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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <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>Design Strategies for Integrating a Quieter Refrigeration Handling System in Automotive HVAC</title>
      <link>https://trid.trb.org/View/2623876</link>
      <description><![CDATA[In both internal combustion engine (ICE) and electric vehicles, Heating, Ventilation, and Air Conditioning (HVAC) systems have become significant contributors to in-cabin noise. Although significant efforts have been made across the industry to reduce noise from airflow handling systems, especially blower noise. Nowadays, original equipment manufacture’s (OEMs) are increasingly focusing on mitigating noise generated by refrigeration handling systems. Since the integration of refrigeration components is vital for the overall Noise Vibrations and Harshness (NVH) refinement of a vehicle, analyzing the impact of each HVAC component during vehicle-level integration is essential. This study focused on optimizing the NVH performance of key refrigeration components, including the AC compressor, thermal expansion valve (TXV), suction pipe, and discharge line. The research began with a theoretical investigation of the primary noise and vibration sources, particularly the compressor and TXV, followed by an analysis of vibration transmission paths through the refrigerant lines. To ensure an optimal acoustic and thermal balance among these four components, both design parameters and dynamic operating characteristics were studied for their impact on thermoacoustic performance inside the vehicle. The compressor was identified as a major source of low and mid frequency noise and vibration, while pressure pulsations in the refrigerant lines contributed to structure-borne and airborne noise. These issues were addressed by developing new design guidelines aimed at improving isolation and damping characteristics. Specific efforts included designing stair-gated modal decoupling strategies to avoid resonance between the compressor bracket and engine or aggregate excitation frequencies. In addition, the standing wave behavior in the suction and discharge lines was analyzed to identify and control resonant modes that amplified NVH issues. The TXV was also studied in detail, with a particular focus on mid-frequency noise caused by its internal dynamics. Parameters such as spring stiffness, natural frequency, and superheat setting behavior were optimized to improve cabin acoustic comfort. The outcome of this paper is a comprehensive component-level NVH validation combined with practical design guidelines for minimizing integration-related noise and vibration issues in HVAC systems. These findings provide a robust framework for engineers to enhance both thermal performance and in-cabin acoustic refinement, ensuring superior comfort in modern vehicles.]]></description>
      <pubDate>Thu, 18 Dec 2025 15:37:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/2623876</guid>
    </item>
    <item>
      <title>Analysis of Frequency at Minimum Dynamic Stiffness for a Hydraulic Engine Mount with Floating Decoupler under High Frequency Excitation</title>
      <link>https://trid.trb.org/View/2539236</link>
      <description><![CDATA[The primary functions of mounts include providing structural support, sound insulation, and vibration damping. Dynamic stiffness and loss angle are critical metrics for evaluating their NVH (Noise, Vibration, and Harshness) performance. This paper examines a floating decoupler hydraulic mount featuring a long decoupler membrane track. A nonlinear lumped parameter model is developed to calculate the dynamic stiffness and loss angle. The model incorporates fluid flow in the lower chamber and variations in the support reaction force of the decoupler membrane under switching conditions. Parameters of the nonlinear lumped parameter model, including rubber stiffness, equivalent piston area, and volumetric compliance of the fluid chamber, were analyzed and calculated using the finite element method. The influence of different decoupler membrane track structures on the frequency corresponding to the minimum high-frequency dynamic stiffness was investigated based on the established model. The results demonstrate that, under high-frequency and small-amplitude conditions, increasing the decoupler membrane track length and decreasing its cross-sectional area result in a lower frequency at which the minimum high-frequency dynamic stiffness occurs. Conversely, under low-frequency large-amplitude conditions, alterations in the decoupler membrane track structure have negligible impact on the dynamic characteristics. A comparison between simulation and experimental results confirms that the developed lumped parameter model accurately represents the dynamic behavior of the hydraulic mount.]]></description>
      <pubDate>Tue, 15 Apr 2025 13:56:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/2539236</guid>
    </item>
    <item>
      <title>Weight Reduction of Structural Vibration Isolation Hydro-Mount Bracket Through Design Analysis and Use of Advanced High Strength Steels</title>
      <link>https://trid.trb.org/View/1818119</link>
