The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform

Mostapha Tarfaoui - One of the best experts on this subject based on the ideXlab platform.

  • determination of mode i ii strain energy release rates in composite foam core sandwiches an experimental study of the composite foam core interfacial fracture resistance
    Composites Part B-engineering, 2017
    Co-Authors: Owaisur Rahman Shah, Mostapha Tarfaoui
    Abstract:

    Abstract The use of composite materials is on the rise in different engineering fields. Following this trend the wind turbine industry has adopted composites as their primary material of choice. For wind turbine blades having large unsupported functional aerodynamic surFaces; the structural stiffness is very important. Stiffness is required to keep the deformations to a minimum under aerodynamic forces. The blade is thus stiffened using sandwich structures at high strain locations within the structure. The lightweight foam cored sandwiches though add stiffness, at the same time pose a challenge for design as the difference in stiffness of both the Face-Plate and the foam core is very high. The resistance to fracture in any part of the structure is an important design parameter to be determined. The determination of fracture resistance quantified here as the Strain Energy Release Rate (SERR) poses some unique challenges when dealing with highly heterogeneous materials in terms of stiffness. In this study some approaches have been analyzed while others are developed to tackle this problem and to measure the Mode I & II SERR of the Face-Plate foam-core interFace. The sandwich core varies in both thickness and density depending on the loading and thus the location along the blade length. However for this study we have used a single density of foam core for the most part of the turbine blade. Different thicknesses of the foam cores are used to determine the effect of scale on the calculated SERR.

  • determination of mode i ii strain energy release rates in composite foam core sandwiches an experimental study of the composite foam core interfacial fracture resistance
    Composites Part B-engineering, 2017
    Co-Authors: Owaisur Rahman Shah, Mostapha Tarfaoui
    Abstract:

    Abstract The use of composite materials is on the rise in different engineering fields. Following this trend the wind turbine industry has adopted composites as their primary material of choice. For wind turbine blades having large unsupported functional aerodynamic surFaces; the structural stiffness is very important. Stiffness is required to keep the deformations to a minimum under aerodynamic forces. The blade is thus stiffened using sandwich structures at high strain locations within the structure. The lightweight foam cored sandwiches though add stiffness, at the same time pose a challenge for design as the difference in stiffness of both the Face-Plate and the foam core is very high. The resistance to fracture in any part of the structure is an important design parameter to be determined. The determination of fracture resistance quantified here as the Strain Energy Release Rate (SERR) poses some unique challenges when dealing with highly heterogeneous materials in terms of stiffness. In this study some approaches have been analyzed while others are developed to tackle this problem and to measure the Mode I & II SERR of the Face-Plate foam-core interFace. The sandwich core varies in both thickness and density depending on the loading and thus the location along the blade length. However for this study we have used a single density of foam core for the most part of the turbine blade. Different thicknesses of the foam cores are used to determine the effect of scale on the calculated SERR.

J Richard Y Liew - One of the best experts on this subject based on the ideXlab platform.

  • nonlinear finite element modelling and parametric study of curved steel concrete steel double skin composite panels infilled with ultra lightweight cement composite
    Construction and Building Materials, 2015
    Co-Authors: Zhenyu Huang, J Richard Y Liew
    Abstract:

    Abstract Curved steel–concrete–steel (SCS) double skin composite structure with shear connectors has been developed and exhibits versatile potential applications in building and offshore constructions. A novel ultra-lightweight cement composite is used as core material and headed shear studs are welded on steel Face Plate to achieve the composite action. This paper demonstrates a comprehensive 3D nonlinear finite element (FE) analysis of curved double skin composite panels infilled with ultra-lightweight cement composite (ULCC) under patch load. Nonlinear FE analyses are performed using ABAQUS to study the load deflection behaviour up to the maximum load resistance. A constitutive model for ultra-lightweight cement composite is generated from standard test data and assigned to the concrete materials. A simplified connector element incorporated tension–elongation behaviour is proposed for the shear studs in the curved double skin composite panels. The accuracy of the FE model is validated using experimental results from the literature in terms of load displacement curves, failure modes and maximum load resistance. An extensive parametric study is carried out to identify the effect of the rise-to-span ratio, span-to-thickness ratio, concrete compressive strength and steel yield strength and loading type on the ultimate resistance.

