Fiber Tension Research Articles

Research on thermal actuation performance of twisted and coiled nylon artificial muscles based on yarn mechanics

Twisted and coiled artificial muscles (TCAMs) are recently introduced as novel structural actuators that offer outstanding performance. TCAMs consisting of nylon or other polymer fibers have the advantages of low cost, large stroke, and high power density, and can be used in the fields of robots and intelligent textiles. Manufacturing process and actuation conditions significantly affect the spiral structure of the fiber. Therefore, it is particularly important to conduct research on the manufacturing mechanics of TCAMs for their future development and applications. In this paper, a modeling based on yarn mechanics and the energy method is established for exploring the actuation performance of TCAMs. Firstly, we analyze the effects of the preparation and actuation conditions on the helical structure of TCAMs. The relationship between the spiral structure and the fiber tension is obtained. Then, we investigated the effects of preparation conditions, actuation load, and operating temperature on the tensile stroke of TCAMs. For silver-coated nylon fibers, the actuation performance of TCAMs decreased with the increase of suspension load. Finally, we verify the correctness of the model through experiments. Conversely, the present model can provide theoretical guidance for experimental research and optimized manufacturing of TCAMs.

An experimental and numerical study on the translaminar fracture of cross-ply non-crimp fabric composites

In this paper, the damage propagation of a cross-ply Non-Crimp Fabric composite under Compact Tension is numerically modelled. The work includes an experimental study through which the internal structure of the composite is characterised, the translaminar fracture toughness values are obtained and the sequence of failure mechanisms are identified. Based on the experimental findings, a new exponential law is introduced during element failure under fibre tension to describe the unloading phase incorporating the fracture toughness as the governing parameter for material degradation. Furthermore, a power law based on the maximum strain criteria for transverse tension and in-plane shear loading is proposed to formulate the interactive damage propagation of the 90o layers. A set of physically-based failure criteria at layer level which account for the induced in- and out-of-plane fibre misalignment is associated with an energy-based damage mechanics method and implemented in Abaqus/Explicit as a VUMAT subroutine. The load–displacement response at all stages as well as the evolution of the translaminar fracture toughness during damage propagation are compared successfully against the experimental results.

Influence of fiber tension during filament winding on the mechanical properties of composite pressure vessels

During the manufacturing of composite pressure vessels, the fiber tension of the filament winding process has an important influence on the mechanical properties as well as on the gravimetric efficiency of the structure and is therefore investigated within this paper. Three series of samples were manufactured and tested: A) steel liners as reference, B) composite vessels with low fiber tension of 3 N, and C) vessels with high fiber tension of 80 N. The manufacturing process is discussed in this paper with special focus on the parameter of fiber tension and its related challenges. Burst tests with strain measurements and acoustic emission (AE) were conducted, and a statistical analysis of the results is presented. Additional numerical investigations on the structural behavior of the vessels and effect on the gravimetric efficiency are performed to support the experimental result. The investigations show that the increase in fiber tension induced compressive stress on the steel liner, leading to an increase in burst pressure and influence on AE. Furthermore, the fiber volume fraction (FVF) of the composite laminate increased due to increased fiber tension, resulting in higher mechanical properties and an improvement in gravimetric efficiency.

Mechanical properties, thermal and chemical effect of polymer cotton bars reinforced with carbon / glass fiber

ABSTRACT Many researchers are interested in using natural fibres to treat due to recent advancements in polymer characteristics. The mechanical properties of three types of bars are studied in this paper: Cotton Fibre-Reinforced Polymer bars, Cotton/Carbon Fibre-Reinforced Polymer bars, and Cotton/Glass Fibre-Reinforced Polymer bars. The goal of the paper was to create low-cost bars with comparable mechanical performance and corrosion resistance to steel reinforcement. The bars were made using two methods: fibres immersed in polymer and fibres coated with polymer by repeated tension and relaxation of fibres. The second method produced better results in terms of the tensile strength of Cot.CFRP, Cot.GFRP, and Cot.FRP bars, which were 688, 477, and 284 MPa, respectively, and the stress–strain curve revealed brittle behaviour for all bars and modulus of elasticity of 43, 31 and 22 GPa. When sand was put on the bar’s surface, the bars demonstrated a good connection with the concrete. It also showed good resistance to moisture, alkaline solutions and acids, as well as heat resistance at temperatures below 200°C.

