In order to study the mechanical properties of the heterogeneous core plate of the wind turbine blade,a modeling method of the core plate based on displacement field variables is proposed.Firstly,the wind turbine blad...In order to study the mechanical properties of the heterogeneous core plate of the wind turbine blade,a modeling method of the core plate based on displacement field variables is proposed.Firstly,the wind turbine blade core plate was modeled according to the theory of modeling heterogeneous material characteristics.Secondly,the three-point bending finite element model of the wind turbine blade core plate was solved by the display dynamic equation to obtain the deformation pattern and force-deformation relationship of the core plate.Finally,the three-point bending static test was conducted to compare with the finite element analysis.The test results show that:the damage form of the wind turbine blade core plate includes elasticity,yield,and failure stages.The main failure modes are plastic deformation,core material collapse,and panel-core delamination.The failure load measured by the test is 1.59 kN,which is basically consistent with the load-displacement result obtained by the simulation,with a difference of only 1.9%,which verifies the validity and reliability of the model.It provides data references for wind turbine blade structure design.展开更多
Truss-core sandwich plates have received much attention in virtue of the high values of strength-to-weight and stiffness-to-weight as well as the great ability of impulseresistance recently. It is necessary to study t...Truss-core sandwich plates have received much attention in virtue of the high values of strength-to-weight and stiffness-to-weight as well as the great ability of impulseresistance recently. It is necessary to study the stability of sandwich panels under the influence of the thermal load. However, the sandwich plates are such complex threedimensional （3D） systems that direct analytical solutions do not exist, and the finite element method （FEM） cannot represent the relationship between structural parameters and mechanical properties well. In this paper, an equivalent homogeneous continuous plate is ideMized by obtaining the effective bending and transverse shear stiffness based on the characteristics of periodically distributed unit cells. The first order shear deformation theory for plates is used to derive the stability equation. The buckling temperature of a simply supported sandwich plate is given and verified by the FEM. The effect of related parameters on mechanical properties is investigated. The geometric parameters of the unit cell are optimized to attain the maximum buckling temperature. It is shown that the optimized sandwich plate can improve the resistance to thermal buckling significantly.展开更多
A novel elastic sandwich metamaterial plate with composite periodic rod core is designed,and the frequency band-gap characteristics are numerically and experimentally investigated.The finite element and spectral eleme...A novel elastic sandwich metamaterial plate with composite periodic rod core is designed,and the frequency band-gap characteristics are numerically and experimentally investigated.The finite element and spectral element hybrid method(FE-SEHM)is developed to obtain the dynamic stiffness matrix of the sandwich metamaterial plate.The frequency response curves of the plate structure under the harmonic excitation are calculated using the presented numerical method and validated by the vibration experiment.By comparing with the frequency response curves of sandwich metamaterial plate with pure elastic rod core,improved band-gap properties are achieved from the designed metamaterial plate with composite periodic rod core.The elastic metamaterial plate with composite periodic rod core can generate more band-gaps,so it can suppress the vibration and elastic wave propagation in the structure more effectively.展开更多
A simple approach to reduce the governing equations for orthotropic corrugated core sandwich plates to a single equation containing only one displacement function is presented, and the exact solution of the natural fr...A simple approach to reduce the governing equations for orthotropic corrugated core sandwich plates to a single equation containing only one displacement function is presented, and the exact solution of the natural frequencies for rectangular corrugated-core sandwich plates with all edges simply-supported is obtained. Furthermore, two special cases of practical interests are discussed in details.展开更多
Co-SiC core-shell powders were prepared by electroless plating. Scanning electron microscopy （SEM） revealed that Co-SiC core-shell powders were of nearly sphere-like shape and were about 0.3 pan. X-ray powder diffra...Co-SiC core-shell powders were prepared by electroless plating. Scanning electron microscopy （SEM） revealed that Co-SiC core-shell powders were of nearly sphere-like shape and were about 0.3 pan. X-ray powder diffraction （XRD） patterns showed that the cobalt powder was hexagonal crystallite. The complex dielectric constant and the complex permeability of Co-SiC core-shell powders-paraffin wax composite were measured by the rectangle wavegnide method. It showed that the dielectric loss was less than 0.1 and the magnetic loss was about 0.2 in 8.2-12.4 GHz for prepared Co-SiC core-shell comoosite oowders.展开更多
Ni/C core-shell composite powders were prepared by electroless nickel-plating. The effects of concentration of NiSO4,bathing temperature,ratio of hydrazine hydrate to NiSO4,pH of the solution,amounts of complexing rea...Ni/C core-shell composite powders were prepared by electroless nickel-plating. The effects of concentration of NiSO4,bathing temperature,ratio of hydrazine hydrate to NiSO4,pH of the solution,amounts of complexing reagent and surfactant,bath load of activated carbon and reaction time,and so on,on the preparation of Ni/C core-shell composite powders were studied. The results show that the principal factors for Ni/C composite powders preparation are bathing temperature,ratio of hydrazine hydrate to NiSO4 and pH of the solution. The optimum conditions are plating at 90 ℃ with pH10.7 and molar ratio of N2H4·H2O to Ni2+of 3.0. The plated nickel powders are observed to be sphere-like in morphology with size about 100 nm. The maximum dielectric loss of Ni/C core-shell composite powders is about 0.35,and its magnetic loss was low with value about 0 in 2-16 GHz.展开更多
It has been been reported that the reduced stiffness of non-homogeneous cylindricallyorthotrpic circular plate varing exponentially with radius r is obtained by using thebending theory of a simple beamThe aim of this ...It has been been reported that the reduced stiffness of non-homogeneous cylindricallyorthotrpic circular plate varing exponentially with radius r is obtained by using thebending theory of a simple beamThe aim of this paper is to verify the effect of radius on the materal properties According to the flat stress-strain relation the values of material properties E E andwhich are the functions of radius r are obtained.Compared with the experimentalvalues the analytical values of the material properties are in essential agreement withtem.展开更多
基金funded by National Natural Science Foundation of China(Grant No.52075305)Natural Science Foundation of Shandong Province(Grant No.ZR2019-MEE076)Zhoucun District School City Integration Development Project(Grant No.2020ZCXCZH01).
