Composite Tapes Research Articles

Laser-induced graphene composite adhesive tape with electro-photo-thermal heating and antimicrobial capabilities

Laser-induced graphene (LIG) and its composites have been demonstrated to be useful in broad-reaching applications such as water and air filtration and sensors. A main advantage of LIG is the embedding of conformal graphene foam in any design into polymeric substrates. However, embedded LIG must be detached from the substrate for a composite nanomaterial, and delamination of LIG has been demonstrated. Here, we incorporated LIG as a composite into a double-sided tape using pressure-sensitive adhesives and delamination from the substrate, and demonstrated its use for electro-photo-thermal applications, including bacterial inactivation. LIG was transferred onto thermally conductive pressure-sensitive adhesive containing carbon black, and a double-sided sticky tape was prepared by sandwiching perforated tissue adhesive between two LIG layers, giving enhanced electrical conductivity in the x, y, and z directions compared to commercial carbon tape. The LIG composite tape showed excellent electrothermal properties with a maximum temperature >120 °C at 10 V and a temperature rise >70 °C under 120 mW/cm2 solar irradiation. The same electrothermal activity was observed after 50 heating and cooling cycles and reached a temperature of ∼111 °C. Bacterial inactivation was observed on the surface of the LIG composite tape at ∼3.5 V, and electro- and photothermal effects caused sterilization of the surfaces up to 99.99%. These electrically conductive LIG composite adhesive tapes might be used in electronic applications for heating surfaces at low voltages (<9 V) or to prevent surface biofilm or microbial growth.

COMPATIBILITY OF REINFORCEMENT AND WOOD IN BEAMS WORKING ON TRANSVERSE BENDING

One of the ways to eliminate the negative shortcomings of wood (dependence of its properties on the structure, defects, the need for use and significant consumption of quality lumber, excessive mass of sections, creep under prolonged load, etc.) and increase technical and economic efficiency is reinforcement of solid and glued trees, steel or composite plastic fittings. This allows you to significantly reduce wood costs, reduce installation weight, improve the quality and reliability of wooden structures that work mainly on the bend.&#x0D; The expediency of reinforcing elements of solid or glued wood with steel and composite polymer reinforcement is substantiated. The rather high compatibility of wood work in the compressed and stretched zones of the bending element of steel reinforcing steel of classes A400C, A500C and composite fiberglass reinforcement, composite basalt reinforcement and composite carbon tape is shown. Reinforcement of solid and glued cross-sectional elements of wooden structures with steel or composite plastic reinforcement or tape can significantly reduce wood costs, reduce height and installation weight, improve quality and reliability.&#x0D; Analysis of the current state of research of reinforced wooden structures indicates the need for a thorough study of the bending of wooden beam elements with combined reinforcement of steel and composite reinforcement and with combined pre-stressed reinforcement. To date, the issue of studying the stress-strain state of reinforced wood in the "calculated cross section" of both the structure and the work of the material in its composition is insufficiently covered. The use of reinforced wood in structures is not regulated by most countries, so there is no general theory of calculation of reinforced wood structures, which would be based on sound clear hypotheses and assumptions and would be based on the basic principles of solid mechanics.

Impact of Adhesive Layer Thickness on the Behavior of Reinforcing Thin-Walled Sigma-Type Steel Beams with CFRP Tapes.

This paper presents selected issues related to the reinforcement of steel element cold-formed with CFRP tapes. The first section of the paper is a review of source literature and a presentation of the basic information on cold-formed thin-walled steel elements and CFRP composite materials, stressing the advantages and disadvantages of using them to reinforce steel structures. Next, the authors present original research on reinforcing bent thin-walled sigma-type steel beams using adhesive CFRP tapes. Reference beams with a cross-section of Σ200 × 70 × 2 and a length of 3 m, reinforced with CFRP tape, were tested in the four-point bending scheme. Then, the paper discusses a developed numerical model that is consistent with the subject matter of the laboratory tests. The developed numerical model was prepared to represent the failure of the connection between the beam and the composite tape. This was followed by a number of numerical analyses in order to determine the optimum adhesive layer that would allow us to achieve the maximum reduction of the displacements and strains in bent thin-walled sigma-type beams. Three thicknesses of the SikaDur adhesive layer were analyzed in the study. Based on the analyzes, it was found that the increase in the thickness of the adhesive layer slightly reduced the strain and displacement in the beams, but caused a significant decrease in the load value, at which damage appeared in the glued joint.