Steel fiber reinforced RC beams in pure torsion—Load‐bearing behavior and modified space truss model

AbstractInvestigations on steel fiber reinforced concrete (RC) beams in torsion show, that the steel fibers positively influence the torsional load‐bearing behavior. Since a systematic evaluation of the previously known test results and the derivation of a generally valid design model were lacking until recently, current codes such as Model Code 2010 do not contain any design models for the consideration of the steel fiber load‐bearing effect in the torsion design. Due to this, the existing torsion tests on steel fiber RC were summarized in a database. Furthermore, on the basis of the test results and observations, the space truss model developed by Rausch and later refined by Lampert and Thürlimann, among others, was further developed and supplemented by additional longitudinal and transverse steel fiber tension struts. This modified space truss model was validated with the database and shows good to very good predictions to the torsion test data.

Experimental characterisation of large in-plane shear behaviour of unidirectional carbon fibre/epoxy prepreg tapes for continuous tow shearing (CTS) process

The continuous tow shearing (CTS) process is an advanced tape placement technique with the ability to steer unidirectional prepreg tapes by in-plane shear deformation without the presence of tape buckling, gaps and overlaps. However, the inherent fibre misalignment within the tape can induce fibre waviness during the shearing process, which is further affected by processing parameters such as temperature, shear rate and fibre tension. In this paper, the effect of those parameters on the shear behaviour of two different unidirectional carbon/epoxy prepreg tapes was experimentally investigated. A bespoke test fixture was designed to shear the tape specimens at various shear rates and fibre tensions. Digital image correlation (DIC) was used to obtain full-field strains of the specimens to investigate the fibre realignment during shearing. Experimental results showed that both temperature and fibre tension significantly affect the uniformity of the fibre realignment. Moreover, the responses of the two prepreg tapes under the same shearing condition were different due to their different impregnation characteristics.

Microstructural damage and response of stiffened composite submersible pressure hull subjected to underwater explosion

ABSTRACT Submerged structures in naval applications are susceptible to underwater explosion and predicting the transient response and damage is a prime concern for the designer. Coupled Arbitrary Lagrangian-Eulerian (ALE) based numerical investigation using LS-DYNA for the inelastic dynamic response and microstructure failures of composite hull subjected to UNDEX is presented. As a prelude to the study, shock pressure in fluid domain and strain values obtained on the composite pressure hull is compared with that available in literature. The numerical study is extended to predict the large deformation, puncture and microstructural behaviours of the hull by varying the charge weight of the explosive. The results of the predicted large deformation, puncture of the hull and the microstructural failures such as fibre tension, fibre compression, matrix shear, matrix tension, and matrix compression based on the Chang- Chang composite failure model, Tsai-Wu failure theory and maximum stress theory are presented.

Determination of fibre tension fracture toughness of composite laminates at high loading rate

The dynamic fracture toughness of composite laminates in fibre tension failure mode is characterized here with compact tension (CT) sample, at loading rate of 25 m/s using bi-directional electromagnetic Hopkinson bars. Digital image correlation (DIC) with high-speed imaging is employed for obtaining the full-field strain fields. A dynamic J-integral method is proposed to analyse the dynamic fracture toughness, the kinetic energy and inertia effects involved in dynamic loading and crack propagation process has been analysed and calibrated. The fracture toughness of fibre tension failure at high loading rate is found to be about 25% lower than that in quasi-static load regime, and the R-curve effect under high loading rate is not significant than that in quasi-static load regime. It is suggested from X-ray CT and SEM images that the fibre pull-out length and size of failure process zone is reduced with increase in loading rate.

Polarized light retardation analysis allows for the evaluation of tension in individual stress fibers

The tension in the stress fibers (SFs) of cells plays a pivotal role in determining biological processes such as cell migration, morphological formation, and protein synthesis. Our previous research developed a method to evaluate the cellular contraction force generated in SFs based on photoelasticity-associated retardation of polarized light; however, we employed live cells, which could have caused an increase in retardation and not contraction force. Therefore, the present study aimed to confirm that polarized light retardation increases inherently due to contraction, regardless of cell activity. We also explored the reason why retardation increased with SF contractions. We used SFs physically isolated from vascular smooth muscle cells to stop cell activity. The retardation of SFs was measured after ATP administration, responsible for contracting SFs. The SFs were imaged under optical and electron microscopes to measure SF length, width, and retardation. The retardation of isolated SFs after ATP administration was significantly higher than before. Thus, we confirmed that retardation increased with elevated tension in individual SFs. Furthermore, the SF diameter decreased while the SF length remained almost constant. Thus, we conclude that a contraction force-driven increase in the density of SFs is the main factor for the rise in polarized light retardation.

