Perpendicular Fiber Research Articles

Influence of Veneer Density on Plywood Thickness and Some Mechanical Properties

Abstract It has been common knowledge that as the density of wood increases, the mechanical properties also improve. In turn, the density of wood depends on many factors, including the wood moisture content, location and cross-section in the trunk, the type of treatment and the parameters of technological processes. There is a great deal of research reported in the scientific literature on the effect of solid wood density on mechanical properties for different wood species as well as for structural timber. However, no research data can be found related investigation of the influence of veneer density on the properties of the birch plywood. In the present study, researching the properties of 7-ply birch plywood (thickness 9 mm), it was concluded that as the density of veneers increases, the bending properties of plywood in the direction of wood fibers (covered veneers) increases. When determining the plywood gluing quality, similar tendencies have been observed. For plywood with a lower density in all veneer plies the gluing quality (tensile-shear test) for perpendicular wood fiber veneers increases in the direction from the symmetry axis or middle veneer to the plywood outer plies, which can be explained by the fact that the outer plies become denser at the time of the hot pressing process. The results of the study will allow birch plywood manufacturers in direct production, sort veneers by density, to produce plywood with very predictable gluing quality, plywood thickness and mechanical properties in bending.

Design and Manufacturing Optoelectronic Sensors for the Measurement of Refractive Index Changes under Unknown Polarization State.

This article proposes a new method for detecting slight refractive index changes under conditions of unknown polarization state. It is argued that an insignificant modification of the tilted fiber Bragg grating (TFBG) structure and selecting the appropriate spectral region allows us to accurately track changes in the refractive index. It has also been proven that the method can be easily made insensitive to temperature and that the sensitivity to changes in the polarization plane of the input light can be significantly reduced, which is crucial in later practical applications. Analytes in the form of an aqueous glucose solution were used to calibrate the sensor. The proposed method, based on perpendicular tilted fiber Bragg grating (P-TFBG), has a wide range of universality because its development and slight modification will enable the detection of glucose, pathogens, and viruses.

Cavitation is the primary mechanism for stone dusting in holmium:YAG laser lithotripsy

Ureteroscopy with holmium(Ho):YAG laser lithotripsy (LL) is the primary treatment modality for kidney stone patients. Despite this, the mechanism of stone dusting in LL is unclear. In this work, we treated 6 × 6 mm cylindrical BegoStone phantoms using 0.2–0.4 J and 20 Hz at various fiber-to-stone standoff distances (SD) either in water or air with perpendicular fiber orientation; the latter eliminates the contribution of cavitation. The laser fiber was advanced at different offset distances (OSD) from a flexible ureteroscope tip to alter LL-induced bubble dynamics. Furthermore, stones were treated in parallel fiber orientation to minimize thermal ablation while isolating cavitation damage. Our results demonstrate that stone damage in water is 2.5- to 90-fold of those produced in air. At OSD = 0.25 mm when the bubble collapsed away from the stone surface due to the presence of the scope tip, stone damage was greatly reduced to the level in air. Moreover, the average crater volume produced by parallel fiber orientation after 100 pulses was comparable with those produced by perpendicular fiber within SD = 0.25–1 mm. Altogether, we conclude that cavitation is the primary mechanism over photothermal ablation for stone dusting in Ho:YAG LL.

Contribution of fiber orientation to enhancing dynamic properties of UHPC under impact loading

This paper investigates the contribution of fiber orientation to enhancing dynamic properties of ultra-high performance concrete (UHPC) under impact loading. Dynamic properties of 27 cylindrical core samples taken from prisms that have predominantly perpendicular, random, and parallel fiber orientations relative to the loading direction were tested. The Spilt Hopkinson Pressure Bar test method was used with strain rates of 160–290 s−1. Fiber orientation of samples after impact was evaluated using computed tomography scan. Test results indicated that the dynamic compressive strength, peak strain, and energy absorption capacity increased by up to 65%, 105%, and 295%, respectively, with the increase in strain rate. For a given strain rate, samples with predominant fiber orientations perpendicular and parallel to the loading direction showed the highest and lowest dynamic properties, respectively. Such spread in dynamic compressive strength, peak strain, and energy absorption capacity due to fiber orientation was up to 40%, 90%, and 135%, respectively. Fiber orientation coefficients along the direction of tensile stress were around 0.7 and less than 0.3 for samples with predominantly perpendicular and parallel fiber orientations, respectively. Good relationships were established to estimate the dynamic properties of UHPC given the quasi-static compressive strength, strain rate, and fiber orientation. A constitutive model to estimate the stress-strain curves of UHPC subjected to impact loading was developed. The model considers the influence of fiber orientation and strain rate. The model was successfully validated using the experimental data and was found to provide accurate prediction of the ascending portions of the stress-strain curves of UHPC under impact loading. The maximum spread between predicted and experimental dynamic compressive strength was limited to 10%.

