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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" />
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    <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>
    </image>
    <item>
      <title>Effect of pore water freezing on the natural frequency of concrete girder bridges</title>
      <link>https://trid.trb.org/View/2606133</link>
      <description><![CDATA[Natural frequencies and modal shapes are critical parameters in bridge health monitoring, yet their sensitivity to environmental factors, particularly temperature and freezing, complicates evaluations. This study presents a framework for quantitatively assessing how pore-water freezing affects the effective modulus and natural frequencies of concrete girder bridges. Concrete is modeled as a multi-phase particle-reinforced composite, with the matrix obtained through homogenization of the solid phases, and pores filled with air, water, or ice as inclusions. Using composite mechanics and the Mori-Tanaka method, a predictive model with ice content is introduced, from which practical bounds for the effective modulus and natural frequencies under freezing conditions are derived. Validation through laboratory tests, scaled bridge model experiments, and field measurements shows excellent agreement between theory and experiment. The substantial increase in concrete’s elastic modulus caused by pore-water freezing markedly elevates the natural frequencies of concrete bridges, with the temperature at which this jump occurs depending on the lowest temperature previously experienced. This framework offers theoretical derivations and practical guidelines for improving safety assessment, design, and maintenance of concrete girder bridges in cold climates.]]></description>
      <pubDate>Mon, 24 Nov 2025 10:23:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2606133</guid>
    </item>
    <item>
      <title>Calculation and Analysis for Multidimensional Natural Frequencies of Cylindrical Motors Based on Precise Analytical Model Considering Distinct Additional Ribs and Anisotropic Material Parameters</title>
      <link>https://trid.trb.org/View/2591501</link>
      <description><![CDATA[The rapid and accurate calculation of stator natural frequencies is a principal foundation for electromagnetic vibration prediction, analysis, and suppression. In response to the shortcomings of existing calculation methods for stator multidimensional natural frequencies that cannot give attention to both rapidity and accuracy, a general and precise analytical model for stator multidimensional natural frequencies of cylindrical motors based on reasonable equivalent models of stators and accurate equivalent method for anisotropic material parameters is established, and the stator multidimensional natural frequencies under different boundary conditions, and dimensional and material parameters are quickly obtained. In addition, the detailed finite element simulation and prototype testing are performed to verify the proposed analytical method (AM) for multidimensional natural frequencies of different types of stator cores and casings, and the comparison shows that the proposed AM has high accuracy and universality for both axially and circumferentially slotted stator cores and casings with longitudinal and ring heat dissipation ribs. Finally, the variation laws of stator multidimensional natural frequencies under different boundary conditions, and dimensional and material parameters are explored and summarized, the analysis reveals that the multidimensional natural frequencies of axially slotted stator cores can be adjusted by changing the yoke average radius and thickness, and those of circumferentially slotted stator cores are sensitive to not only yoke average radius and thickness but also the number and height of teeth, which lays the foundation for adjusting the multidimensional natural frequencies of cylindrical motors and suppressing electromagnetic vibrations.]]></description>
      <pubDate>Fri, 26 Sep 2025 13:39:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2591501</guid>
    </item>
    <item>
      <title>Free Vibration Analysis of Bidirectional Functionally Graded Beams Using a Novel Perturbation Theory–Based Approach</title>
      <link>https://trid.trb.org/View/2592024</link>
      <description><![CDATA[Bidirectional (2D) functionally graded material (FGM), which is characterized by a continuous spatial gradient in two directions in both its microstructure and material properties, exhibits numerous benefits, including interfacial delamination prevention, frequency regulation, and stress concentration elimination. Because they are load-bearing structures, the natural frequencies of bidirectional functionally graded (2D FG) beams play a crucial role in structural design, and these frequencies are usually calculated using the numerical generalized differential quadrature method (GDQM) based on interpolation. Instead of the GDQM, this study pioneered a perturbation approach (PA) as an alternative for the first time. Unlike traditional perturbation theory, the authors' approach used a homogeneous beam as an approximate reference model, whereas the gradients of the material properties were selected as the perturbation parameters to approximate the intricacies of the 2D FG beam. Through analysis of the PA, it was found that the solution could be simplified, resulting in a 22% reduction in calculation time. First, a free vibration model of a 2D FG beam was proposed based the rule of mixtures, Timoshenko beam theory, and Hamilton’s principle. Second, by applying the PA, the 2D FG beam was equivalent to a homogeneous beam and a small material perturbation. The high-precision results showed that the PA is adaptive and widely applicable. Finally, analyses of the results were conducted. It was found that the truncation of higher-order terms constituted the primary source of error and the inaccuracy of the PA, and also that the relative error of the frequency decreased with an increase in the power-law exponent. The PA-calculated frequencies were mostly slightly higher than those calculated using the GDQM.]]></description>
