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Li-wen Chen - One of the best experts on this subject based on the ideXlab platform.

  • Effects of insulated rail joint on the wheel/rail contact Stresses under the condition of partial slip
    Wear, 2006
    Co-Authors: Yung-chuan Chen, Li-wen Chen
    Abstract:

    Abstract The effect of insulated rail joint (IRJ) on the wheel–rail normal and tangential contact Stress distribution is studied using the finite element method. In this investigation, contact elements are used to simulate the interaction between wheel and rail. Numerical simulations are used to explore the effects of contact distances and materials of IRJ on the contact Stress and the Maximum Shear Stress distributions. Numerical results show that the presence of IRJ might significantly affect the wheel–rail contact Stress distributions. The results also indicate that Carter's theory is no longer effective in predicting the tangential Stress distribution of the wheel–rail contact near an IRJ. The tangential Stress causes the location of Maximum Shear Stress shifted toward the rail surface as the wheel–rail contact point moves closer to the IRJ. The Maximum Shear Stress value is more sensitive to a braked force than to a tractive force as the wheel–rail contact point is within the IRJ region.

  • Effects of insulated rail joint on the wheel/rail contact Stresses under the condition of partial slip
    Wear, 2006
    Co-Authors: Yung-chuan Chen, Li-wen Chen
    Abstract:

    The effect of insulated rail joint (IRJ) on the wheel-rail normal and tangential contact Stress distribution is studied using the finite element method. In this investigation, contact elements are used to simulate the interaction between wheel and rail. Numerical simulations are used to explore the effects of contact distances and materials of IRJ on the contact Stress and the Maximum Shear Stress distributions. Numerical results show that the presence of IRJ might significantly affect the wheel-rail contact Stress distributions. The results also indicate that Carter's theory is no longer effective in predicting the tangential Stress distribution of the wheel-rail contact near an IRJ. The tangential Stress causes the location of Maximum Shear Stress shifted toward the rail surface as the wheel-rail contact point moves closer to the IRJ. The Maximum Shear Stress value is more sensitive to a braked force than to a tractive force as the wheel-rail contact point is within the IRJ region. © 2005 Elsevier B.V. All rights reserved.

Yung-chuan Chen - One of the best experts on this subject based on the ideXlab platform.

  • Effects of insulated rail joint on the wheel/rail contact Stresses under the condition of partial slip
    Wear, 2006
    Co-Authors: Yung-chuan Chen, Li-wen Chen
    Abstract:

    Abstract The effect of insulated rail joint (IRJ) on the wheel–rail normal and tangential contact Stress distribution is studied using the finite element method. In this investigation, contact elements are used to simulate the interaction between wheel and rail. Numerical simulations are used to explore the effects of contact distances and materials of IRJ on the contact Stress and the Maximum Shear Stress distributions. Numerical results show that the presence of IRJ might significantly affect the wheel–rail contact Stress distributions. The results also indicate that Carter's theory is no longer effective in predicting the tangential Stress distribution of the wheel–rail contact near an IRJ. The tangential Stress causes the location of Maximum Shear Stress shifted toward the rail surface as the wheel–rail contact point moves closer to the IRJ. The Maximum Shear Stress value is more sensitive to a braked force than to a tractive force as the wheel–rail contact point is within the IRJ region.

  • Effects of insulated rail joint on the wheel/rail contact Stresses under the condition of partial slip
    Wear, 2006
    Co-Authors: Yung-chuan Chen, Li-wen Chen
    Abstract:

    The effect of insulated rail joint (IRJ) on the wheel-rail normal and tangential contact Stress distribution is studied using the finite element method. In this investigation, contact elements are used to simulate the interaction between wheel and rail. Numerical simulations are used to explore the effects of contact distances and materials of IRJ on the contact Stress and the Maximum Shear Stress distributions. Numerical results show that the presence of IRJ might significantly affect the wheel-rail contact Stress distributions. The results also indicate that Carter's theory is no longer effective in predicting the tangential Stress distribution of the wheel-rail contact near an IRJ. The tangential Stress causes the location of Maximum Shear Stress shifted toward the rail surface as the wheel-rail contact point moves closer to the IRJ. The Maximum Shear Stress value is more sensitive to a braked force than to a tractive force as the wheel-rail contact point is within the IRJ region. © 2005 Elsevier B.V. All rights reserved.

