>https://trid.trb.org/View/1561882</link>
      <description><![CDATA[This article aims to assess and discuss the performances of a hybrid methodology by considering the radiation of a curved structure-cavity system with attached noise control treatments. The hybrid method uses a Patch Transfer Functions (PTF) approach to couple the standard finite element method of the curved structure and cavity with an analytical model of the sound package, i.e. Green functions based model. First, the used approach is presented. Then, the accuracy of the proposed methodology is assessed for two different curved noise control treatments, namely (i) light foam and (ii) light foam with a mass layer. The obtained results are systematically compared to three models, namely full Finite Element/Boundary Element (FEM/BEM) strategies, and to two sub-structuring approaches where the sound package is modeled by (i) a locally reacting model and (ii) FEM. It is shown that the proposed method predicts accurately and efficiently the dynamic behavior of curved trimmed vibroacoustic systems. Moreover, such hybrid approach is suitable for speeding up and facilitating the integration of acoustic treatments, especially at the early stage of the design process where several configurations of the acoustic treatments are tested with the same structure and cavity.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561882</guid>
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    <item>
      <title>Passive Treatment Solutions for the Reduction of Vehicle Exterior Tire Noise</title>
      <link>https://trid.trb.org/View/1561881</link>
      <description><![CDATA[The recently updated pass-by noise measurement procedure prescribes a mix of acceleration tests and constant speed tests. This has led to an increased relevance of tire noise relative to the past, when the procedure prescribed only acceleration tests. In addition, the next phase of the roadmap for pass-by noise limits for passenger vehicles is 70 dB(A) by 2020, later followed by 68 dB(A). In this context, exterior tire noise has drawn increasing attention. OEMs, suppliers of passive acoustic treatments, road manufacturers and tire manufacturers are, at the moment, devoting strong efforts to the definition of solutions for the control of exterior noise.         This paper is concerned with the potential of existing passive exterior treatments to reduce the exterior noise generated by the tires. Different countermeasures are analyzed, namely wheelhouse liners, under-engine shields, under-body panels and under-trunk panels. The goal is to provide a sensitivity analysis with respect to the absorption characteristics and a ranking of the relevance of these treatments in the perspective of taking rational decisions to lessen the exterior noise. Results are based, on one hand, on advanced FEM simulation applied on a full generic vehicle and, on the other hand, on ATF measurements done on a European C-segment vehicle. In this way, in one single predictive system, all the acoustic parts likely to contribute to the reduction of tire noise are taken into account. Plus, it is possible to derive part configuration solutions associated with quantified objective of pass-by noise reduction.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561881</guid>
    </item>
    <item>
      <title>The Use of “Big Data” for the Analysis and Design of Vehicle Sound Packages</title>
      <link>https://trid.trb.org/View/1561880</link>
      <description><![CDATA[With the ever-decreasing timescales and increased performance requirements afforded to OEM’s, it has become essential that NVH suppliers provide optimum palliative solutions that comply with a vehicles acoustic targets.         The acoustic effect of any palliative treatment attached to a vehicle body system depends on its ability to attenuate noise energy passing through or radiating from the system or its interaction with reflected sound from other areas. Acoustic performance uses targets relating to sound insertion loss (SIL) and / or sound absorption and these are identified to the component supplier by the OEM at the “request for quotation” (RFQ) stage. For many potential suppliers, especially those with a limited portfolio of material options, success or failure is quite straightforward. However, the problem occurs when the material and processing opportunities cover wide parameters and the available combinations and permutations are extensive. It is no longer a simple choice to get the best solution. Ultimately, competitiveness relies on the optimum choice of material types, combinations and processing along with associated cost and this requires a detailed understanding of the ‘physics’ involved. Whilst material prediction software is frequently used to spot check performance prior to actual material testing this technique cannot guarantee success. It is also very time consuming and requires considerable training. The aim of this project was to use “Big Data” to automate the selection process.         This paper describes the Authors work with “Big Data” combined with associated algorithms, so that once a system target is received a range of suitable solutions can be offered without pre-determination of parameters. It covers the creation of the “Big Data” landscapes and the integration of the procedure into a web based easily accessible application.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561880</guid>
    </item>
    <item>
      <title>The Patch-Transfer-Function (PTF) Method Applied to Numerical Models of Trim Materials Including Poro-Elastic Layers</title>
      <link>https://trid.trb.org/View/1561879</link>
