Effect of Fiber Orientation

Figure 6 Effect of fiber orientation on (a) tensile strength and (b) tensile modulus of PALF-LDPE composites.

The higher thermal conductivity of inorganic fillers increases the thermal conductivity of filled polymers. Nevertheless, a sharp decrease in thermal conductivity around the melting temperature of crystalline polymers can still be seen with filled materials. The effect of filler on thermal conductivity for PE-LD is shown in Fig. 2.5 [22], This figure shows the effect of fiber orientation as well as the effect of quartz powder on the thermal conductivity of low density polyethylene. 

To illustrate the effect of fiber orientation on material properties of the final part, Fig. 8.60 [5] shows how the fiber orientation distributions that correspond to 67 50 and 33% initial mold coverage affect the stiffness of the finished plates. The Folgar-Tucker model has been implemented into various, commercially available compression mold filling simulation programs and successfully tested with several realistic compression molding applications. 

For tests other than E-84, there have been some studies on the effects of fiber loading and fiber layup on composite flammability. This has primarily been work done by the U.S. Navy on the flammability of composites used in naval vessel flammability,19-20 or work by Kandola et al.10-21-22 on the effect of fiber type and content on polymer composites studied by cone calorimeter. More work is being conducted in studying the effects of fiber orientation and lay-up not on overall flammability performance, but flammability performance under structural load. This is the most important for aircraft, vehicles, and buildings where the composites are structural members. The concern here is... 

An interesting aspect of the work on UHMW polyethylene was the possibility of studying the anisotropy of the conductivity since aligned samples of stretch-oriented fibers could be produced and the effect of fiber orientation investigated. These experiments showed charge transport to be favored by a factor of approximately 20 along the direction of the oriented fibers compared with perpendicular to the fibers. This represented the first measurement of anisotropic conduction using the PR-TRMC technique. 

Figure 7.9 illustrates the effect of fiber orientation on wear rate. " The surface roughness of the mating surfaces influences wear. Adhesion of fibers to the matrix and their dispersion are other essential parameters of the aramid fibers performance. Large surface area of the aramid fibers caused mechanical inter-... 

Liu Y et al (2009) Effects of fiber orientation and diameter on the behavior of human dermal fibroblasts on electrospun PMMA scaffolds. J Biomed Mater Res A 90A(4) 1092-1106... 

The scattering-absorption of incident beams by a long circular cylinder has also been studied by van de Hulst [50], He also considers other particle shapes. Wang and Tien [62], Tong and Tien [63], and Tong et al. [64] consider fibers used in insulations. They use the efficiencies derived by van de Hulst [50] and examine the effects of ks and d on the overall performance of the insulations. The effect of fiber orientation on the scattering-phase function of the medium is discussed by Lee [65]. The effective radiative properties of a fiber-sphere composite is predicted by Lee et al. [66]. 

Chou 1. Effect of fiber orientation and moisture absorption on the interlaminar fracture toughness of CFRP laminates. Adv Compos Mater 1998 7 377-94. http //dx.doi.org/ 10.1163/156855198X00264. 

The orientation averaging method can also be applied to thermal expansion coefficients. To account for the effect of fiber orientation distribution, one writes the thermoelastic constitutive equation for the unidirectional composite as... 

Synergism between the conductive networks was examined, and the effects of fiber orientation and fiber length on composite resistance were evaluated. The resistance of the composites containing both carbon fiber and carbon black fillers was also compared with that of composites containing only carbon black or carbon fibers. 

Table 9.4 shows the effect of fiber orientation on the properties. The large differences in tensile strength and modulus of unidirectional laminates tested at 0 and 90° should be noted. 

The effects of fiber orientation on physical properties. Plastics Design Forum. 9/10 (1979). 

Fig. 17. Effect of Fiber Orientation on Tensile Strength of FP/Al Composites (Yf=55%)...

TABLE 4-5. EFFECT OF FIBER ORIENTATION IN THE SURFACE SKINS OF 20% GLASS-REINFORCED SHEET ... 

Effect of Fiber Orientation in the Surface Skins of 20% Glass-Reinforced Sheet.. 4-30... 

CF Fan, SL Hsu. Effects of fiber orientation on the stress distribution in model composites. J Polym Sci B Polym Phys Ed 27 2605-2619, 1989. 

Filler anisotropy has a similar effect on yield stress and tensile strength as well as on modulus both increase with increasing aspect ratio and orientation. The two factors are interconnected here too, so both must be known to predict composite properties accurately. The important effect of fiber orientation is shown by Fig. 5, where the strength of glass fiber reinforced PP composites is plotted against the alignment of the fibers [32]. A considerable increase in strength is observed when the fibers have parallel orientation to the direction of the external load (0°), as expected. 

Many researchers have carried out investigations in interaction of radiation and conduction heat loss in determining the total thermal insulation of the porous medium. Lee [18] considered the fibers as infinitely long cylinders and obtained the effect of fiber orientation in the radiative properties of the fibrous media and found that the highest insulation is obtained when the fibers are oriented parallel to the direction of heat flow and the highest radiative heat transfer takes place when the fibers are perpendicular to the heat flow direction. 

One of the main aims of a big research project in our group is the generation of a comprehensive database which is necessary for the applicability of fatigue life calculation with local S/N curves for fiber reinforced composites. In this work the effect of fiber orientation and concentration as well as stress ratio R on fatigue behavior of two materials was investigated. The stress Ratio R is defined by equation 1, where a is the lower stress amplitude and CTq is the higher stress amplitude of a sinusoidal loading. 

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