The Experts below are selected from a list of 828 Experts worldwide ranked by ideXlab platform

Ippei Susuki - One of the best experts on this subject based on the ideXlab platform.

  • strength optimization of Multidirectional Laminates in an in plane combined stress state
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1991
    Co-Authors: Ippei Susuki
    Abstract:

    Abstract The objective of this research is to develop a design method to translate the strength characteristics of unidirectional composites to that of a Multidirectional Laminate with maximum strength. Laminates are assumed to be symmetric about the midplane surface and to consist of plies with 0°, 90°, 45° and −45° fibre orientations. A simple transformation was introduced to normalize an in-plane combined stress state and to express all of them in the closed stress regions. Any set of in-plane stresses will be described as a point in one of the regions which are called the tension-dominated, compression-dominated and shear-dominated regions. A personal computer program was prepared for finding the optimal combinations of a maximum of four-ply groups to obtain the maximum strength for a given set of external stresses. The ply compositions with thickness ratios and strength ratios of the optimized Laminate are obtained for those normalized regions. The importance of taking into consideration the “strength discontinuities” of Multidirectional Laminate into the optimization processes are discussed. The numerical results using T300-N5208 graphite-epoxy and APC2 graphite-poly(ether-ether-ketone) composites show that, at the highest point, the strength of optimized Laminate is about six times that of a quasi-isotropic Laminate.

Marino Quaresimin - One of the best experts on this subject based on the ideXlab platform.

  • Modelling the electrical resistance of Multidirectional Laminates with off-axis cracks
    Composite Structures, 2020
    Co-Authors: Michele Zappalorto, Paolo Carraro, Riccardo Pietrogrande, Marino Quaresimin
    Abstract:

    Abstract In this work, an analytical model is developed to calculate the electrical resistance of a conductive symmetric Multidirectional Laminate with cracks in multiple layers. To this end, initially, an analytical solution is derived for Laminates with cracks in a single layer and, subsequently, the case of cracks in multiple layers is treated using a superposition approach. The accuracy of the analytical model is checked by comparison with the results of several numerical analyses. Later on, the electrical model is used in combination with an existing stiffness degradation model, documenting that a well-defined correlation does exist between the electrical resistance and the stiffness loss of a Multidirectional damaged Laminate. This allowed damage charts to be drawn, that can be used to assess the stiffness degradation of composites based on electrical measurements.

  • Modelling the electrical resistance change in a Multidirectional Laminate with a delamination
    Composites Science and Technology, 2018
    Co-Authors: Francesco Panozzo, Michele Zappalorto, L. Maragoni, Stefan Klaus Nothdurfter, Axel Rullo, Marino Quaresimin
    Abstract:

    Abstract In this work, the electrical response of a Multidirectional symmetric composite Laminate with a delamination is studied analytically, numerically and experimentally. An analytical model is initially developed to predict the electrical resistance of the composite Laminate as a function of the delamination extent. The model was first validated against the results of a bulk of finite element analyses, considering different lay-ups and electrical resistivity. The model predictions were then compared to experimental data obtained through a dedicated experimental campaign performed on unidirectional and Multidirectional Double Cantilever Beam (DCB) specimens. A satisfactory agreement was found in all the cases, thus supporting the accuracy of the analytical model.

Z.m. Huang - One of the best experts on this subject based on the ideXlab platform.

  • Simulation of inelastic response of Multidirectional Laminates based on stress failure criteria
    Materials Science and Technology, 2000
    Co-Authors: Z.m. Huang
    Abstract:

    AbstractThe primary purpose of this paper is to simulate the non-linear stress–strain curve of a Multidirectional Laminate subjected to an arbitrary in plane load using constituent material data and Laminate geometrical parameters. The simulation is performed at a ply level. The classical Laminated plate theory is employed to determine the load shared by each lamina in the Laminate, while internal stresses in the constituent fibre and matrix of the lamina are obtained using a recently developed bridging micromechanics model. Thus, various failure criteria can be incorporated to detect the failure of a lamina in the Laminate, and a progressive failure process is assumed by stiffness discount. Another objective of this paper is to investigate the influence of three typical failure criteria, i.e. the maximum normal stress criterion, the Tsai–Wu criterion, and the Hashin–Rotem criterion, on the simulation. Prediction has been made for T300/5208 graphite–epoxy Laminates of a number of layups subjected to uniax...