Stress transfer mechanism and shear strength of multilayer composite superconducting tape

The interlayer stress transfer mechanism is the key to understand the delamination behaviour and determine the shear strength of multilayer composite superconducting tapes. Besides, it helps understanding the strain state of the superconducting material layer and further predicting its transport properties. In this paper, a theoretical model is established to investigate the stress transfer mechanism between layers of composite superconducting tapes. The stress distributions of a three-layer composite system are calculated based on the interlayer shear stiffness model. Then, the strain transmissibilities between different layers are further calculated considering the plastic deformation of the copper layer. Moreover, based on the proposed theoretical model, the shear strength of the composite superconducting tape is calculated. The model quantifies the stress transfer behavior between different layers of superconducting tapes, which provides the theoretical basis for the determination of the shear strength and suggests selecting a proper Hastelloy layer thickness can adjust the strain of the YBCO layer.

On the High-Resolution Discretization of the Maxwell Equations in a Composite Tape and the Heating Effects Induced by the Dielectric Losses

Electromagnetic field propagation inside composite materials represents a challenge where fiber-scale simulation remains intractable using classical simulation methods. The present work proposes an original 3D simulation with a mesh resolution fine enough to resolve the fiber scale, thanks to the use of Proper Generalized Decomposition (PGD)-based space decomposition, which avoids the necessity of considering homogenized properties and considers the richest description of the involved physics from the solution of the Maxwell equations. This high-resolution simulation enables comparing the electromagnetic field propagation in a composite part, depending on the considered frequency and the fiber’s/wave polarization’s relative orientation. The electromagnetic fields are then post-processed to identify the heat generation terms and- the resulting induced thermal field. The results prove the ability of the PGD-based discretization to attain extremely high levels of resolution, the equivalent of 1010 finite-element degrees of freedom. The obtained results show an enhanced wave penetration when the electric field polarization coincides with the fiber orientation. On the contrary, when the electric field is polarized along the normal to the fiber orientation, both the penetration and the associated heating reduce significantly, compromising the use of homogenized models, rendering them unable to reproduce the observed behaviors.

Fabrication and Superconducting Properties of 19-Filamentary Sr0.6K0.4Fe2As2/Ag/Monel Composite Wires and Tapes

Fabrication and Superconducting Properties of 19-Filamentary Sr0.6K0.4Fe2As2/Ag/Monel Composite Wires and Tapes

A Study of the Laser Drilling Processes of Hts Composite Tapes as a Method of Creating the Magnetic Flux Artificial Pinning

A Study of the Laser Drilling Processes of Hts Composite Tapes as a Method of Creating the Magnetic Flux Artificial Pinning

Flexible LLDPE laminated Aluminum and Nickel foil composite tapes for EMI shielding

Flexible LLDPE laminated Aluminum and Nickel foil composite tapes for EMI shielding

Behavior of timber-concrete composite with defects in adhesive connection

Rigid timber to concrete connection is the most effective solution for timber-concrete composite members subjected to the flexure which provides full composite action and better structural behaviour. One of the most used technologies to produce glued connection of the timber-concrete composite is “dry” method, which includes gluing together of timber and precast concrete slab. This technique has high risk of forming a poor-quality rigid connection in timber-concrete composite, and there are difficulties in controlling the quality of the glued connection. The effect of the non-glued areas in connection between composite layers on the shear stresses and energy absorption were investigated by finite element method and laboratorian experiment. Three timber-concrete composite panels in combination with carbon fibre reinforced plastic composite tapes in the tension zone with the span 1.8 m were statically loaded till the failure by the scheme of three-point bending. Mid-span displacements were measured in the bending test. One specimen was produced by dry method, by gluing together cross-laminated timber panel and prefabricated concrete panel. Timber-concrete qualitative connection of the other two specimens was provided by the granite chips, which were glued on the surface of the cross-laminated timber by epoxy, and then wet concrete was placed. Dimensions of the crushed granite pieces changes within the limits from 16 to 25 mm. The investigated panel with different amount and sizes of non-glued areas in the timber to concrete connection was numerically modelled. Obtained results shown, that the increase of shear stresses is influenced not so much by a total amount of non-glued areas, but by the size of the individual defective areas. Moreover, large non-glued areas significantly reduce the energy absorption of elements subjected to the flexure, which was observed experimentally for defective panel produced by the classical dry method with almost 4 times larger mid-span displacements than for panel with full composite action provided by the proposed production technology of the timber to concrete rigid connection. So, the proposed technology based on the use of granite chips, provides a high-quality connection between timber and concrete layers, with insignificant ration between possible defect and total connection surface area, which is equal to the area of ​​one granite chips edge.

