Fiber Spacing Research Articles

Effect of Sinusoidal Fiber Waviness on Non-Linear Dynamic Performance of Laminated Composite Plates with Variable Fiber Spacing

This study investigated influence of varying waviness characteristics of fiber, represented by path amplitude Δ and different numbers of half sine waves k , on the elastic-plastic dynamic behaviour of laminated composite plates with variable fiber spacing. The analysis was based on the equations for action of constant axial dynamic loading and two-dimensional layered approach with classical first order shear deformation theory with five degrees of freedom per node, and it was performed with FORTRAN 94 programming language. Von-Karman’s assumptions were used for the discretization of the laminated plates to include geometric nonlinearity for nine-node Lagrangian isoperimetric quadrilateral elements. Complete bond between the layers was assumed with no delamination, which was based on first-order shear deformation theory. The Newmark implicit time integration method and Newton-Raphson iteration were simultaneously used to solve the nonlinear governing equation in conjunction. It was proven in the research that the nonlinear performance of the laminated composite plate was affected by the studied waviness parameters Δ and k , and also by the variable distribution pattern selected for this study.

Highly precisive arrangement of continuous carbon fiber and its reinforcing effect on hydroxyapatite

In order to efficiently prepare continuous fiber reinforced composites with high mechanical property, a macro-micro operation device was developed to arrange fiber with high precision. Continuous carbon fiber reinforced hydroxyapatite (CF/HA) composites with highly precisive fiber arrangement was subsequently prepared according to a demanded performance. The arranged fiber spacing and fiber angle of the CF preforms by this device was 101.15 ± 11.72 μm and 0.14 ± 0.38°, respectively. Compared to the traditional arrangement with the arranged fiber spacing of about 300–500 μm, the arrangement accuracy by this device enhanced about 66 %–80 %. The continuous CF/HA composites with designed fiber spacing prepared by this device possessed synchronously enhanced toughness and strength. Compressive strength of the CF/HA composites with designed fiber spacing of 300 μm (CF03p/HA) increased by 311.54 % compared with pure HA. Fracture toughness of the CF03p/HA composites was 1.68 MPa m1/2. Even though the fiber content in CF03p/HA composites was only one-sixth to one-tenth of that in the composites prepared by the traditional method, the compressive strength was 4.12 times that of pure HA. The study provides an effective method for preparing micro fiber reinforced composites featuring excellent mechanical performance even by adding low fiber content.

Microstructural evolution of highly aligned discontinuous fiber composites during longitudinal extension in forming

The longitudinal extensional viscosity of a highly aligned discontinuous fiber (ADF) thermoplastic matrix composite is investigated to develop a model and validate microstructural evolutionary mechanisms. Samples stretched at constant temperature and strain rate are shown to exhibit a strain softening behavior. X-ray CT analysis and optical micrographs show that the composite microstructure deconsolidates before forming and evolves with deformation. The conventional unit cell micromechanical model includes the effects of matrix viscosity, fiber aspect ratio and fiber volume fraction. This model is modified to include the stiffening effect of fiber spacing variability, and the softening effects of porosity and decreasing fiber overlap length with elongation. Calibration of the model reveals that matrix shear strain rate is an order of magnitude higher than previously predicted due to local fiber spacing. This effect is captured by a fiber spacing variability parameter which scales average spacing down by an order of magnitude. The observed strain softening behavior is described and a combinations of fiber overlap length reduction and local fiber spacing increase.

Correction to: Positivity of anticanonical divisor in algebraic fibre spaces

Correction to: Positivity of anticanonical divisor in algebraic fibre spaces

Configuration space of helical chiral self-assembly of micro/nano-fibers

As undertaking various key functions, helical chiral structures are widely presented in nature. Herein, we develop a general theoretical framework to guide the formation of helical chiral structures through self-assembly of micro/nano-fibers driven by adhesion. By analyzing the spiral contact geometric characteristics of multiple fibers and extending the JKR theory, an analytical model for adhesive contact between helical interfaces is proposed. Further, the complete configuration space of self-assembled fibers depending on the adhesion work, elastic modulus, aspect ratio, and initial helix angle is theoretically obtained. A diversity of helical configurations that far beyond existing experimental findings are predicted, which stems from the existence of multiple energy minimum points on the configuration-energy map. This work reveals the mechanism of adhesion-driven helical chiral structures, and provides theoretical foundation for guiding high-efficient fabrication of helical chiral structures through self-assembly method, which could promote the wide application of chiral structures in fields such as optics, catalysis and drug screening.

