Fiber Taper Research Articles

Effect of Flashlamp Heating System Parameters on the Wedge Peel Strength of Thermoplastic Carbon Fiber Tape in the Automated Tape Placement Process

Laser-assisted automated tape placement systems are currently the state of the art regarding thermoplastic tape placement. Flashlamp heating systems are rather new in this field of application and offer high energy density with low safety requirements and moderate costs compared to laser-assisted automated tape placement systems. In this study, the effect of processing parameters on interlaminar bonding of carbon fiber-reinforced polyamide 6 tapes is investigated using a flashlamp heating system. The temperature during placement is monitored using an infrared camera, and the bonding strength is characterized by a wedge peel test. The bonding quality of the tapes placed between 210 °C and 330 °C at a lay-up speed of 50 mm/s is investigated. Thermogravimetric analysis, differential scanning calorimetry, and micrographs are used to investigate the material properties and effects of the processing conditions on the thermophysical properties and geometric properties of the tape. No significant changes in the thermophysical or geometric properties were found. Moisture within the tapes and staining of the quartz guides of the flashlamp system have significant influence on the bonding strength. The highest wedge peel strength of dried tapes was found at around 330 °C.

Continuous tow shearing for the automated manufacture of defect-free complex 3D geometry composite parts

It has always been challenging to manufacture a composite structure with complex geometry using automated fibre placement (AFP) process. The tool surface is difficult to be tessellated using fibre tapes with a finite width, without producing gaps and overlaps, and fibre steering along non-geodesic fibre paths produces various defects such as tape buckling and pull-up. In this work, a defect-free fibre-steering process on a complex surface was demonstrated by realising the continuous tow shearing (CTS) process in three dimensions. A new head control algorithm was developed, which defines the head orientations and trajectories based on the pin-jointed net model to manipulate the fibre tow using both in-plane shear and out-of-plane twisting deformations. Fibre steering process utilising this new algorithm was tested on a doubly-curved surface, using an industrial robot arm equipped with a CTS prototype head, and its layup quality and accuracy were assessed by using a three-dimensional laser profile scanner. An experimental comparison with the conventional AFP process showed that the new control algorithm enables defect-free fibre steering on complex 3D surfaces allowing for simplifying the design and analysis of novel composite structures.

Low-loss and compact photonic lantern based on a step-index double cladding fiber.

The fulfilment of the adiabatic criterion is indispensable for the realization of a low-loss photonic lantern (PL), concurrently imposing a stringent restriction on the taper transition length of the PL. Here, by relaxing the adiabatic criterion, a low-loss and compact PL based on a step-index double cladding fiber (SI-DCF) is theoretically proposed and experimentally demonstrated. The use of SI-DCF can reduce the mode field diameter (MFD) expansion ratio during the tapering processing and greatly decrease the taper transition length required for adiabatic tapering. We initially evaluate the variation of both MFD and effective refractive index (RI) along the fiber tapering based on three types of fiber structures, including the modified standard single-mode fiber (SSMF), the graded-index fiber (GIF), and the proposed SI-DCF. In comparison with the commonly used fiber geometry, the SI-DCF can reduce the MFD expansion ratio from 77.73% to 38.81%, leading to more than half reduction of the tapering length for both 3-mode and 6-mode PLs. Then, two kinds of SI-DCF with different core diameters are fabricated to realize a 3-mode PL. The fabricated PL possesses a 1.5 cm tapering length and less than 0.2 dB insertion loss (IL). After splicing with the commercial few-mode fiber, the PL has an average IL of 0.6 dB and more than 13 dB LP11 mode purity over the C-band. Finally, a transfer matrix measurement indicates that the fabricated PLs have a mode coupling of less than -10 dB at 1550 nm.

The need for speed – Does the force–velocity property significantly alter strain distributions within skeletal muscle?

