Fiber Torsion Research Articles

Preparation processes and thermal conductivities of magnetic field- and torsional vibration-induced superoriented carbon fiber composites

With the advancement of semiconductor technology, advanced electronic devices have become increasingly efficient, highly integrated and multifunctional, producing a large amount of heat during operation, thus decreasing the device efficiency and increasing the requirements for thermal interface materials. The use of a magnetic field to prepare pitch-based carbon fibers (CFs) with ultrahigh axial thermal conductivities and aspect ratios is a promising method for preparing thermal interface materials. However, past methods are not adequately simple or effective. Herein, we propose a simple, efficient method for preparing a novel thermally conductive CF interface material with a superoriented and closely arranged structure. The thermal conductivity of the vertical plane can reach 82.026 W m-1 K-1, which is higher than that of many other alloys. During the experiment, we prove that the torsional vibration of the vibrating plate can greatly resolve the issue of powder bridging generated during preparation. In addition, we discover and explain the heat return conduction phenomenon through numerical simulation. Our innovative preparation process and our analysis of thermal conduction can provide a new method and unique view for the design of thermal interface materials.

Torque‐tuned I‐V characteristics in a piezoelectric semiconductor composite fiber

AbstractThis paper studies the multi‐physical fields in a torsional composite fiber composed of a non‐piezoelectric semiconductor (PS) core coated with a piezoelectric dielectric shell. Based on the three‐dimensional framework of piezoelectricity and drift‐diffusion theory, we develop a nonlinear one‐dimensional model that incorporates the warping deformation, shear deformation, and axial variations of the electric field and charge transportations. A One‐dimensional model is linearized for small perturbations of charges, and we obtain the analytical solutions for single rods or PN junctions when torques are applied, which explicitly illustrates the electromechanical fields and redistribution of mobile charges. We also examine how the thickness of the composite rods affects the interaction between the piezoelectric and semiconductor components in the model. The optimal thickness ratio for maximizing the overall mobility of carriers has been discovered. This enables us to modify the thickness ratio to achieve the greatest PS interaction performance. Based on the nonlinear equations, we analyze the relationships between electric currents and applied voltages on the end of rods. Finally, we examine how twisting moments influence the characteristics of this I‐V relationship. The presented study provides a potential application for mechanical switches or sensors for PSs.

A torsion balance as a weak-force testbed for novel optical inertial sensors

Torsion balances (TBs) are versatile instruments known for their ability to measure tiny forces and accelerations with high precision. We are currently commissioning a new TB facility to support the development and testing of novel optical inertial sensor units for future gravity-related space missions. Here, we report on the status of our apparatus and present first sensitivity curves that demonstrate acceleration and torque sensitivities of 5⋅10−11ms−2 and 1⋅10−12NmHz−1 at frequencies around 4mHz , respectively. Capacitive sensors and optical levers measure the dynamics of the system with a displacement sensitivity of down to 9⋅10−10mHz−1 for the former and 2⋅10−11mHz−1 for the latter. Combining the readout of the suspended inertial member (IM) with environmental sensor signals, the system is characterized, and limiting noise sources are identified. We find that, in particular, the coupling of ambient seismic motion is limiting over a broad frequency range and show that due to its high susceptibility to ground motion, our TB is also a promising platform for exploring ground motion sensing in multiple degrees of freedom. Future upgrades will focus on mitigating seismic noise by controlling the torsion fiber suspension point using piezoelectric actuators and the integration of precision interferometric readout of the IM. These improvements will further increase the sensitivity towards the thermal noise limit which constrains the performance to 1⋅10−13ms−2Hz−1 at 4mHz .

