Combining the linear transformation and the solution technique for the cubic equation, a general closed-form analytic solution for bulk waves in orthotropic anisotropic materials is obtained. This method is straightfo...Combining the linear transformation and the solution technique for the cubic equation, a general closed-form analytic solution for bulk waves in orthotropic anisotropic materials is obtained. This method is straightforward and general. Degenerated cases include transversely isotropic, cubic, and isotropic materials. Numerical computations are carried out on a fiber-reinforced composite plate modeled as a transversely isotropic media. The fibers are parallel to the top and bottom surfaces of the plate, and they are rotated counterclockwise around the plate normal through different angles. The two-dimensional slowness curves corresponding to different rotations are presented graphically. The wave propagation characteristics displayed in slowness surfaces for different fiber orientation are analyzed. Key words composite material - anisotropic media - wave propagation - slowness PASC 2001 0343.8 - 042 Project supported by the Science Foundation of Shanghai Municipal Commission of Education (Grant No. 03AK48)展开更多
When the size of inhomogeneous particles in composite material is much smaller than the incidence wavelength, the average dielectric properties can be expressed in terms of effective permittivity ε<sub>eff</...When the size of inhomogeneous particles in composite material is much smaller than the incidence wavelength, the average dielectric properties can be expressed in terms of effective permittivity ε<sub>eff</sub> which is treated as macroscopically homogeneous. For many years, effective permittivity was usually studied by dipole polarizability as an electrostatic problem.It did not illustrate how the scattering was omitted. Actually, a particulate material can be treated as a random medium whose dielectric constant is randomly fluctuated between particle ε<sub>s</sub> and background material ε<sub>b</sub> The electric properties of such materi-展开更多
This paper presents a composite model of the natural keratin fibres (wool and hair) whichconsists essentially of isotropic viscoelastic filaments, oriented parallel to each other in the fibreaxial direction, embedded ...This paper presents a composite model of the natural keratin fibres (wool and hair) whichconsists essentially of isotropic viscoelastic filaments, oriented parallel to each other in the fibreaxial direction, embedded in an isotropic viscoelastic matrix. The model accurately fits the exper-imental data on the fibre axial stress relaxation moduli and provides upper and lower bounds forthe initial/final values for the fibre transverse tensile and shear stress relaxation moduli andtransverse Poisson’s ratio. The partially water penertrable filament phase of the composite modelis identified as the microfibrils in the fine structure of keratin. The strong anisotropy of keratinsin mechanical properties and hygral/thermal expansion is analyzed in terms of composite struc-ture and mechanical as well as the thermal/hygral properties of the two constituent phases.展开更多
文摘Combining the linear transformation and the solution technique for the cubic equation, a general closed-form analytic solution for bulk waves in orthotropic anisotropic materials is obtained. This method is straightforward and general. Degenerated cases include transversely isotropic, cubic, and isotropic materials. Numerical computations are carried out on a fiber-reinforced composite plate modeled as a transversely isotropic media. The fibers are parallel to the top and bottom surfaces of the plate, and they are rotated counterclockwise around the plate normal through different angles. The two-dimensional slowness curves corresponding to different rotations are presented graphically. The wave propagation characteristics displayed in slowness surfaces for different fiber orientation are analyzed. Key words composite material - anisotropic media - wave propagation - slowness PASC 2001 0343.8 - 042 Project supported by the Science Foundation of Shanghai Municipal Commission of Education (Grant No. 03AK48)
基金Project supported by the National Natural Science Foundation of China,Shanghai Applied Physics CentreShanghai Research & Development Foundation of Applied Material.
文摘When the size of inhomogeneous particles in composite material is much smaller than the incidence wavelength, the average dielectric properties can be expressed in terms of effective permittivity ε<sub>eff</sub> which is treated as macroscopically homogeneous. For many years, effective permittivity was usually studied by dipole polarizability as an electrostatic problem.It did not illustrate how the scattering was omitted. Actually, a particulate material can be treated as a random medium whose dielectric constant is randomly fluctuated between particle ε<sub>s</sub> and background material ε<sub>b</sub> The electric properties of such materi-
文摘This paper presents a composite model of the natural keratin fibres (wool and hair) whichconsists essentially of isotropic viscoelastic filaments, oriented parallel to each other in the fibreaxial direction, embedded in an isotropic viscoelastic matrix. The model accurately fits the exper-imental data on the fibre axial stress relaxation moduli and provides upper and lower bounds forthe initial/final values for the fibre transverse tensile and shear stress relaxation moduli andtransverse Poisson’s ratio. The partially water penertrable filament phase of the composite modelis identified as the microfibrils in the fine structure of keratin. The strong anisotropy of keratinsin mechanical properties and hygral/thermal expansion is analyzed in terms of composite struc-ture and mechanical as well as the thermal/hygral properties of the two constituent phases.