Biomechanical origins of inherent tension in fibrin networks

Blood clots form at the site of vascular injury to seal the wound and prevent bleeding. Clots are in tension as they perform their biological functions and withstand hydrodynamic forces of blood flow, vessel wall fluctuations, extravascular muscle contraction and other forces. There are several mechanisms that generate tension in a blood clot, of which the most well-known is the contraction/retraction caused by activated platelets. Here we show through experiments and modeling that clot tension is generated by the polymerization of fibrin. Our mathematical model is built on the hypothesis that the shape of fibrin monomers having two-fold symmetry and off-axis binding sites is ultimately the source of inherent tension in individual fibers and the clot. As the diameter of a fiber grows during polymerization the fibrin monomers must suffer axial twisting deformation so that they remain in register to form the half-staggered arrangement characteristic of fibrin protofibrils. This deformation results in a pre-strain that causes fiber and network tension. Our results for the pre-strain in single fibrin fibers is in agreement with experiments that measured it by cutting fibers and measuring their relaxed length. We connect the mechanics of a fiber to that of the network using the 8-chain model of polymer elasticity. By combining this with a continuum model of swellable elastomers we can compute the evolution of tension in a constrained fibrin gel. The temporal evolution and tensile stresses predicted by this model are in qualitative agreement with experimental measurements of the inherent tension of fibrin clots polymerized between two fixed rheometer plates. These experiments also revealed that increasing thrombin concentration leads to increasing internal tension in the fibrin network. Our model may be extended to account for other mechanisms that generate pre-strains in individual fibers and cause tension in three-dimensional proteinaceous polymeric networks.

Analysis of the Integration of Aramid Fiber Tension Struts in a Box-shaped Pressure Vessel

Shared vehicle architectures for fuel cell electric vehicles (FCEVs) and battery electric vehicles (BEVs) allow significant cost reduction in development and production by enabling economies of scale. Therefore, a box-shaped design for a type 4 pressure vessel is developed, which allows an efficient storage of hydrogen in conventional battery design spaces. For a load capable design, the top and bottom of the tank wall are connected with tension struts made of aramid fibers. Based on an analytical design, the geometry of the vessel is defined and a manufacturing process is developed using tufting as key technology for the insertion of the aramid fiber tension struts. The load transfer between the CFRP tank wall and the tension struts is crucial for the mechanical strength of the containment. Fiber loops are evaluated by guiding the tension struts through the CFRP tank wall and deflecting the load. In tensile tests, strengths of at least 1720 MPa are measured for this configuration. The tightness of the containment is ensured by a polymer liner and its adhesion to the struts. The interface between aramid fiber struts and the liner is investigated on strut-level analytically and in experiments. Different shear moduli of the investigated polymers show a major influence on the shear stress in the liner. For the application in the tension-braced pressure vessel, liner materials with the lowest possible modulus should be used to reduce the stress peaks in the liner. Finally, a design corridor for the dimensions of the tension struts and preferred material properties for the liner can be derived. For the investigated material, a strut diameter of 1 mm with a strut spacing of 3 to 5 mm is recommended.

Analytical modeling of chip formation mechanism in cutting unidirectional carbon fiber reinforced polymer

Fiber orientation of the unidirectional carbon fiber reinforced polymer (UD CFRP) dominates the chip formation in the cutting process owing to its anisotropy. Existing analytical cutting models focus on cutting force prediction based on the pre-defined chip formation modes obtained from experimental analyses at different fiber orientation ranges. This paper presents the analytical prediction of CFRP chip formation modes, including fiber tension, fiber compression, matrix tension, and matrix compression, based on the stress state in the chip formation region in the fiber orientation range of [0°,180°]. The chip formation angle and the stresses activating the material failure on the chip formation plane are predicted with the minimum cutting energy principle. The transition of the chip formation mode as the fiber orientation increases, and the variations of the chip morphology and cutting forces owing to the change of chip formation mode are predicted and analyzed. The chip formation angle, chip morphology, and cutting forces are compared between the simulations and the measurements through orthogonal cutting experiments of UD CFRP at different uncut chip thicknesses and fiber orientations.

Continuous Stabilization and Carbonization of a Lignin-Cellulose Precursor to Carbon Fiber.