      <pubDate>Tue, 02 Sep 2025 08:49:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2592024</guid>
    </item>
    <item>
      <title>Effect of designed stiffener configuration on natural frequency and buckling behaviour of 5 MW NREL wind turbine blade structure using FE method</title>
      <link>https://trid.trb.org/View/2571804</link>
      <description><![CDATA[Long and flexible offshore wind turbine blades are easily damaged during extreme wind conditions (typhoon or tornado). A parametric study was conducted in this work using the finite element method to study the effect of stiffener configurations, including stiffener number, thickness, and spacing, on the aeroelastic response and buckling of the wind turbine blade by modeling the National Renewable Energy Laboratory (NREL) 5 MW blade structure design. This study investigates wind turbine blade stiffeners' buckling behaviour and natural frequencies. The results show that the critical buckling load value increases significantly as the number of stiffeners, stiffener thickness, and spacing width between stiffeners increase. The modal analysis results show that the variation in the number and thickness of stiffeners increases the natural frequencies of the flaps and torsional modes but decreases the edgewise mode. Variation of the distance between stiffeners increases the flapwise and edgewise modes' natural frequencies.]]></description>
      <pubDate>Mon, 21 Jul 2025 08:56:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/2571804</guid>
    </item>
    <item>
      <title>Dynamic natural frequency estimation of an automobile driver's seat</title>
      <link>https://trid.trb.org/View/2556933</link>
      <description><![CDATA[While driving a car, the comfort of the driver is crucial. By considering seated concerns for the drivers' comfort and health, the exceptional and skilled designers' concept should be successful. On a standard car seat, the bottom and upper body sections, in addition to the head support, are significant. The seat's vibration-attenuation design is crucial to the comfort of the driver. Components of the human body are sensitive to lower frequency vibration, and problems occur when they are frequently subjected to it. An individual's health will be harmed by prolonged vibration exposure. In this work, the finite element method with experimental modal analysis has been used to estimate and evaluate the natural frequencies in the driver's seat which affect to the human body. Since it has been shown that some of these frequencies coincide with the ones that are dependent on the human body, the natural frequencies associated with a driving seat that affect the human body can be changed without modifying the design.]]></description>
      <pubDate>Fri, 18 Jul 2025 15:10:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/2556933</guid>
    </item>
    <item>
      <title>Dynamic natural frequency estimation of an automobile driver's seat</title>
      <link>https://trid.trb.org/View/2519007</link>
      <description><![CDATA[While driving a car, the comfort of the driver is crucial. By considering seated concerns for the drivers' comfort and health, the exceptional and skilled designers' concept should be successful. On a standard car seat, the bottom and upper body sections, in addition to the head support, are significant. The seat's vibration-attenuation design is crucial to the comfort of the driver. Components of the human body are sensitive to lower frequency vibration, and problems occur when they are frequently subjected to it. An individual's health will be harmed by prolonged vibration exposure. In this work, the finite element method with experimental modal analysis has been used to estimate and evaluate the natural frequencies in the driver's seat which affect to the human body. Since it has been shown that some of these frequencies coincide with the ones that are dependent on the human body, the natural frequencies associated with a driving seat that affect the human body can be changed without modifying the design.]]></description>
      <pubDate>Fri, 23 May 2025 15:34:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2519007</guid>
    </item>
    <item>
      <title>Analytical Kinetic Model for Accurate Square-Slot Stator Natural Frequency Prediction</title>
      <link>https://trid.trb.org/View/2511667</link>
      <description><![CDATA[This article introduces a novel kinetic modeling technique that accurately predicts the natural frequencies of the square-slot stator and can be used in the early design stage of an electrical vehicle (EV) traction motor. The model is an improvement of the classic energy approach, with a small increase in computational cost but a much higher accuracy, especially for high-order vibration modes. A 3-D equivalent teeth model based on open cylindrical shell (OCS) theory and the corresponding 3-D face coupling method are first proposed. The derivation of the high-accuracy model from the classic energy method is thoroughly explained. To cut down the computational cost, a simplification of the proposed kinetic model which utilizes the cyclic symmetry of the stator is then implemented. Further, based on this, the natural frequency of a wounded stator and a real traction motor stator considering water-cooling parts are also investigated. To validate the effectiveness of the proposed model, structural simulations and experiments are carried out. Results of the classic energy method are also provided to highlight the improvement in accuracy.]]></description>
      <pubDate>Fri, 04 Apr 2025 10:30:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511667</guid>
    </item>
    <item>
