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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>
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    <item>
      <title>Study on The Evaluation Method of Piston Slap Using Engine Background Noise</title>
      <link>https://trid.trb.org/View/2695901</link>
      <description><![CDATA[Previous piston slap noise predictions using simulation models evaluated indicators such as the piston's kinetic energy and the cylinder block's wall vibrations, but these have not always aligned with auditory evaluations. In this study, we quantified the exceedance value using cylinder block vibrations and engine background noise to establish an effective detection method for piston slap based on a predictive model. As a result, a good correlation with auditory evaluations was confirmed. Consequently, this approach enabled the prediction of piston slap noise in newly developed engines.]]></description>
      <pubDate>Fri, 31 Jul 2026 09:23:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/2695901</guid>
    </item>
    <item>
      <title>Development of wear condition diagnosis model for main bearing with SVM algorithm</title>
      <link>https://trid.trb.org/View/2647081</link>
      <description><![CDATA[As one of the important friction components of internal combustion engine, the main bearing is exposed to complex dynamic loads and is prone to wear during long-term operation. It is of great significance to study the wear condition monitoring of main bearing. Time domain analysis and wavelet packet decomposition (WPD) are carried out to analyze the block vibration signals under different working conditions. The influence of engine speed, torque, oil temperature and main bearing clearance on the block vibration is analyzed. On this basis, the characteristic parameters reflecting the main bearing state are extracted to form the input vector and the support vector machine (SVM) model is established. Then the key parameters of the SVM, including penalty factor and kernel function parameter are optimized by grid search method and gray wolf optimizer (GWO). The optimized diagnosis model is used to identify the wear state of main bearing. The result indicates that the recognition accuracy and the running time of the model optimized by GWO is 97.22% and 9.13 s respectively. So GWO-SVM diagnosis model can effectively recognize the main bearing wear state, mitigating the risks of unplanned downtime and secondary damage caused by main bearing failure.]]></description>
      <pubDate>Wed, 25 Mar 2026 16:41:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2647081</guid>
    </item>
    <item>
      <title>Proposal of an Engine Vibration Simulation Model Considering Slip Friction and Vibration Transmission Between Engine Block Mating Surfaces</title>
      <link>https://trid.trb.org/View/2556931</link>
      <description><![CDATA[A previous research revealed that slippage occurs at the mating surface between the upper and lower blocks of an engine, but numerical simulations have been unable to reproduce the mating surface and its vibration characteristics. In this study, the FE model of the engine block was changed to an FE model that is taken into account the mating surface between the upper and lower blocks, and the effect on the vibration transmission characteristics was numerically investigated.]]></description>
      <pubDate>Tue, 01 Jul 2025 13:38:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2556931</guid>
    </item>
    <item>
      <title>Experimental Investigation of the Strains and Stresses in the Cylinder Block of a Marine Diesel Engine</title>
      <link>https://trid.trb.org/View/1787221</link>
      <description><![CDATA[The cylinder block of a high-speed marine diesel engine is a complex structure subjected to a complex loading. The design optimization of the cylinder block requires a reliable Finite Element Model (FEM), capable to predict, with a reasonable accuracy, the actual strains and stresses. The experimental investigation presented in the paper is meant to provide the necessary information for a better estimation of the boundary conditions and the validation of the FEM of the cylinder block. In order to obtain an image of the stress field in the cylinder block, a system of 10 strain gauge rosettes have been placed at significant locations on the cylinder block. The temperature at the location of the rosettes was measured with an optical pyrometer and a method has been developed to calculate this temperature using the measured strain. A fairly good agreement was obtained between the measured and the calculated temperatures during the cooling of the engine. The measured stresses during steady state operation of the engine show a good correlation with the variation of the forces acting on the main bearings of the crankshaft.]]></description>
      <pubDate>Sat, 30 Nov 2024 15:27:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1787221</guid>
    </item>
    <item>
      <title>Coupling analysis of cylinder block for two-stroke aviation piston engine</title>
      <link>https://trid.trb.org/View/2435010</link>