On the Structural Peculiarities of Self-Reinforced Composite Materials Based on UHMWPE Fibers.

The structure of self-reinforced composites (SRCs) based on ultra-high molecular weight polyethylene (UHMWPE) was studied by means of Wide-Angle X-ray Scattering (WAXS), X-ray tomography, Raman spectroscopy, Scanning Electron Microscopy (SEM) and in situ tensile testing in combination with advanced processing tools to determine the correlation between the processing conditions, on one hand, and the molecular structure and mechanical properties, on the other. SRCs were fabricated by hot compaction of UHMWPE fibers at different pressure and temperature combinations without addition of polymer matrix or softener. It was found by WAXS that higher compaction temperatures led to more extensive melting of fibers with the corresponding reduction of the Herman’s factor reflecting the degree of molecular orientation, while the increase of hot compaction pressure suppressed the melting of fibers within SRCs at a given temperature. X-ray tomography proved the absence of porosity while polarized light Raman spectroscopy measurements for both longitudinal and perpendicular fiber orientations showed qualitatively the anisotropy of SRC samples. SEM revealed that the matrix was formed by interlayers of molten polymer entrapped between fibers in SRCs. Moreover, in situ tensile tests demonstrated the increase of Young’s modulus and tensile strength with increasing temperature.

Study of methods for controlling direction and velocity of liquid jets formed during subcooled boiling

The mechanism of submerged jets generation during subcooled surface and volumetric water boiling is studied experimentally and numerically. The boiling take place near the tip of the optical fiber through which the laser radiation is supplied. It is shown that the interaction of a collapsing bubble with the end face of the optical fiber leads to the symmetry breaking of the bubble, following by the water jet generation. The jet velocity depends on the collapse rate as well as on the ratio of the maximum bubble radius reached during the inflation stage to the fiber radius and, therefore, on the laser radiation intensity. Other problem parameters affecting characteristics of the generated jets are the temperature of the surrounding liquid and the fiber radius. Experiments with two perpendicular optical fibers demonstrate vector summation of the velocities of the jets generated by each individual fiber. Presented results might contribute to the development of new operating medical technologies for laser surgical treatment of a wide range of common diseases.

Dynamic Tensile Response of Caprine Muscles Using Split Hopkinson Pressure Bar

Computer modeling and numerical simulation has become an efficient diagnostic tool to predict the human body injuries caused due to high speed automotive impacts, blast and ballistic impacts. Soft tissues such as muscles and skin in human body are exposed to varying strain rates under dynamic loadings during impacts. The prediction of impact-induced injuries requires a thorough understanding of mechanical behaviour of soft tissues for computational modeling of human body. In the present study, uniaxial tensile tests were conducted on caprine lower extremity muscles in the strain rate range of (500s^-1-3500s^-1) using custom-made split Hopkinson pressure bar (SHPB) apparatus. The challenges in the dynamic testing of soft tissues such as measurement of weak transmitted signals, use of viscoelastic pressure bars, tensile loading of specimen and generation of constant strain rate were addressed in dynamic tensile testing of soft tissues using polymeric SHPB. The attenuation and dispersion in waves are corrected using isolated incident bar tests. The stress-strain results were determined from the reconstructed waves for the tests conducted on lower extremity caprine muscles. The muscle specimens were tested along and perpendicular to the fiber direction to study the directional dependency of tissue behaviour. The stress-strain response was found to be non-linear and significant dependant on strain rate when tested along and perpendicular to fiber direction at same strain rates. It is also observed that at the same strain rate, the specimen stress of caprine muscle along the perpendicular fiber direction is higher than that along the fiber direction. The obtained results may further be used to develop finite element human body models and safety systems for human body in high rate scenario.

