The Experts below are selected from a list of 11343 Experts worldwide ranked by ideXlab platform

Deguang Shang - One of the best experts on this subject based on the ideXlab platform.

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

James C. Iatridis - One of the best experts on this subject based on the ideXlab platform.

  • Direct measurement of intervertebral disc Maximum Shear Strain in six degrees of freedom: Motions that place disc tissue at risk of injury
    Journal of biomechanics, 2007
    Co-Authors: John J. Costi, Ian A. F. Stokes, Mack Gardner-morse, Jeff Laible, Heather Scoffone, James C. Iatridis
    Abstract:

    Human intervertebral disc specimens were tested to determine the regions of largest Maximum Shear Strain experienced by disc tissues in each of three principal displacements and three rotations, and to identify the physiological rotations and displacements that may place the disc at greatest risk for large tissue Strains and injury. Tearing of disc annulus may be initiated by large interlamellar Shear Strains. Nine human lumbar discs were tagged with radiographic markers on the endplates, disc periphery and with a grid of wires in the mid-transverse plane and subjected to each of the six principal displacements and rotations. Stereo-radiographs were taken in each position and digitized for reconstruction of the 3-D position of each marker. Maximum tissue Shear Strains were calculated from relative marker displacements and normalized by the input displacement or rotation. Lateral Shear, compression, and lateral bending were the motions that produced the mean (95% confidence interval) largest regional Maximum Shear Strains (MSS) of 9.6 (0.7) %/mm, 9.0 (0.5) %/mm, and 5.8 (1.6) %/° respectively, and which occurred in the posterior, posterolateral and lateral peripheral regions of the disc. After taking into account the reported Maximum physiological range of motion for each degree of freedom, motions producing the highest physiological MSS were lateral bending (57.8 (16.2)%) and flexion (38.3 (3.3)%), followed by lateral Shear (14.4 (1.1)%) and compression (12.6 (0.7)%).

  • direct measurement of intervertebral disc Maximum Shear Strain in six degrees of freedom motions that place disc tissue at risk of injury
    Journal of Biomechanics, 2007
    Co-Authors: John J. Costi, Ian A. F. Stokes, Jeff Laible, Heather Scoffone, Mack Gardnermorse, James C. Iatridis
    Abstract:

    Human intervertebral disc specimens were tested to determine the regions of largest Maximum Shear Strain (MSS) experienced by disc tissues in each of three principal displacements and three rotations, and to identify the physiological rotations and displacements that may place the disc at greatest risk for large tissue Strains and injury. Tearing of disc annulus may be initiated by large interlamellar Shear Strains. Nine human lumbar discs were tagged with radiographic markers on the endplates, disc periphery and with a grid of wires in the mid-transverse plane and subjected to each of the six principal displacements and rotations. Stereo-radiographs were taken in each position and digitized for reconstruction of the three-dimensional position of each marker. Maximum tissue Shear Strains were calculated from relative marker displacements and normalized by the input displacement or rotation. Lateral Shear, compression, and lateral bending were the motions that produced the mean (95% confidence interval) largest mean MSS of 9.6 (0.7)%/mm, 9.0 (0.5)%/mm, and 5.8 (1.6)%/ degrees , respectively, and which occurred in the posterior, posterolateral and lateral peripheral regions of the disc. After taking into account the reported Maximum physiological range of motion for each degree of freedom, motions producing the highest physiological MSS were lateral bending (57.8 (16.2)%) and flexion (38.3 (3.3)%), followed by lateral Shear (14.4 (1.1)%) and compression (12.6 (0.7)%).

Xiaowei Wang - One of the best experts on this subject based on the ideXlab platform.

  • multiaxial fatigue life prediction based on short crack propagation model with equivalent Strain parameter
    Journal of Materials Engineering and Performance, 2018
    Co-Authors: Xiangfeng Zhao, Mingliang Song, Deguang Shang, Xiaowei Wang
    Abstract:

    The Maximum Shear Strain and the normal Strain excursion on the critical plane are regarded as the primary parameters of the crack driving force to establish a new short crack model in this paper. An equivalent Strain-based intensity factor is proposed to correlate the short crack growth rate under multiaxial loading. According to the short crack model, a new method is proposed for multiaxial fatigue life prediction based on crack growth analysis. It is demonstrated that the method can be used under proportional and non-proportional loadings. The predicted results showed a good agreement with experimental lives in both high-cycle and low-cycle regions.

  • Multiaxial Fatigue Life Prediction Based on Weight Function Method Under Random Loading
    DEStech Transactions on Engineering and Technology Research, 2017
    Co-Authors: Xiaowei Wang, Deguang Shang, Yu-juan Sun
    Abstract:

    Based on Strain parameters, a weight function method is proposed to determine the critical plane under variable amplitude axial-torsion loading. The critical plane is determined by averaging the Maximum absolute Shear Strain plane during the time for one block loading. The averaging process is conducted through a weight function, which is proposed based on the Maximum Shear Strain. Then, combined with the life prediction model and Wang-Brown’s cycle counting method, the proposed method is used to predict the fatigue life under variable amplitude loading. The experimental data of En15R steel and 7050-T7451 aluminum alloy are used to verify the proposed method, and a good result is obtained.

Philippe Bompard - One of the best experts on this subject based on the ideXlab platform.

  • The effects of variable stress amplitude on cyclic plasticity and microcrack initiation in austenitic steel 304L
    Computational Materials Science, 2012
    Co-Authors: Véronique Aubin, Colette Rey, Philippe Bompard
    Abstract:

    Abstract In this paper, recent results of the numerical simulation and experimental investigation of variable stress amplitude effects on cyclic plasticity and microcrack initiation in 304L steel are presented. A volume of the material corresponding to a realistic microstructure, containing about 150 grains, has been modeled on the basis of crystal plasticity theory. This model takes account of dislocation densities on the 12 slip systems, isotropic and kinematic hardening, grain sizes, crystal orientations and elastic anisotropy. In order to investigate the effects of variable stress amplitude on cyclic plasticity, the fatigue tests were conducted under stress amplitude of 220–320 (overload) −220 MPa. Four loading paths were considered, which only differ in signs of the beginning and end of the overload block but not in level of amplitude. The fields of local stress and Strain, Maximum Shear Strain amplitude of 12 slip systems and the normal stress on the critical plane of Maximum Shear Strain amplitude were simulated before, during and after overload. The numerical studies performed on a realistic polycrystalline aggregate of 304L have demonstrated that overload effects on cyclic plasticity and microcrack initiation are significant in all these four loading paths. By comparison with experimental results, local stress and Maximum Shear Strain amplitude may be the good indicators for prediction of crack initiation under variable stress amplitude.