A New Double-Step Process of Shortening Fibers without Change in Molding Equipment Followed by Electron Beam to Strengthen Short Glass Fiber Reinforced Polyester BMC.

It is vital to maximize the safety of outdoor constructions, airplanes, and space vehicles by protecting against the impact of airborne debris from increasing winds due to climate change, or from bird strikes or micrometeoroids. In a widely-used compression-molded short glass fiber polyester bulk-molded compound (SGFRP-BMC) with 55% wt. CaCO3 filler, the center of the mother panel has lower impact strength than the outer sections with solidification texture angles and short glass fiber (SGF) orientations being random from 0 to 90 degrees. Therefore, a new double-step process of: (1) reducing commercial fiber length without change in molding equipment; followed by a (2) 0.86 MGy dose of homogeneous low-voltage electron beam irradiation (HLEBI) to both sides of the finished samples requiring no chemicals or additives, which is shown to increase the Charpy impact value (auc) about 50% from 6.26 to 9.59 kJm-2 at median-accumulative probability of fracture, Pf = 0.500. Shortening the SGFs results in higher fiber spacing density, Sf, as the thermal compressive stress site proliferation by action of the CTE difference between the matrix and SGF while the composite cools and shrinks. To boost impact strength further, HLEBI provides additional nano-compressive stresses by generating dangling bonds (DBs) creating repulsive forces while increasing SGF/matrix adhesion. Increased internal cracking apparently occurs, raising the auc.

Clearing the light path: Proteoglycans and their important roles in the lens and cornea

AbstractSome of the earliest studies of glycans were performed on mammalian corneas and lenses with many of the key concepts we currently recognize as being fundamental to our understanding of basic cell biology arising from these studies. Proteoglycans and their glycosaminoglycan (GAG) side chains are essential components of the extracellular matrix (ECM) of the lens capsule. They also are present in the anterior corneal epithelial basement membrane and the posterior (Decemet's) basement membrane, and they organize collagen fiber diameters and spacing in the corneal stroma to maintain stromal clarity. Studies using genetically engineered mice and characterization of spontaneously arising mutations in genes controlling proteoglycan synthesis have generated new insight into the roles played by proteoglycans in signal transduction. We now know that proteoglycans and GAGs can regulate cell signaling and the maintenance of avascularity and immune privilege that are hallmarks of these tissues. In addition, proteoglycan‐rich matrices provide the pathways for immune cells to populate the surface of the lens as a response to corneal wounding and in a model of experimental autoimmune uveitis. Here we describe what is known about proteoglycans and GAGs in the cornea and lens. This knowledge has begun to provide promising leads into new proteoglycan‐based treatments aimed at restoring and maintaining homeostasis in the cornea. Future studies are needed to determine how these new drugs impact the recruitment of immune cells to the lens for functions in restoring/maintaining homeostasis in the eye.

A representation formula for members of SBV dual

We give an integral representation formula for members of the dual of $SBV(\mathbb{R}^n)$ in terms of functions that are defined on $\hat{\mathbb{R}}^n$, an appropriate fiber space that we introduce, consisting of pairs $(x,[E]_x)$ where $[E]_x$ is an approximate germ of an $(n-1)$-rectifiable set $E$ at $x$.

On the 4-dimensional minimal model program for Kähler varieties

In this article we establish the following results: Let (X,B) be a dlt pair, where X is a Q-factorial Kähler 4-fold – (i) if X is compact and KX+B∼QD≥0 for some effective Q-divisor, then (X,B) has a log minimal model, (ii) if (X/T,B) is a semi-stable klt pair, W⊂T a compact subset and KX+B is effective over W (resp. not effective over W), then we can run a (KX+B)-MMP over T (in a neighborhood of W) which ends with a minimal model over T (resp. a Mori fiber space over T). We also give a proof of the existence of flips for analytic varieties in all dimensions and the relative MMP for projective morphisms between analytic varieties.