Skeletal muscles are complex structures with nonlinear constitutive properties. This complexity often requires finite element (FE) modeling to better understand muscle behavior and response to activation, especially the fiber strain distributions that can be difficult to measure in vivo. However, many FE muscle models designed to study fiber strain do not include force–velocity behavior. To investigate force–velocity property impact on strain distributions within skeletal muscle, we modified a muscle constitutive model with active and passive force–length properties to include force–velocity properties. We implemented the new constitutive model as a plugin for the FE software FEBio and applied it to four geometries: 1) a single element, 2) a multiple-element model representing a single fiber, 3) a model of tapering fibers, and 4) a model representing the bicep femoris long head (BFLH) morphology. Maximum fiber velocity and boundary conditions of the finite element models were varied to test their influence on fiber strain distribution. We found that force–velocity properties in the constitutive model behaved as expected for the single element and multi-element conditions. In the tapered fiber models, fiber strain distributions were impacted by changes in maximum fiber velocity; the range of strains increased with maximum fiber velocity, which was most noted in isometric contraction simulations. In the BFLH model, maximum fiber velocity had minimal impact on strain distributions, even in the context of sprinting. Taken together, the combination of muscle model geometry, activation, and displacement parameters play a critical part in determining the magnitude of impact of force–velocity on strain distribution.

Triceps Tendon Reattachment Using Mini Plates and Screws After Failure of Olecranon Avulsion Fracture Fixation in Osteoporotic Bone: A Case Report.

This is a case report of an 85-year-old woman with osteopenia who underwent olecranon avulsion fracture repair with supplemental triceps tendon repair following a fall on an outstretched arm. The initial procedure failed due to osteoporotic bone quality and an atraumatic disruption of the olecranon fracture fixation. The patient subsequently underwent further surgical intervention with an olecranon avulsion fracture excision and a novel triceps tendon repair technique using plate augmentation and fiber tape. Surgeons may consider this novel approach as an initial treatment for elderly patients with osteopenia or osteoporosis undergoing olecranon avulsion fracture fixation, to prevent the failure and consequent revision surgery.

Composite membrane of graphene oxide and gold nanoparticles functionalized S fiber taper aptasensor for highly sensitive bisphenol A detection.

The S fiber taper (SFT) aptasensor with a composite sensitive membrane of graphene oxide and gold nanoparticles was proposed for the rapid and highly sensitive detection of bisphenol A (BPA). The SFT was obtained using a fusion splicer; subsequently, the composite film was deposited on its surface, and the specific aptamer was covalently bonded to the surface of gold nanoparticles. The detection mechanism relies on monitoring changes in the external refractive index induced by the specific binding of BPA to the aptamer. The developed SFT aptasensor exhibited a remarkable sensitivity of 15.5 nm/nM and a limit of detection as low as 0.01 nM for BPA. These findings highlight the aptasensor's potential for diverse monitoring applications.

High-Throughput Additive Manufacturing of Continuous Carbon Fiber-Reinforced Plastic by Multifilament.

Additive manufacturing (or 3D printing) of continuous carbon fiber-reinforced plastics with fused deposition modeling is a burgeoning manufacturing method because of its potential as a powerful approach to produce lightweight, high strength and complex parts without the need for a mold. Nevertheless, it cannot manufacture parts rapidly due to low throughput. This paper proposes a high-throughput additive manufacturing of continuous carbon fiber-reinforced plastics by multifilament with reference to fiber tape placement. Three filaments were fed and compaction printed simultaneously by a robotic manufacturing system. The coupled thermal-mechanical model of the filament deformation during printing was developed to eliminate the initial interval between the filaments and improved mechanical properties. Furthermore, the mathematical relationship between filament deformation and printing parameters consisting of printing temperature, printing speed and roller pressure was proposed using response surface methodology with the line width as the response. The tensile tests demonstrate that the tensile properties of printed parts are positively correlated with the line width, but not infinitely improved. The maximum tensile strength and tensile modulus are 503.4 MPa and 83.11 Gpa, respectively, which are better than those obtained by traditional methods. Void fraction and scanning electron microscope images also reveal that the appropriate line width achieved by the reasonable printing parameters contributes to the high-throughput multifilament additive manufacturing of continuous carbon fiber-reinforced plastics. The comparison results indicate that the high-throughput multifilament additive manufacturing proposed in this paper can effectively improve the speed of continuous carbon fiber-reinforced plastics additive manufacturing without degrading the mechanical performance.

Fiber-taper collected emission from NV centers in high-Q/V diamond microdisks.