      <description><![CDATA[The aluminum alloy block is a component of aircraft piston engine, and it is prone to fatigue cracks when working in a thermal mechanical coupling state for a long time. Establish a GT-POWER simulation model for a certain type of engine, verify the accuracy of the model, obtain boundary parameters such as temperature and pressure of the engine block under harsh operating conditions through the model, and divide the cylinder wall into gradients based on the engine operating conditions to obtain the surface heat transfer coefficient of the block, and then obtain the temperature field distribution of the engine body. The coupling analysis of the cylinder burst pressure and temperature field of the engine block under harsh working conditions showed that the maximum stress of the engine block was 292.55 MPa and the maximum deformation was 0.39 mm, with thermal load being the main factor causing deformation. Conduct a complete engine bench test, and under the 1000 h bench durability test, there are no cracks on the engine block, indicating that the design and analysis meet the requirements.]]></description>
      <pubDate>Thu, 07 Nov 2024 11:52:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2435010</guid>
    </item>
    <item>
      <title>Development of an Evaluation Method for Fretting Fatigue at the Mating Surface between a Cylinder Block and Main Bearing Cap with Temperature Fluctuations</title>
      <link>https://trid.trb.org/View/2367901</link>
      <description><![CDATA[Fretting is a phenomenon in which a fatigue crack is initiated by a small relative slip between two objects, resulting in crack propagation and fracture at stresses far below the fatigue limit [1, 2]. Since the mechanism behind fretting is complex and covers multiple disciplines, it is not easy to develop a consistent evaluation method. In the field of engine development, fretting events can also pose an issue due to the complexity of the mechanism. In particular, it has been a challenge to help predict changes in the presence and severity of fretting events, as the engine temperature fluctuates with operating conditions. As one method for evaluating fretting, Sato, et al. have made predictions using analytical models based on the finite element method. However, their predictions did not take into account temperature fluctuations in the system, and they were unable to predict events in which the occurrence of fretting fatigue changed with temperature fluctuations. In this study, first, tests were conducted on an actual engine to examine the effect of temperature on the occurrence of fretting. In addition, the mating surface was observed in detail after the tests. Specifically, the microcracks on the mating surface were measured, and the damaged areas were analyzed for their composition. As a result, it was found that the main factors influencing the occurrence of fretting were the relative slip velocity caused by thermal expansion and the relative slip rate and stress amplitude caused by the crank load. Traditionally, fretting has been evaluated based on the stress amplitude at the mating surface and the relative slip caused by the crank load. In this study, the relative slip caused by thermal expansion due to the difference in thermal expansion coefficients between the two objects was incorporated into the evaluation, making it possible to evaluate fretting while taking the effect of temperature into account. The influence of each factor was quantified using a three-dimensional nonlinear finite element method. Simulations included bolt-tightening force, cyclic crankshaft force, and temperature variation. The simulation results were combined with test results from various engine types to develop experimental criteria.]]></description>
      <pubDate>Thu, 25 Apr 2024 16:20:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/2367901</guid>
    </item>
    <item>
      <title>Engine Excitation Decomposition Methods and V Engine Results</title>
      <link>https://trid.trb.org/View/1790726</link>
      <description><![CDATA[Engine excitation forces have been studied in the past using one of two methods; a lumped sum or a totally distributed approach. The lumped sum approach gives the well-understood engine inherent unbalance and the totally distributed approach is used in engine CAE models to determine the overall engine response. The approach that will be described in this paper identifies an intermediate level of sophistication. The methodology implemented considers single cylinder forces on the engine block, piston side thrust and main bearing forces, and decomposes them into their order content. The forces are then phased and geometrically distributed appropriately for each cylinder and then each order is analyzed relative to know distributions that are noise, vibration and harshness (NVH) concerns, V-block breathing, block side wall breathing, and block lateral and vertical bending. This analysis provides insight into the relative magnitude and frequency of the excitation driving each of the distributions and analyzes differences that can be attributed to the number of cylinders, the bank angle and the firing order.]]></description>
      <pubDate>Tue, 19 Dec 2023 17:03:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1790726</guid>
    </item>
    <item>
      <title>Diesel Engine Performance by Improving Cylinder Bore under Firing Conditions (Second Report)</title>
      <link>https://trid.trb.org/View/2259903</link>
