Fibre orientation 64 67 effect

These long fibres give better product performance although injection moulding machine modifications may be necessary to prevent fibre damage and reduce undesirable fibre orientation effects in the mould. 

Modern representations of the virtual heart, therefore, describe structural aspects like fibre orientation in cardiac muscle, together with the distribution of various cell types, active and passive electrical and mechanical properties, as well as the coupling between cells. This then allows accurate reproduction of the spread of the electrical wave, subsequent contraction of the heart, and effects on blood pressure, coronary perfusion, etc. It is important to point out, here, that all these parameters are closely interrelated, and changes in any one of them influence the behaviour of all others. This makes for an exceedingly complex system. 

Fig. 16. Single voxel STEAM spectra of the SOL muscle (top) and the TA muscle (bottom). Different fibre orientation in those muscles results in clearly different patterns of the lines in the spectra In SOL (feathered muscle with oblique fibres), IMCL and EMCL signals show lower frequency separation than in TA (spindle-shaped muscle) due to bulk susceptibility effects. Furthermore, in SOL the Cr2 doublet merges into one resonance, the Cr3 triplet is less resolved, and TAU is shifted towards TMA.

In conclusion, muscular spectroscopy profits of the higher field strength. Clearly narrower IMCL resonances and nearly unchanged susceptibility based broad EMCL signals occur at higher field strength. Dipolar coupling effects especially observed in TA (with parallel muscle fibre orientation to Bg) have to be further studied in detail. 

Morton J. and Groves G.W. (1974). The cracking of composites consisting of discontinuous ductile fibers in a brittle matrix-effect of fibre orientation. J. Mater. Sci. 9, 1436-1445. 

There has been much interest in flow and flow orientation effects with polymer melts containing anisometric particles which may be plate-like or fibrous. Flow-induced orientation of short reinforcing fibres is an area of considerable commercial importance, which is beyond the scope of the review [30]. 

However, the friction of the Duroid 5813 (about 0.34) was practically unaffected by fibre orientation, unlike the other two composites which gave the lowest friction when sliding was normal to the fibre orientation. This may indicate that in the Duroid 5813 the friction was to a considerable extent determined by the molybdenum disulphide, which was randomly oriented, or by the PTFE, whereas in the epoxy composites the friction was strongly influenced by the fibres themselves. Table 12.5 shows the relationship between fibre orientation and specific wear rate for the Duroid 5813. It should be noted that although the effect of fibre orientation is significant, ail three wear rates are of the same order of magnitude. 

Sung N-H. and Suh, N.R., Effect of Fibre Orientation on Friction and Wear of Fibre-Reinforced Polymeric Composites, Wear, 53, 129, (1979). 

ABSTRACT The optimisation of charcoal production in a retort kiln calls for control of the carbonization mass and energy flows. These depend essentially on three types of factors the physico-chemical characteristics of the raw material, the operational parameters and the reactor parameters. Carbonization experiments have been conducted to assess and to model the effect of four physical characteristics moisture content (two levels 0 %, 37 % dry basis), density (two levels beech wood (650 - 740 kg/m anhydrous basis) and poplar wood (398 - 426 kg/m anhydrous basis)), dimension and shape (two levels cubes of 4 cm side and blocks of 4x4x 16 cm, length parallel to the fibres orientation). The carbonization final temperature was 500° C, the residence time at this temperature was 100 min. The heating rates were 2 and 20°... 

Finite element modelling of the effects of a 14% volume fraction of glass fibre with an aspect ratio of 30 (Fig. 4.29b), used fibre orientations that fitted a maximum entropy distribution. It predicted that the longitudinal Young s modulus increased non-linearly with cos B, and that constant strain conditions applied for averaging the properties of the unidirectional composite. 

Raman spectroscopy is equally suitable for the analysis of gases, liquids, fibres, single crystals, surface features, etc. Intact measurements permit one to investigate the native molecular structure in biopolymers, living and other systems. It permits studies of eye lenses, the end processes of muscle contraction, components of living cells, and of ancient manuscripts and art objects, etc. The crystallinity of polymeric materials and orientation effects in fibres, monitored by FT-Raman spectra, could be very useful in technological control and in forensic science. 

Natural fibres, such as wool or cotton, have a curled or irr ular shape. Yams and fabrics made from these fibres are bulky and have a high thermal insulation and a pleasant grip and appearance. Many methods have been developed to give synthetic yams and fibres simUar properties. This is called texturisation. In texturisation processes unannealed yams or fibres are usually deformed by twisting, stuffing or knitting. They are then heat-set in the deformed state, which makes the deformation more or less permanent Most of those processes can be applied to split fibres but we shall only deal with techniques in which orientation effects play an important role. 

Chand, N. Jain, D. (2005). Effect of Sisal Fibre Orientation on Electrical Properties of Sisal Fibre Reinforced Epoxy Composites. Composites Part A, Vol.36, No.5, (May 2005),... 

In agreement with the foregoing, it could be shown experimentally that the double refraction of regenerated fibres changed if their crystalline portion (consistii of the crystalline modification cellulose II) was transformed into another modification (cellulose IV) without chai ir the orientation of the fibre These effects, which impose certain restrictions as to the possibility of quantitative evaluation of orientation from optical measurements, arise from the influence of the internal field (cf. p. 586). 

Fibre orientation is another important parameter that influences the mechanical behaviour of short-fibre composites. This is because the fibres in such composites are rarely oriented in a single direction, which is necessary to obtain the maximum reinforcement effects. During the processing of short-fibre composites, a continuous and... 

As step-lap joints have similar features to lap and donble-lap Joints, every design aspect that has been indicated in the design of lap Joints shonld also be considered in the design of step-lap joints. In step-lap Joints factors snch as fibre orientation on the bond surface still have a major effect on the Joint strength (see 5.3.1.4), while tapering the adherend ends becomes irrelevant. 

Dootson M, Sargent JP, Wolstenholm GH, Yates B, Time and temperature effects in the thermal expansion characteristics of carbon fibre reinforced plastics. Composites, 73-78, Apr 1980. Parker SFH, Chandra M, Yates B, Dootson M, Walters BJ, The influence of distribution between fibre orientations upon the thermal expansion characteristics of carbon fibre reinforced plastics. Composites, 281-287, Oct 1981. 

Fig. 11.9 Effect of fibre loading on percentage of fibre orientation of the composites...

George et al. [27] studied stress relaxation behaviour of pineapple fibre-reinforced polyethylene composites. They found stress relaxation to be decreased with an increase of fibre content due to better reinforcing effect It is also reported by George et al. [28] that properties of fibre-reinforced composites depend on many factors like fibre-matrix adhesion, volume fraction of fibre, fibre aspect ratio, fibre orientation as well as stress transfer efficiency of the interface. Luo and Netravah [29] found an increase in the mechanical properties of green composites prepared from PALFs and poly(hydroxybutyrate-co-valerate) resin (a biodegradable polymer) with the fibres in the longitudinal direction. However, the researchers reported a negative effect of the fibres on the properties in the transverse direction. 

Effect of fibre orientation in the composite part Figure 7.34 Schematics highlighting the positioning of reinforcements... 

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