Fiber-coupled microdisks are a promising platform for enhancing the spontaneous emission from color centers in diamond. The measured cavity-enhanced emission from the microdisk is governed by the effective volume (V) of each cavity mode, the cavity quality factor (Q), and the coupling between the microdisk and the fiber. Here we observe room temperature photoluminescence from an ensemble of nitrogen-vacancy centers into high Q/V microdisk modes, which when combined with coherent spectroscopy of the microdisk modes, allows us to elucidate the relative contributions of these factors. The broad emission spectrum acts as an internal light source facilitating mode identification over several cavity free spectral ranges. Analysis of the fiber taper collected microdisk emission reveals spectral filtering both by the cavity and the fiber taper, the latter of which we find preferentially couples to higher-order microdisk modes. Coherent mode spectroscopy is used to measure Q ∼ 1 × 105 - the highest reported values for diamond microcavities operating at visible wavelengths. With realistic optimization of the microdisk dimensions, we predict that Purcell factors of ∼50 are within reach.

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.

A Compact Device of Optical Fiber Taper Coupled Monolayer Silver Nanoparticles for Raman Enhancement

A Compact Device of Optical Fiber Taper Coupled Monolayer Silver Nanoparticles for Raman Enhancement

Pediatric AC Joint Fracture Dislocation: Arthroscopy-assisted Reduction and Internal Bracing

Introduction: Acromioclavicular joint injuries are common injuries around shoulder and comprise around 9–12% and are rare in pediatric population. Many surgeries have been described which include open stabilization, arthroscopic assisted, or complete arthroscopic. We describe our technique of arthroscopic-assisted fixation in AC joint acute injuries, in which we arthroscopically pass fiber tape and tunnels across coracoid base and clavicle to stabilize the upward forces, followed by double breasting for AC joint with fiber tape to balance the horizontal forces. Case Report: A 9-year-old female kid with a history of falls with left shoulder pain and diagnosed with fracture dislocation of the left ac joint. The patient in beach chair position. Arthroscopically, fibertape was passed through a drill hole near to cc ligament and cinch loop was done through it and around coracoid. With a mini-incision, AC joint further stabilized. Conclusion: Similar case reports are very few and arthroscopic management of same is nearly none. Advantages of our procedure are relatively low cost of the implant, and no anchors or metal implants at AC joint to avoid impingement. Open AC joint stabilization addresses the disc in joint. Disadvantages are a long learning curve. Keywords: Pediatric AC joint, acromioclavicular joint dislocation, arthroscopic AC joint, AC joint internal bracing, acute AC joint dislocation.

Effect of tapered natural fiber on elastic properties of sisal fiber-reinforced composite: An experimental and micromechanics approach

In the characterization of natural fiber-reinforced composites, it is crucial to consider the nonuniform cross-section of fibers extracted from plants or leaves, which results from the inherent variation in fiber diameter. This variation is a key aspect of the actual reinforcement behavior, and disregarding it by assuming a uniform cross-section can violate the physical understanding of the composite’s mechanics. This study focuses on characterizing the elastic properties of a natural tapered sisal fiber-reinforced epoxy composite, taking into account the variation in fiber diameter along its length. To achieve this, both experimental, analytical, and micromechanics methods are employed. The experimental approach involves conducting tests to measure the mechanical properties of the composite, while the micromechanics analysis provides a framework to understand the reinforcement behavior and predict the composite’s mechanical response. The study aims to identify and present various elastic properties of the composite, including the longitudinal modulus, transverse modulus, in-plane and out-of-plane shear modulus, and major and minor Poisson’s ratios. The fiber taper angle has a significant effect on longitudinal and transverse modulus and interfacial stresses. The longitudinal modulus experiences a reduction of 25.9% when increasing the taper angle from [Formula: see text] to [Formula: see text] at a higher fiber volume fraction (40%). However, at a lower volume fraction of the same fiber (10%), the reduction in modulus is limited to 5.74%. Similarly, the transverse modulus is also affected by the taper angle. At the higher fiber volume fraction, there is a decrease of 24.52%, whereas at the lower volume fraction and higher taper angle of the fiber, the decrement is 4.94%.