      <description><![CDATA[In automotive industry, acoustic trim materials are widely used in order to reach passenger comfort targets. The dynamic behavior of the poro-elastic materials is typically modelled by the Biot theory, which however leads to expensive numerical finite element calculations.         One way to deal with it is to use the Patch-Transfer-Function (PTF) sub-structuring method, which couples subdomains at their interfaces through impedance relations. This was done already for systems including locally reacting poro-elastic materials.         In this paper, a methodology is presented allowing to numerically assess the PTF impedance matrices of non-locally reacting trim materials using the Biot based poro-elastic model solved by the finite element method (FEM). Simplifications of the trim impedance matrices are introduced resulting in considerable calculation cost reductions. The associated prediction errors are discussed by means of a numerical case study. The numerical test case consisted of a clamped plate covered with a double layer trim radiating into a rectangular air cavity. It is shown that a considerable calculation time reduction may be achieved while keeping prediction accuracy at an acceptable level.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561879</guid>
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    <item>
      <title>Efficient Trim Modelling Simulation Method for Vehicle Design Phase</title>
      <link>https://trid.trb.org/View/1561878</link>
      <description><![CDATA[During the design phase of a vehicle, it is important to have a simulation tool, which allows to make multiple runs and check the sensitivity of the acoustic response to several trim configurations with a quick turnover time.         The Statistical Energy Analysis (SEA) is widely used to investigate such problems for airborne excitation. For structure-borne excitation, classical methods based on a simplistic modeling of the trim using 1D oscillators and non-structural mass are not accurate enough to capture the actual behavior of the trim. On the other hand, a detailed Finite Element-Poroelastic Element Method (FE-PEM) modeling strategy of the trim may be time consuming. Besides the large number of degrees of freedom required to accurately model dissipative materials (e.g. poroelastic), a FE-based approach also needs a preprocessing phase where each layer of the trims must be carefully meshed. This task can be time consuming when the response of several configurations of the same system must be simulated, like, for instance, in an optimization process.         In this paper, two alternative strategies based on the Transfer Matrix Method (TMM) are proposed to evaluate the surface impedance of the trim. This impedance can be applied to the FEM model of the bare vehicle and allow a first design change analysis before a more detailed concept validation done using FE-PEM.         The method will be demonstrated on industrial example.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561878</guid>
    </item>
    <item>
      <title>A Case Study of a Full Inverse Poroelastic Characterization of an Open-Cell Porous Material Using an Impedance Tube: The Need to Properly Prepare the Material and to Control the Measurement</title>
      <link>https://trid.trb.org/View/1561877</link>
      <description><![CDATA[This paper presents a case study on the full inverse characterization of the material properties of an open-cell poroelastic foam using impedance tube measurements. It aims to show the importance of controlling the lateral boundary condition in the impedance tube, and selecting an appropriate acoustic model to obtain the most accurate material properties. The case study uses a four-inch thick melamine foam and a 100-mm diameter tube. The foam is mechanically cut to fit within the circular tube. However, the cutting process is not perfect and a tiny lateral air gap exists between the material and the tube (i.e. the foam diameter is 99.5 mm for a 100-mm diameter tube). The typical characterization procedure is to mix direct and indirect measurements to retrieve the material properties of the foam. First, open porosity, bulk density, and static airflow resistivity are directly measured. Second, tortuosity, viscous and thermal characteristic lengths, and elastic properties are identified by inverse characterization using impedance tube measurements. The inverse characterization uses different choices of frame behavior models (rigid, limp, or elastic), and lateral boundary conditions (with and without lateral air gap). The paper discusses the effects of the choice of the frame behavior model and lateral boundary condition. Notably, it shows that the tiny air gap can seriously affect the inversely characterized material properties. Moreover, the choice of the frame model impacts less the quality of the inversion, but allows or not the characterization of the elastic properties. Finally, the paper concludes with recommendations and guidelines to improve the accuracy of the inverse characterization procedure, and discusses its limitations.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561877</guid>
    </item>
    <item>
      <title>An Application of Acoustic Metamaterial for Reducing Noise Transfer through Car Body Panels</title>
      <link>https://trid.trb.org/View/1561876</link>
      <description><![CDATA[This paper presents the design of an additional structure based on acoustic metamaterial (AMM) for the reduction of vibro-acoustic transfer function of a car body panel. As vehicles are lighter and those engine forces are bigger recently, it has become more difficult to reduce the vibration and noise transfer through body panels by using just conventional NVH countermeasures. In this research, a new approach based on AMM is tried to reduce the vibration and noise transfer of a firewall panel. First, a unit cell structure based on the locally resonant metamaterial is devised and the unit cell’s design variables are studied to increase the wave attenuation in the stop band of a dispersion curve, where the Floquet-Bloch theorem is used to estimate the dispersion curve of a two-dimensional periodic structure. Also, the vibration transfer and the vibro-acoustic transfer are predicted in a FE model of meta-plate which is composed of a periodic system of the devised unit cell. Next, the driving point mobility of a meta-plate is tested and its design is updated for the better performance in a vehicle. Finally, the revised structures which are mounted on a firewall are tested to verify the vibration transfer and vibro-acoustic transfer characteristics in the firewall. As a result, it is shown that the suggested meta-plate structure has a good effect on reducing the noise transfer through car body panels.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561876</guid>
