The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Anastasios P Vassilopoulos - One of the best experts on this subject based on the ideXlab platform.

  • Complex Stress State effect on fatigue life of grp laminates part ii theoretical formulation
    International Journal of Fatigue, 2002
    Co-Authors: T P Philippidis, Anastasios P Vassilopoulos
    Abstract:

    The synergistic effect of in-plane Stress tensor components on fatigue strength is not traditionally considered in the design of thin-wall box-beam structures, e.g. composite rotor blades in general. Fatigue life calculations account only for the normal Stresses due to bending and centrifugal forces, neglecting the contribution of shear and transverse normal Stresses. The theoretical formulation of a life prediction methodology accounting for all in-plane Stress tensor components, through the use of a multiaxial fatigue strength criterion, is presented here. Comparison of theoretical predictions with experimental results from constant amplitude, uniaxial, off-axis tests demonstrates the drastic effect of shear and transverse normal Stresses, besides that of axial normal Stress, in reducing operational life of a GRP structural laminate.

  • Complex Stress State effect on fatigue life of grp laminates part i experimental
    International Journal of Fatigue, 2002
    Co-Authors: T P Philippidis, Anastasios P Vassilopoulos
    Abstract:

    In structural applications of thin-wall, box beam constructions with composites, the effect of Complex Stress States is not properly taken into account in determining operational life and fatigue response in general, due either to misconceptions or lack of experimental data and theoretical models. Results from a recent research project, presented here in two parts, aim to contribute to the better understanding of fatigue behaviour of GRP laminates under Complex in-plane Stress States. An initial estimate on the effect of neglecting shear and transverse normal Stresses in fatigue life calculations is provided, based on experimental data and theoretical considerations. It is concluded that in structural GRP laminates, shear and transverse normal Stresses have an important contribution in reducing operational life, irrespective of their magnitude, usually small compared to axial normal Stresses.

Erik Serrano - One of the best experts on this subject based on the ideXlab platform.

  • experimental and numerical investigations of cross laminated timber elements at in plane beam loading conditions
    Construction and Building Materials, 2019
    Co-Authors: Mario Jelec, Henrik Danielsson, Vlatka Rajcic, Erik Serrano
    Abstract:

    Abstract Cross laminated timber (CLT) at in-plane beam loading conditions presents a Complex Stress State wherefore several failure modes and geometry parameters need to be considered in design. The work presented here includes experimental investigations of CLT beams for comparison and validation of an analytical model and design proposals previously suggested by the authors. All relevant failure modes are considered; bending failure and shear failure modes I, II and III. The main focus is, however, on shear failure mode III relating to shear failure in the crossing areas between orthogonally bonded longitudinal and transversal lamination. The analytical model presented is an improvement of the analytical model which has been suggested to be used as the basis for design equations for the next version of Eurocode 5. The two design proposals presented are based on that improved analytical model. Experimental results show good agreement with the improved model and both design proposals. In order to study the influence of different lamination placements and varying lamination widths, comparisons between the improved analytical model and FE-analyses regarding magnitude and distribution of internal forces are presented and good agreement is obtained. Experimental and analytical results indicate only a small influence of reduced lamination widths close to the beam edges. This is a finding which is of practical interest since CLT beams in general are cut from larger elements, with no consideration of the location of the individual laminations with respect to the edges of the beam.

  • cross laminated timber at in plane beam loading prediction of shear Stresses in crossing areas
    Engineering Structures, 2018
    Co-Authors: Henrik Danielsson, Erik Serrano
    Abstract:

    Abstract Cross Laminated Timber (CLT) at in-plane beam loading conditions present a very Complex Stress State and many failure modes need to be considered in design. The work presented here aims at finding improvements of a specific analytical model for Stress analysis and strength verification that has been suggested in literature and which is also suggested as a basis for design equations for the next version of Eurocode 5. Although the model has appealing properties it suffers from some drawbacks related to the assumed distributions of internal forces which, based on comparison to finite element analysis, appear to be inaccurate. The main focus in this paper is on model predictions regarding the distribution and magnitude of internal forces acting in the crossing areas between longitudinal and transversal laminations. The proposed modified model assumptions regarding the distribution of lamination shear forces, which in turn influence the forces acting in the crossing areas, are suggested to be taken into account in design of CLT beams.

T P Philippidis - One of the best experts on this subject based on the ideXlab platform.

  • Complex Stress State effect on fatigue life of grp laminates part ii theoretical formulation
    International Journal of Fatigue, 2002
    Co-Authors: T P Philippidis, Anastasios P Vassilopoulos
    Abstract:

    The synergistic effect of in-plane Stress tensor components on fatigue strength is not traditionally considered in the design of thin-wall box-beam structures, e.g. composite rotor blades in general. Fatigue life calculations account only for the normal Stresses due to bending and centrifugal forces, neglecting the contribution of shear and transverse normal Stresses. The theoretical formulation of a life prediction methodology accounting for all in-plane Stress tensor components, through the use of a multiaxial fatigue strength criterion, is presented here. Comparison of theoretical predictions with experimental results from constant amplitude, uniaxial, off-axis tests demonstrates the drastic effect of shear and transverse normal Stresses, besides that of axial normal Stress, in reducing operational life of a GRP structural laminate.

