Directional property isotropic transversely

Isotropic transverse construction Refers to a material that exhibits a special case of or-thotropy in which properties are identical in two orthotropic dimensions but not the third. Having identical properties in both transverse but not in the longitudinal direction. 

Fluoropolymers produce a transparent film fabricated in thin gauges ranging typically from 0.012 mm to 0.040 mm thickness. The film is produced by stretching an extruded sheet or tube in two orthogonal directions—the machine direction and the transverse direction. Stretching is carried out at a temperature below the melting point of the polymer and results in a partial orientation of polymer molecules in the direction of stretch. In principle, biaxially oriented film is isotropic—its properties are the same in both the machine and transverse directions. In practice, film produced by the tenter process tends to be more highly oriented in the machine direction whereas the blown process produces a film that is more nearly isotropic. 

From the tensile test, another important property is measured and that is the Poisson ratio value (t, which is a measure of the contraction strain 8, in the transverse direction when a strain e is applied in the longitudinal direction. Stretching takes place in the load direction but shortening takes place in the other two directions for isotropic materials. 

If at every point of a material there is one plane in which the mechanical properties are equal in all directions, then the material is called transversely isotropic. If, for example, the 1-2 plane is the plane of isotropy, then the 1 and 2 subscripts on the stiffnesses are interchangeable. The stress-strain relations have only five independent constants ... 

Anisotropic material In an anisotropic material the properties vary, depending on the direction in which they are measured. There are various degrees of anisotropy, using different terms such as orthotropic or unidirectional, bidirectional, heterogeneous, and so on (Fig. 3-19). For example, cast plastics or metals tend to be reasonably isotropic. However, plastics that are extruded, injection molded, and rolled plastics and metals tend to develop an orientation in the processing flow direction (machined direction). Thus, they have different properties in the machine and transverse directions, particularly in the case of extruded or rolled materials (plastics, steels, etc.). 

Biaxial orientation leads to isotropic properties in blown film, that is, properties that are eqnal in the two primary directions the film was stretched (i.e., parallel to the flat bit ). Orientation in the machine direction of the film is controlled primarily by take-up ratio, defined above. To control orientation in the transverse direction, we measure something called the blow-up ratio, while the forming ratio provides an indication of the degree of isotropy. 

The liner is an elastic plastic isotropic material. Besides, the laminate behaviour is different from a layer to another and each layer behaves according to the fibre direction. The fibre is assumed to have a transverse isotropy and equivalent properties in the (2-3) plane which normal axis (1) refers to the fibre longitudinal direction, as shown in Figure 1. 

The anisotropy of cortical bone tissue has been described in two symmetry arrangements. Lang [1969], Katz and Ukraincik [1971], and Yoon and Katz [1976a,b] assumed bone to be transversely isotropic with the bone axis of symmetry (the 3 direction) as the unique axis of symmetry. Any small difference in elastic properties between the radial (1 direction) and transverse (2 direction) axes, due to the apparent gradient in porosity from the periosteal to the endosteal sides of bone, was deemed to be due essentially to the defect and did not alter the basic symmetry. For a transverse isotropic material, the stiffness matrix [Qj] is given by... 

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