Electroluminescent Fabric Woven by Ultrastretchable Fibers for Arbitrarily Controllable Pattern Display.

Flexible textile displays can be revolutionary for information transmission at any place and any time. Typically, textile displays are fabricated by traditional rigid electronics that sacrifice mechanical flexibility of devices or by flexible electronics that do not have an appropriate choice to arbitrarily control single pixels. This work reports on an electroluminescent fabric woven by ultrastretchable fibers (electroluminescent fibers up to 400% stretch, electrode fibers up to 250% stretch), which can exhibit the pixel-based arbitrarily controllable pattern display by a mobile phone application. To realize ultrastretchability, we made these fibers by encapsulating liquid metals on a polyurethane core (high elasticity). To realize arbitrary control, the design shows a plain-woven structure comprising ZnS-based electroluminescent fibers and perpendicular electrode fibers. The cross-points between the electroluminescent fiber and the electrode fiber form pixels that can be switched on or off independently and can further form the pixel-based arbitrarily controllable pattern display. By doping with different elements, ZnS-based electroluminescent fibers can emit green, blue, or yellow lights. Meanwhile, the fabrication of these fibers employs dip-coating, a scalable manufacturing method without high temperature or vacuum atmosphere. These fabrics show great potential in a wide range of applications such as wearable electronic devices, healthcare, and fashion design.

The Effects of Polystyrene Species and Fiber Direction on Thermal Conductivity of Plywood

Thermal conductivity of wood material is superior to other building materials because of its porous structure. Thermal conductivity is used to estimate the ability of insulation of material. Thermal conductivity of wood material has varied according to wood species, direction of wood fiber, specific gravity, moisture content, resin type, and addictive members used in manufacture of wood composite panels. The aim of study was to determine the effect of polystyrene species and fiber direction on thermal conductivity of plywood panels. In the study, two different wood types (black pine and spruce), two different fiber directions (parallel and perpendicular to the plywood fiber direction), two different types of insulator (expanded polystyrene-EPS and extruded polystyrene-XPS) and phenol formaldehyde glue were used as the adhesive type. Thermal conductivity of panels was determined according to ASTM C 518 & ISO 8301. As a result of the study, the lowest thermal conductivity values were obtained in the perpendicular fiber direction of the spruce plywood using XPS as insulation material. The use of XPS as an insulation material in plywood has given lower thermal conductivity values than EPS.

Facelift With Power-Assisted Dissection: A Preliminary Report.

Subcutaneous elevation of the skin has remained a key component in all facelift techniques. The aim of this preliminary report was to introduce the ABC facelift as a 3-step method addressing photodamage, soft tissue laxity, and areas of bone and volume loss. The procedure consists of: (A) anatomic and regenerative adipose grafting prior to skin elevation; (B) the use of a Baraf elevator for takedown of perpendicular subcutaneous fibers following hydrodissection of the skin flaps with tumescent solution; and (C) cautery dissection of the superficial muscular aponeurotic system (SMAS) and platysma in the neck. Thirty-four patients (31 females; 3 male), aged 50 to 77 years at the date of procedure, underwent an ABC facelift. Dissection of the skin flaps and SMAS elevation were faster than with traditional methods, averaging 10 to 15 minutes per hemiface. Bleeding was reduced (average estimated blood loss, 12 mL) and the skin flaps appeared better perfused with less venous engorgement and ecchymosis than achieved with sharp scissor dissection. In general, patients appeared to have shorter postoperative recovery courses and less social downtime secondary to bruising and edema. The ABC facelift addresses facial laxity, volume loss, and skin aging with 3 simple steps: anatomic and regenerative fat grafting, combined with power-assisted dissection of the skin and cautery elevation of the SMAS. The use of more advanced hydrodissection tools to achieve further improvements in layer separation is currently being investigated.