      <title>Calculation, Analysis, and Verification of Natural Frequencies of Stators With Unequal-Length Casings of Rotating Motors</title>
      <link>https://trid.trb.org/View/2511658</link>
      <description><![CDATA[Overcoming the drawback of low accuracy in stator natural frequency calculation results caused by excessive simplification of the casing in existing analytical methods (AMs), a universal and accurate AM for the natural frequencies of stators with unequal-length casings of rotating motors is proposed. The stator yoke and frame are considered as a composite shell with uneven material parameters, inside which the continuous conditions of displacements and strains can be ensured, and complex structures such as teeth, windings, heat dissipation ribs, junction boxes, and feet can be accurately considered. Afterward, the energy equations of each part of the stator are derived and the characteristic equation of natural frequencies is accurately constructed based on the energy method. The natural frequencies of two prototypes of the stator with casing and the stator with windings and casing are quickly and accurately calculated. In addition, detailed finite element analysis and prototype testing are performed to verify the stability of the proposed calculation method for stator natural frequencies and the accuracy of calculation results. Finally, the vibration characteristics of the stator are analyzed, the excitation mechanism of strong electromagnetic vibrations and the suppression basis are accurately revealed, and the variation laws of stator natural frequencies with dimensional and material parameters are summarized, which lays a solid theoretical foundation for the rapid adjustment of stator natural frequencies and effective suppression of electromagnetic vibrations. The analysis shows that the extension lengths of casing ends significantly impact stator natural frequencies, and the dimensional and material parameters of the casing must be accurately considered in the analysis and calculation of stator natural frequencies.]]></description>
      <pubDate>Mon, 31 Mar 2025 08:54:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511658</guid>
    </item>
    <item>
      <title>Determination of the Tightness of Bearing Rings of Axle Box Unit of Freight Car Bogie by the Method of Frequency Analysis of Free Vibrations</title>
      <link>https://trid.trb.org/View/2407751</link>
      <description><![CDATA[The destruction of the bearing ring of the axle box unit inevitably leads to the uncoupling of the car, which is the cause of time and material losses. The problem of determining the tightness of the bearing ring without removing it is urgent, its solution will improve the efficiency and reduce the time of testing. Experimental studies have been carried out to determine the frequencies of natural vibrations of samples with various interference forces, as well as free rings. The experiment consisted of exciting oscillations in the sample and recording the reflected pulses. Also, natural frequencies were calculated analytically using mathematical modeling tools. It is found that for samples with interference from 40 to 110 microns were not observed natural frequencies below 15 kHz. For free rings, the minimum natural frequency is 1.7 kHz. A method is proposed for determining the bearing ring tightness, which consists in exciting oscillations of the set duty cycle by a transducer installed on the surface of the sample. Recording of reflected pulses is carried out by an emitting transducer. After that, the dependence of the number of reflected pulses on the emitted frequency is determined, by the nature of which the value of the interference is determined. It was found that the quality of the acoustic contact has a significant impact on the results.]]></description>
      <pubDate>Wed, 19 Mar 2025 16:56:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/2407751</guid>
    </item>
    <item>
      <title>Impact of internal lattice structures on the weight and natural frequencies of a low pressure turbine blade</title>
      <link>https://trid.trb.org/View/2483275</link>
      <description><![CDATA[Vibration characteristics play a crucial role in the overall performance of Low-pressure (LP) turbine blades and different techniques are developed to enhance vibrational response by increasing natural frequencies. The present analysis aims to develop a new technique based on the investigation of improvement in natural frequencies and mass reduction of a topology-optimized blade design through location-based integration of lattice structures inside the blades. FE models are developed for three different lattice locations based on mode shape behavior obtained through modal analysis of two different nickel-based alloys at stressed and unstressed conditions. The results show that the internal BCC lattice at specific locations showed better vibrational characteristics compared to other incorporated lattice structures, and validates the location-based integration scheme for enhancement of natural frequencies and reduced mass in applied conditions. By this method, 5.7% mass reduction was achieved from an already 35% mass-reduced blade along with enhancement in the first and second natural frequencies by 8.2% and 5.9% respectively when unstressed. At stressed condition, the natural frequencies increased by ≈7.7% and ≈6.6%.]]></description>
      <pubDate>Wed, 29 Jan 2025 17:00:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2483275</guid>
    </item>
    <item>
      <title>Natural frequency estimation for an automobile wheel rim's design by using FEM</title>
      <link>https://trid.trb.org/View/2459028</link>