      <description><![CDATA[A cylinder block with cylindrical bore considering deformation by assembling cylinder head and thermal stress under the highest thermal load condition is expected improving engine performances as analyzed by CAE. Test results verified that the friction force, noise level, blow-by gas flow rate, and lubricating oil consumption were reduced by cylindrical bore. Besides improved high-load performance, this cylinder block enhanced engine performance under low-load conditions with low thermal stress. Cylindrical bore has impact for reduction by 2.7% with zero pin-offset piston and improvement other performances for normal bore.]]></description>
      <pubDate>Mon, 30 Oct 2023 13:45:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/2259903</guid>
    </item>
    <item>
      <title>Study on the influence of various factors on block vibration</title>
      <link>https://trid.trb.org/View/2237138</link>
      <description><![CDATA[The influence of engine speed, torque, oil temperature, and piston liner clearance on the block vibration was studied with experimental test and wavelet packet decomposition method (WPD). The wavelet packet function of db10 and decomposition level of four was confirmed based on the Shannon entropy. The frequency analysis of the block vibration measured at motor-driven condition showed that the spectrum energy was mainly concentrated in the range of 4–5, 10–15, and 20–25?kHz. The energy of each frequency band obtained from WPD was contrasted at different engine speed, torque, oil temperature, and piston-liner clearance conditions. On this basis, the interaction between different factors was further investigated. The sensitive frequency band of block vibration was confirmed for different factors.]]></description>
      <pubDate>Mon, 25 Sep 2023 09:15:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/2237138</guid>
    </item>
    <item>
      <title>Engine Block Vibration Measures for Time Detection of Diesel Combustion Phases</title>
      <link>https://trid.trb.org/View/1819214</link>
      <description><![CDATA[This work fits into a research program in which the multi-cylinder diesel engine block vibration signal is used with the purpose of developing and setting up a methodology able to monitor and optimize the combustion behavior by means of non-intrusive transducer. Previously published results have demonstrated the direct relationship existing between in-cylinder pressure and engine block vibration signals in a fixed frequency band. It was also shown sensitivity of the engine surface vibration to variation of injection parameters, when the accelerometer is placed in sensitive location of the engine block. Moreover, the accelerometer trace has revealed to be able to locate in the crank–angle domain important phenomena characterizing the combustion process. The aim of the present work is to extend the results presented in [9] with the final aim of establishing a reliable relation between the main characteristics of the in-cylinder pressure curve and the vibration trend by means of a deeper insight into the engine block signal. In this paper, the previously developed steps of the research program are briefly presented. Then, the processing technique is described and the results obtained by applying a wide variation of the engine operating conditions are presented and discussed.]]></description>
      <pubDate>Thu, 21 Jul 2022 13:39:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1819214</guid>
    </item>
    <item>
      <title>Experimental and Numerical Investigations of Tumble Motion on an Optical Single Cylinder Engine</title>
      <link>https://trid.trb.org/View/1832840</link>
      <description><![CDATA[This paper is focused on the experimental and numerical investigation of tumble motion on a single cylinder optical engine on three important parameters like engine load conditions, engine speed and level of tumble. Experiments are conducted in an optical engine and the velocity fields are measured with the aid of advanced particle image velocimetry (PIV) measurement technique. For simulation, multiple cases were considered to develop the numerical process for transient in-cylinder aerodynamics to capture the tumble motion and turbulence level in a Spark Ignited (SI) engine. The simulation results, velocity fields of each case were directly compared with the corresponding test results for different crank positions of the engine. On comparison, a good agreement between the measurement and the simulation is obtained for different configurations.]]></description>
      <pubDate>Fri, 18 Mar 2022 12:17:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1832840</guid>
    </item>
    <item>
      <title>An Automated Workflow for Efficient Conjugate Heat Transfer Analysis of a Diesel Engine</title>
      <link>https://trid.trb.org/View/1847660</link>