Sinapius Michael - One of the best experts on this subject based on the ideXlab platform.

  • Experimental and numerical multiscale approach to thermally cycled FRP
    'Elsevier BV', 2020
    Co-Authors: Lüders Caroline, Kalinka Gerhard, Li Wei, Wille Tobias, Sinapius Michael
    Abstract:

    Due to the different thermal expansion of the constituent materials, cyclic thermal loading of FRP induces alternating stresses in the material at two scales: at the micro scale (level of fibre-matrix-interaction) and at the macro scale (level of the Multidirectional Laminate). Especially the micro scale effect is not comprehensively investigated yet. Additionally, computational investigations mostly neglect this effect due to the homogenous modelling of the composite material. As this effect is assumed to significantly contribute to the fatigue of FRP at thermal loads, the present paper suggests an experimental and numerical multiscale approach including experiments at the different involved material scales to separately observe the effects acting at these scales. The approach also includes numerical modelling for each scale to complement the knowledge gained from the experiments and to create a basis for the consideration of the micro effect even in macroscopic fatigue models treating homogeneous modelled composites. The main focus of the contribution is to bring the overall approach up for discussion, rather than to present the multiscale modelling details

  • Fatigue of fibre reinforced plastics due to cryogenic thermal cycling
    'SAGE Publications', 2019
    Co-Authors: Lüders Caroline, Sinapius Michael
    Abstract:

    Due to the different thermal expansion of the constituent materials, cyclic thermal loading of fibre reinforced plastics induces alternating stresses in the material at two scales: (1) at the microscale (level of fibre–matrix-interaction) and (2) at the macroscale (level of the Multidirectional Laminate). Especially the effect of the thermal-induced stresses at the microscale is not comprehensively investigated yet. In the present paper, the effects of both scales are analysed. For the investigation of the microscale effect, unidirectional Laminates are thermally cycled between 293 K and 90 K up to 1000 times. Afterwards, by mechanical tests at room temperature, the elasticity and strength properties in the different material directions are determined as function of the number of thermal cycles. Additionally, thermally cycled specimens are microscopically investigated in order to observe the matrix crack forming process at thermal fatigue loading. Contrary to the expectations, no significant matrix cracking and therefore no significant reduction of the elasticity and strength properties due to the thermal cycling are observed. In order to analyse the effect of the superposition of the thermal-induced stresses on micro- and macroscale, cross-ply Laminates are investigated in the same manner. In these Laminates matrix cracks are detected after 1000 cycles, which, however, do not reduce the stiffness and strength of the cross-ply Laminate

Michele Zappalorto - One of the best experts on this subject based on the ideXlab platform.

  • Modelling the electrical resistance of Multidirectional Laminates with off-axis cracks
    Composite Structures, 2020
    Co-Authors: Michele Zappalorto, Paolo Carraro, Riccardo Pietrogrande, Marino Quaresimin
    Abstract:

    Abstract In this work, an analytical model is developed to calculate the electrical resistance of a conductive symmetric Multidirectional Laminate with cracks in multiple layers. To this end, initially, an analytical solution is derived for Laminates with cracks in a single layer and, subsequently, the case of cracks in multiple layers is treated using a superposition approach. The accuracy of the analytical model is checked by comparison with the results of several numerical analyses. Later on, the electrical model is used in combination with an existing stiffness degradation model, documenting that a well-defined correlation does exist between the electrical resistance and the stiffness loss of a Multidirectional damaged Laminate. This allowed damage charts to be drawn, that can be used to assess the stiffness degradation of composites based on electrical measurements.

  • Modelling the electrical resistance change in a Multidirectional Laminate with a delamination
    Composites Science and Technology, 2018
    Co-Authors: Francesco Panozzo, Michele Zappalorto, L. Maragoni, Stefan Klaus Nothdurfter, Axel Rullo, Marino Quaresimin
    Abstract:

    Abstract In this work, the electrical response of a Multidirectional symmetric composite Laminate with a delamination is studied analytically, numerically and experimentally. An analytical model is initially developed to predict the electrical resistance of the composite Laminate as a function of the delamination extent. The model was first validated against the results of a bulk of finite element analyses, considering different lay-ups and electrical resistivity. The model predictions were then compared to experimental data obtained through a dedicated experimental campaign performed on unidirectional and Multidirectional Double Cantilever Beam (DCB) specimens. A satisfactory agreement was found in all the cases, thus supporting the accuracy of the analytical model.