Effect of Electrostatic Field Assisted Thawing on the Quality of Previously Frozen Beef Striploins

The objective of this study was to evaluate the impact of applying electrostatic field (EF)–assisted thawing on the quality attributes of previously frozen beef striploin. Beef striploins from both sides of 12 USDA Choice carcasses were halved, frozen at −40°C, and thawed under 4 EF voltage treatments: 0 kV (control), 2.5 kV, 5 kV, and 10 kV. After reaching the internal temperature of −1°C, striploins were weighed for yield calculation, swabbed for microbial analysis, fabricated into steaks, and assigned to either 0- or 14-d aging period and retail displayed for 0 or 7 d. Subjective and objective color measurements were taken during the retail display. Upon completion of retail display, Warner-Bratzler shear force (WBSF), cook loss, sarcomere length, troponin-T degradation, muscle fiber spacing, lipid oxidation, antioxidant capacity, pH, and proximate analysis were performed. All EF treatments increased purge loss compared to the control (P<0.05) and did not improve thawing speed, with samples from 10 kV actually taking the longest to thaw (P<0.05). The 2.5 kV and 5 kV samples aged 14 d showed less discoloration than those from 0 kV and 10 kV, and 5 kV samples aged 14 d had higher a* than those from the other treatments (P<0.05). Samples thawed under 10 kV showed a reduction in WBSF compared to the control (P<0.05), but there was no impact of EF on aerobic plate count, sarcomere length, troponin-T degradation,relative fat %, crude protein %, moisture %, purge protein concentration, pH, lipid oxidation, or antioxidant capacity for either the hydrophilic (water soluble) and lipophilic (lipid soluble) portion of the samples (P>0.05). Overall, our study determined that there was no economic benefit to apply EF during thawing regarding yield and purge loss. However, the application of EF may improve tenderness and extend shelf life of beef during retail display.

Conharmonically flat and conharmonically symmetric warped product manifolds

This article presents characterizations of warped product manifolds based on the flatness and symmetry of the conharmonic curvature tensor. It is proved that when a warped product manifold is conharmonically flat, both the base and fiber manifolds exhibit constant sectional curvatures. In addition, the specific forms of the conharmonic curvature tensor are derived for both the base and fiber manifolds. It is demonstrated that in a conharmonically symmetric warped product manifold, the fiber manifold has a constant sectional curvature, while the base manifold is both Cartan-symmetric and conharmonically symmetric. In this scenario, the form of the conharmonic curvature tensor on the fiber manifold is determined. We characterize the generalized Robertson–Walker (GRW) space-time through the flatness and the symmetry of the conharmonic curvature tensor. It is shown that a conharmonically flat (symmetric) GRW space-time is a perfect fluid. Finally, a conharmonically flat standard static space-time is investigated.

Distribution of coarse aggregate and steel fibers in ultra-high performance concrete containing coarse aggregate (UHPC-CA) and their effect on the flexural performance

The addition of coarse aggregate in ultra-high performance concrete offers several benefits, including the reduction of self-shrinkage, cost reduction, and increased modulus of elasticity. However, it also affects the dispersion space of steel fibers, resulting in a combined effect that both enhances and limits their respective advantages. An image method was used to describe the dispersion of steel fibers and coarse aggregate in the specimens along their length, width and height directions, respectively. The impact of dispersion of steel fibers and coarse aggregate on bending performance was investigated by four-point bending tests using various surfaces as the bottom tensile zone. Furthermore, the damage occurrence mode and crack development process are discussed using micro-morphology and cross-sectional graphs. The results show that the combined effect of steel fibers and coarse aggregate is not conducive to dispersion in the length direction but prevents settling due to gravity during vibration. Differences in bending properties among various surfaces in the bottom tension zone was significant, but the synergy between steel fibers and coarse aggregate reduced these differences by 1.5–2.4 times. Steel fibers in ultra-high performance concrete containing coarse aggregate act as crack arrestors, resulting in ductile damage. Cracks develop partly through the coarse aggregate and partly along the interface transition zone, indicating that the addition of coarse aggregate does not compromise flexural strength.

