Determination of the effective porosity of a single filter fiber

In this work, a numerical simulation of the aerosol motion when flowing around a single porous filter fiber with a diameter of 5 mm is carried out. The fiber is formed by a set of microfibers in a random arrangement. The size of the microfibers varies from 0.1 mm to 0.5 mm. For each fixed size of microfibers, a fiber model with different porosity of the medium was created. The porosity ranged from 0.7 to 0.9. The calculations were carried out in the ANSYS software package (v. 19.0). Studies have shown that a porous filter fiber model provides the maximum deposition efficiency for highly inert particles is provided by a porous filter fiber model with a microfiber size of 0.1 mm and a medium porosity of 0.9.

Numerical Simulation of Fiber Motion in the Condensing Zone of Lateral Compact Spinning with Pneumatic Groove

Lateral compact spinning with pneumatic groove is a spinning process to gather fibers by common actions of airflow and mechanical forces. Compared with ring spinning, it can more effectively reduce yarn hairiness and enhance yarn strength. However, fiber motion in the agglomeration area is complex. And, it is important to establish a new fiber model to accurately describing the fiber motion. The objectives of this research were to create a new fiber model to simulate the agglomeration process, to analyze yarn properties of the lateral compact spinning with pneumatic groove, and to compare with other spinning yarns through a series of tests. The new fiber model was based on the finite element method implemented in MATLAB and was to show the fiber motion during the agglomeration area. The simulation generated results were close to the real motion of fibers in spinning. In the lateral compact spinning with pneumatic groove, fiber bundle through the agglomeration area can be gathered, and the output of the fiber bundle was nearly to cylinder before yarn twisted. The experiments demonstrated that the lateral compact spinning with pneumatic groove can improve the yarn properties: increase the yarn twist, enhance the yarn strength, and reduce the yarn hairiness.

Cyclic response of a reinforced concrete frame: Comparison of experimental results with different hysteretic models

<abstract> <p>An accurate hysteresis model is fundamental to well capture the non-linearity phenomena occurring in structural and non-structural elements in building structures, that are usually made of reinforced concrete or steel materials. In this sense, this paper aims to numerically estimate through simplified non-linear analyses, the cyclic response of a reinforced concrete frame using different hysteretic models present in the literature. A commercial Finite Element Method package is used to carry out most of the simulations using polygonal hysteretic models and a fiber model, and additionally, a MATLAB script is developed to use a smooth hysteresis model. The experimental data is based on the experiments carried out in the Laboratório Nacional de Engenharia Civil, Portugal. The numerical outcomes are further compared with the experimental result to evaluate the accuracy of the simplified analysis based on the lumped plasticity or plastic hinge method for the reinforced concrete bare frame. Results show that the tetralinear Takeda's model fits closely the experimental hysteresis loops. The fiber model can well capture the hysteresis behavior, though it requires knowledge and expertise on parameter calibration. Sivaselvan and Reinhorn's smooth hysteresis model was able to satisfactorily reproduce the actual non-linear cyclic behavior of the RC frame structure in a global way.</p> </abstract>

A micromechanical unit cell model with an octagonal fiber for continuous fiber reinforced composites

This paper presents a novel micromechanical unit cell model for continuous fiber reinforced composites, which features a fiber with an octagonal cross-section embedded in surrounding matrix, and was named as octagonal fiber model. The cross-section of octagonal fiber model was subdivided into five by five sub-regions, and the conditions of equilibrium and deformation compatibility were applied to derive expression of effective ply properties, and stress amplification factors, which correlate microstresses in sub-regions with ply stresses. For E-glass/epoxy and carbon/epoxy material systems with different fiber volume fractions, effective ply properties and stress amplification factors in sub-regions were evaluated using derived formulae. Results from octagonal fiber model were then compared with those from multiple analytical methods and finite element unit cell model. It was shown that effective ply properties predicted by octagonal fiber model were generally in good agreement with those from finite element model, and octagonal fiber model outperformed other analytical counterparts in estimating stress amplification factors, demonstrating the potential of octagonal fiber model.

Solitary wave solutions of Kaup–Newell optical fiber model in mathematical physics and its modulation instability

Soliton solutions which signify long wave parallel to the magnetic fields of Kaup–Newell optical fiber model are discussed in this paper by two different methods. The improved simple equation method (ISEM) and exp[Formula: see text]-expansion scheme are employed to solve the model to construct the solutions of the model in different cases. The achieved solutions are represented in different and general forms such as logarithmic or exponential function, trigonometric and hyperbolic trigonometric functions, etc. Also, the modulation instability of the model is analyzed which confirms that all obtained exact results are stable. Several solutions from achieved solutions are novel.