      <description><![CDATA[The internal combustion engine’s performance is affected by in-cylinder combustion processes and heat transfer rates through the combustion chamber walls. Hot spots may affect the reliability and durability of the engine components. Design of efficient and effective coolant systems requires accurate accounting of the heat fluxes into and out of the solid parts during the engine operation. The need to assess the engine’s performance early in the design process has motivated the use of a computational approach to predict such data. A more accurate representation of the engine’s operation is obtained by coupling the thermal, flow, and combustion analysis of the various components, such as the combustion chamber, ports, engine block, and its cooling system. Typically, a stand-alone CFD simulation does not capture the complex nature of the problem, and the manual transfer of data between multiple analyses may lead to an onerous or error-prone workflow requiring multiple user interventions. Here the authors present an accurate and efficient workflow for the conjugate heat transfer analysis of a diesel engine conducted using Ansys System Coupling software [1]. This workflow allows a full coupling between the fluid flow and combustion processes inside the combustion chamber, performed using Ansys Forte software [2], with the fluid flow and thermal analysis on the surrounding engine block carried out using Ansys Fluent [3]. The coupling is fully automated within a framework that handles the data exchange and manages the iterative solution between the two solvers to convergence.]]></description>
      <pubDate>Mon, 27 Sep 2021 09:59:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/1847660</guid>
    </item>
    <item>
      <title>Examination of Micro Groove Bearing for Aluminum Block Engine</title>
      <link>https://trid.trb.org/View/1867235</link>
      <description><![CDATA[In the crankshaft bearing part of an aluminum block engine, the clearance changes depending on the temperature due to the difference in the coefficient of thermal expansion between the aluminum block and the forged crankshaft. In order to react to the change in the oil clearance due to temperature variation, the author has tried to apply Micro Groove Bearing (MGB) with excellent running-in characteristics using a 4L V8 gasoline engine made of aluminum block. The results show that the best specification of MGB has been 2.5-3.0μｍ in depth and 0.15-0.25mm in width and the engine starting friction at -30℃ has been 90-160 Nm and the crankshaft friction has been about 40% of the total friction. No damage has been found in the test bearings for the revolution speed of 1000-4000r/min. under full load.]]></description>
      <pubDate>Mon, 27 Sep 2021 09:45:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/1867235</guid>
    </item>
    <item>
      <title>Investigation into Mixed and Hydrodynamic Frictions of PEO Coatings and Cast Iron</title>
      <link>https://trid.trb.org/View/1779558</link>
      <description><![CDATA[A linerless aluminum (Al) engine block has potential to reduce the weight of an automotive engine and improve the fuel economy. However, the Al cylinder surface of an aluminum engine block is not usually strong enough to withstand the sliding wear against piston rings. A few surface processing technologies are used to protect the surface of cylinders. Among them, a thermal spraying coating, such as plasma transferred wire arc (PTWA) is already popular. Plasma electrolytic oxidation (PEO) coating is also proposed for increasing the wear resistance of aluminum-silicon (Al-Si) alloys and reducing the friction between the cylinder and piston. In this work, two different PEO coatings with a thickness of around 23 μm were prepared on an Al-Si alloy A356, and a high speed pin-on-disc tribometer was used to study the tribological behavior of the coatings at oil lubricant conditions. A cast iron sample was also used to do similar tribological tests for comparison. The coefficient of friction (COF) vs surface roughness (Rₐ: 0.2 - 0.8 μm) and sliding speeds (up to 6.07 m/s) were particularly studied. The results show that the COF significantly decreased with the increase of sliding speeds, and a smoother coating surface generally exhibited a lower COF and a steeper descent rate of the COF. While such observations seem true for both PEO coatings and the cast iron sample, the polished PEO coatings can have a lower COF than cast iron. The study indicates that the Al-Si alloy with PEO coatings could be further explored as a feasible solution to reduce the weight and improve the fuel efficiency of an Al engine.]]></description>
      <pubDate>Mon, 03 May 2021 11:48:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1779558</guid>
    </item>
    <item>
      <title>Investigation of liner cavitation considering coupling effect between engine vibration and acoustic field of water coolant passage</title>
      <link>https://trid.trb.org/View/1755509</link>
      <description><![CDATA[The engine vibration gives rise to pressure fluctuation of water coolant; therefore, the coupled system between engine structure and acoustic field of water coolant passage needs to be established to calculate the response of engine vibration and water coolant pressure fluctuation. A rectangular tank is used to evaluate water pressure induced by structural impact vibration. The dynamic characteristics of structural-acoustic coupled system are discussed by changing water depth. Considering the resonance effect, the relationship between natural frequencies of structure and acoustic field is examined by variation of sound speed. The equation of motion of engine structure coupled with acoustic field of water coolant passage is established to calculate coolant pressure fluctuation during engine working condition. The effect of piston slap forces on pressure fluctuation is evaluated. The influence of acoustic characteristics of water coolant passage on pressure fluctuation is discussed by varying sound speed.]]></description>
      <pubDate>Mon, 21 Dec 2020 10:06:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1755509</guid>
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