The anisotropy of the crystal along different directions of the lattice atoms are arranged periodically and different density level, the resulting physical and chemical properties of the crystal in different directions are also different, which is the crystal anisotropy. Crystal anisotropy of a concrete manifestation of the crystal in different directions on the elastic modulus, hardness, coefficient of thermal expansion, thermal conductivity, electrical resistivity, the electric displacement vector, electric polarization intensity, magnetic susceptibility and refractive index is different. As an important feature of the crystal, the anisotropy has a very important value. Commonly Miller index to mark the different orientation of the crystal. Parallel to grain shrinkage even when
wood water content caused by the reduced volume shrinkage phenomenon called shrinkage, shrinkage world pie network information , also known as the wood Anisotropy "
, for example, from the fiber saturation point, down to 0% of moisture content, small, 0.1 to 0.3%, stripes and radial shrinkage of 3.66% and tangential shrinkage as high as 9.63%, the volume shrinkage of 13.8%, so when the wood grain is not straight uneven surface and internal evaporation rate inconsistent, the various parts of the degree of shrinkage not appear bent, twisted and irregular deformation, shrinkage unevenness will be cracks.
Uneven texture, all aspects of strength inconsistent. Called parallel to grain) of wood along the trunk side (habit strength than the vertical trunk of the transverse (horizontal stripes) is much greater. Cases picture shows the direction of the compressive strength of Pine and Hardwood. All aspects of strength, size, constructed of tubular cells arranged to find out why. Wood fiber longitudinal links the strongest, and therefore parallel to grain tensile strength. Pressure on grain of wood, each cell is like a column, the pressure to a certain extent, the cell wall inward warping and destruction. Tensile strength parallel to grain compressive strength parallel to grain. Compression stripes, tubular cells are likely to be crushed, so the strength is only about 1/8 of the compressive strength parallel to grain, bending strength between tensile, compressive between.
Anisotropy, also known as the "heterogeneity". Objects all or part of the nature of the physical, chemical and other with the direction of each show some differences in the features. In different directions, the measured performance value. The characteristics of geophysics in the
anisotropic the anisotropy
physical properties of the measurement direction changes. Geophysical applications anisotropy is sometimes limited to "as the anisotropy, to distinguish products body experience the point of anisotropy.
A, in anisotropic media, the elastic stress and strain tensor contains 21 independent Changshu. If there are two directions of the same nature (transversely isotropic), reduced to five independent constants. Isotropic medium only two independent elastic constants. There are three body wave propagation in anisotropic media, the two S-wave, a P wave front does not necessarily orthogonal to the direction of propagation, Snell's law need to be modified. Aeolotropy can also be used as the anisotropy to explain.
B, seismic exploration, the anisotropy used to refer to the difference between a lithological units parallel to the ground level of speed and velocity perpendicular to the ground level. Speed along the level (for example, with refraction measured) than the speed of the vertical level (eg, logging) in general 10-15% higher.
C, anisotropy is also sometimes used to (unreasonably) refers to the difference between the speed of the parallel strata and vertical strata in the entire sequence. Formation rate in this sequence, all layers the contribution proportional to the thickness, parallel to the speed of formation because of the high velocity layer priority to the dissemination of energy, while the larger.
D World Steel Pipe News , microscopic anisotropy is that flaky mineral particles and cracks parallel to the stratigraphic arrangement of leaving the perpendicular and parallel to the physical nature of the strata.
Macroscopic anisotropy refers to the physical properties of the geological observations in the thin layer was significantly different from the other parts.
F, rock excitation polarization anisotropy is less than the resistivity anisotropy. , Parallel to the schistosity true resistivity is less than the true resistivity perpendicular to the foliation in the schist-like rock.
G, resistivity anisotropy coefficient refers to the square root of the resistivity measured perpendicular to the strata and parallel to the measured resistivity ratio, its value is often between 1 and 2.