The first example of hollow polynaphthoylenebenzimidazole fiber preparation

A new unique two-stage method for spinning hollow polynaphthoylenebenzimidazole (PNBI) fibers has been proposed. Polyacrylonitrile (PAN) fiber having a porous morphology was coated with poly(o-aminophenylene)- naphthoylenimide (PANI-O) precursor to form a composite fiber with a core–shell structure and subsequently this composite fiber precursor was heat treated in air. The inner PAN fiber underwent oxidative cyclization, accompanied by its high shrinkage, while the PANI-O shell, due to heterocyclization, turned into a PNBI-O shell, and the inner space of the hollow fiber was only partially filled with cyclized PAN.

Correlation between volume weight, porosity and moisture content in Central Kalimantan’s Peatlands

Peat is determined by soil characteristics consisting of maturity, color, low PD, low BD, texture, and organic content, which are different from mineral soil types, which can store more water with relatively high porosity, can decrease if drought due to lack of peat wetting with fiber spaces blackish brown with a fine structure. The purpose of this study was to determine the physical and chemical properties of peat as a water storage container and to determine the correlation between volume weight, porosity, and water content. The method used is a descriptive method, Sieve analysis, using ring samples and eagle auger camp. Laboratory results show that the BD value is small, the PD value is small, the water content value is high, the peat has maturity levels of Sapric and Hemic, and the texture consists of coarse sand, medium sand, and fine sand > of dust, no silt or clay, has a relative ash content low, high organic matter. The correlation is that when the BD and PD values are low, high water content means high porosity, large water storage, drought easily during the dry season, so fires easily occur.

Volume of Seifert representations for graph manifolds and their finite covers

AbstractFor any closed orientable 3‐manifold, there is a volume function defined on the space of all Seifert representations of the fundamental group. The maximum absolute value of this function agrees with the Seifert volume of the manifold due to Brooks and Goldman. For any Seifert representation of a graph manifold, the authors establish an effective formula for computing its volume, and obtain restrictions to the representation as analogous to the Milnor–Wood inequality (about transversely projective foliations on Seifert fiber spaces). It is shown that the Seifert volume of any graph manifold is a rational multiple of . Among all finite covers of a given nongeometric graph manifold, the supremum ratio of the Seifert volume over the covering degree can be a positive number, and can be infinite. Examples of both possibilities are discovered, and confirmed with the explicit values determined for the finite ones.

Winding pattern design of composite cylinders considering the effect of fiber stacking

Winding pattern design is a critical step in the production of composite cylinders. Traditional design methods often overlook the impact of stacking fibers layer by layer, leading to deviations between the actual and intended winding trajectories. To ensure consistence between the actual winding outcomes and design objectives, the effect of fiber stacking on the winding patterns was examined in this study. Two winding pattern design methods were proposed: the fixed tangent-point method (FTPM) and the minimum center angle deviation method (MCADM). A comparison was conducted on the variations in the number of tangent points, thread guide round trips, and the radius of the polar hole under the two different methods. Winding experiments were then employed to verify the feasibility of these approaches. The results showed that fiber stacking on the dome was the main reason for the change in winding patterns. Priority can be given to schemes within the design overlap domain for the design of multi-layer winding patterns. While FTPM ensures consistent fiber coverage and tape spacing, it may lead to hole expansion. Additionally, applying multiple layers can alter the dome's shape significantly from the original design. In contrast, MCADM offers slightly variable fiber coverage and spacing without causing hole expansion, achieving the desired dome shape more accurately.