  • tensile resistance of j hook connectors used in steel concrete steel sandwich structure
    Journal of Constructional Steel Research, 2014
    Co-Authors: J Richard Y Liew, Minhong Zhang
    Abstract:

    Abstract Steel-Concrete-Steel (SCS) sandwich panel with ultra-lightweight cement composite core has been proposed to produce slim decking for bridge and building construction. One special feature of this lightweight sandwich panel is the use of J-hook connectors to improve the structural performance against combined actions of vertical shear and bending moment on the section. The proposed J-hook connectors provide effective bond between the steel and concrete, prevent local buckling and separation of the steel Face Plate, and enhance the transverse shear resistance to the structure. This paper investigates the tensile resistance of this new form of J-hook connectors by performing tensile tests on 79 sandwich specimens with various types of core materials including normal weight concrete, lightweight concrete, and ultra-lightweight cement composite. Their ultimate tensile resistances were obtained and corresponding failure modes were reported. The main parameters that influenced the tensile resistance of J-hook connectors were discussed and analyzed. Theoretical methods were developed to predict the tensile resistance of the J-hook connectors and their accuracy was verified against test results. Finally, recommended methods were proposed for design purposes.

Owaisur Rahman Shah - One of the best experts on this subject based on the ideXlab platform.

  • determination of mode i ii strain energy release rates in composite foam core sandwiches an experimental study of the composite foam core interfacial fracture resistance
    Composites Part B-engineering, 2017
    Co-Authors: Owaisur Rahman Shah, Mostapha Tarfaoui
    Abstract:

    Abstract The use of composite materials is on the rise in different engineering fields. Following this trend the wind turbine industry has adopted composites as their primary material of choice. For wind turbine blades having large unsupported functional aerodynamic surFaces; the structural stiffness is very important. Stiffness is required to keep the deformations to a minimum under aerodynamic forces. The blade is thus stiffened using sandwich structures at high strain locations within the structure. The lightweight foam cored sandwiches though add stiffness, at the same time pose a challenge for design as the difference in stiffness of both the Face-Plate and the foam core is very high. The resistance to fracture in any part of the structure is an important design parameter to be determined. The determination of fracture resistance quantified here as the Strain Energy Release Rate (SERR) poses some unique challenges when dealing with highly heterogeneous materials in terms of stiffness. In this study some approaches have been analyzed while others are developed to tackle this problem and to measure the Mode I & II SERR of the Face-Plate foam-core interFace. The sandwich core varies in both thickness and density depending on the loading and thus the location along the blade length. However for this study we have used a single density of foam core for the most part of the turbine blade. Different thicknesses of the foam cores are used to determine the effect of scale on the calculated SERR.

  • determination of mode i ii strain energy release rates in composite foam core sandwiches an experimental study of the composite foam core interfacial fracture resistance
    Composites Part B-engineering, 2017
    Co-Authors: Owaisur Rahman Shah, Mostapha Tarfaoui
    Abstract:

    Abstract The use of composite materials is on the rise in different engineering fields. Following this trend the wind turbine industry has adopted composites as their primary material of choice. For wind turbine blades having large unsupported functional aerodynamic surFaces; the structural stiffness is very important. Stiffness is required to keep the deformations to a minimum under aerodynamic forces. The blade is thus stiffened using sandwich structures at high strain locations within the structure. The lightweight foam cored sandwiches though add stiffness, at the same time pose a challenge for design as the difference in stiffness of both the Face-Plate and the foam core is very high. The resistance to fracture in any part of the structure is an important design parameter to be determined. The determination of fracture resistance quantified here as the Strain Energy Release Rate (SERR) poses some unique challenges when dealing with highly heterogeneous materials in terms of stiffness. In this study some approaches have been analyzed while others are developed to tackle this problem and to measure the Mode I & II SERR of the Face-Plate foam-core interFace. The sandwich core varies in both thickness and density depending on the loading and thus the location along the blade length. However for this study we have used a single density of foam core for the most part of the turbine blade. Different thicknesses of the foam cores are used to determine the effect of scale on the calculated SERR.

