The Experts below are selected from a list of 1590 Experts worldwide ranked by ideXlab platform

Peter Gudmundson - One of the best experts on this subject based on the ideXlab platform.

  • An anisotropic fibre-network model for mechano-sorptive creep in paper
    International Journal of Solids and Structures, 2008
    Co-Authors: Jessica Strömbro, Peter Gudmundson
    Abstract:

    In this paper a simplified network model for mechano-sorptive creep is presented, which is a further development of an earlier paper [Strombro, J., Gudmundson, P., 2008. Mechanosorptive creep under ...

  • An anisotropic fibre-network model for mechano-sorptive creep in paper
    International Journal of Solids and Structures, 2008
    Co-Authors: Jessica Strömbro, Peter Gudmundson
    Abstract:

    AbstractIn this paper a simplified network model for mechano-sorptive creep is presented, which is a further development of an earlier paper [Strömbro, J., Gudmundson, P., 2008. Mechano-sorptive creep under compressive loading – a micromechanical model. International Journal of Solids and Structures 45 (9), 2420–2450.]. It is assumed that the anisotropic hygroexpansion of the fibres leads to large stresses at the fibre bonds when the moisture content changes. The resulting stress state will accelerate creep if the fibre material obeys a constitutive law that is non-linear. Fibre kinks are included in order to capture experimental observations of larger mechano-sorptive effects in compression than in tension. Moisture dependent material parameters and anisotropy in the fibre distribution have been introduced. Theoretical predictions based on the model are compared to experimental results for an anisotropic paper both under tensile and compressive loading at varying moisture content and it is found that the important features in the experiments are captured by the model. Different kinds of drying conditions have also been examined

  • Size-dependent yield strength and surface energies of thin films
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005
    Co-Authors: Per Fredriksson, Peter Gudmundson
    Abstract:

    The strain gradient plasticity theory recently proposed by Gudmundson [P. Gudmundson, J. Mech. Phys. Solids 52 (2004) 1379-1406] is used to analyse the behaviour of a thin film on an elastic substrate. Boundary conditions for the film-substrate interface are introduced via a surface energy that depends on the plastic strain state at the interface. Finite element results show a strong dependence on the surface energy. If the surface energy is small, no size effects appear. On the other hand, if a stiff interface is simulated, corresponding to a large surface energy, a thickness dependence of the yield strength is found. The application of several alternative strain gradient models would predict a thickness dependent hardening, but strictly not a size dependence of the yield strength. The presently predicted thickness dependence on yield strength and hardening is supported by experimental results.

  • Size-dependent yield strength of thin films
    International Journal of Plasticity, 2005
    Co-Authors: Per Fredriksson, Peter Gudmundson
    Abstract:

    Biaxial strain and pure shear of a thin film are analysed using a strain gradient plasticity theory presented by Gudmundson [Gudmundson, P., 2004. A unified treatment of strain gradient plasticity. ...

  • Numerical Verification of a Procedure for Calculation of Elastic Constants in Microcracking Composite Laminates
    Journal of Composite Materials, 1992
    Co-Authors: Peter Gudmundson, Sören Östlund
    Abstract:

    The accuracy of the Gudmundson and Ostlund (1992) method for the calculation of thermoelastic constants in composite laminates with matrix cracks is verified by comparing the Gudmundson and Ostlund theory with three-dimensional finite element calculations of cracked thick (Theta, -Theta)M glass fiber reinforced epoxy laminates for a wide range of different matrix crack densities. Results indicate that the Gudmundson and Ostlund theory (which is based solely on ply property data and matrix crack densities), in combination with the theory for infinite crack densities, covers all ranges of crack densities with a very good accuracy. The simple procedure is applicable to general 2D and 3D laminates of arbitrary layups and yields all components of the stiffness tensor. 17 refs.

Hiroshi Saito - One of the best experts on this subject based on the ideXlab platform.

  • Spatio-Temporal Correlation of Interference in MANET Under Spatially Correlated Shadowing Environment
    IEEE Transactions on Mobile Computing, 2020
    Co-Authors: Tatsuaki Kimura, Hiroshi Saito
    Abstract:

    Correlation of interference affects spatio-temporal aspects of various wireless mobile systems, such as retransmission, multiple antennas and cooperative relaying. In this paper, we study the spatial and temporal correlation of interference in mobile ad-hoc networks under a correlated shadowing environment. By modeling the node locations as a Poisson point process with an i.i.d. mobility model and considering Gudmundson (1991)' s spatially correlated shadowing model, we theoretically analyze the relationship between the correlation distance of log-normal shadowing and the spatial and temporal correlation coefficients of interference. Since the exact expressions of the correlation coefficients are intractable, we obtain their simple asymptotic expressions as the variance of log-normal shadowing increases. We found in our numerical examples that the asymptotic expansions can be used as tight approximate formulas and useful for modeling general wireless systems under spatially correlated shadowing.

Per Fredriksson - One of the best experts on this subject based on the ideXlab platform.

Tatsuaki Kimura - One of the best experts on this subject based on the ideXlab platform.

  • Spatio-Temporal Correlation of Interference in MANET Under Spatially Correlated Shadowing Environment
    IEEE Transactions on Mobile Computing, 2020
    Co-Authors: Tatsuaki Kimura, Hiroshi Saito
    Abstract:

    Correlation of interference affects spatio-temporal aspects of various wireless mobile systems, such as retransmission, multiple antennas and cooperative relaying. In this paper, we study the spatial and temporal correlation of interference in mobile ad-hoc networks under a correlated shadowing environment. By modeling the node locations as a Poisson point process with an i.i.d. mobility model and considering Gudmundson (1991)' s spatially correlated shadowing model, we theoretically analyze the relationship between the correlation distance of log-normal shadowing and the spatial and temporal correlation coefficients of interference. Since the exact expressions of the correlation coefficients are intractable, we obtain their simple asymptotic expressions as the variance of log-normal shadowing increases. We found in our numerical examples that the asymptotic expansions can be used as tight approximate formulas and useful for modeling general wireless systems under spatially correlated shadowing.

Per-lennart Larsson - One of the best experts on this subject based on the ideXlab platform.