Uncertain buckling characteristics of thermally loaded and internally defected variable fiber spacing composite laminates

The present investigation underscores the efficacy of laminated plates with variable fiber spacing (VFS) in the context of internal defects. The study involves the evaluation of the variability in buckling strength when faced with multiple tiers of damage; this is achieved through the implementation of an improved first-order shear deformation theory (IFSDT) within a finite element (FE) framework. Various types of fiber distribution (DT) are being examined to evaluate the effects of damage situated at both corner and mid locations. The application of a radial basis function network (RBFN)-based surrogate model demonstrates its potential as a feasible alternative to the computationally demanding Monte-Carlo simulations (MCS) for investigating the stochastic nature of buckling; the developed surrogate model requires reduced input sampling data to quantify buckling uncertainty. This study examines the stochastic nature of different material characteristics and observed that the uncertainty in the buckling response decreases with the increased damage severity. The assessment of the probability of failure is conducted subsequently. Following this, the damage ratios are influenced by randomness, leading to the pattern that an increased damage ratio corresponds to a more pronounced deviation in buckling uncertainty.

Near-infrared H2S telemetry system under non-cooperative target with a novel mixed heterodyne optical structure scheme for high efficiency

A gas leakage telemetry system under non-cooperative target was designed and developed based on laser absorption spectroscopy technology, targeting the combination frequency absorption band of Hydrogen sulfide (H2S) gas molecules. A distributed feedback (DFB) laser centered at 1578 nm was adopt, with mature packaging process and high market maturity. The returned signal of diffuse reflection is extremely weak, decreasing exponentially with the increase of telemetry distance, and direct detection technology is difficult to achieve ideal performance at telemetry distance and lower detection limit. Thus, heterodyne detection technology was introduced to significantly amplify diffuse reflection signal and improve the signal-to-noise ratio (SNR) of telemetry system. For further detection sensitivity, wavelength modulation spectroscopy (WMS) technology was combined to suppress background noise through the electrical modulation of DFB laser. Alternating signal was applied to the laser to alter its output characteristics during the process of laser oscillation. Compared with exterior modulation methods, this interior modulation method does not require additional modulator, which avoids optical loss and is more economical. Combining the advantages of fiber structure and space optical path structure, a novel mixed heterodyne optical structure which was more applicable to this system was independently designed after the specific analysis of main noise sources. Then, the effect of heterodyne detection technology was verified in contrast of direct detection technology. Sensor performance was validated through calibration and stability experiments. The limit of detection (LoD) reached a minimum of 3.44 parts-per-million (ppm·m) with a 98 s averaging time. And the packaged system was fully capable of detecting the hazardous critical concentration of H2S and acting as an alarm mechanism.

A segment-coupled six-mode multiplexer based on multi-core fiber

In this paper, a segment-coupled six-mode multiplexer based on multi-core fiber (MCF) is proposed to achieve multiplexing of LP01, LP11, LP21, LP02, LP31 and LP12 modes according to the principle of mode coupling and phase matching. The mode multiplexer consists of a two-part fiber waveguide that supports six modes of transmission at 1.55 μm wavelength. The transmission performance is analyzed with the finite element method (FEM) and the beam propagation method (BPM). The simulation results show that the insertion loss (IL) of the mode multiplexer is less than 1 dB in the wavelength range of 1.5439–1.5558 μm, and the lowest IL is 0.1837 dB. The coupling efficiencies (CEs) of the six modes are 99.7 %, 92.0 %, 98.6 %, 98.3 %, 97.4 % and 86.6 %, respectively. The designed mode multiplexer dramatically improves fiber space utilization while achieving more higher-order mode conversion. The mode multiplexer can be applied to the mode division multiplexing (MDM) system to solve the problem of mode multiplexing and demultiplexing.

Birationally rigid Fano-Mori fibre spaces

Abstract In this paper, we prove the birational rigidity of Fano-Mori fibre spaces $\pi \colon V\to S$ , every fibre of which is a Fano complete intersection of index 1 and codimension $k\geqslant 3$ in the projective space ${\mathbb P}^{M+k}$ for M sufficiently high, satisfying certain natural conditions of general position, in the assumption that the fibre space $V/S$ is sufficiently twisted over the base. The dimension of the base S is bounded from above by a constant, depending only on the dimension M of the fibre (as the dimension of the fibre M grows, this constant grows as $\frac 12 M^2$ ).