Using machine learning to enlarge the measurement range and promote the compactness of the optical fiber torsion sensor based on the Sagnac interferometer

The support vector regression (SVR) algorithm is presented to demodulate the torsion angle of an optical fiber torsion sensor based on the Sagnac interferometer with the panda fiber. Experimental results demonstrate that with the aid of SVR algorithm, the information in the transmission spectrum of the sensor can be used fully to realize the regression prediction of the directional torsion angle. The full torsion angle ranges from −360° to 360° can be predicted with a mean absolute error (MAE) of 2.24° and determination coefficient (R2) of 0.9996. The impact of the angle sampling interval and wavelength resolution of the spectrometer on the prediction accuracy of the directional torsion angle and the suitability of the SVR algorithm for compact optical fiber sensor and other optical fiber torsion sensors based on the Sagnac interferometer are discussed. Moreover, the multi-objective SVR algorithm is used to eliminate the interference of strain during torsion angle measurement. The SVR algorithm can efficiently enlarge the measurement range of the torsion angle and break through the challenge of demodulating sensing signal for compact fiber torsion sensor. Compared to the prediction accuracy of common machine learning algorithms of artificial neural network (ANN) algorithm, random forest (RF) algorithm, and K-nearest neighbor (KNN) algorithm, the SVR algorithm has the advantages of higher measurement accuracy and shorter testing time.

Artificial-neural-network-assisted distributed directional optical fiber torsion sensor with the SSAF-based Sagnac interferometer

Artificial-neural-network-assisted distributed directional optical fiber torsion sensor with the SSAF-based Sagnac interferometer

Highly sensitive torsion sensor based on helical eccentric dual-core fiber Michelson interferometer

An optical fiber torsion sensor was academically put forward and experimentally demonstrated by applying a Michelson interferometer (MI) based on a helical eccentric dual core fiber (HEDCF). The sensor consists of an eccentric dual core fiber (EDCF), a taper, and a helical structure based on the EDCF. Since there is a large interval between a centric core and an eccentric core of the EDCF, the helical structure can greatly improve the torsion sensitivity of the sensor. When the twisting direction is consistent with the pre-twisting direction, the optical path difference (OPD) of MI negative increases during the twisting process, and the spectral resonance wavelength shifts blue. Experimental results show that the greater the degree of helical addition, the higher the torsional sensitivity. The torsion sensitivity can reach as high as −7.01 nm/(rad/m) in clockwise (CW) direction in the range of 0–9.595 rad/m. Moreover, the satisfactory sensitivity, stable structure and small temperature crosstalk, let it a valuable select in torsion sensing domain, and is promising to be useful for broad applications across engineering fields.

Torsional Optical Fiber Stress Analysis and Vortex-Induced Vibration Study of Three-Core Submarine Cable

Due to current scouring, submarine cables are prone to be exposed, suspended, and even vortex-induced vibration, which is not conducive to the safe operation of the power grid. In this contribution, the finite element simulation model of a 35 kV three-core optical fiber composite submarine cable with a suspended span length of 9.5 m is established. The natural frequency of the model is obtained through modal analysis. Then the vortex-induced vibration is simulated by the fluid–structure coupling method, and the stress distribution and change law of the torsional optical fiber is extracted. The results show that in the submarine cable, there appears to be a beating vibration and locking phenomena respectively, under two flow velocities. The transverse vibration amplitude of the latter increases significantly due to a resonance state. When the flow direction is perpendicular to the submarine cable, the stress distribution of the torsional optical fiber at the initial moment and at the 1/2 T moment of a vibration cycle approximately represents a mirror image relationship. In addition, the frequency of the stress change is the same as the frequency of the vortex-induced vibration, which can judge whether the vortex-induced vibration occurs. Moreover, the vortex-induced vibration range can be determined by the maximum stress change location.

A novel method for reducing yarn hairiness with dynamic and static friction rollers on the yarn guide

Fiber torsional control is critical for reducing the hairiness of high-quality yarns during the yarn formation process. However, the applied fiber torsion that facilitates fiber motion and transfer in conventional ring spinning is still under exploration. In this study, we designed a device with dynamic- and static-friction rollers for reducing harmful hairiness. The key mechanisms and mechanical model of the applied forces on fiber torsion and motion contacting dynamic- and static-friction rollers were theoretically analyzed. Exceptional fiber torsion was obtained by creating gradient friction resistance from the varied applied pressures while providing full internal and external transfer to forcibly capture and trap exposed fibers into the main yarn body. Compared to conventional ring-spun yarns, yarns spun by the dynamic-friction roller exhibited reduced harmful hairiness, improved tensile properties, a tighter yarn surface, and improved yarn irregularity. However, the excessive force applied by the static-friction roller deformed exposed fibers to cause fiber accumulation and fiber loss, resulting in reduced yarn performance. These results can be used to develop novel spinning methods for various fiber materials for high-quality yarn production.