      <description><![CDATA[Vibration Isolation Mounts are designed to isolate noise, reduce resonant vibration and lower structure-borne noise. The external mounting bracket that encases the fluid filled inner mount is usually made from relatively thick (~3 mm) high strength low alloy steel and has critical structural and durability requirements. In this study, a practical approach combining FEA and physical testing was used effectively in component design with complex functional requirements. A new lighter weight configuration with ~ 8% weight savings was validated to pass all the structural and durability requirements.]]></description>
      <pubDate>Mon, 24 Oct 2022 10:22:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/1818119</guid>
    </item>
    <item>
      <title>Sensitivity Analysis for Structure Borne Noise Reduction of Diesel Engine</title>
      <link>https://trid.trb.org/View/1795997</link>
      <description><![CDATA[The demands resulting from stringent noise legislations are increasing rapidly. It has become necessary to establish optimum design methods for low noise engines. In this paper, a methodology for structure borne engine noise control using the combination of experimental and computer aided techniques is presented. Sensitivity analysis for noise reduction is carried out for various structural modifications. The major structural improvements include addition of ribs, stiffening plate and crankcase shape modifications. The final models were validated using experimental analysis techniques.]]></description>
      <pubDate>Mon, 26 Sep 2022 17:22:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/1795997</guid>
    </item>
    <item>
      <title>Experimental and Numerical Analyses of Performances and Noise Emission of a Common Rail Light Duty D.I. Diesel Engine</title>
      <link>https://trid.trb.org/View/1813572</link>
      <description><![CDATA[This paper illustrates a numerical and experimental analysis of performances and overall noise radiated from a common rail light duty diesel engine. The engine was equipped with two different injection systems: an under development low-cost fuel injector and a commercial Bosch one, employed for automotive applications. The injectors behaviour was compared throughout an experimental investigation that was carried out on a naturally aspirated, four strokes, two valves, single cylinder engine (225 cm³ displacement). Both engine performances, pollutant and noise emissions were measured at different operating conditions for two injection strategies. Concerning the acoustic analysis, both structure born and gasdynamic noise contributions were estimated using different experimental techniques. Contemporarily to the above campaign, a one-dimensional simulation of the investigated engine was performed, finalized to provide some information on the spray combustion and heat release realized by the two fuel injection systems (FIS). The numerical results were then compared to the experimental ones, in terms of heat release fraction, in-cylinder pressure signal and gas dynamic noise emissions.]]></description>
      <pubDate>Mon, 26 Sep 2022 09:12:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1813572</guid>
    </item>
    <item>
      <title>Strategies for Minimizing the Noise Impact of a Range Extender for an Electric Vehicle</title>
      <link>https://trid.trb.org/View/1998895</link>
      <description><![CDATA[The car buying public’s enthusiasm for electric vehicles continues to accelerate rapidly, driven by a desire to fulfil global climate change objectives, and supported by tax incentives. However, range anxiety persists as one of the main barriers to take-up, because larger battery packs remain heavy and expensive (cell price reductions are slowing). One way to mitigate these disadvantages is to fit a range extender system, powered by an efficient internal combustion engine, but such systems can cause noise concerns.Ricardo has developed a simulation-based approach, pragmatically applicable at concept stage, to define the range extender operating conditions that minimize the impact on noise heard by the driver and passengers inside the vehicle. Transfer path analysis considered both air-borne and structure-borne noise contributions from the range extender, in context with noise contributions from electric drive unit, road and wind, under various typical vehicle operating conditions.The study found that the range extender was almost always audible - subjectively, humans were able to identify the engine tones remarkably clearly even at low noise levels. A simple objective metric was developed and proved to be a useful indicator. However, with some powertrain noise reductions, the model showed that the range extender noise could be reduced to a ‘distant hum’, particularly at higher vehicle speeds.]]></description>
      <pubDate>Tue, 26 Jul 2022 14:12:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/1998895</guid>
    </item>
    <item>
      <title>Numerical Simulation of Aerodynamic Noise in a Turbocharger</title>
      <link>https://trid.trb.org/View/1832974</link>