Influence of Muscle Fiber Direction on Migration of Salmonella Enteritidis, Staphylococcus aureus, and Escherichia coli into Raw Chicken Breast

The influence of muscle fiber direction (parallel or perpendicular) in relation to the inoculation surface on migration of Salmonella Enteritidis, Staphylococcus aureus, and Escherichia coli into raw chicken breasts was examined. Chicken breast samples with two types of surface fibers (running parallel or perpendicular to the surface) were inoculated with cultures of each bacterium. Inoculated samples were stored for 5 min, 1 h, or 24 h at 4°C. After storage, the samples were divided into segments, and bacterial counts were determined in different regions (inoculation surface, inoculation surface to 1 cm, 1 to 2 cm, 2 to 4 cm, and 4 to 6 cm). The migration of bacteria did not change at 5 min or 1 h regardless of fiber direction. However, after 24 h each bacterium was detected at 4 to 6 cm in the pieces of sample with a perpendicular muscle fiber surface cut. Although these bacteria were detected at 4 to 6 cm in samples with muscle fibers perpendicular to the inoculated surface, these results do not clearly indicate that bacteria migrated into the chicken breast. To monitor actual migration of bacteria into the chicken breast, the tops of the perpendicular muscle fibers of the breast sample were inoculated with bioluminescent E. coli Xen-14. Various regions of the breast sample (inoculation surface and cut surfaces at 1, 2, 4, and 6 cm) were stamped directly on growth medium. Culture revealed that the bacteria migrated directly under the contaminated site and dispersed along the surface of the chicken breast segments. More bacteria distributed laterally than migrated directly below the contamination site. These results suggest that the direction of the muscle fibers is a major factor influencing migration of pathogenic bacteria into chicken breast.

Myelin water imaging and R2* mapping in neonates: Investigating R2* dependence on myelin and fibre orientation in whole brain white matter.

R2* relaxation provides a semiquantitative method of detecting myelin, iron and white matter fibre orientation angles. Compared with standard histogram-based analyses, angle-resolved analysis of R2* has previously been shown to substantially improve the detection of subtle differences in the brain between healthy siblings of subjects with multiple sclerosis and unrelated healthy controls. Neonates, who are born with very little myelin and iron, and an underdeveloped connectome, provide researchers with an opportunity to investigate whether R2* is intimately linked with fibre-angle or myelin content as it is in adults, which may in future studies be explored as a potential white matter developmental biomarker. Five healthy adult volunteers (mean age [±SD] = 31.2 [±8.3] years; three males) were recruited from Vancouver, Canada. Eight term neonates (mean age = 38.6 ± 1.2 weeks; five males) were recruited from the Children's Hospital of Chongqing Medical University neonatal ward. All subjects were scanned on identical 3 T Philips Achieva scanners equipped with an eight-channel SENSE head coil and underwent a multiecho gradient echo scan, a 32-direction DTI scan and a myelin water imaging scan. For both neonates and adults, bin-averaged R2* variation across the brain's white matter was found to be best explained by fibre orientation. For adults, this represented a difference in R2* values of 3.5 Hz from parallel to perpendicular fibres with respect to the main magnetic field. In neonates, the fibre orientation dependency displayed a cosine wave shape, with a small R2* range of 0.4 Hz. This minor relationship in neonates provides further evidence for the key role myelin probably plays in creating this fibre orientation dependence later in life, but suggests limited clinical application in newborn populations. Future studies should investigate fibre-orientation dependency in infants in the first 5 years, when substantial myelin development occurs.

Investigation of Milling of Carbon Fiber Reinforced Plastic

Abstract The use of fiber-reinforced plastics has increased significantly in the past decades. Consequently, the demand for finishing and machining of such materials has also escalated. During machining, the fiber-reinforced materials exhibit machining problems dissimilar to the problems of metals. These are fiber pull-out, fiber breakage in the cutting zone, matrix smearing and delamination. The purpose of this experiment is to investigate the characteristics of the resultant force (Fe) dur-ing the milling of carbon fiber reinforced plastic as a function of input machining parameters. For the force measurements, CFR with perpendicular (0°-90°) fiber orientation was machined. The experimental design involved the central composite design method. To analyze and evaluate the measurements, we applied the response surface methodology.