文摘In order to study the mechanical properties of the heterogeneous core plate of the wind turbine blade,a modeling method of the core plate based on displacement field variables is proposed.Firstly,the wind turbine blade core plate was modeled according to the theory of modeling heterogeneous material characteristics.Secondly,the three-point bending finite element model of the wind turbine blade core plate was solved by the display dynamic equation to obtain the deformation pattern and force-deformation relationship of the core plate.Finally,the three-point bending static test was conducted to compare with the finite element analysis.The test results show that:the damage form of the wind turbine blade core plate includes elasticity,yield,and failure stages.The main failure modes are plastic deformation,core material collapse,and panel-core delamination.The failure load measured by the test is 1.59 kN,which is basically consistent with the load-displacement result obtained by the simulation,with a difference of only 1.9%,which verifies the validity and reliability of the model.It provides data references for wind turbine blade structure design.
基金Project supported by the National Natural Science Foundation of China(No.91116008)
文摘Truss-core sandwich plates have received much attention in virtue of the high values of strength-to-weight and stiffness-to-weight as well as the great ability of impulseresistance recently. It is necessary to study the stability of sandwich panels under the influence of the thermal load. However, the sandwich plates are such complex threedimensional （3D） systems that direct analytical solutions do not exist, and the finite element method （FEM） cannot represent the relationship between structural parameters and mechanical properties well. In this paper, an equivalent homogeneous continuous plate is ideMized by obtaining the effective bending and transverse shear stiffness based on the characteristics of periodically distributed unit cells. The first order shear deformation theory for plates is used to derive the stability equation. The buckling temperature of a simply supported sandwich plate is given and verified by the FEM. The effect of related parameters on mechanical properties is investigated. The geometric parameters of the unit cell are optimized to attain the maximum buckling temperature. It is shown that the optimized sandwich plate can improve the resistance to thermal buckling significantly.
基金the National Natural Science Foundation of China(No.11761131006)the Research Team Project of Heilongjiang Natural Science Foundation under Grant No.TD2020A001.
文摘A novel elastic sandwich metamaterial plate with composite periodic rod core is designed,and the frequency band-gap characteristics are numerically and experimentally investigated.The finite element and spectral element hybrid method(FE-SEHM)is developed to obtain the dynamic stiffness matrix of the sandwich metamaterial plate.The frequency response curves of the plate structure under the harmonic excitation are calculated using the presented numerical method and validated by the vibration experiment.By comparing with the frequency response curves of sandwich metamaterial plate with pure elastic rod core,improved band-gap properties are achieved from the designed metamaterial plate with composite periodic rod core.The elastic metamaterial plate with composite periodic rod core can generate more band-gaps,so it can suppress the vibration and elastic wave propagation in the structure more effectively.
文摘A simple approach to reduce the governing equations for orthotropic corrugated core sandwich plates to a single equation containing only one displacement function is presented, and the exact solution of the natural frequencies for rectangular corrugated-core sandwich plates with all edges simply-supported is obtained. Furthermore, two special cases of practical interests are discussed in details.
基金This work was financially supported by the Science Fund for Distinguished Young Scholars of Henan Province, China (No. 0512002400)
文摘Co-SiC core-shell powders were prepared by electroless plating. Scanning electron microscopy （SEM） revealed that Co-SiC core-shell powders were of nearly sphere-like shape and were about 0.3 pan. X-ray powder diffraction （XRD） patterns showed that the cobalt powder was hexagonal crystallite. The complex dielectric constant and the complex permeability of Co-SiC core-shell powders-paraffin wax composite were measured by the rectangle wavegnide method. It showed that the dielectric loss was less than 0.1 and the magnetic loss was about 0.2 in 8.2-12.4 GHz for prepared Co-SiC core-shell comoosite oowders.
基金Project (0512002400) supported by Science Fund for Distinguished Young Scholars of Henan Province, China
文摘Ni/C core-shell composite powders were prepared by electroless nickel-plating. The effects of concentration of NiSO4,bathing temperature,ratio of hydrazine hydrate to NiSO4,pH of the solution,amounts of complexing reagent and surfactant,bath load of activated carbon and reaction time,and so on,on the preparation of Ni/C core-shell composite powders were studied. The results show that the principal factors for Ni/C composite powders preparation are bathing temperature,ratio of hydrazine hydrate to NiSO4 and pH of the solution. The optimum conditions are plating at 90 ℃ with pH10.7 and molar ratio of N2H4·H2O to Ni2+of 3.0. The plated nickel powders are observed to be sphere-like in morphology with size about 100 nm. The maximum dielectric loss of Ni/C core-shell composite powders is about 0.35,and its magnetic loss was low with value about 0 in 2-16 GHz.
文摘It has been been reported that the reduced stiffness of non-homogeneous cylindricallyorthotrpic circular plate varing exponentially with radius r is obtained by using thebending theory of a simple beamThe aim of this paper is to verify the effect of radius on the materal properties According to the flat stress-strain relation the values of material properties E E andwhich are the functions of radius r are obtained.Compared with the experimentalvalues the analytical values of the material properties are in essential agreement withtem.