    </item>
    <item>
      <title>Simulation and Application of Lightweight Damping Sandwich Material for I.C. Engines</title>
      <link>https://trid.trb.org/View/1561875</link>
      <description><![CDATA[Making lighter engines is in the agenda of all OEMs in order to make their cars lighter and to reduce CO2 emission based on regulations. On the other hand, the noise regulations are getting more stringent and the customer impression of interior sounds is still an important aspect in vehicle development. Vehicle noise legislation has been revised numerous times since it was first established in February 1970. The latest revision in EU legislation introduces a revised test method which is used to enforce diminishing noise limits in three phases (EU Regulation No. 540/2014). Since 2016 the noise limit for passenger cars has been 72 dB(A). It will be reduced to 70 dB(A) in 2020 and to 68 dB(A) in 2024. These vehicle pass by noise limits cascade down to limitations on engine noise.         New engine designs face a trade-off between a lightweight design and fulfilling the NVH targets. The conventional design updates are done by adding ribs and usually mass to the engine. On the other hand, the advanced lightweight materials with high damping characteristics have been developed which help lightweight good NVH design. Nonetheless the correct use of these materials requires proper material data measurement and proper material, thickness selection. The temperature effect should not be ignored as well specially in engine application. In this paper, the method of measuring the material properties is explained. Then a simulation model is introduced and validated for the application of such a material to the case of a rectangular beam. Finally, the application of such a material is presented for an engine front cover. The high damping effect is shown, and the correlation of models to measurement for two different temperatures is shown. This method can be used to select the damping and materials and improve the engine NVH.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561875</guid>
    </item>
    <item>
      <title>An Overview of Microstructural Approaches for Modelling and Improving Sound Proofing Properties of Cellular Foams: Developments and Prospects</title>
      <link>https://trid.trb.org/View/1561874</link>
      <description><![CDATA[Significant advances have been made over the last 15 years in the field of modelling the acoustic properties of foams from the description of their microstructures. It entails a multidisciplinary work at the junction between physico-chemistry and mechanics of porous media, which involves a dialogue between different disciplines and requires the joint development of several techniques (imaging, upscaling, numerical computations, and experimental identification). It seems to be of timely interest to take stock of the methodological developments that have provided guidance on how to manufacture the new generation of foams with enhanced properties and to identify possible future methodological developments.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561874</guid>
    </item>
    <item>
      <title>Active Noise Cancellation System to Tackle Charge Sustain Idle Noise in a PHEV Vehicle</title>
      <link>https://trid.trb.org/View/1561873</link>
      <description><![CDATA[With the advent of PHEV vehicles OEMs face additional NVH issues. A particularly new issue is a low frequency booming noise caused during charging of batteries using the internal combustion engine. During charging the engine is operated at low rotational speeds and high loads, leading to pronounced low frequency noise. While in the past reducing low frequency noise either required large absorbers and/or heavy dampers, today the issue can be tackled by use of an Active Noise Cancellation system.         Jaguar Land Rover decided to introduce an Active Noise Cancellation system in the PHEV variants of some of their vehicles. The system builds upon software by Müller-BBM Active Sound Technology GmbH and makes use of the existing audio amplifiers. The only extra hardware component required are microphones in the vehicle headliner.         Overall the ANC system only adds minimum weight to the vehicle but allows for noise reduction in excess of 10 dB at frequencies below 40 Hz during charge sustain idle operation. In addition, the system enabled JLR to cancel noise at other operating conditions, allowing several mass-dampers to be removed, offering weight opportunities of around 5 kg. This contribution will show how the system is designed, and it will give an idea on the ANC system performance in different operating conditions.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561873</guid>
    </item>
    <item>
      <title>Development of Mass Producible ANC System for Broad-Band Road Noise</title>
      <link>https://trid.trb.org/View/1561872</link>
      <description><![CDATA[The mass producible broad-band ANC system for road noise is developed with fully digital control system. For this configuration, installation packages are intensively considered by minimizing size of the controller, simplifying wiring system and implementing virtual microphone techniques. Virtual microphone technique enables error microphone to be installed in remote position of driver’s ear, and therefore, increases installation degree of freedom significantly. To enhance noise control performance with the minimum latency, filter design of FxLMS algorithm is optimized while additional audio compensation techniques are applied to maintain audio performance of amplifier. The present ANC system is equipped to HMC (Hyundai Motor Company) new release of hydrogen driven vehicle, which is introduced in the technology promotion event in Pyeongchang Olympic 2018.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561872</guid>