A Displacement-Based Fiber Element to Simulate Interactive Lateral Torsional and Local Buckling in Steel Members

Collapse in steel structures is often controlled by loss of load carrying capacity of steel columns due to interactive buckling, which involves interactions between local and global (i.e., lateral and lateral torsional) buckling. Commonly used concentrated plastic hinge or fiber-based elements do not simulate the physics of this response, potentially leading to inaccuracy in performance assessment. A nonlinear fiber-beam-column element [termed the Torsion Fiber Element (TFE)] to simulate monotonic interactive buckling in steel beam-columns is presented. The element, implemented in the OpenSees platform, incorporates St. Venant as well as warping torsion through enrichment of strain interpolation functions, in addition to axial and flexural deformation modes. Local buckling is represented through a softening multiaxial constitutive relationship. The efficacy of this approach is examined by comparing its results against those obtained from continuum finite element simulations as well as experimental data on beam-columns subjected to monotonic loading. The comparisons indicate that the element can functionally represent the physics underlying interactive buckling, resulting in effective prediction of the overall monotonic load-deformation response, as well as internal deformation and stress fields. Limitations of the element in its current form are summarized, along with prospective improvements.

A micro-force measurement torsion pendulum design with dual laser detection

Aiming at the ground test and evaluation of the suspended test bench of the high microgravity scientific experiment cabinet in the Tianhe core module of the space station to obtain its exact thrust resolution, a micro-force measurement torsion device with dual laser detection is designed. The main configuration of the device is the suspension fiber torsion pendulum, and tungsten wire with a length of 400 mm and a diameter of 800 μm is used as the suspension fiber. Under micro thrust, the suspension fiber is twisted, which drives the mirrors at both ends of the scale arm to rotate along the suspension fiber. The displacement detection of the reflector is carried out, and the magnitude of the micro thrust is calculated in combination with the theorem of momentum. Experimental results indicate that the design of the torsion of micro-force measurement provides an effective test method for the ground test of the suspension test bench. The device can be used to measure and evaluate the micro-propulsion force of the air jet port. After replacing the tungsten fiber with a diameter of 1mm, it can also replace the air floating platform to carry out the air jet closed-loop control verification work, which can effectively and accurately complete the ground test and evaluation of the suspension test bench.

Direction-Discriminating torsion sensor based on optical fiber Mach-Zehnder interferometer

Optical fiber torsion sensors play a pivotal role in artificial intelligence, construction engineering, structural health monitoring and other fields. Research on low cost, simple structures and measurement methods has become a priority for researchers. Here, we propose an intensity-modulated and direction-recognizing torsion sensor based on two mode fiber with a sandwich structure, that serves as a mode interferometer formed by fundamental modes LP01 and second order core modes LP11 excited by means of offset fusion splicing. The capacity of intensity modulation and torsional direction recognition comes from the antisymmetric phase of fiber mode, which makes the sensor work like Marius’ law. The antisymmetric phase of the LP11 mode leads to an asymmetric transmission spectrum, whose direction enables the sensor to distinguish the torsion direction. Peaks and troughs in the measured spectrum interchange when the torsion direction is reversed. The initial angle between two offset directions enables control of the zero-crossing point within in the twisting range. The torsion sensitivity reaches 364%/(rad/cm) with a measurement accuracy of ± 0.22 rad/m.

