Fiber length analysis

This is of fundamental importance in the pulp and paper industry which uses a light obscuration method - the Kajaani FS-200. This instrument is also used in the chemical industry for measuring the length of man-made fibers. 

The Advanced Fiber Information System (AFIS) [66] contains a mechanism for opening a hand fed ribbon of fibers so that individual fibers can be presented aerodynamically to an electro-optical system for measuring fiber length. Length measurements for 10,000 individual fibers can be obtained in 5 min. 

The assumption made when the Coulter counter was first developed was that the variability in speed of the fibers, as they passed through the sensor, was small and could be assumed constant [67]. Analysis showed that this assumption was incorrect and a later instrument included a sensor to measure fiber speed [68]. Since the fibers are aligned with flow, the pulse length is a measure of fiber length and the pulse height is a measure of fiber width. The results showed excellent agreement with Suter-Webb measurements. The AFIS is widely used for cotton fiber measurement in the dry state. 

The Coulter principle has also been applied to fiber length determination [74,75] in which the aperture length was made greater than the fiber length. This approach is interesting in that the pulse duration is a measure of fiber length and pulse height is a measure of fiber volume. 

Elzone used a long flow tube upstream of the sensing zone to provide laminar flow and fiber alignment [76] this flow is caused to join a clear liquid sheath that centralizes the fibers in the aperture. 

---

The analysis of the distribution curves of the fiber filler length after compression permits one to conclude that a variation of the fiber average length at compression may be approximately considered as a function of the value of applied pressure irrespective of the composition of the mixture and the state of the polymer [47]. In this case, it should be taken into consideration that longer fibers are destroyed more easily. This is bound up with destruction due to bending at the fiber contact points, the number of which depends directly on the fiber length. 

Specific results are calculated for SiC fiber-glass matrix composites with the elastic constants given in Table 4.1. A constant embedded fiber length L = 2.0 mm, and constant radii a = 0.2 mm and B = 2.0 mm are considered with varying matrix radius b. The stress distributions along the axial direction shown in Fig. 4.31 are predicted based on micromechanics analysis, which are essentially similar to those obtained by FE analysis for the two extremes of fiber volume fraction, V[, shown in Fig. 4.32. The corresponding FAS distribution calculated based on Eqs. (4.90) and (4.120), and IFSS at the fiber-matrix interface of Eqs. (4.93) and (4.132) are plotted along the axial direction in Fig. 4.32. 

Gray, R..1. (1984). Analysis of the effect of embedded fiber length on the fiber debonding and pull-out from an elastic matrix. J. Mater. Sci. 19, 861-870. 

Fiber Length Distribution, for industrial applications, the fiber length and length distribution are of primary importance because they are closely related to the performance of the fibers in matrix reinforcement. Representative distributions of fiber lengths and diameters can be obtained through measurement and statistical analysis of microphotographs fiber length distributions have also been obtained recently from automated optical analyzers. 

A concentration boundary layer theory clearly is needed to relate C to C, so that membrane properties such as L, a, and P can be correlated with R, at various operating conditions. Slso, since ir in Equations 1 and 5 is an independently determined function of C, a boundary ayer theory could correlate the observed filtrate velocity, J (averaged along the fiber length), with average applied pressure AP. For sufficiently high axial flow velocities, C == C, and a major theoretical barrier to data analysis is removeS. Some early work in reverse osmosis ( ) was done with flat-sheet membranes and large feed stream velocities. 

For thermomechanical analysis (TMA), applicable only to dry fibers, a load of 0.005 g/den. was applied to the fiber and a scan rate of 20°C/mln was used. An X-Y recorder was used to record fiber length as a function of temperature. 

Because fiber length is not changed by cosmetic treatments, length is not relevant for the type of analysis that considers changes by cosmetic treatments. For flyaway hair manageability, any change that increases static... 

Fibers exert their effect by restraining the deformation of the matrix while the latter transfers the external loading to the fibers by shear at the interface. The resultant stress distributions in the fiber and the matrix tend to be complex. Theoretical analysis becomes further complicated because fiber length, diameter, and... 

For many fiber-polymer systems (L/D) is in the range 10 50. From this analysis, it is evident that fiber length is important to the development of maximum tensile properties in the composite. It is also apparent that changes in the composite tensile strength are monotonically dependent on fiber concentration. 

Prospective flax fiber tests include a standard test method for flax fiber bundle strength and elongation similar to the Stelometer, fiber length and distribution, fineness distribution via image analysis, wax content via NIR, density measurement, and numerous flax mat characterization tests. Prior work has indicated that NIR spectroscopy has potential for determining wax content in flax fibers (Sohn et al. 2006). Potential standards could exist for farmers to predict fiber content in stems in the field by near-infrared spectroscopy (Barton et al. 2002). The Composites Innovation Center (QC) in Winnipeg is working on a system to characterize flax fiber mats and subsequent composites. 

Micromechanical models such as Cox shear-lag and Halpin-Tsai are often used to predict the stiffness and strength of discontinuously short-fiber reinforced composites. Experimental results of tensile measurements are then compared or correlated with such theoretical models. The shear-lag analysis originally proposed by Cox considered a discontinuous fiber embedded in an elastic matrix with a perfectly bonded interface and loaded in tension along the fiber direction [25]. The analysis tabes into account the difference in strain displacements of the fiber and matrix along the interface. The stress transfer depends on the interfacial shear stress between the fiber and the matrix. The stress transfer from fiber ends is neglected in the analysis. The Cox model incorporates the aspect ratio (a = l/d where I is the fiber length and d the diameter) of the fiber into... 

Hadingham PT (1983) The stress state in the human left ventricle. Adv Cardiovascular Phys 5 88-105 Heethaar RM, Pao YC, Ritman EL (1977) Computer aspects of three-dimensional finite-element analysis of stresses and strains in the intact heart. Comp and Biomed Res 10 291-295 Horowitz A, Perl M, Sideman S Minimization of fiber length changes and mechanical work in the heart muscle. Submitted for publication... 

---