    </item>
    <item>
      <title>Active Noise Control and Masking Sound on Speech of a Back-Seat Passenger at a Driver’s Seat</title>
      <link>https://trid.trb.org/View/1561871</link>
      <description><![CDATA[Passengers sitting on the back seats of cars while talking on their mobiles can easily experience the invasion of their speech privacy by the driver. Protecting speech privacy can be done by utilizing masking sounds - masking sound may be so loud that it annoys both drivers and speakers. In this research, the feasibility of utilizing active noise control (ANC) which aims to reduce the level of speech at the driver’s seat and, hence, is able to lower the needed level of masking sounds while still protecting the speech privacy is investigated. Speech reception threshold (SRT), which is a subjective measurement method for speech intelligibility, is proceeded for seeing the effect of ANC on speech intelligibility when the masking sound is in use. The SRT measurement result implied that utilizing ANC to reduce the speech level of the back-seat passenger at the driver’s seat is able to lower the needed level of masking sound for keeping the speech privacy.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561871</guid>
    </item>
    <item>
      <title>Nonlinear Acoustic Analysis of Loudspeakers in the Exhaust Dynamic Sound Technology</title>
      <link>https://trid.trb.org/View/1561870</link>
      <description><![CDATA[An ongoing trend among automotive exhaust suppliers is the application of loudspeakers in their systems to tailor the exhaust sound to the customers’ needs. In addition to it, undesirable engine order noise can be cancelled by a closed loop control system. Due to the high sound pressure from the engine, the loudspeaker is often required to run at its power maximum. A higher input power eventually causes a nonlinear behavior, resulting in undesirable sound pressure level or harmonic distortion. Thus, the understanding of nonlinear behavior of loudspeakers and the recognition of dominant effects are required. This paper presents the main nonlinearities of loudspeakers and the comparison of theories on linear and non-linear loudspeaker models. For validation of the model, one loudspeaker enclosure and one typical exhaust system with a loudspeaker have been calculated. Ultimately it was found that a nonlinear loudspeaker model would be essential for a precise tuning of active exhaust sound systems.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561870</guid>
    </item>
    <item>
      <title>Finite Element Based Active Vibration Control of Hierarchical Honeycomb Plates Integrated with Piezoelectric Actuator</title>
      <link>https://trid.trb.org/View/1561869</link>
      <description><![CDATA[Hierarchical honeycomb (HH) structures with level of hierarchy more in the honeycomb construction (by replacing the vertices of a regular hexagonal lattice with smaller hexagons) are widely used in engineering applications mainly due to their superior mechanical behavior and lightweight high strength characteristic. At the same time, the role of hierarchy and control gain on the dynamic behavior of HH structures with surface-bonded actuator remains largely unexplored.         In this study, we investigated the active vibration control behavior of the HH structure with surface-bonded piezoelectric actuators. The HH plate like structures was constructed with two identical face sheets and placed HH core in-between. By using ANSYS parametric design language (APDL), the proportional-integral-derivative (PID) control algorithm was incorporated into the finite element model for performing the closed-loop control simulations. The accuracy of the present method was validated with other researchers’ results. Furthermore, different parametric cases such as the effects of control gain and level of hierarchy to the transient vibration behavior of HH plates with surface-bonded actuators were investigated.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561869</guid>
    </item>
    <item>
      <title>Managing Increasing Exhaust System Variants for Passenger Vehicles</title>
      <link>https://trid.trb.org/View/1561868</link>
      <description><![CDATA[In all major markets, the legislation on emissions (CO2, NOx, and PM) and on pass-by noise limits have been drastically lowered over the last years and will be even lower in the near future. This will have an enormous impact on the design of future passenger cars, their powertrains, and finally their exhaust systems with an inherent cost penalty. Moreover, the individual market requirements in Europe, Asia and the Americas differ in some respect often calling for individual variants. The increasing number of vehicle models and platform derivatives e.g. sedan, hatchback, coupe, convertible, sports utility vehicle, cross-over etc. leads to a huge variety of exhaust systems even within a single OEM platform let alone a whole OEM product portfolio. This causes significant effort in development, tooling, manufacturing, part handling, and logistics. The Active Noise Cancellation technology (ANC) has been investigated in the automotive industry for many years. The basic principles are well understood and active engine mounts as well as in-cabin active noise cancellation are in series production for a few years. For exhaust muffler systems, several studies at prototype level have demonstrated technical feasibility and resulted in substantial benefits for acoustical performance and sound design. Moreover, advantages in package space, weight, and backpressure have been demonstrated for different engines. In this publication, an overview of different active exhausts compared to conventional cold-end systems will be given and the advantages in development time, reduction in the number of variants and possible cost impacts will be analyzed.       ]]></description>
      <pubDate>Mon, 26 Nov 2018 16:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561868</guid>
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