      <description><![CDATA[Turbocharger is an important part of the turbocharged diesel engine. Due to the increase of mass flow rate and pressure ratio, aerodynamic noise of turbocharger has become more apparent. And turbocharger noise becomes one of the major noise sources of the main engine system of the ship. In the paper, the aerodynamic noise is predicted by using Computational fluid mechanics (CFD) and indirect boundary element method (IBEM) based on Lighthill acoustic analogy theory. Unsteady viscous flow in the centrifugal Compressor is simulated with finite volume method using the single stator and rotor blade passages and the characteristic of compressor is agreed well with the experimental value. The flow field characteristics and frequency spectrum of the fluctuating pressure are analyzed which agree well with the theoretical value. Dipole is the main noise source in compressor and the datum of pressure fluctuation at rotor blade are extracted. The boundary element model of the volute is established and the scattering effect on sound propagation is taken into account. Using indirect boundary element method, radiation noise field at compressor entrance at the blade passing frequency and its harmonics are predicted. The results can provide a useful reference to low noise design and structure optimization of centrifugal compressor.]]></description>
      <pubDate>Wed, 23 Feb 2022 16:16:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1832974</guid>
    </item>
    <item>
      <title>REDUCING FUEL SUPPLY MODULE NOISE with RUBBER STRUCTURE in a VEHICLE TANK APPLICATION</title>
      <link>https://trid.trb.org/View/1919264</link>
      <description><![CDATA[The noise requirements for automotive components have been updated in the recent years due to the consumer demand for low noise inside the cars. Indeed, it was performed an experimental study aiming the reduction of acoustic noise emitted by Fuel Supply Module (FSM), which is installed inside the fuel tank, using a rubber structure under it. The FSM is responsible to deliver sufficient quantities of fuel to the engine and maintain the pressure required for efficient fuel injection in all operating states. The study presents a basic theory regarding the motor noise source identification based on frequency domain analysis as well as noise control by vibration isolation. The present work analyzed the noise performance influence of rubber support under the FSM using a statistical approach, testing twenty-five samples in an anechoic chamber on Robert Bosch Ltda and a data spectrum average analyzed the influence of rubber support on the parts to compare the product results with this component and without. It was also evaluated the influence of the rubber hardness in different noise orders. The average results showed no difference between the different rubber hardness grades on noise, however, removing this structure, has an increase on sound pressure level on the fuel supply module. Consequently, the reported acoustic-noise prove that, for the considered application, the rubber support can reduce acoustic-noise emissions on specific orders.]]></description>
      <pubDate>Tue, 22 Feb 2022 10:38:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/1919264</guid>
    </item>
    <item>
      <title>Energy-averaged method for ship mechanical noise prediction under kinematic excitation in the full frequency domain</title>
      <link>https://trid.trb.org/View/1905976</link>
      <description><![CDATA[Mechanical noise plays a key role in ship acoustic performance design as an important component of underwater sound radiation. In this paper, a numerical method for predicting ship mechanical noise, energy-averaged method, is proposed considering coupling mechanism, numerical model and kinematic excitation in full frequencies. In the method, vibroacoustic BEM coupling equations are established by the equivalent generalized force converted from kinematic loads based on the energy-averaged method in low-mid frequencies, and the vibroacoustic transfer functions obtained by SEA are modified in high frequencies, which can reduce computational errors resulting from an offset of natural frequency between a numerical model and a real structure, kinematic loads with incomplete information, and pathological matrices. The accuracy and reliability of the energy-averaged method are verified by the hydroacoustic experiments. The simulated and experimental results are comprehensively evaluated by overall errors, correlation coefficients, and standard deviations. The errors between the simulation and the experiment are 0.75 dB, 0.51 dB, and 1.21 dB in different frequency regions for the shaker case, respectively, while those are 0.41 dB and 0.82 dB in the different diesel engine cases. Additionally, the phenomenon of acoustic cavity resonances cannot be neglected in low frequencies, and the acoustic cavity must be modelled to predict mechanical noise.]]></description>
      <pubDate>Fri, 28 Jan 2022 09:13:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1905976</guid>
    </item>
    <item>
      <title>An Experimental Study of the Effects of a Nonlinear Store on the Steady-State Dynamics of a Test Airplane</title>
      <link>https://trid.trb.org/View/1877177</link>