      <description><![CDATA[The rim of the wheel, which is its outermost portion, supports the tyre and is a key element in maintaining its round shape. This paper discusses how to design wheel rims and how to evaluate them while considering things like cracking, bending, impact loads, vibration, tyre hold pressure, rust, dents, other structural failures. Increased vibration, reduced air pressure, and even structural failure can result from these harms. In this paper the natural frequencies were obtained by the modal analysis in Ansys for the structural steel and the aluminium alloy materials to validate the natural frequencies along with the total deformation obtained using the FEM tool. With the use of Ansys, natural frequencies with various mode shapes may be designed, analysed, and calculated, making it simple to identify the components that are most susceptible to resonance and deformation. A wheel rim's natural operating frequency is 150.98 Hz, which does not coincide with the natural frequencies and suggests that there is no inclination towards resonance. For the materials structural steel and aluminium alloy, the ten mode forms of natural frequencies were documented in the form of a table. The wheel rim avoids the crucial resonance because the working or operational frequency is different from the natural frequency.]]></description>
      <pubDate>Wed, 22 Jan 2025 09:33:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2459028</guid>
    </item>
    <item>
      <title>CAE Simulation Based Structural Assessment of Steering Wheel</title>
      <link>https://trid.trb.org/View/2474920</link>
      <description><![CDATA[The structural integrity of the steering wheel is important for vehicle operations. It is subjected to various load conditions during the vehicle motion. It thus becomes important to understand various aspects of the same which include stiffness, natural frequency, and regulatory requirements i.e. body block test, head form impact test, etc. Simulation plays an important role in understanding the structural integrity and validation requirements of products at the design stage itself. This paper discusses the modeling and simulation of the steering wheel at both the armature level and the complete steering wheel level. As armature is critical from a structural strength and stiffness point of view, certain simulations like modal analysis are performed first at the armature level, and design iterations were done to achieve the natural frequency target.The list of simulations performed includes modal analysis, bending rigidity, static compression, bending stiffness, body block test and head form test as per AIS-096. Simulation results which include deformation, stress, energy absorption and 'g' levels during impact were studied.]]></description>
      <pubDate>Mon, 13 Jan 2025 10:24:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/2474920</guid>
    </item>
    <item>
      <title>Modal research of permanent magnet synchronous motor for electric vehicles</title>
      <link>https://trid.trb.org/View/2447019</link>
      <description><![CDATA[Aiming at the vibration and noise problems caused by the constant rise in speed of the permanent magnet synchronous motor (PMSM) of electric vehicles, the natural frequency of motor stator is first analysed using the lumped mass method. Simultaneously, a fast equivalent modelling approach of motor stator with winding as added mass and material anisotropy is proposed. The finite element model of PMSM is established based on the established equivalent stator model, and its natural frequency and vibration shape are investigated. Finally, the motor's modal test is carried out on the modal test platform. The results show that the difference between the natural frequency simulation and the test results is less than 3%, and that the vibration modal characteristics of each order are consistent. The feasibility and accuracy of the fast equivalent modelling method are verified, laying the groundwork for the following optimised design of PMSM vibration and noise.]]></description>
      <pubDate>Fri, 15 Nov 2024 09:49:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2447019</guid>
    </item>
    <item>
      <title>Serpentine Belt Span Vibrations caused by Dynamic Pulley and Crankshaft Oscillations</title>
      <link>https://trid.trb.org/View/1786983</link>
      <description><![CDATA[In practical operation, serpentine belts are subjected to parametric excitation caused by tension and translation speed fluctuations from pulley rotations and crankshaft speed oscillations. Each of these excitation sources has spectral content at multiple frequencies and arbitrary phases. Stability boundaries for primary, secondary, and simultaneous primary/secondary parametric instabilities are determined analytically. The classical result that primary instability occurs when one of the excitation frequencies is close to twice a natural frequency changes as a result of multiple excitation frequencies. Unusual interactions occur for the practically important case of simultaneous primary and secondary instabilities.]]></description>
      <pubDate>Thu, 07 Nov 2024 11:52:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1786983</guid>
    </item>
    <item>
      <title>Optimization of an Engine Cradle in Frequency Domain</title>
      <link>https://trid.trb.org/View/1786894</link>
      <description><![CDATA[The application of optimization technique in the frequency domain, to move the frequencies outside certain range, is presented. An engine cradle under development had very high responses in 50 - 60 Hz. range. A modal analysis identified the cause as the mounting springs' natural frequencies. Optimization technique (direct linearization method) was applied to change the spring stiffnesses to move its natural frequencies outside the range of interest. Response plots at various salient locations on the engine cradle, before and after optimization, confirmed the analysis. The large response in the frequency domain was moved outside the 50 - 60 Hz. range.]]></description>
      <pubDate>Thu, 07 Nov 2024 11:52:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1786894</guid>
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