Algorithm for topology optimization of a structure made of anisotropic material with consideration of the reinforcement orientation parameters

Advanced design methods offer not only a number of methods of modeling structures but also quite profound optimization approaches. The topology optimization is one of such advantageous methods. There are several implementations of this type of structural analysis, but the most common option is to deal with the material density as a generalized parameter. The development of 3D printing technologies increases the interest in algorithms of this type. However, it mostly refers to printing with metal or plastic, which implies the material isotropy. Advances in continuous fiber printing systems and automatic placement machines using composite tapes make it possible for engineers to control not only a material’s position, but also to choose the local orientation of reinforcing elements. Such systems require optimization algorithms taking into account additional parameters characterizing the material anisotropy. In this case the traditional problem of the topology optimization should first be modified for the model of an orthotropic material with restrictions on the value of the angle of rotation of the reinforcement lines along the print path. In this paper, an idea of such a topology optimization algorithm is proposed, which is implemented using the Abaqus finite element modeling facilities, and examples of solving typical problems are considered.

Method of Experimental Research of New Construction of Beams from Glued Wood with Combined Reinforcement

Structures of glued wood have significant advantages in comparison with structures made of metal or reinforced concrete (less mass, better resistance to the action of chemically aggressive environments, high fire resistance, aesthetic attractiveness, eco-friendliness). However, at the same time, scientists are looking for new ways to improve the characteristics of such wood. We also proposed a new construction of combined reinforcement of glued beams in which the steel bar reinforcement of the periodic profile was arranged in the grooves of the compressed zone, and in the stretched zone reinforcement was carried out with the external composite tape made of carbon fiber. This combination increases both rigidity and bearing capacity of the elements that we are testing from glued wood for work on transverse bending. The method of experimental research on the transverse bend of a new construction of glued beam beams with combined reinforcement was developed. The proposed method fully allows us to examine and experimentally investigate the stress-strain state under load of glued beams from combined reinforcement at different stages of their work.

Method for the Microstructural Characterisation of Unidirectional Composite Tapes

The outstanding properties of carbon fibre-reinforced polymer composites are affected by the development of its microstructure during processing. This work presents a novel approach to identify microstructural features both along the tape thickness and through the thickness. Voronoi tessellation-based evaluation of the fibre volume content on cross-sectional micrographs, with consideration of the matrix boundary, is performed. The method is shown to be robust and is suitable to be automated. It has the potential to discriminate specific microstructural features and to relate them to processing behaviour removing the need for manufacturing trials.

The effect of Laser-Induced deconsolidation on the compaction behavior of thermoplastic composite tapes

The effects of laser-induced deconsolidation on the compaction process of CF/PEEK tapes were investigated. First, tapes with different degrees of deconsolidation were manufactured using a laser heater. This procedure resulted in samples with different waviness, thickness, void content and surface roughness values. Then, as-received and laser-deconsolidated tapes were compacted under two different temperature histories and four different pressure levels. Waviness induced by laser-deconsolidation vanished when the material was heated up to the glass transition temperature even at a very low compaction pressure. Unlike waviness; increased thickness, void content and surface roughness due to laser-deconsolidation remained between the glass transition and melting temperatures. After the melting temperature was exceeded, the effects of laser-deconsolidation were dependent on the applied pressure and initial degree of deconsolidation. The final surface roughness, thickness and degree of effective intimate contact were affected by the degree of laser-deconsolidation when a compaction pressure of less than 300 kPa was applied.

