The Experts below are selected from a list of 8442 Experts worldwide ranked by ideXlab platform

Tienchong Chang - One of the best experts on this subject based on the ideXlab platform.

  • Torsional Behavior of chiral single-walled carbon nanotubes is loading direction dependent
    Applied Physics Letters, 2007
    Co-Authors: Tienchong Chang
    Abstract:

    The torsion of carbon nanotubes is studied by molecular dynamics simulations. The Torsional Behavior of a chiral single-walled carbon nanotube (SWCNT) is dependent on the loading directions due to its structural asymmetry. The critical buckling shear strain of a SWCNT in one direction may be 1.8 times higher than that in the opposite direction. This means that one can choose the most appropriate SWCNT for his special purpose in designing a Torsional component (e.g., oscillators and springs) of nanomechanical devices using carbon nanotubes. Meanwhile, the finding indicates that a simple thin shell model is not suitable for predicting Torsional Behavior of small SWCNTs at large strains.

Serkan Engin - One of the best experts on this subject based on the ideXlab platform.

  • Torsional Behavior of steel fiber reinforced concrete beams
    Construction and Building Materials, 2012
    Co-Authors: Fuad Okay, Serkan Engin
    Abstract:

    Abstract Torsion of structural members and the Behavior of steel fiber reinforced concrete became the area of interest of many researchers in the past and it is still newsworthy. In this study, 12 reinforced concrete (R/C) beams with Steel Fiber Reinforced Concrete (SFRC) were tested to observe the failure under Torsional moments. The volumetric steel fiber content, fiber aspect ratio, and the longitudinal reinforcement were the variables of the investigation. Unit Torsional angle of twist versus Torsional moment (torque) response of each specimen was monitored during the experiments, and the effect of above variables on this response was critically investigated. It was observed that not only the torque capacity of R/C beam is modified by the addition of Steel Fiber Reinforcement (SFR) but also the energy absorption capacity is significantly affected by the SFR addition. Besides, an empirical equation relating the torque to twist for SFRC beams is proposed and tested against the test data.

Kang Su Kim - One of the best experts on this subject based on the ideXlab platform.

  • analytical model for Torsional Behavior of rc members combined with bending shear and axial loads
    Journal of building engineering, 2020
    Co-Authors: Sun Jin Han, Kang Su Kim
    Abstract:

    Abstract In this study, a Torsional Behavior analysis model is developed for reinforced concrete (RC) members subjected to combined loads. In the analytical model, a member section is considered to be idealized as panel elements, on which a flexural analysis is first done considering axial forces to derive normal stresses acting on the cross-section. The panel elements are then analyzed with the normal stresses using the smeared truss model that satisfies the equilibrium and compatibility conditions. The various member forces are combined in terms of stress, in which the initial crack angle, the effective thickness affected by the combined stresses, and the distribution of the longitudinal reinforcement are reflected. From the combined stresses in the idealized panel elements, the member strengths are determined by applying multi-potential capacity criteria in which aggregate interlock failure, concrete crushing, and spalling of concrete cover are considered. The analytical model is verified by comparing it with existing test results, and it is found that the proposed model well evaluates the Torsional Behavior of RC members with and without shear force, bending moment, and axial force.

  • Torsional Behavior model of steel-fiber-reinforced concrete members modifying fixed-angle softened-truss model
    Composites Part B: Engineering, 2013
    Co-Authors: Deuck Hang Lee, Jin Ha Hwang, Joo Won Kang, Kang Su Kim
    Abstract:

    Abstract Steel-fiber-reinforced concrete (SFRC) is an efficient cement-based composite material that can compensate for the drawbacks of the material properties of conventional concrete and has better structural performances than conventional concrete. It can improve Torsional Behavior as well as flexural and shear Behavior. However, analysis of the Torsional Behavior of SFRC members is quite complicated because force equilibrium and strain compatibility in a three-dimensional space should be satisfied. Accordingly, many studies proposed empirical evaluation equations for the Torsional strength of SFRC members based on experimental results. Therefore, this study derived a constitutive model of SFRC in tension, which greatly influences the Torsional Behavior of SFRC, based on the test results of SFRC shear panels under biaxial stress, and this tensile Behavior model was introduced to a fixed-angle softened-truss model. A theoretical evaluation model based on the modified fixed-angle model for Torsional Behavior of SFRC was developed, and the performance of the analytical model was also evaluated compared to test results obtained from literature.