  • Complex Stress State effect on fatigue life of grp laminates part i experimental
    International Journal of Fatigue, 2002
    Co-Authors: T P Philippidis, Anastasios P Vassilopoulos
    Abstract:

    In structural applications of thin-wall, box beam constructions with composites, the effect of Complex Stress States is not properly taken into account in determining operational life and fatigue response in general, due either to misconceptions or lack of experimental data and theoretical models. Results from a recent research project, presented here in two parts, aim to contribute to the better understanding of fatigue behaviour of GRP laminates under Complex in-plane Stress States. An initial estimate on the effect of neglecting shear and transverse normal Stresses in fatigue life calculations is provided, based on experimental data and theoretical considerations. It is concluded that in structural GRP laminates, shear and transverse normal Stresses have an important contribution in reducing operational life, irrespective of their magnitude, usually small compared to axial normal Stresses.

Vlatka Rajcic - One of the best experts on this subject based on the ideXlab platform.

  • experimental and numerical investigations of cross laminated timber elements at in plane beam loading conditions
    Construction and Building Materials, 2019
    Co-Authors: Mario Jelec, Henrik Danielsson, Vlatka Rajcic, Erik Serrano
    Abstract:

    Abstract Cross laminated timber (CLT) at in-plane beam loading conditions presents a Complex Stress State wherefore several failure modes and geometry parameters need to be considered in design. The work presented here includes experimental investigations of CLT beams for comparison and validation of an analytical model and design proposals previously suggested by the authors. All relevant failure modes are considered; bending failure and shear failure modes I, II and III. The main focus is, however, on shear failure mode III relating to shear failure in the crossing areas between orthogonally bonded longitudinal and transversal lamination. The analytical model presented is an improvement of the analytical model which has been suggested to be used as the basis for design equations for the next version of Eurocode 5. The two design proposals presented are based on that improved analytical model. Experimental results show good agreement with the improved model and both design proposals. In order to study the influence of different lamination placements and varying lamination widths, comparisons between the improved analytical model and FE-analyses regarding magnitude and distribution of internal forces are presented and good agreement is obtained. Experimental and analytical results indicate only a small influence of reduced lamination widths close to the beam edges. This is a finding which is of practical interest since CLT beams in general are cut from larger elements, with no consideration of the location of the individual laminations with respect to the edges of the beam.

V N Bastun - One of the best experts on this subject based on the ideXlab platform.

  • deformation of damaged elastic brittle isotropic materials with a fixed concentration of microdefects in a Complex Stress State
    Journal of Strain Analysis for Engineering Design, 2011
    Co-Authors: D V Babich, V N Bastun
    Abstract:

    The character of deformation of elastic—brittle isotropic materials weakened by flat microdefects in the form of circular or elliptic microcracks randomly dispersed over volume is studied in the Complex Stress State. It is assumed that concentration of the microcracks under loading remains constant. Equations of State for such materials are derived depending on the Stress State mode and sign of applied Stresses. The damaged material is simulated by a linear elastic isotropic medium under all-round compression or tension and under biaxial compression, by a linear elastic transversally isotropic medium under biaxial tension, and by a non-linear orthotropic medium under compression along one axis and tension along another axis. To determine compliance characteristics entering into the equations of State, the continual model of a cracked medium and a method based on the equivalence principle of deformation energy of this medium are used. A numerical example is presented.

  • deformation of damaged elastic brittle isotropic materials with a fixed concentration of microdefects in a Complex Stress State
    Journal of Strain Analysis for Engineering Design, 2011
    Co-Authors: D V Babich, V N Bastun
    Abstract:

    The character of deformation of elastic—brittle isotropic materials weakened by flat microdefects in the form of circular or elliptic microcracks randomly dispersed over volume is studied in the Complex Stress State. It is assumed that concentration of the microcracks under loading remains constant. Equations of State for such materials are derived depending on the Stress State mode and sign of applied Stresses. The damaged material is simulated by a linear elastic isotropic medium under all-round compression or tension and under biaxial compression, by a linear elastic transversally isotropic medium under biaxial tension, and by a non-linear orthotropic medium under compression along one axis and tension along another axis. To determine compliance characteristics entering into the equations of State, the continual model of a cracked medium and a method based on the equivalence principle of deformation energy of this medium are used. A numerical example is presented.

  • Study of the Elastoplastic Deformation of Hardened Metals under Static Loading in View of Their Structure. The Case of a Complex Stress State
    International Applied Mechanics, 2001
    Co-Authors: V N Bastun, S. B. Nizhnik
    Abstract:

    A generalization is made of the results of experimental investigations into the elastoplastic deformation of initially isotropic structural materials with a stable and metastable structure loaded along rectilinear and slightly curved paths. It is revealed and physically substantiated why some hypothesis of plastic theory, which are valid for materials with a stable structure, are not fulfilled for deformationally unstable metals. It is indicated how much the study results can be used in calculations and to improve the technology of manufacturing thin-walled shell structural elements by optimizing their strength, plasticity, and crack resistance