Antonio Carlos Shimano - One of the best experts on this subject based on the ideXlab platform.

  • ANÁLISE FOTOELÁSTICA DE PARAFUSO DE SISTEMA DE FIXAÇÃO VERTEBRAL THE PHOTOELASTIC ANALISYS OF VERTEBRAL FIXATION SYSTEM SCREWS
    2020
    Co-Authors: Sarah Fakher Fakhouri, Dayana Pousa Paiva De Siqueira, Cleudmar Amaral De Araújo, Helton Luiz Aparecido Defino, Antonio Carlos Shimano
    Abstract:

    ABSTRACT Introduction: The photoelasticity is used for assessing the ten-sions/deformations involved in photoelastic materials when submitted to a given load by the observation of optical effects. The screw performance and mechanical functions are directly associated to the quality of the screws fixation in the vertebrae. Photoelasticity is an important tool to perform comparative studies of this nature. Objective: The aim of this study was to compare, by using photoelasticity, internal Stresses produced by the screw with an external diameter of 6 mm, when submit-ted to two different pullout strengths. Materials and Methods: For this, four photoelastic models were produced. The simu-lation was conducted by using two pullout strengths: 0.75 and 1.50 kgf. The Maximum Shear Stresses were calculated on 19 points around the screws, using the Tardy compensation me-thod. Results:The values of Maximum Shear Stress were higher with the load of 1.50 kgf. Conclusion: Thus, the screw will be more susceptible to pullout when heavier loads are applied.According to our analysis, we also found that the site with the highest Maximum Shear Stress was found to be at the peak of creast, particularly near the tips of the screws, regardless of the load employed.

  • The photoelastic analisys of vertebral fixation system screws
    Acta Ortopedica Brasileira, 2020
    Co-Authors: Sarah Fakher Fakhouri, Dayana Pousa Paiva De Siqueira, Cleudmar Amaral De Araújo, Helton Luiz Aparecido Defino, Antonio Carlos Shimano
    Abstract:

    Introduction: The photoelasticity is used for assessing the tensions/deformations involved in photoelastic materials when submitted to a given load by the observation of optical effects. The screw performance and mechanical functions are directly associated to the quality of the screws fixation in the vertebrae. Photoelasticity is an important tool to perform comparative studies of this nature. Objective: The aim of this study was to compare, by using photoelasticity, internal Stresses produced by the screw with an external diameter of 6 mm, when submitted to two different pullout strengths. Materials and Methods: For this, four photoelastic models were produced. The simulation was conducted by using two pullout strengths: 0.75 and 1.50 kgf. The Maximum Shear Stresses were calculated on 19 points around the screws, using the Tardy compensation method. Results:The values of Maximum Shear Stress were higher with the load of 1.50 kgf. Conclusion: Thus, the screw will be more susceptible to pullout when heavier loads are applied. According to our analysis, we also found that the site with the highest Maximum Shear Stress was found to be at the peak of creast, particularly near the tips of the screws, regardless of the load employed.

Jeong Whan Yoon - One of the best experts on this subject based on the ideXlab platform.

  • A Stress-Based Model for Shear Ductile Fracture
    Key Engineering Materials, 2019
    Co-Authors: Jeong Whan Yoon
    Abstract:

    A Stress-based model is developed to describe Shear ductile fracture of lightweight metals. The proposed function couples the effect of the Maximum Shear Stress and the Stress triaxiality on fracture limits of metals during plastic deformation. Effect of the Maximum Shear Stress in the proposed fracture model is correlated with the influence of the Lode parameter on fracture limits. The proposed fracture model is applied to depict the fracture locus of AA2024-T351. The predicted fracture locus is compared with experimental results of the alloy. The comparison demonstrates that the proposed fracture model reasonably characterizes the fracture Stress in various loading conditions of compression, Shear and tension.