Fuad Okay - One of the best experts on this subject based on the ideXlab platform.

  • Torsional Behavior of steel fiber reinforced concrete beams
    Construction and Building Materials, 2012
    Co-Authors: Fuad Okay, Serkan Engin
    Abstract:

    Abstract Torsion of structural members and the Behavior of steel fiber reinforced concrete became the area of interest of many researchers in the past and it is still newsworthy. In this study, 12 reinforced concrete (R/C) beams with Steel Fiber Reinforced Concrete (SFRC) were tested to observe the failure under Torsional moments. The volumetric steel fiber content, fiber aspect ratio, and the longitudinal reinforcement were the variables of the investigation. Unit Torsional angle of twist versus Torsional moment (torque) response of each specimen was monitored during the experiments, and the effect of above variables on this response was critically investigated. It was observed that not only the torque capacity of R/C beam is modified by the addition of Steel Fiber Reinforcement (SFR) but also the energy absorption capacity is significantly affected by the SFR addition. Besides, an empirical equation relating the torque to twist for SFRC beams is proposed and tested against the test data.

Fabrizio Ponti - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of the Interactions Between Indicated and Reciprocating Torques for the Development of a Torsional Behavior Model of the Powertrain
    Journal of Engineering for Gas Turbines and Power, 2008
    Co-Authors: Fabrizio Ponti, Luca Solieri
    Abstract:

    Torque-based engine control systems usually employ a produced torque estimation feedback in order to verify that the strategy target torque has been met. Torque estimation can be performed using static maps describing the engine behaviour or using models describing the existing relationships between signals measured on the engine and the indicated torque produced. Signals containing information on the combustion development, suitable for this purpose, are, among other, the ion-current signal, the vibration signals obtained from accelerometers mounted on the engine block, or the instantaneous engine speed fluctuations. This paper presents the development and the identification process of an engine-driveline Torsional Behavior model that enables indicated torque estimation from instantaneous engine speed measurement. Particular attention has been devoted to the interactions between indicated and reciprocating torques, and their effects over instantaneous engine speed fluctuations. Indicated and reciprocating torques produce, in fact, opposite excitations on the driveline that show opposite effects on the engine speed waveform: for low engine speed usually indicated torque prevails, while the opposite applies for higher engine speed. In order to correctly estimate indicated torque from engine speed measurement it is therefore necessary to correctly evaluate the reciprocating torque contribution. Reciprocating torque is usually described using a waveform as a function of crank angle, while its amplitude depends on the value of the reciprocating masses. As mentioned before, knowledge of the reciprocating masses is fundamental in order to obtain correct estimation of the indicated torque. The identification process that has been setup for the engine-driveline Torsional model enables to evaluate the relationship between torques applied to the engine and the corresponding engine speed waveform even without knowing the value of the reciprocating masses. In addition, once this model has been setup, it is possible to estimate with high precision the value of the reciprocating masses. Particular attention has been devoted also to the feasibility of the application of the identified model on-board for torque estimation; for this reason the model has been developed in a very simple form. The approach proved to be effective both on gasoline and diesel engine, both for engine mounted on a test cell and on-board, with different engine configurations. Examples of application are given for some of the configurations investigated.Copyright © 2007 by ASME

  • Development of a Torsional Behavior Powertrain Model for Multiple Misfire Detection
    Journal of Engineering for Gas Turbines and Power, 2008
    Co-Authors: Fabrizio Ponti
    Abstract:

    Many methodologies have been developed in the past for misfire detection purposes based on the analysis of the instantaneous engine speed. The missing combustion is usually detected, thanks to the sudden engine speed decrease that takes place after a misfire event. Misfire detection and, in particular, cylinder isolation are nevertheless still a challenging issue for engines with a high number of cylinders, for engine operating conditions at low load or high engine speed, and for multiple misfire events. When a misfire event takes place, a Torsional vibration is excited and shows up in the instantaneous engine speed wave form. If a multiple misfire occurs, this Torsional vibration is excited more than once in a very short time interval. The interaction between these successive vibrations can generate false alarms or misdetection, and an increased complexity when dealing with cylinder isolation. This paper presents the development of a powertrain Torsional Behavior model in order to identify the effects of a misfire event on the instantaneous engine speed signal. The identified wave form has then been used to filter out the Torsional vibration effects in order to enlighten the missing combustions even in the case of multiple misfire events. The model response is also used to speed up the setup process for the detection algorithm employed, thus evaluating, before running specific experimental tests on a test bench facility, the values for the threshold and the optimal setup of the procedure. The proposed algorithm is developed in this paper for an SI L4 engine; its application to other engine configurations is possible, as is also discussed in this paper.

  • Analysis of the Interactions Between Indicated and Reciprocating Torques for the Development of a Torsional Behavior Model of the Powertrain
    ASME 2007 Internal Combustion Engine Division Fall Technical Conference, 2007
    Co-Authors: Fabrizio Ponti, Luca Solieri
    Abstract:

    Torque-based engine control systems usually employ a produced torque estimation feedback in order to verify that the strategy target torque has been met. Torque estimation can be performed using static maps describing the engine behaviour or using models describing the existing relationships between signals measured on the engine and the indicated torque produced. Signals containing information on the combustion development, suitable for this purpose, are, among other, the ion-current signal, the vibration signals obtained from accelerometers mounted on the engine block, or the instantaneous engine speed fluctuations. This paper presents the development and the identification process of an engine-driveline Torsional Behavior model that enables indicated torque estimation from instantaneous engine speed measurement. Particular attention has been devoted to the interactions between indicated and reciprocating torques, and their effects over instantaneous engine speed fluctuations. Indicated and reciprocating torques produce, in fact, opposite excitations on the driveline that show opposite effects on the engine speed waveform: for low engine speed usually indicated torque prevails, while the opposite applies for higher engine speed. In order to correctly estimate indicated torque from engine speed measurement it is therefore necessary to correctly evaluate the reciprocating torque contribution. Reciprocating torque is usually described using a waveform as a function of crank angle, while its amplitude depends on the value of the reciprocating masses. As mentioned before, knowledge of the reciprocating masses is fundamental in order to obtain correct estimation of the indicated torque. The identification process that has been setup for the engine-driveline Torsional model enables to evaluate the relationship between torques applied to the engine and the corresponding engine speed waveform even without knowing the value of the reciprocating masses. In addition, once this model has been setup, it is possible to estimate with high precision the value of the reciprocating masses. Particular attention has been devoted also to the feasibility of the application of the identified model on-board for torque estimation; for this reason the model has been developed in a very simple form. The approach proved to be effective both on gasoline and diesel engine, both for engine mounted on a test cell and on-board, with different engine configurations. Examples of application are given for some of the configurations investigated.

  • Development of a Torsional Behavior Powertrain Model for Multiple Misfire Detection
    ASME 2005 Internal Combustion Engine Division Spring Technical Conference, 2005
    Co-Authors: Fabrizio Ponti
    Abstract:

    Many methodologies have been developed in the past for misfire detection purposes based on the analysis of the instantaneous engine speed. The missing combustion is usually detected thanks to the sudden engine speed decrease that takes place after a misfire event. Misfire detection and in particular cylinder isolation is anyhow still a challenging issue for engines with a high number of cylinders, for engine operating conditions at low load or high engine speed and for multiple misfire events. When a misfire event takes place in fact a Torsional vibration is excited and shows up in the instantaneous engine speed waveform. If a multiple misfire occurs this Torsional vibration is excited more than once in a very short time interval. The interaction among these successive vibrations can generate false alarms or misdetection, and an increased complexity when dealing with cylinder isolation. The paper presents the development of a powertrain Torsional Behavior model in order to identify the effects of a misfire event on the instantaneous engine speed signal. The identified waveform has then been used to filter out the Torsional vibration effects in order to enlighten the missing combustions even in the case of multiple misfire events. The model response is also used to quicken the setup process for the detection algorithm employed, evaluating before running specific experimental tests on a test bench facility, the values for the threshold and the optimal setup of the procedure. The proposed algorithm is developed in this paper for an SI L4 engine; Its application to other engine configurations is possible, as it is also discussed in the paper.© 2005 ASME