Analysis and Comparative Study of Intermittent-Spiral Long Period Fiber Grating

A torsion sensor based on intermittent-spiral long period fiber grating (IS-LPFG) is proposed based on the interaction mechanism of elliptical birefringence (IMEB). The IS-LPFG is fabricated by periodically polishing the four mutually orthogonal surfaces of a pre-twisted single-mode fiber (SMF) by CO₂ laser. The interaction of birefringence caused by the intermittent-spiral distribution and the individual spiral structure determines the performance of torsion sensing. The torsion sensitivity reaches to 0.15 nm/(rad/m) in the case of superposition-IMEB, but also decreases to 0.08 nm/(rad/m) in the case of counteraction-IMEB. The experimental results are highly consistent with the simulation results. Through the exploration of the interaction of elliptic birefringence, it provides us with a method to control the birefringence in the fiber and improve the fiber torsion sensitivity based on H-LPFG.

A highly sensitive torsion sensor based on symmetrically polished SMS fiber structure

We propose and experimentally demonstrate an optical fiber torsion sensor based on symmetrically polished single-multi-single mode (SP-SMS) fiber structure. The polished structure enhances the torsion response effectively, which is fabricated by a high-frequency CO2 laser. Experimental results show that the high sensitivity of the proposed torsion sensor reaches 1.032 nm/(rad m−1) in the range from − 10.261 rad/m to 10.261 rad/m. Meanwhile, the temperature response of the sensor is also investigated, which is 21 pm/°C in the range from 30 °C to 150 °C. Moreover, the structure has the features of low cost, simple fabricating method and small temperature crosstalk.

Seven-core fiber torsion sensor with microcavity structure based on intensity measurement

A seven-core fiber torsion sensor with microcavity structure based on intensity measurement is proposed. It is composed of a seven-core fiber (SCF) and two multi-mode fibers (MMF). The first end of the SCF has a microcavity structure. Because the mode fields between the MMF and SCF do not match at the splicing point, the phenomenon of mode interference will be formed between cladding modes and core modes. Experimental results show that in a clockwise situation, the intensity of transmission spectrum increases in the torsion range of 0∼70°, the torsion sensitivity is 0.098 dB/∘. And in a counterclockwise situation, the intensity of transmission spectrum decreases, the torsion sensitivity is 0.103 dB/∘. The sensor has a simple structure and easy to fabricate, so it has wide application prospects in the field of torsion sensing.

High sensitivity directional torsion sensor based on double-helix long-period grating in tapered polarization-maintaining fiber

We propose a fiber torsion sensor based on double-helix long-period grating (DH-LPG) written in a tapered polarization-maintaining fiber (PMF). A series of DH-LPGs were fabricated in the tapered PMFs with waist diameters of 85 to 67 μm by a CO2-laser heating and twisting system. The torsion, temperature and surrounding refractive index sensing characteristics were investigated experimentally. Thanks to the special structures combined DH-LPGs with tapered PMFs, the proposed sensor can realize directional torsion measurement. The maximum torsion sensitivity of the proposed grating could be up to -2.28 nm/(rad/m) when the tapered waist diameter was 67 μm. The DH-LPGs have potential application in field of all-fiber high sensitivity directional torsion sensing.

Humidity- and Water-Responsive Torsional and Contractile Lotus Fiber Yarn Artificial Muscles.

Materials that dynamically respond to their environment have diverse applications in artificial muscles, soft robotics, and smart textiles. Inspired by biological systems, humidity- and water-responsive actuators that bend, twist, and contract have been previously demonstrated. However, more powerful artificial muscles with large strokes and high work densities are needed, especially those that can be made cost-effectively from eco-friendly materials. We here derive such muscles from naturally abundant lotus fibers. A coiled lotus fiber yarn muscle provides a large, reversible tensile stroke of 38% and a work capacity during contraction of 450 J/kg, which is 56 times higher than that of natural skeletal muscles and higher than that for any other reported natural fiber muscles. In addition, highly twisted lotus fiber yarn muscles provide a fully reversible torsional stroke of 200°/mm of muscle length and a peak rotation speed of 200 rpm, with a generated specific torque of 488 mN·m/kg for a 2.5 cm long muscle. Potential applications of these lotus fiber yarn muscles are demonstrated for a weight-lifting artificial limb and a smart textile.

Highly improved water tolerance of hydrogel fibers with a carbon nanotube sheath for rotational, contractile and elongational actuation

Coating a carbon nanotube sheath improved the water tolerance of hydrogel fibers, and inserting a twist produces large-stroke torsional, contractile, and elongational fiber actuators.