  • correlation of the Maximum Shear Stress with micro mechanisms of ductile fracture for metals with high strength to weight ratio
    International Journal of Mechanical Sciences, 2018
    Co-Authors: Jeong Whan Yoon, Qi Chao, Junghan Song
    Abstract:

    Abstract Mechanisms of ductile fracture are investigated experimentally in a wide range of loading conditions from compressive upsetting to the balanced biaxial tension for two metals with high strength-to-density ratio of DP980 (t1.2) steel sheets and a bulk aluminum alloy of AA7075. Specimens are carefully designed to achieve various loading conditions from Shear at low Stress triaxiality to the balanced biaxial tension at high Stress triaxiality for DP980, while both tensile and compressive tests are conducted for AA7075. Fractured specimen surfaces are analyzed macroscopically focusing on their relations with the Maximum Shear Stress. It is observed that all the specimens tend to fail along the direction of the Maximum Shear Stress in various loading states of plane strain compression, uniaxial compression, Shear, uniaxial tension, plane strain tension and the balanced biaxial tension. Scanning electron microscope analyses of fracture surfaces are also conducted to explore the underlying mechanism of void coalescence since coalescence of voids is viewed as the last step of ductile fracture after nucleation and growth of voids. It is noted that fractured voids elongate along the direction of the Maximum Shear Stress for all specimens with the Stress triaxiality ranging from about −0.57 in compression to 0.67 in the balanced biaxial tension. The experiments of DP980 and AA7075 reveal that ductile fracture takes place along the direction of the Maximum Shear Stress in the wide loading conditions of compressive upsetting, Shear, uniaxial tension, plane strain tension and the balanced biaxial tension with Stress triaxiality below 0.67. Thus, ductile fracture is expected to be governed by the Maximum Shear Stress in these wide loading conditions of compression, Shear and tension. It is suggested that effect of the Maximum Shear Stress must be correctly coupled in modeling of ductile fracture in these loading conditions with uncoupled and coupled ductile fracture criteria.

Jianyu Zhang - One of the best experts on this subject based on the ideXlab platform.

  • A sectional critical plane model for multiaxial high-cycle fatigue life prediction
    2020
    Co-Authors: Xinxin Qi, Jiaying Wang, Jianyu Zhang
    Abstract:

    A Stress-based sectional critical plane model for multiaxial fatigue life prediction is proposed. The proposed model considers the effects of material properties and loading paths on the crack initiation and propagation behaviors. By introducing the ratio of Maximum Shear Stress amplitude to Maximum normal Stress amplitude, it is divided into three sections in which the Maximum normal Stress plane, Maximum damage plane and Maximum Shear Stress amplitude plane are considered as the critical planes, respectively. To verify the accuracy and applicability of the proposed model, experimental data of 30CrMnSiA steel conducted by the authors and other test data of different materials from the existing literatures are utilized. For 30CrMnSiA steel, the prediction results of the proposed model demonstrate that 79.3% and 93.7% of the prediction results are within the ±2 times and ±3 times scatter band of fatigue life. For the experimental data from the existing literatures, more than 85% and 70% of the results predicted by the proposed model are within ±3 times scatter band of fatigue life for steel and aluminum alloy materials, respectively.

  • effect of mean Stress on 2a12 t4 aluminum alloy under tension torsion constant amplitude loading
    Key Engineering Materials, 2016
    Co-Authors: Jianyu Zhang
    Abstract:

    Fatigue tests have been carried out to investigate the effects of mean-Stress and phase-difference on the tension-torsion fatigue failure of 2A12-T4 aluminum alloy. The results show that for fully reversed tension-torsion loading, the fatigue life increases with the increase of phase angle, but the fatigue life decreases with the increase of phase angle, when mean-Stress exists, both for Shear mean-Stress and normal mean-Stress. Fracture appearance shows that the crack initiation is on the direction of Maximum Shear Stress amplitude plane. Critical plane criteria based on the linear combination of the Maximum Shear Stress amplitude and Maximum normal Stress are studied and further discussion on the drawbacks of this kind of criteria are performed.