The demand for carbon fibers (CFs) based on renewable raw materials as the reinforcing fiber in composites for lightweight applications is growing. Lignin–cellulose precursor fibers (PFs) are a promising alternative, but so far, there is limited knowledge of how to continuously convert these PFs under industrial-like conditions into CFs. Continuous conversion is vital for the industrial production of CFs. In this work, we have compared the continuous conversion of lignin–cellulose PFs (50 wt % softwood kraft lignin and 50 wt % dissolving-grade kraft pulp) with batchwise conversion. The PFs were successfully stabilized and carbonized continuously over a total time of 1.0–1.5 h, comparable to the industrial production of CFs from polyacrylonitrile. CFs derived continuously at 1000 °C with a relative stretch of −10% (fiber contraction) had a conversion yield of 29 wt %, a diameter of 12–15 μm, a Young’s modulus of 46–51 GPa, and a tensile strength of 710–920 MPa. In comparison, CFs obtained at 1000 °C via batchwise conversion (12–15 μm diameter) with a relative stretch of 0% and a conversion time of 7 h (due to the low heating and cooling rates) had a higher conversion yield of 34 wt %, a higher Young’s modulus (63–67 GPa) but a similar tensile strength (800–920 MPa). This suggests that the Young’s modulus can be improved by the optimization of the fiber tension, residence time, and temperature profile during continuous conversion, while a higher tensile strength can be achieved by reducing the fiber diameter as it minimizes the risk of critical defects.

Application of Automatic Molding and Processing Technology of Composite Materials in Automatic Control System

Nanotechnology is the most emerging scientific technology most likely to be applied to the market, and its potential importance is beyond doubt. Some developed countries have invested a lot of money in research activities. At the same time, composite materials are also very important. The purpose of this article is to explore the application of automatic molding and processing technology of composite materials in automatic control system. In this article, the packet identifier (PID) algorithm in the automated process is used to realize real-time control in the control system, and it is explained by the two experimental methods and analysis of the experiment of the tension control system and the automatic molding experiment of the resin system composite material, and the results are obtained in the molding. The content index of diethylene ako in finished product death knight (DK) is about 96.0%; the comprehensive yield index is more than 83%, and as the fiber tension increases, the maximum fluctuation of tension generally shows an increasing trend. It can be concluded that the automatic molding of composite materials can improve the automation level of the control system, reduce the difficulty and intensity of workers’ work, and increase the safety and performance of the process and production from other perspectives, and bring more convenient and effective application to the automation technology in industrial production.

Experimental investigation on multi-layered filament wound basalt/E-glass hybrid fiber composite tubes

In this study, the mechanical damage of Basalt/E-glass hybrid fiber-reinforced polymer composite tubes was evaluated experimentally using Micro hardness on transverse direction, uni-directional static tensile loading, and Quasi-static compressive loading. The Burn-off test method has been studied for the volumetric fraction of hybrid composite tubes. The multi-layer hybrid composite tubes composed of eight layers of plies at constant fiber tension of 20N, a constant mandrel rotation speed of 45 RPM and constant winding angle of ±55° for basalt fiber and ±90° for E-glass fiber were fabricated through a 3-axis filament winding machine with a seamless amalgamation of the stage by stage curing in the furnace. Eleven tube arrangements with fiber content proportion of {100%, 25:75%, 50:50% and 75:25%} with various stacking sequence were studied. The test results provide that these mechanical property’s behavior was moderately affected by the proportion of fiber content and most of the time affected by the variation of layer stacking sequence. Adding 50% of basalt and 50% E-glass fiber sharing of BGH7 hybrid combination of basalt laminate placed in the outer side increases the mechanical characterization compared to the 25% and 75% sharing of basalt and E-glass fiber. The fractured fibrous matrix of the tensile specimens and compressive specimens was assessed using a scanning electron microscope (SEM).

Influence of Filament Winding Tension on the Deformation of Composite Flywheel Rotors with H-Shaped Hubs.

The residual stress plays an important role in composite flywheel rotors composed of filament windings. The fiber tension during high-prestressed winding is the main source of the rotor deformation and residual stress of composite layers. In this study, the effect of the winding tension gradient on deformation was monitored in real-time. Two types of in-plane winding tension fluctuation methods were developed to investigate the effect of tension on deformation. Online and offline measurements were performed for the strain acquisition. A wireless strain instrument was used for online deformation monitoring and a laser scanner was used for the offline surface reconstruction. Additionally, different filament winding strategies were carried out to improve the efficiency of the winding tension by finite element analysis. The results indicated that the deviation between numerical and experimental results was within 8%. Based on the proposed numerical method, the influence of the in-plane and out-of-plane winding tension gradient distributions on the rotation process of the H-shaped rotor was analyzed. An in-plane winding strategy with variable tension was developed, which increased the initial failure speed by 160%.

