Transverse direction

In the transverse direction of the quadrupoles, an ion will oscillate among the poles in a complex fashion, depending on its mass, the voltages (U, V), and the frequency (to) of the alternating RF potential. By suitable choices of U, V, and to, it can be arranged that only ions of one mass will oscillate stably about the central axis in this case, all other ions will oscillate... 

Under the influence of the varying electric fields, +(U + Vcostot) and -(U + Vcostot), the resultant electric potential (F) in the x-y plane (transverse direction) of the quadrapoles is given by Equation 25.1. 

Extmsion of polyethylene and some polypropylenes is usually through a circular die into a tubular form, which is cut and collapsed into flat film. Extmsion through a linear slot onto chilled rollers is called casting and is often used for polypropylene, polyester, and other resins. Cast, as well as some blown, films may be further heated and stretched in the machine or in transverse directions to orient the polymer within the film and improve physical properties such as tensile strength, stiffness, and low temperature resistance. 

Oriented In-Plane Texture. In this kind of film the properties (H and in the various in-plane directions (texture and nontexture directions) are different. The texture of the film can be supported by the texture of the substrate and the crystal lattice can be smaller in the texture direction than in the transverse direction. This can be the source for strain-induced magnetic anisotropy (magnetostriction). It is also found that the crystal is aligned in the texture direction (92). 

The second parameter, tear strength, describes the film resistance to tear propagation. It is measured with a special apparatus, the Ehnendorf Tear Tester (ASTM D1922), and defined as the weight of a loaded pendulum capable of tearing a notched piece of film. Two values are usually measured for each film sample. One determines tear propagation in the machine direction of the film, the other in the transverse direction. 

Av wt of the dart sufficient to break the film in 50% of tests (ASTM D4272-90, Method A). MD = machine direction TD = transverse direction. 

The manufacturers stress ease of processing as a particular feature of the material. Recommended melt temperatures are in the range 320-340°C and mould temperatures are 135-165°C. Mould shrinkage of glass-filled grades is usually of the order of 0.2-0.4% in the flow direction and up to twice this value in the transverse direction. The materials are notable for their ability to withstand vapour phase and infrared soldering processes. 

Low smoke emission (roughly comparable to that of a polycarbonate). Very low coefficient of thermal expansion in the flow direction (0-15 cm/ cm/°C) but correspondingly higher in the transverse direction (27-76 cm/ cm/°C). 

Such is the anisotropy that flexural modulus may be four times as high in the flow direction as in the transverse directions. This difference may be reduced by incorporating fillers such as glass fibre or mica. 

The properties of a unidirectional fibre will not be nearly so good in the transverse direction compared with the longitudinal direction. As a material in service is likely to be subjected to stresses and strains in all directions it is important to be aware of the properties in all directions. The transverse direction will, of course, be the weakest direction and so it is necessary to pay particular attention to this. 

Consider the situation of a thin unidirectional lamina under a state of plane stress as shown in Fig. 3.9. The properties of the lamina are anisotropic so it will have modulus values of E and Ei in the fibre and transverse directions, respectively. The values of these parameters may be determined as illustrated above. 

A single ply unidirectional carbon fibre reinforced PEEK material has a volume fraction of fibres of 0.58. Use the data given below to calculate the Poisson s Ratio for the composite in the fibre and transverse directions. 

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