“Un-forming” fibre-steered preforms: Towards fast and reliable production of complex composites parts

Automated Fibre Placement (AFP) allows for efficient deposition of composite prepreg materials at large scale in a reliable and reproducible way, while keeping human effort to a minimum. However, the technique is not perfectly suited to manufacturing small/medium parts with complex geometries. Deviation between as-designed and as-manufactured parts is almost inevitable, as is the occurrence of process-induced defects. In this study, an alternative design and manufacturing process is proposed. Instead of depositing composite tapes directly onto the complex mould, a flat tailored preform made from steered fibre tows is created first, and then the flat preform is subsequently formed into a 3D complex shape. The fibre path in the flat tailored preform is derived from a new virtual ‘un-forming’ process of a complex 3D part design with target fibre paths. To demonstrate the process, a small doubly curved composite part was un-formed. Fibre-steered tailored preforms were created using the continuous tow shearing (CTS) technique and then formed into the target shape using double diaphragm forming. The as-manufactured part was compared with the as-designed part as well as a part manufactured from straight fibre prepreg. The results demonstrated the feasibility of the virtual un-forming process and the potential of proposed manufacturing route.

К ВОПРОСУ О ПРОЧНОСТИ КОМПОЗИТНОГО ШАРОБАЛЛОНА

In modern launch vehicles, combined composite structures in the form of thin-walled spherical shells are used as pressure accumulators and tanks. Such balloons consist of an inner metal body (liner), which ensures tightness, and an outer reinforcing composite shell, which ensures the operability of the structure.The paper presents a methodology for the design calculation of a combined composite balloon by using zonal winding on a liner. An analysis of publications on this topic showed that the requirements for the strength and continuity of the tape covering the entire surface of the balloon depend on the tape geometry, its width, thickness, the ultimate strength of the bundle along the fibers, the number of zones and the angular coordinates of the beginning of the zones. The even distribution of the location of the beginning of each zone, accepted by the authors in publications, leads to the need to use an excess number of winding turns to fulfill the strength conditions than is necessary for a continuous coverage of the zone surface.A rational design of the reinforcing composite shell will be in the case when the strength conditions and the conditions of the coating continuity are met in each zone with the same number of required tape turns. The algorithm is based on a sequential calculation of zone parameters. According to the known coordinate of the beginning of the first zone, the required number of turns of the tape is determined, which is necessary to fulfill the condition of the continuity of the coverage of the zone. The strength conditions in the first zone determine the angular coordinate of the beginning of the second zone. The calculation of the parameters of each zone is made taking into account the influence of the value of the width and thickness of the wound tape. Each subsequent zone is determined in the same way, taking into account all the previous zones.The paper compares the results obtained by the proposed method with the results known in the press. The performed numerical experiments showed that the proposed engineering technique allows to reduce the weight of the composite tape by 30%, and the designed spherical shell in this case will be thinner and has a more uniform distribution of the shell thickness along the meridian.

Calculation, design and manufacture of heteropolar magnetic levitation and linear drive systems of maglev transport