A prospective study comparing tendon-to-bone interface healing using an interposition bioresorbable scaffold with a vented anchor for primary rotator cuff repair in sheep

The purpose of this study was to evaluate the biomechanical and histologic properties of rotator cuff repairs using a vented anchor attached to a bioresorbable interpositional scaffold composed of aligned PLGA (poly(l-lactide-co-glycoside)) microfibers in an animal model compared to standard anchors in an ovine model. Fifty-six (n = 56) skeletally mature sheep were randomly assigned to a repair of an acute infraspinatus tendon detachment using a innovative anchor-PLGA scaffold device (Treatment) or a similar anchor without the scaffold (Control). Animals were humanely euthanized at 7 and 12 weeks post repair. Histologic and biomechanical properties of the repairs were evaluated and compared. The Treatment group had a significantly higher fibroblast count at 7 weeks compared to the Control group. The tendon bone repair distance, percentage perpendicular fibers, new bone formation at the tendon-bone interface, and collagen type III deposition was significantly greater for the Treatment group compared with the Control group at 12 weeks (P ≤ .05). A positive correlation was identified in the Treatment group between increased failure loads at 12 weeks and the following parameters: tendon-bone integration, new bone formation, and collagen type III. No statistically significant differences in biomechanical properties were identified between Treatment and Control Groups(P > .05). Use of a vented anchor attached to a bioresorbable interpositional scaffold composed of aligned PLGA microfibers improves the histologic properties of rotator cuff repairs in a sheep model. Improved histology was correlated with improved final construct strength at the 12-week time point.

Study of the synergistic effects of fiber orientation, fiber phase and resin phase in a fiber-reinforced composite material on its tribological properties

A new fiber-reinforced composite (FRC) material composed of phenolic resin, nylon fabric and graphene was fabricated and tested to investigate the synergistic effects of fiber orientation, fiber and resin on the tribological properties of FRC materials. The experimental wear tests, where the FRC material specimens were worn against Si3N4 ceramic balls, were conducted using R-tec commercial tribotester. The coefficients of friction (COF), wear profiles and micro-morphologies of the test specimens were determined and compared. The mechanical properties of the test specimens were analyzed to discern their friction and wear mechanisms. The experimental results showed that fiber with a high shore hardness and good a heat distortion temperature produced good wear resistance, as the reinforcing phase in the FRC material. The resin phase became soft and deformed easily during the wear process, because of its low heat distortion temperature, which caused it to migrate to the contact surfaces where it acted as a lubricant. Both the perpendicular and parallel fiber surfaces exhibited a low COF and excellent wear-resistance properties. The large non-uniform wear of the fiber nodes and the resin at the fiber node surface produced a rough surface resulting in substantial wear and a high COF. The understanding gained herein was helpful in comprehending the effects of the various phases in FRC materials as well as the FRC friction and wear mechanisms, and will be useful for future design of FRC materials with low friction, and high wear resistance properties.

Transport of flexible fibers in confined microchannels

When transported in confined geometries rigid fibers show interesting transport dynamics induced by friction with the top and bottom walls. Fiber flexibility causes an additional coupling between fiber deformation and transport and is expected to lead to more complex dynamics. A first crucial step for their understanding is the characterization of the deformed fiber shape. Here we characterize this shape for a fiber transported in a confined plug flow perpendicular to the flow direction using a combination of microfluidic experiments and numerical simulations. In the experiments, size, initial orientation, and mechanical properties of the fibers are controlled using micro-fabrication techniques and in-situ characterization methods.The numerical simulations use modified Brinkman equations as well as full 3D simulations. We show that the bending of a perpendicular fiber results from the force distribution acting on the elongated object and is proportional to the elasto-viscous number, comparing viscous to elastic forces. We quantitatively characterize the influence of the confinement on the fiber deformation. The precise understanding of the deformation of a flexible fiber in a confined geometry can also be used in future to understand the deformation and transport of more complex deformable particles in confined flows, as for example vesicles or red blood cells.

In vivo imaging of the fibrillar architecture of the posterior vitreous and its relationship to the premacular bursa, Cloquet's canal, prevascular vitreous fissures, and cisterns.