      <description><![CDATA[Local nonlinearities can affect the global dynamics of their linear host structures. In the context of fixed-wing aircraft, failure of store mounting can result in strong local nonlinearities. In this work, we experimentally mimic store mounting failure conditions in a model airplane subject to harmonic excitation. Two identical stores are mounted under the wings and are placed symmetrically opposite each other. The configuration where both stores are “locked”, i.e., mounting is very stiff, serves as the baseline linear system. The second configuration involves unlocking one of the stores, enabling a geometrically nonlinear flexure connection between the unlocked store and the wing. The flexure lets the store interact with the first flexible mode of the airplane, resulting in large relative displacements between the store and wing. In addition, the configuration allows for vibro-impacts between the wing and store. Results show that the strong local vibro-impacts enable excitation of high-frequency modes unexcited in the baseline linear system. This is indicative of energy transfer from low to high frequency modes of the primary structure.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:38:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/1877177</guid>
    </item>
    <item>
      <title>Acoustic Optimization of Mechatronic Direct Injection Systems and Analysis of the Effects on Robustness in System Operation</title>
      <link>https://trid.trb.org/View/1856246</link>
      <description><![CDATA[The tightening of the emission legislation and political and social demands for sustainable mobility are forcing the automotive industry to develop complex, high precision mechatronic drive systems. The increasing precision of mechatronic components generally leads to an increase in structural excitation and thus to a rise in noise. The so-called ticking of the fuel injection system has a rather low sound pressure level compared to the residual engine noise. Nevertheless, the impulsive and high frequency noise character leads to a decline concerning the perception of comfort and sound quality. In order to identify the sound quality of fuel injection systems as a frontloading measure, a system test bench has been developed which represents the structure-borne and airborne sound radiation of the stand-alone injection system in a close to series configuration. In this paper, measures for the acoustic optimization of injection systems and their effects on the robustness of the system are discussed. The focus is on engine idling, since at this operating point the ticking of the injectors and high-pressure pump can be perceived most clearly due to the low masking effects of other noise sources. For this purpose, the injection parameters were measured during full engine operation and transferred to the system test bench. By using a special development control unit, it was possible to modify the parameters, quantify their influence on the acoustic behavior and, based on this, define NVH optimized control strategies. For the robustness evaluation of the NVH optimized control strategies, key functions of the injection system were analyzed under varying boundary conditions in system operation on an injection rate test bench.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:38:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1856246</guid>
    </item>
    <item>
      <title>Test Method, Simulation and Micro-process Dynamic Model for Noise Analysis of Auto Hydraulic Shock Absorber</title>
      <link>https://trid.trb.org/View/1833014</link>
      <description><![CDATA[In order to measure the noise of auto shock absorbers, a test bench used to detect piston-rod vibration responses of shock absorbers and measuring analyzer named SANTS-I were developed. The vibration response data was detected by bench tests, which shows that there are high-frequency violent peaks on the sine curve of piston-rod oscillating with relative low frequency. In order to explain the interior work dynamic mechanism of shock absorbers, a schematic Micro-process Dynamic Model with 10 steps particularly divided extension and compression stroke in more detail, and dynamic differential equations for each step were presented and discussed. Furthermore, numerical simulation for the inner impacts interaction between piston and damping fluid of hydraulic shock absorber was realized by ADINA software, by the establishment of a gas-liquid two-phase finite element model. It was understood by the Micro-process Dynamic Model and numerical simulation that the cause of the abnormal noise is violent vibrations excited by inner clearance impact interaction between piston and damping oil fluid. And adherence action between valve plate and its seat, friction between piston and cylinder barrel and vaporization of damping oil fluid would intensify the impacts around the piston top dead center (TDC) and bottom dead center (BDC). Therefore, high-frequency vibration of the piston is excited and transferred to body structure of automobile, and the abnormal noise is generated.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:38:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1833014</guid>
    </item>
    <item>
      <title>Multiphase Flow Simulations of Poppet Valve Noise and Vibration</title>
      <link>https://trid.trb.org/View/1832164</link>