ANALISA STRUKTUR ABUTMENT UNDERPASS JALAN NASIONAL STA 6+850 PROYEK JALAN TOL RUAS BINJAI – LANGSA SEKSI BINJAI – PANGKALAN BRANDAN

Prestressed concrete bridge STA 6+850 Provincial Road Penggal Binjai-Langsa Freeway is one of the footbridges connecting the fast road from Binjai To Langsa with a total bridge length of 30 meters and a total bridge width of 26.90 meters (2 lanes). Preparation of the prestressed walkway for Provincial Road STA 6+850 Freeway at the Binjai-Langsa joint is based on RSNI-T-02-2005 for loading on the walkway. Based on RSNI-T-02-2005, the loading for the prestressing walkway spans 30 meters with a total of 3 tendons, where one tendon is 19 standards with a diameter of 12.7 millimeters. The tension in the flexural compression fiber due to the influence of prestressing, dead load and live load is 0.45 fci' (13500 kPa). Control of overturning stability in the X and Y directions on the abutment, the number of safety (SF) against overturning is greater than the allowable SF = 2.2 (safe). The carrying capacity of the pile foundation bearing capacity (Qg) was analyzed based on SPT data, the value obtained was 87207.33 kN using Meyerhoff's (1956) method from SPT field data.

Effect of pre-twist in the spinning triangle on yarn strength

The spinning triangle is the morphologic transformed area of fiber assembly, which influences the yarn structure and appearance quality. In the spinning triangle, the pre-twist was formed due to the twisting torque, it changed part of fibers delivered path and thus the way of fibers arrangement in yarn body. In this paper, a model of spinning triangle with pre-twist was proposed to study the effects of pre-twist position and other spinning parameters on the fiber tension in the spinning triangle and yarn strength. Three representative cases were discussed respectively, namely the pre-twist region on the left side, middle position, and right side. The following results were obtained: (1) yarn strength shown a W-shape tendency with the pre-twist region moved from left to right; (2) the increase of inclination angle boosted yarn strength and the increase of height of spinning triangle made the decrease of yarn strength when fiber buckling was considered; (3) the increase of spinning tension promoted yarn strength, but did not change the influence of pre-twist on yarn strength.

About prestretch in homogenized constrained mixture models simulating growth and remodeling in patient-specific aortic geometries

Evolution of mechanical and structural properties in the Ascending Thoracic Aorta (ATA) is the results of complex mechanobiological processes. In this work, we address some numerical challenges in order to elaborate computational models of these processes. For that, we extend the state of the art of homogenized constrained mixture (hCM) models. In these models, prestretches are assigned to the mixed constituents in order to ensure local mechanical equilibrium macroscopically, and to maintain a homeostatic level of tension in collagen fibers microscopically. Although the initial prestretches were assumed as homogeneous in idealized straight tubes, more elaborate prestretch distributions need to be considered for curved geometrical models such as patient-specific ATA. Therefore, we introduce prestretches having a three-dimensional gradient across the ATA geometry in the homeostatic reference state. We test different schemes with the objective to ensure stable growth and remodeling (G&R) simulations on patient-specific curved vessels. In these simulations, aneurysm progression is triggered by tissue changes in the constituents such as mass degradation of intramural elastin. The results show that the initial prestretches are not only critical for the stability of numerical simulations, but they also affect the G&R response. Eventually, we submit that initial conditions required for G&R simulations need to be identified regionally for ensuring realistic patient-specific predictions of aneurysm progression.

Mechanotransduction-The relationship between gravity, cells and tensile loading in extracellular matrix

Gravity plays a central role in vertebrate development and evolution. Mechanotransduction involves the tensile tethering of veins and arteries, connections between the epidermis and dermis in skin, tensile stress concentrations that occur at tissue interfaces, cell-cell interactions, cell-collagen fiber stress transfer in extracellular matrix and fluid shear flow. While attention in the past has been directed at understanding the myriad of biochemical players associated with mechanotransduction pathways, less attention has been focused on determining the tensile mechanical behavior of tissues in vivo. Fibroblasts sit on the surface of collagen fibers in living skin and exert a retractile force on the fibers. This retractile force pulls against the tension in collagen fibers in skin. After fibroblast-collagen fiber interactions are altered either by changes in fibroblast adhesion or after formation of cancer associated fibroblasts, and changes in cell junctions, alterations in the retractive force leads to changes in mechanotransduction. The purpose of this paper is to present a model of tensile forces that occur at the fibroblast-collagen fiber interface and how these forces are important in extracellular matrix physiology in health and disease.