To describe the fibrillar architecture of the posterior cortical vitreous and identify variations across eyes of different axial lengths in vivo. Sixty-four eyes of 32 subjects were examined with swept-source optical coherence tomography (SS-OCT). Grading of vitreous degeneration, presence of vitreous cisterns/lacunae, posterior hyaloid status, directionality of vitreous fibers and their relations to vitreous spaces, and lamellar reflectivity of the posterior vitreous were assessed. A consistent pattern of fibrillar organization was discovered. Eyewall parallel fibers formed a dense meshwork over the retinal surface and fibers oriented in a perpendicular fashion to this meshwork were found to envelop the various vitreous spaces, intersecting at variable angles of insertion to the eyewall parallel fibers. Lamellar reflectivity suggestive of splitting of the cortical fibrillar meshwork was detected in 27 eyes (42%) with 56% of these eyes demonstrating perpendicularly oriented intersecting fibers. Fifty-six percent of eyes with lamellar reflectivity had an axial length > 25mm. SS-OCT imaging revealed fibrillar organization of the posterior vitreous. Eye wall parallel hyperreflectivity of cortical vitreous was a universal finding. This pattern is suggestive of a splitting of cortical vitreous tissue and may represent a precursor to vitreoschisis. Perpendicular fibers appear to be important constituents of the walls of the various liquid vitreous spaces.

Template-free perpendicular growth of a poly(3,4-ethylenedioxythiophene) fiber array by bipolar electrolysis under an iterative potential application

A perpendicular PEDOT fiber array was successfully grown from a bipolar electrode (BPE) surface by electropolymerization of aromatic monomers.

Model Test Ultimate Bearing Capacity of Bakau Piles Foundation on Soft Soil Deposit

The pile foundation is one of the deep foundation types commonly used to support building loads when hard soil layers are deeply located. To determine the ultimate bearing capacity of a pile foundation of the load test results, there are several methods commonly used to interpretation test results such as Davisson method, Mazurkiewich method, Chin method, Buttler Hoy method and De Beer method. The aim of this study was to determine the characteristics of soft soil and bakau piles used in the study and to analyze the size of the bearing capacity ultimate of pile foundation that is modeled on a small scale in the laboratory. From the test results of material characteristics of the soil used is organic clay type with medium plasticity with specific gravity 2.75, liquid limit, LL = 50.36% and plasticity index, PI = 13.2%. While the results of testing the characteristics of bakau piles obtained average water content of 21.58%, tensile strength of 18.51 MPa, compressive strength of parallel fiber 23.75 MPa and perpendicular fiber 14.10 MPa, bending strength 106, 22 MPa, and strong split 29.91 MPa. From the result of loading test of the foundation model in the laboratory, it is found that the ultimate bearing capacity of the model without foundation is 41.00 kN with the ultimate settlement of 14.00 mm, the model of the 20 cm long bakau piles foundation is 52.00 kN with the ultimate settlement of 13.00 mm, the foundation model a 30 cm long bakau piles foundation of 54.00 kN with a 10.00 mm ultimate settlement, a 40 cm long bakau piles foundation model of 56.00 kN with an ultimate settlement of 8.50 mm.

Solving Heterogeneities in Defibrillation for a Vascular Remodel of the Human Heart

Introduction: Current mathematical models impede the amelioration of defibrillation protocol. Heterogeneities such as intracellular clefts, scarring, blood vessels, and fiber orientation are excluded in modeling. Such geometries pose a positive curvature, magnifying resistance when faced with electrical shock. Thus, such geometries have the potential of revolutionizing AED machines-a prospect we have not gained enough data on to consider. Objective: The purpose of my study is to quantify the effect of each non-conformity in relation to the electrical dynamics of the human heart. Post-quantification, I hypothesize that the electrical impedance decreases as the heterogeneity size decreases. Posed with such a window of pertinence, my goal is to remodel the human heart including all heterogeneities-a previous infeasibility. Methodology: Using CHASTE cardiac software library, electrical shock was applied to cardiac tissue engineered in Mesh Lab. Cardiac tissue, the slab geometries, contained blood vessels in the center of varying vessel size-400, 200, 100μm. Results: Overall, the results showed that without heterogeneities biological reality and computational modeling have severe discrepancies; mainly, the experimentally supported therapy of low-energy ant fibrillation shows failure in math modeling. Perpendicular fiber orientation perceived shock at a 1.74x more efficacies. In the most sensitive case scenario, 400 and 200μm affected the defibrillating wave-front, while the 100μm heterogeneity did not. Conclusion: All heterogeneities cannot be extracted by magnetic resonance angiography due to its limiting factor of magnetic susceptibility; however, by filtering can anatomically accurate mathematical remodel capable of representing the necessary cardiac vessels is created.