Mm Length Of Fiber Research Articles

Novel continuous fiber bending experiment to determine size- and spatial-distribution of surface defects in glass fibers

Tensile strength models for unidirectional composites require scaling of fiber strength distributions to small length scales in the range of the fiber radius to the ineffective length (5–200 μm). No test methods currently exist to measure and validate fiber strength at these length scales. In this paper, a novel continuous fiber bending test method is developed to measure the size and spatial distribution of defects in S-glass fibers. For this test method, a single glass fiber was placed between Kapton film and tape, and the sample is subjected to a sequence of controlled radii of curvatures ranging from 350 μm to 25 μm in a confocal microscope. From the bending tests, the number of defects and spacings between the defects over 780 mm length of fiber are obtained for each level of flexural stress. The Kapton film confines the fiber fragments and maintains fiber alignment allowing the same sample to be tested at lower radius of curvature (higher flexural strain/stress). The associated defect size is calculated using fracture mechanics. These results are used to map the size- and spatial-distribution of critical defects on the tension surface of a glass fiber. A methodology is presented to map additional defects around the circumference of the fiber, while maintaining the size and spatial distribution obtained from the bending tests. The results show that the lognormal distribution best fits the spatial distribution of defects along the fiber axis. The results also indicate that extrapolating the Weibull strength distribution (be it bimodal or unimodal) to gage lengths less than 200 μm leads to serious errors in fiber strength prediction.

Influence of Different Lengths and Volumes of Basalt Fibre on Mechanical Properties of Concrete

In this research work, the influence of basalt fiber lengths and volumes on mechanical properties of concrete such as compressive strength, flexure strength and split tensile strength are studied. 12 and 24 mm lengths of basalt fiber having the same diameter (13 µm) were used in the experimental work. The influence of 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.4% and 0.5% volume of basalt fiber on mechanical properties of concrete have been studied. The results of conventional concrete and basalt fiber reinforced concrete were compared. Normal strength concrete M30 grade was considered in the work and the mechanical properties were measured at 3, 7 and 28 days of hydration period. The experimental investigation shows that high dosage of fibers creates workability problems such as mixing, clumping and balling effects. Experimental results show that there is no improvement in the compressive strength of concrete when basalt fibers were added in plain concrete mix at all ages of concrete. Moreover, the compressive strength values become unstable when basalt fibers are added to concrete. Maximum value of split tensile strength and flexure strength was obtained for 0.35% (9.275 kg/m³) basalt fiber content for both 12mm and 24mm length of basalt fiber at all ages of concrete. Comparing both 12mm and 24mm basalt fiber lengths, the 24 mm length of fiber has shown superior performance in relation to flexure strength and split tensile strength. Overall, the optimum length of basalt fiber is 24 mm and the optimum volume fraction of basalt fiber is 0.35%.

Mechanical and water absorption properties of Acacia Arabica bark fiber/polyester composites: Effect of alkali treatment and fiber volume fraction

In this work, the water absorption and mechanical properties of alkali (NaOH) treated and untreated Acacia Arabica bark fiber composites were fabricated by hand lay-up technique. Effect of chemically treated fiber increased the surface roughness and mechanical properties as well as decreased the water absorption. Moreover, fibers were randomly oriented varying from 10% to 35% volume fraction (Vf) and also varying in the length of 10 mm to 50 mm. Tensile, flexural and water absorption tests were conducted as per ASTM standard. It was found that, the 25% volume fraction with 30 mm length of fiber had better properties compared with other compositions. The fractured specimens of tensile and flexural test were evaluated under scanning electron microscope to study the fiber pull-outs of the materials.

Low-noise tunable deep-ultraviolet supercontinuum laser

The realization of a table-top tunable deep-ultraviolet (UV) laser source with excellent noise properties would significantly benefit the scientific community, particularly within imaging and spectroscopic applications, where source noise has a crucial role. Here we provide a thorough characterization of the pulse-to-pulse relative intensity noise (RIN) of such a deep-UV source based on an argon (Ar)-filled anti-resonant hollow-core (AR HC) fiber. Suitable pump pulses are produced using a compact commercially available laser centered at 1030 nm with a pulse duration of 400 fs, followed by a nonlinear compression stage that generates pulses with 30 fs duration, 24.2 μJ energy at 100 kHz repetition rate and a RIN of < 1%. Pump pulses coupled into the AR HC fiber undergo extreme spectral broadening creating a supercontinuum, leading to efficient energy transfer to a phase-matched resonant dispersive wave (RDW) in the deep-UV spectral region. The center wavelength of the RDW could be tuned between 236 and 377 nm by adjusting the Ar pressure in a 140 mm length of fiber. Under optimal pump conditions the RIN properties were demonstrated to be exceptionally good, with a value as low as 1.9% at ~ 282 nm. The RIN is resolved spectrally for the pump pulses, the generated RDW and the broadband supercontinuum. These results constitute the first broadband RIN characterization of such a deep-UV source and provide a significant step forward towards a stable, compact and tunable laser source for applications in the deep-UV spectral region.

