Influence Of Fiber Parameters Research Articles

Effects of jute fiber length and weight percentage on quasi-static flexural and dynamic mechanical properties of jute/polyester composites for thin-walled structure applications

Natural fiber reinforced polymer composites are being widely used in aerospace and automotive applications. These are due to their low density and cost, better biodegradability and higher specific strength and modulus, which replace E-glass fiber reinforced polymer composites. Moreover, quasi-isotropic properties can be achieved with randomly orientated short natural fiber composites. These composite structures are subjected to dynamic loading and exposed to different temperatures and frequencies during their service. In this research, the influence of fiber parameters (fiber length and loading) on quasi-static flexural and dynamic mechanical properties of jute/polyester composites was studied. Dynamic mechanical properties were investigated at different frequencies (0.2, 0.5, 1.0, 2.0 and 5 Hz) and temperatures from 35 °C up to 190 °C. It has found that the composite sample with 5 mm length and 25 wt% (5JP25) exhibited the highest flexural strength of 94 MPa and flexural modulus of 7.45 GPa. However, the composite sample with 15 mm length and 25 wt% (15JP25) exhibited a higher average storage modulus and a lower average loss factor indicating the good fiber–matrix adhesion, compared with the other samples. The Cole-Cole plot of the composite sample with the fiber weight percentage of 25 wt%, indicated a perfect semi-circle. Good correlations were observed between the flexural and initial storage moduli values of pure polyester and composites.

Threshold for stimulated Brillouin scattering in few-mode fibers.

In this paper, the stimulated Brillouin scattering (SBS) threshold of step-index few-mode fibers (FMFs) is theoretically analyzed. The scattering characteristics of FMFs are analyzed using the mathematical model of the Brillouin scattering spectrum. The gain spectrum of Brillouin scattering and the influence of fiber parameters on the SBS threshold of FMFs are discussed, and the SBS theoretical threshold is obtained according to the parameters of FMFs. A new experimental system for measurement of the SBS threshold of FMFs based on two photonic lanterns is built that can eliminate the Fresnel reflection. The measured SBS thresholds of the LP01 and LP11 modes over 9.8km two-mode fiber are 10.93dBm and 11.35dBm, respectively, and the measured SBS thresholds of LP01, LP11, LP21, and LP02 over 11km four-mode fiber are 10.18, 10.38, 11.71, and 12.23dBm, respectively. The experimental results agree well with the theoretical analysis, and the deviation is less than 0.7dB. The theoretical analysis has guiding significance for setting the incident power in FMF communication and sensing. The experimental system can accurately measure the SBS thresholds of FMFs.

A novel special optical fiber with magneto-optic nonreciprocal phase shift under transversely applied magnetic field

A novel special optical fiber, which is very sensitive to magnetic field, is proposed. The two beam lights counter-propagating in this kind of fiber can generate large nonreciprocal phase shift. It can be used in ultra-low magnetic field detection. In this paper, the related theory is derived in detail. The influence of fiber parameters on the effect is simulated and analyzed. It is proved that a magnetic field sensor with pTesla-level precision could be demonstrated with this kind of special fiber in this paper.

Constitutive modeling of steel-polypropylene hybrid fiber reinforced concrete using a non-associated plasticity and its numerical implementation

This paper presents a non-associated plasticity-based constitutive model for hybrid steel–polypropylene fiber reinforced concrete (HFRC) materials in an attempt to characterize the stress–strain responses under multiaxial loading scenarios. Together with a five-parameter loading surface and uncoupled hardening and softening regimes, a nonlinear plastic potential function is particularly introduced into the constitutive model with the material constants experimentally determined through a true triaxial compression test, which allows a more accurate estimation of the volumetric dilatency of HFRC. The influence of fiber parameters on the plastic flow direction is also addressed. Furthermore, the developed model is implemented into ABAQUS finite element package through a User-defined Material (UMAT) subroutine that can be applicable for the convenient use in numerical simulation of HFRC materials. A substepping scheme with error control for integrating the elasto-plastic stress–strain rate equations is presented in detail. Subsequently, the proposed model is evaluated by available multiaxial compression test results of both plain concrete and FRC reported by other researchers. It is shown that the constitutive model can realistically capture the stress–strain responses as well as the volumetric deformation of HFRC having various fiber reinforcement indices.

Influence of Fiber Parameters on Stress-Induced Group Delay Variation in Hole-Assisted Fibers

We have studied a specific type of hole-assisted fibers (HAFs) for parallel transmission systems. A fiber ribbon using HAFs will be suitable for parallel transmission systems when used in a small space. Additional skew occurs when a fiber ribbon is used under nonuniform stress environment. We focus on stress-induced group delay variations. Influence of fiber parameters, such as a core diameter 2a and a relative refractive index difference Δ, on stress-induced group delay variations is investigated using a finite-element method. We also study the influence of hole-structure variations.

Guidance in Kagome-like photonic crystal fibres II: perturbation theory for a realistic fibre structure

A perturbation theory is developed that treats a localised mode embedded within a continuum of states. The method is applied to a model rectangular hollow-core photonic crystal fibre structure, where the basic modes are derived from an ideal, scalar model and the perturbation terms include vector effects and structural difference between the ideal and realistic structures. An expression for the attenuation of the fundamental mode due to interactions with cladding modes is derived, and results are presented for a rectangular photonic crystal fibre structure. Attenuations calculated in this way are in good agreement with numerical simulations. The origin of the guidance in our model structure is explained through this quantitative analysis. Further perspectives are obtained through investigating the influence of fibre parameters on the attenuation.

Influence of fiber parameters on skew in single-mode fiber ribbons

The influence of fiber parameters on skew has been experimentally clarified by using single-mode 16-fiber ribbons with different fiber parameters. The skews are measured for fibers in 16-fiber ribbons. It is found that not only the relative refractive index difference /spl Delta/ but also the ratio of the mode field diameter to the core diameter influence the skew. The time of flight is measured for 16-fiber ribbons under several temperature and strain values. Although the time of flight is influenced both by temperature and strain, it is confirmed experimentally that skew is independent of fiber parameters. These results indicate that the skew of a fiber ribbon under a uniform environment can be determined from fiber parameter differences. Previously proposed equations for evaluating the skew are used to design fibers in a fiber ribbon in order to realize fiber ribbons with the desired skew value.

Application of a New Hairiness Meter to the Study of Sources of Yam Hairiness

Some of the sources of hairiness of cotton yarns and their blends are investigated. The influence of fiber parameters, spinning process, and yarn parameters are discussed. Also, some contradictions found in the literature in connection with certain aspects of the influence of these parameters on hairiness are clarified.

Factors Influencing the Cohesion of Worsted Yarns

In the present paper the different factors influencing the cohesion of worsted yarns, expressed as minimum twist of cohesion, are examined. The study involves (a) the influence of the testing conditions, (b) the influence of fiber parameters, and (c) the influence of the treatments undergone by the fiber.