Distributed measurement of supercontinuum generation along a silica fiber taper using a confocal spectrometer

A highly sensitive distributed measurement technique is employed to map supercontinuum generation along a tapered silica optical fiber. This technique, which utilizes a confocal Raman micro-spectrometer, relies on analyzing far-field frequency-resolved Rayleigh scattering along the waveguide with micrometer-scale spatial resolution and high spectral resolution. Non-destructive and non-invasive, the mapping system enables observation of every stage of supercontinuum generation along the fiber cone, including cascade Raman scattering, four-wave mixing, and dispersive wave generation. Consequently, it unveils unique nonlinear spatial dynamics that are beyond the reach of standard spectral analyzers.

Study of the thermal protection characteristics of composite aerated concrete lintels when optimizing the life cycle of a building

The article is devoted to the study of the effectiveness of various methods of reinforcing composite aerated concrete lintels intended for window and door openings in the construction of civil buildings. The authors have developed a composite aerated concrete lintel for window and door openings, which includes two or three aerated concrete blocks and a seam at the ends made with polyurethane glue. The lintel reinforcement is made in the form of tape and parts of carbon fiber tape attached to aerated concrete blocks. The article provides a comparative analysis of various methods of reinforcing lintels made of aerated concrete, including steel rods and glass-composite reinforcement, as well as external tape reinforcement using carbon tapes. The results of the study allow us to conclude that external tape reinforcement with carbon fiber tapes is the most effective method. The most thermally efficient type of lintel reinforcement is external tape reinforcement with carbon fiber tapes, since the reduced heat transfer resistance is 6-10% higher than that of similar lintels with another type of reinforcement, and 10-28% higher than traditionally used lintels (reinforced solid lintels and composite U-shaped lintels).

Generating a nanoscale blade-like optical field in a coupled nanofiber pair

An optical field with sub-nm confinement is essential for exploring atomic- or molecular-level light-matter interaction. While such fields demonstrated so far have typically point-like cross-sections, an optical field having a higher-dimensional cross-section may offer higher flexibility and/or efficiency in applications. Here, we propose generating a nanoscale blade-like optical field in a coupled nanofiber pair (CNP) with a 1-nm-width central slit. Based on a strong mode coupling-enabled slit waveguide mode, a sub-nm-thickness blade-like optical field can be generated with a cross-section down to ∼0.28 nm×38 nm at 1550 nm wavelength (i.e., a thickness of ∼λ0/5000) and a peak-to-background intensity ratio (PBR) higher than 20 dB. The slit waveguide mode of the CNP can be launched from one of the two nanofibers that are connected to a standard optical fiber via an adiabatical fiber taper, in which a fundamental waveguide mode of the fiber can be converted into a high-purity slit mode with high efficiency (>98%) within a CNP length of less than 10 μm at 1550 nm wavelength. The wavelength-dependent behaviors and group velocity dispersion in mode converting processes are also investigated, showing that such a CNP-based design is also suitable for broadband and ultrafast pulsed operation. Our results may open up new opportunities for studying light-matter interaction down to the sub-nm scale, as well as for exploring ultra-high-resolution optical technology ranging from super-resolution nanoscopy to chemical bond manipulation.

Arthroscopic Reduction and Fixation with Fiber Wire Suture Tape for PCL Avulsion Fractures.

The internal and external rotation over 90° of flexion is restricted by posterior cruciate ligament (PCL). PCL also restricts posterior translation of tibia at all angles of flexion. The purpose of this study was to compare preoperative and postoperative functional outcomes (Lysholm scores and IKDC scores) in patients with PCL avulsion injuries managed with fixation by fiber wire suture tape. This was a prospective cohort study. The study group included 20 patients with PCL avulsion injuries with a mean age of 49.5years (12 males and 8 females). All patients underwent treatment with high-strength 2-0 fiber tape tied around the PCL tibial insertion under arthroscopy for reduction and fixation. There was increase in Lysholm score of 20 follow-up patients, from preoperative 36.9 ± 3.9 to a postoperative score of 96.1 ± 3.5. An increase in IKDC scores to 95.4 ± 3.1 from 52.9 ± 9.2 was also seen. Significant differences were found between preoperative and postoperative values. 19 patients regained function and one patient required manipulation under anesthesia. Satisfactory reduction was showed in X-ray and 3D CT scan for all 20 patients. If the PCL avulsion fracture injury is not identified and adequately treated, it can cause serious morbidity. Although newer studies demonstrate equivalent functional outcomes with arthroscopic treatment, open reduction with internal fixation (ORIF) with Cortico-Cancellous (CC) screw fixation is still a common treatment option. Improve postoperative functional outcome with minimal complications, author recommends PCL avulsion fracture fixation with arthroscopic fiber wire suture tape.