      <description><![CDATA[A deeper understanding of the complex phenomenology associated with the multiphase flow-induced noise and vibration in a dynamic valve is of critical importance to the automotive industry. To this purpose, a two-dimensional axisymmetric numerical model has been developed to simulate the complex processes that are responsible for the noise and vibration in a poppet valve. More specifically, an Eulerian multiphase flow model, a dynamic mesh and a user-defined function are utilized to facilitate the modeling of this complicated two-phase fluid-structure interaction problem.         For a two-phase flow through the valve, our simulations showed that the deformation and breakup of gas bubbles in the gap between the poppet and the valve seat generates a vibration that arises primarily from the force imbalance between the spring and the two-phase fluid flow induced forces on the poppet. A spectral analysis of the transient pressure force on the poppet revealed the presence of a strong cyclical behavior consisting of two major components. There was a low-frequency peak located at about 87 Hz which is associated with the frequency of the poppet vibration (and which we interpret to be the source of the mechanical noise) and a high-frequency peak located at about 970 Hz which is associated with compressibility effects and unsteady vortex motions in the spring chamber. The poppet vibration and noise is influenced by numerous factors such as the flow condition, the spring system properties, and the geometry of the valve.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:37:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/1832164</guid>
    </item>
    <item>
      <title>Body Load Identification for BEV Based on Power Spectrum Decomposition under Road Excitation</title>
      <link>https://trid.trb.org/View/1830817</link>
      <description><![CDATA[As motor assembly of Battery Electric Vehicle (BEV) replaces engine system of Internal Combustion Engine (ICE) vehicle, interior structure-borne noise induced by road random excitation becomes more prominent under middle and high speed.         The research is focused on central driving type BEV. In order to improve interior noise in middle and low frequency range, dynamic load of BEV body must be identified. Consequently the structural noise induced by road excitation is conducted. The limitations of common identification method for dynamic body load are analyzed. The applied several identification methods are proposed for deterministic dynamic load such as engine or motor. Random dynamic load generated by road excitation is different from deterministic dynamic load. The deterministic load identification method cannot be applied to the random load directly. An identification method of dynamic body load for BEV is presented based on power spectrum decomposition. The procedure of BEV body load identification is described. Finally the validation of the method is demonstrated by experiments.         From the experimental results, the identification accuracy satisfies the requirement of engineering application. Compared to traditional matrix inversion method, power spectrum decomposition method can effectively reduce the testing work while maintaining the better identification accuracy. The research results provide theoretical basis and experimental foundation for analysis and optimization control of BEV interior noise.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:37:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/1830817</guid>
    </item>
    <item>
      <title>Experimental Determination of Acoustic Cavity Resonances of Vehicle Sub-Systems</title>
      <link>https://trid.trb.org/View/1829734</link>
      <description><![CDATA[The present quiet and comfortable automobiles are the result of years of research carried out by NVH engineers across the world. Extensive studies helped engineers to attenuate the noise generated by major sources such as engine, transmission, driveline and road excitations to a considerable extent, which made other noise sources such as intake, exhaust and tire perceivable inside. Many active and passive methods are available to reduce the effect of said noise sources, but enough care needs to be taken at the design level itself to eliminate the effect of cavity resonances. Experimental investigation of cavity resonances of real systems is necessary besides the FEA model based calculations.         Acoustic cavity resonance of vehicle sub systems show their presence in the interior noise through structure borne and air borne excitations. Cavity resonances for some systems e.g. intake can only be suppressed through resonators. The exact location and nature of acoustic cavity resonance needs to be found as accurately as possible to bring out the best from a resonator.         Different approaches are used to excite and identify the cavity resonances depending on the operational differences of various systems. Cabin cavity modes are analyzed by arranging an array of microphones inside the cabin and exciting the cavity with help of a low frequency volume acceleration source. The cavity modes of inflated tire are analyzed by placing accelerometers circumferentially and exciting the cavity by intermittent deflation. The cavity resonances of intake system are investigated using microphones by providing excitation through a low frequency volume acceleration source. Acoustic modal analysis is carried out to identify and understand the mode shapes.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:37:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/1829734</guid>
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