Effect of Fibre Length on Mechanical Properties of Randomly Oriented Short Jute Fibre Reinforced Epoxy Composite

Natural fibres show many advantages such as low density, low cost, environmental friendly, biodegradable and high specific mechanical performance. This work investigates the tensile, flexural and impact properties of epoxy and randomly oriented short jute fibre reinforced epoxy composite. The composite was prepared using Hand lay-up method with 30wt. % of jute fibre in the various lengths of 5, 10, 15 and 20mm into epoxy matrix. The results show that the tensile and flexural properties were found maximum for the composite with 15mm length of fibre whereas the impact properties were found maximum for the composite with 20mm length of fibre.

On crystallographic orientation in crystal core optical fibers

Recently developed glass-clad semiconductor core optical fibers offer potential advantages over present optical fiber materials, including greatly enhanced Raman cross-sections and extended infrared transparency. While fibers have been fabricated that exhibit a high degree of crystallinity there has not been any in-depth analysis of the nature of the crystallographic orientation of the core material relative to the fiber axes. This crystallographic analysis is of important scientific and technological value since optical fiber fabrication is a highly non-equilibrium process; consequently, achieving high degrees of crystallinity is counter-intuitive. In this work, the crystallographic orientation of germanium core optical fibers was analyzed using single crystal X-ray diffraction and electron backscatter diffraction techniques. Over nearly a 100 mm length of fiber the Ge cores were found to be polycrystalline with the 〈1 0 0〉 and 〈1 1 0〉 orientations dominant implying a dendritic growth mechanism. Single crystal regions were observed routinely in lengths greater than 8 mm with the longest being about 15 mm.

AFM observation of surface topography of fibre Bragg gratings fabricated in germanium–boron codoped fibres and hydrogen-loaded fibres

This paper reports the measurement of the surface topology of optical fibres containing a fibre Bragg grating (FBG) using an atomic force microscope (AFM). The AFM observation was made on FBGs fabricated via the phase mask technique in germanium–boron codoped optical fibres, in hydrogen-loaded germanium–boron codoped fibres and in standard telecommunications optical fibres. The surface images reveal that a spatial corrugation pattern was induced by the UV-irradiation, with a period that is half of the period of the phase mask. This UV-induced surface structure was found only on the side of the fibre facing towards the incident UV-irradiation and did not appear on the rear surface. The AFM probe scanned a 10×10 μm 2 surface area at seven sites along the 6.0 mm length of fibre that was exposed to the UV-irradiation. The amplitude of the spatial corrugation pattern observed on the AFM image was quantified for each site. It was found that the amplitude in a range of 0.7–3.2 nm was a function of UV-laser intensity distribution and the type of fibre. Hydrogen loaded optical fibres exhibited a corrugation with an amplitude twice as large as that observed in the Ge–B doped fibres that were not hydrogen-loaded. This correlates with the increase in photosensitivity produced by the hydrogen loading. A similar UV-induced spatial corrugation was also observed on standard telecom fibres, but without inducing the refractive index change in the fibre core. The observation of surface topology provides an insight into the structural changes induced during FBG fabrication. UV-induced densification and laser ablation could account for the formation of the surface troughs.

In situ surface enhanced resonance Raman scattering analysis of a reactive dye covalently bound to cotton.

An in situ surface enhanced resonance Raman scattering (SERRS) procedure is described for the analysis of a reactive dye covalently bound to a single strand of a cotton fibre. This procedure can be completed in 5 h, whereas an alternative enzyme digestion method takes approximately 21 h. These two fibre preparation methods give similar spectra from picogram quantities of dye present on a 2-5 mm length of fibre. The in situ nature of the analysis and the small sample size make this method particularly suitable for forensic applications.

Control of number and distribution of synapses during ectopic synapse formation in adult rat soleus muscles

Changes in the number and distribution of synaptic inputs and acetylcholine receptor clusters were studied during the formation of ectopic nerve-muscle junctions between the transplanted fibular nerve and the denervated soleus muscle of adult rats. The tibial nerve was cut 3 weeks after implanting the fibular nerve. New sites of transmission were first detected 3 days after the cut. These sites were located electrophysiologically, marked by dye and found to coincide with clusters of acetylcholine receptors. There were no ectopic clusters away from fibular nerve sprouts and no clusters on muscles which had not been denervated. Three days after cutting the tibial nerve, the acetylcholine receptor clusters and probably also the sites of transmission, were randomly distributed along individual muscle fibres. Six days after the cut, the clusters continued to be randomly distributed whereas the synaptic inputs were either close together (within 300 μm) or more than 600 μm apart. Two weeks later the spatial distributions of both clusters and inputs were similar with peaks around 100–300 μm, 1200–1400 μm and 2000–2600 μm. No ectopic clusters were closer than 0.5 mm to the original endplate. We conclude that nerve-muscle contacts and associated acetylcholine receptor clusters initially form at random. One or a few of these contacts develop further and, as a result, the surrounding regions undergo changes that prevent the contacts initially formed there from being maintained. Apparently, in this preparation, approximately 1.5 mm length of fibre is needed to support the maturation and maintenance of each ectopic endplate (mean length 111 μm).