J N Reddy - One of the best experts on this subject based on the ideXlab platform.

  • active piezoelectric structure acoustic control of a soft core sandwich panel using volume velocity and a weighted sum of spatial gradient control metric
    Journal of Vibration and Control, 2017
    Co-Authors: Kiran Chandra Sahu, Jukka Tuhkuri, J N Reddy
    Abstract:

    In this paper, the active control of sound transmission through a simply supported soft-core sandwich panel is analytically studied. Since, the sound transmission through soft-core sandwich panels in the low-frequency region mainly occurs due to flexural and dilatational modes, and therefore to control these structural modes, volume velocity and weighted sum of spatial gradients (WSSG) are used to drive a piezoceramic actuator (PZT) attached on the exterior side of the bottom Face Plate. Sound power level and voltage required to drive the PZT are compared for different values of isotropic core loss factor. Numerical studies indicate that both control metrics are capable of attenuating the flexural and the dilatational modes of the sandwich panel, and hence, reduce significant amount of sound power in a wider frequency range. By carefully selecting the modes to calculate the scaling factors, WSSG provides comparable control to volume velocity. However, the necessary voltage required to drive the PZT to min...

  • active structural acoustic control of a softcore sandwich panel using multiple piezoelectric actuators and reddy s higher order theory
    Journal of Low Frequency Noise Vibration and Active Control, 2015
    Co-Authors: Kiran Chandra Sahu, Jukka Tuhkuri, J N Reddy
    Abstract:

    The purpose of the present work is to theoretically investigate the active control of radiated sound power from a simply supported soft-core sandwich panel with a line moment excitation. Since noise transmission in the low frequency region through a soft-core sandwich panel mainly occurs due to flexural and dilatational modes, therefore, the focus of this study is to control these modes and achieve sound attenuation in a large frequency band. Two control methods, volume velocity and weighted sum of spatial gradients (WSSG) are used to drive three piezoelectric actuators (PZTs) attached on the exterior side of the bottom Face Plate. The governing equation of the sandwich panel with the PZTs is derived using the Hamilton’s principle considering Reddy’s third order shear deformation theory. Numerical studies indicate that while the line moment is at the mid vertical line, WSSG is able to attenuate the radiated sound power irrespective of core loss factor whereas volume velocity could not. However, both the c...

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

  • seismic behaviour of double skin composite shear walls with overlapped headed studs
    Construction and Building Materials, 2018
    Co-Authors: Jiabao Yan, Tao Wang
    Abstract:

    Abstract This paper proposes a type of double skin composite (DSC) shear walls with boundary columns to make solutions to improve ductility of high-rise buildings. In this DSC shear wall system, overlapped headed studs were used to achieve composite action between the steel Face Plate and concrete core. Seven DSC shear walls were tested under combined axial compressive force and horizontal cyclic loads to evaluate the seismic behaviours of this DSC shear wall. Key parameters in this test program include height of overlapped headed studs, axial force ratio, introducing steel tubes in boundary columns, and aspect ratio of the DSC shear wall. The test results exhibited that the tested seven specimens failed in flexure mode characterized by local buckling of steel Face Plate, tensile fracture of steel boundary column, and concrete crushing. Test results also show that using higher headed studs in DSC shear walls improved their deformation capacity and energy dissipation capacity. Increasing axial force on the DSC shear walls did not compromise their energy dissipation capacities but slightly reduced their ductility. Introducing steel tube in the DSC shear walls significantly improved the ultimate resistance, ductility, and energy dissipation of the DSC shear walls. Decreasing the aspect ratio from 2.0 to 1.0 nearly doubles the ultimate resistance and energy dissipation capacity of the DSC shear walls. Theoretical models were also developed to predict the ultimate load carrying capacity of the DSC shear walls under horizontal loads. The validations of the predictions by the developed analytical models against 14 test results confirm the accuracy of the developed theoretical models.