Tuning the reversibility of hair artificial muscles by disulfide cross-linking for sensors, switches, and soft robotics.

Tensile and torsional artificial muscles from biocompatible and biodegradable materials are highly desired for soft robotics, sensors, and controllers in bio-related applications. Twisted fibers can be used to prepare tensile and torsional artificial muscles, while torsional tethering is always required to avoid release of the inserted twist, which adds complexity to the device design. Moreover, the tuning of the reversibility of twisted fiber artificial muscles has not been realized. Here disulfide cross-linking was used to prepare novel tether-free hygroresponsive tensile and torsional fiber artificial muscles in twisted hair fibers. Increasing the cross-linking level converted the fiber artificial muscle from irreversible to reversible actuation. Different types of actuations including rotation, contraction, and elongation were realized for the twisted, the homochirally coiled, and the heterochirally coiled hair fibers, respectively. A reversible torsional fiber artificial muscle showed 122.4° mm-1 rotation, homochiral and heterochiral fiber artificial muscles showed 94% contraction and 3000% elongation, respectively, and a maximum work capacity and energy density of 6.35 J kg-1 and 69.8 kJ m-3, respectively, were realized, on exposure to water fog. This work provides a new strategy for preserving the inserted twist in bio-fiber artificial muscles and for tuning of muscle reversibility, which show application perspectives in biocompatible smart materials, sensors, and robotics.

New measuring method of fiber alignment in precision torsion pendulum experiments**Project supported by the National Natural Science Foundation of China (Grant No. 11305057).

Testing the extreme weak gravitational forces between torsion pendulum and surrounding objects will indicate new physics which attracts many interests. In these measurements, the fiber alignment plays a crucial role in fulfilling high precision placement measurement, especially in measuring the deviation between the fiber and source mass or other objects. The traditional way of the fiber alignment requires to measure the component of the pendulum body and then transfer to the torsion fiber by some complicated calculations. A new method is reported here by using a CCD camera to get the projection image of the torsion fiber, which is a direct and no-contact measurement. Furthermore, the relative position change of the torsion fiber can also be monitored during the experiment. In our experiment, the alignment between the fiber and the center of the turntable has been operated as an example. Our result reaches the accuracy of several micrometers which is higher than the previous method.

Twist-Direction-Discriminable Torsion Sensor Using Long-Period Fiber Grating Inscribed on Polarization-Maintaining Photonic Crystal Fiber

Here we propose and experimentally demonstrate an optical fiber torsion sensor with twist direction discrimination capability by incorporating a long-period fiber grating (LPFG) inscribed on polarization-maintaining photonic crystal fiber (PMPCF) by CO2 laser pulses. An LPFG formed on PMPCF has an input-polarization-dependent resonance dip, and two separated resonance dips, designated as the shorter wavelength-dip (SWD) and longer wavelength-dip (LWD), are obtained with respect to orthogonal input polarization. The torsion response of the sensor head was investigated in a wide twist angle range of −220° to 220° for the two resonance dips. Highly linear torsion responses of the SWD and LWD could be obtained with adjusted ${R}^{{2}}$ values of ~0.9960 and ~0.9967, respectively, in a twist angle range from −160° to 160°, when their transmittance levels measured in a logarithmic scale were converted into a linear scale. The torsion sensitivities of the SWD and LWD were measured as −5.067 and 4.830 %/rad in this twist angle range of high linearity, respectively. In particular, its temperature response was also examined in a temperature range from 35 to 85 °C. With pre-torsion applied to the sensor head at twist angles of 220° and −220°, the temperature sensitivities of the SWD and LWD were measured as ~3.64 and ~9.75 pm/°C in terms of the dip wavelength and $-{2.87}\times {10}^{-{3}}$ and ${5.45}\times {10}^{-{5}}$ dB/°C in terms of the dip transmittance, respectively. The experimental results corroborate that our sensor can perform virtually temperature-insensitive torsion measurement with twist direction discrimination capability and good linearity in a wide measurement range.