High Spatial Resolution Thermometer Microprobe Based on the Nitrogen-Vacancy Centers Ensemble in the Diamond Particle With Tapered Fiber

High Spatial Resolution Thermometer Microprobe Based on the Nitrogen-Vacancy Centers Ensemble in the Diamond Particle With Tapered Fiber

New Approach for Processing Recycled Carbon Staple Fiber Yarns into Unidirectionally Reinforced Recycled Carbon Staple Fiber Tape.

This study describes a novel process in which staple fiber yarns made from recycled carbon fibers (rCFs) and polyamide 6 (PA6) fibers are further processed into semi-finished tape products in a modified impregnation and calendaring process. In this process, the staple fiber yarns are heated above the melting temperature of the polymer, impregnated, and stretched to staple fiber tapes (SF tapes) in the calendaring unit. SF tapes with different degrees of stretching and/or repasses were produced. The individual width and thickness were measured in line by a laser profile sensor. From these tapes, preforms were manually laid and processed into laminates in an autoclave. The important physical properties of the unidirectionally reinforced laminates made of the tapes were compared with organic sheets wound from staple fiber yarns. With increasing stretching, both the fiber orientation and mechanical properties improved compared to the organic sheets made from unstretched staple fiber yarns. An improvement in fiber orientation relative to the process direction from 66.3% to 91.9% (between ±10°) and 39.1% to 71.6% (between ±5°), respectively, was achieved for a two-stage stretched tape. The tensile and flexural moduli were increased by 15.2% and 14.5%, respectively.

Fiber Bragg Grating Salinity Sensor Array Based on Fiber Tapering and HF Etching

We propose a seawater salinity sensor array based on a micro/nanofiber Bragg grating structures, which allows for the simultaneous measurement of temperature and salinity. The proposed sensing structure is fabricated through a process involving optical fiber tapering, femtosecond laser inscription, and chemical etching. The equivalent refractive index (RI) of this sensor structure is influenced by the surrounding RI, resulting in a Bragg characteristic wavelength shift that can be used for salinity sensing. The experimental results show that the salinity sensitivity for two cascaded sensor arrays is 8.39 pm/‰ and 7.71 pm/‰, while the temperature sensitivity is 8.28 pm/°C and 8.03 pm/°C, respectively. This sensor structure is compact, exhibits excellent linearity, and offers good repeatability. It holds great potential for applications in seawater environmental monitoring and quantitative studies of seawater dispersion characteristics.

On the Analyses of Cure Cycle Effects on Peel Strength Characteristics in Carbon High-Tg Epoxy/Plasma-Activated Carbon PEEK Composite Interfaces: A Preliminary Inquiry

In this study, a high-Tg aerospace-grade epoxy composite plate was co-curing welded using a unidirectional PEEK thermoplastic carbon fibre tape to develop advanced composite joints. To account for the surface roughness and the weldability of carbon–epoxy/carbon–PEEK composites, plasma treatments were performed. The co-curing was conducted by the following steps: each treated thermoplastic tape was first placed in the mould, and followed by nine layers of dry-woven carbon fabrics. The mould was sealed using a vacuum bag, and a bi-component thermoset (RTM6) impregnated the preform. To understand the role of curing kinetics, post-curing, curing temperature, and dwell time on the quality of joints, five cure cycles were programmed. The strengths of the welded joints were investigated via the interlayer peeling test. Furthermore, cross-sections of welded zones were assessed using scanning electron microscopy in terms of the morphology of the PEEK/epoxy interphase after co-curing. The preliminary results showed that the cure cycle is an important controlling parameter for crack propagation. A noticeable distinction was evident between the samples cured first at 140 °C for 2 h and then at 180 °C for 2 h, and those cured initially at 150 °C for 2 h followed by 180 °C for 2 h. In other words, the samples subjected to the latter curing conditions exhibited consistently reproducible results with minimal errors compared to different samples. The reduced errors confirmed the reproducibility of these samples, indicating that the adhesion between CF/PEEK and CF/RTM6 tends to be more stable in this curing scenario.