The Experts below are selected from a list of 45 Experts worldwide ranked by ideXlab platform

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

  • closed form error space calculation for parallel hybrid manipulators considering joint clearance input uncertainty and Manufacturing Imperfection
    Mechanism and Machine Theory, 2019
    Co-Authors: Qiangqiang Zhao, Jun Hong
    Abstract:

    Abstract This study proposes a generalized approach to error space calculation for parallel/hybrid manipulators resulting from joint clearance, input uncertainty, and Manufacturing Imperfection. First, the local pose deviation caused by each error is parameterized using exponential coordinates, and the distribution is defined as a Gaussian on the motion group. Second, the linear relationship between the local pose error caused by the disturbance of the passive joint and that by other error sources is derived based on the Baker–Campbell–Hausdorff formula. Third, closed-form formulas are developed for error propagation on independent and non-independent group elements, thereby determining the covariance and mean of the pose error distribution of the end-effector. Fourth, the error space and maximum deviation along/about each axis are extracted from the covariance matrix and mean at the designated confidence level. Finally, four numerical cases are presented to demonstrate the effectiveness and advantages of the proposed method. The experimental evidence indicates that the proposed method can be applied to planar and spatial parallel/hybrid manipulators and has a significantly high computation speed.

  • Closed-form error space calculation for parallel/hybrid manipulators considering joint clearance, input uncertainty, and Manufacturing Imperfection
    Mechanism and Machine Theory, 2019
    Co-Authors: Qiangqiang Zhao, Jun Hong
    Abstract:

    Abstract This study proposes a generalized approach to error space calculation for parallel/hybrid manipulators resulting from joint clearance, input uncertainty, and Manufacturing Imperfection. First, the local pose deviation caused by each error is parameterized using exponential coordinates, and the distribution is defined as a Gaussian on the motion group. Second, the linear relationship between the local pose error caused by the disturbance of the passive joint and that by other error sources is derived based on the Baker–Campbell–Hausdorff formula. Third, closed-form formulas are developed for error propagation on independent and non-independent group elements, thereby determining the covariance and mean of the pose error distribution of the end-effector. Fourth, the error space and maximum deviation along/about each axis are extracted from the covariance matrix and mean at the designated confidence level. Finally, four numerical cases are presented to demonstrate the effectiveness and advantages of the proposed method. The experimental evidence indicates that the proposed method can be applied to planar and spatial parallel/hybrid manipulators and has a significantly high computation speed.

G. A. Ramadass - One of the best experts on this subject based on the ideXlab platform.

  • non linear buckling analysis of imperfect thin spherical pressure hull for manned submersible
    Journal of Ocean Engineering and Science, 2017
    Co-Authors: Sb Pranesh, D. Sathianarayanan, Deepak Kumar, Anantha V Subramanian, G. A. Ramadass
    Abstract:

    Abstract Thin spherical pressure hulls are used as a human occupancy in deep water applications. DNV and other standards specify the Imperfection allowed for pressure hulls. Numerical analyses are carried out to find the buckling pressure for both perfect and imperfect thin spherical pressure hulls, considering the geometric and material non-linearities. It is observed that there is a huge variation in the elastic and inelastic buckling pressure in perfect spherical pressure hulls. Moreover, if the Manufacturing Imperfections are considered in the inelastic numerical analysis, still there is a reduction in the buckling pressure. Design criteria, for deep water pressure hulls, is that both buckling pressure and yield pressure must be greater than the design pressure. In the elastic analysis, if t/D > 0.006 buckling pressure is always greater than the yield pressure whereas in the inelastic analysis, the buckling pressure is falling below the yield pressure for all t/D ratios. Hence, inelastic numerical analysis with Manufacturing Imperfection has to considered in the design of deep water spherical pressure hulls of manned submersibles.

  • Manufacturing Imperfection sensitivity analysis of spherical pressure hull for manned submersible
    Marine Technology Society Journal, 2013
    Co-Authors: Bhaskaran Pranesh, D. Sathianarayanan, S Ramesh, G. A. Ramadass
    Abstract:

    Any pressure hull invariably has Imperfections as a result of the Manufacturing procedure. Imperfections in a spherical pressure hull are the basis for localized buckling and deformation behavior. Numerical analysis and analytical calculations are carried out to predict the buckling behavior and strength of a pressure hull made of titanium alloy (Ti-6Al-4V) for both perfect and imperfect pressure hulls. Finite element analysis is carried out for different Imperfection angles to see the effect on strength and buckling. Results of numerical analysis show that there is considerable reduction in both buckling pressure and strength as a result of Imperfections. Hence, allowable deviation due to Imperfection for a spherical pressure hull has to be considered for thickness calculations.

Qiangqiang Zhao - One of the best experts on this subject based on the ideXlab platform.

  • closed form error space calculation for parallel hybrid manipulators considering joint clearance input uncertainty and Manufacturing Imperfection
    Mechanism and Machine Theory, 2019
    Co-Authors: Qiangqiang Zhao, Jun Hong
    Abstract:

    Abstract This study proposes a generalized approach to error space calculation for parallel/hybrid manipulators resulting from joint clearance, input uncertainty, and Manufacturing Imperfection. First, the local pose deviation caused by each error is parameterized using exponential coordinates, and the distribution is defined as a Gaussian on the motion group. Second, the linear relationship between the local pose error caused by the disturbance of the passive joint and that by other error sources is derived based on the Baker–Campbell–Hausdorff formula. Third, closed-form formulas are developed for error propagation on independent and non-independent group elements, thereby determining the covariance and mean of the pose error distribution of the end-effector. Fourth, the error space and maximum deviation along/about each axis are extracted from the covariance matrix and mean at the designated confidence level. Finally, four numerical cases are presented to demonstrate the effectiveness and advantages of the proposed method. The experimental evidence indicates that the proposed method can be applied to planar and spatial parallel/hybrid manipulators and has a significantly high computation speed.

  • Closed-form error space calculation for parallel/hybrid manipulators considering joint clearance, input uncertainty, and Manufacturing Imperfection
    Mechanism and Machine Theory, 2019
    Co-Authors: Qiangqiang Zhao, Jun Hong
    Abstract:

    Abstract This study proposes a generalized approach to error space calculation for parallel/hybrid manipulators resulting from joint clearance, input uncertainty, and Manufacturing Imperfection. First, the local pose deviation caused by each error is parameterized using exponential coordinates, and the distribution is defined as a Gaussian on the motion group. Second, the linear relationship between the local pose error caused by the disturbance of the passive joint and that by other error sources is derived based on the Baker–Campbell–Hausdorff formula. Third, closed-form formulas are developed for error propagation on independent and non-independent group elements, thereby determining the covariance and mean of the pose error distribution of the end-effector. Fourth, the error space and maximum deviation along/about each axis are extracted from the covariance matrix and mean at the designated confidence level. Finally, four numerical cases are presented to demonstrate the effectiveness and advantages of the proposed method. The experimental evidence indicates that the proposed method can be applied to planar and spatial parallel/hybrid manipulators and has a significantly high computation speed.

Sb Pranesh - One of the best experts on this subject based on the ideXlab platform.

  • non linear buckling analysis of imperfect thin spherical pressure hull for manned submersible
    Journal of Ocean Engineering and Science, 2017
    Co-Authors: Sb Pranesh, D. Sathianarayanan, Deepak Kumar, Anantha V Subramanian, G. A. Ramadass
    Abstract:

    Abstract Thin spherical pressure hulls are used as a human occupancy in deep water applications. DNV and other standards specify the Imperfection allowed for pressure hulls. Numerical analyses are carried out to find the buckling pressure for both perfect and imperfect thin spherical pressure hulls, considering the geometric and material non-linearities. It is observed that there is a huge variation in the elastic and inelastic buckling pressure in perfect spherical pressure hulls. Moreover, if the Manufacturing Imperfections are considered in the inelastic numerical analysis, still there is a reduction in the buckling pressure. Design criteria, for deep water pressure hulls, is that both buckling pressure and yield pressure must be greater than the design pressure. In the elastic analysis, if t/D > 0.006 buckling pressure is always greater than the yield pressure whereas in the inelastic analysis, the buckling pressure is falling below the yield pressure for all t/D ratios. Hence, inelastic numerical analysis with Manufacturing Imperfection has to considered in the design of deep water spherical pressure hulls of manned submersibles.

D. Sathianarayanan - One of the best experts on this subject based on the ideXlab platform.

  • non linear buckling analysis of imperfect thin spherical pressure hull for manned submersible
    Journal of Ocean Engineering and Science, 2017
    Co-Authors: Sb Pranesh, D. Sathianarayanan, Deepak Kumar, Anantha V Subramanian, G. A. Ramadass
    Abstract:

    Abstract Thin spherical pressure hulls are used as a human occupancy in deep water applications. DNV and other standards specify the Imperfection allowed for pressure hulls. Numerical analyses are carried out to find the buckling pressure for both perfect and imperfect thin spherical pressure hulls, considering the geometric and material non-linearities. It is observed that there is a huge variation in the elastic and inelastic buckling pressure in perfect spherical pressure hulls. Moreover, if the Manufacturing Imperfections are considered in the inelastic numerical analysis, still there is a reduction in the buckling pressure. Design criteria, for deep water pressure hulls, is that both buckling pressure and yield pressure must be greater than the design pressure. In the elastic analysis, if t/D > 0.006 buckling pressure is always greater than the yield pressure whereas in the inelastic analysis, the buckling pressure is falling below the yield pressure for all t/D ratios. Hence, inelastic numerical analysis with Manufacturing Imperfection has to considered in the design of deep water spherical pressure hulls of manned submersibles.

  • Manufacturing Imperfection sensitivity analysis of spherical pressure hull for manned submersible
    Marine Technology Society Journal, 2013
    Co-Authors: Bhaskaran Pranesh, D. Sathianarayanan, S Ramesh, G. A. Ramadass
    Abstract:

    Any pressure hull invariably has Imperfections as a result of the Manufacturing procedure. Imperfections in a spherical pressure hull are the basis for localized buckling and deformation behavior. Numerical analysis and analytical calculations are carried out to predict the buckling behavior and strength of a pressure hull made of titanium alloy (Ti-6Al-4V) for both perfect and imperfect pressure hulls. Finite element analysis is carried out for different Imperfection angles to see the effect on strength and buckling. Results of numerical analysis show that there is considerable reduction in both buckling pressure and strength as a result of Imperfections. Hence, allowable deviation due to Imperfection for a spherical pressure hull has to be considered for thickness calculations.