Background: The methods of calculation and elements of the technology for creating heteropolar magnetic systems of levitation, lateral stabilization and a rotor-runner of a traction linear synchronous motor for the development of the transport technology "Russian Maglev" in order to achieve an increased levitation gap of 0.2 m, reduce the threshold speed of the exit vehicle in levitation mode up to 10 km/h.&#x0D; Aim: to develop methods for calculating and designing heteropolar poles from elementary permanent magnets, coils of the same type based on composite low-temperature superconductors and high-temperature tape superconductors of the second generation and a step-by-step technology for their production.&#x0D; Tasks:&#x0D; &#x0D; Creation of an on-board magnetic system of levitation and lateral stabilization, allowing to provide a levitation gap of 0.2 m, a threshold value of vehicle speed of 10 km/h when transition to levitation mode, to reduce stray magnetic fields to the level of the natural field of terrestrial magnetism of 50 T;&#x0D; Creation of a rotor-runner of a linear synchronous motor with an ironless stator with a power of 10 MW.&#x0D; &#x0D; Methods: outlines the main calculation methodologies: "analysis" and "synthesis". The "analysis" methodology is adopted in solving the "direct" calculation problem, when the configuration of the magnetic system is set and the magnetic field in the working area is calculated, and, if necessary, the stray magnetic fields. This methodology can be effectively applied if there is experience in creating magnetic systems. Otherwise, the "synthesis" methodology is applied, which is used in solving the "inverse" calculation problem, in which the picture of the distribution of the magnetic field in the working zone is set and the configuration of the magnetic system is found (synthesized).&#x0D; Results of the study performed:&#x0D; &#x0D; The parameters and characteristics of high-energy permanent magnets made of rare-earth metals, low-temperature and high-temperature superconducting winding materials have been analyzed, the choice of permanent magnets and superconducting winding material has been made;&#x0D; Calculations of the magnetic system of permanent magnets in the "Halbach assembly" and in the traditional assembly in a toothed ferromagnetic core have been carried out;&#x0D; Calculations of a track coil with a rectangular cross-section of the winding are performed;&#x0D; Methods for calculating and optimizing superconducting magnetic systems from a set of similar track modules have been developed;&#x0D; &#x0D; Conclusions: The results of the performed fundamental research will allow starting the calculation, design and construction of conveyor-main passenger and freight lines of maglev transport, as well as urban public transport.

RIGID CONNECTION WITH GRANITE CHIPS IN THE TIMBER-CONCRETE COMPOSITE

Timber-concrete composite panels enables to combine advantages of pure timber and pure concrete panels in one structural member especially in the case, when the rigid timber-concrete connection is provided. The effectiveness of timber and concrete use and load-carrying capacity of the timber-concrete composite panels will grow in the case. The new concept of rigid timber to concrete connection was developed by the using of the granite chips as the keys to provide high quality of the glued connection. Behaviour of the timber-concrete composite panels were investigated by finite element method and laboratorian experiment. Three timber-concrete composite panels in combination with carbon fibre reinforced plastic composite tapes in the tension zone with the span 1.8 m were statically loaded till the failure by the scheme of three-point bending. One specimen was produced by dry method, by gluing together cross-laminated timber panel and prefabricated concrete panel. Timber-concrete connection of the other two specimens was provided by the granite chips, which were glued on the surface of the cross-laminated timber by epoxy, and then wet concrete was placed. Dimensions of the crushed granite pieces changes within the limits from 16 to 25 mm. The current study focuses on determining the effect of the use of granite chips for timber-concrete composite panels with adhesive connection between layers. The effect of the use of granite chips in rigid connection is determined by comparison of mid-span displacements and level of failure load of the two variants of the timber-concrete composite panels. Three-dimensional finite element models of timber-concrete composite with rigid connection was developed and validated by experiment data. Obtained results shown, that the use of the granite chips in rigid timber to concrete connection allow to make a quality rigid connection. Possibility to increase by 28% level of failure load of the timber-concrete composite panels by the adding of granite chips was stated. Maximal vertical mid-span displacements of the panels decrease about 3.8 times at the same time.

ASSESSMENT OF CARRYING CAPACITY OF THE ROUND IN PLAN REINFORCED CONCRETE FOUNDATION FOR THE SILO

During the design, installation and operation of silos, they have defects and damage of various kinds, which affect the stress-strain state and durability of structural elements. Timely inspections and determination of technical conditions of structural elements of the structure and the site as a whole, will establish the possibility of its further safe operation or the need to restore operational properties by ensuring structural safety and reliability of structures. Therefore, the development of design schemes, methods of calculating the stress-strain state, life expectancy and further reinforcement for round reinforced concrete elements of silos with local damage, is quite relevant. Improper maintenance and operation of structural elements, as well as errors in the design and installation in the future lead to unusable for normal operation and sometimes an emergency. The development of projects to strengthen existing structures is a very responsible matter. The most common solution for strengthening existing foundations is to increase the area of support of the foundation cushion, which is not always possible in a compact building. The purpose of the work is to determine the technical condition of the building structures of the silo and the results of calculations performed in the PC Lira, to offer options for strengthening the foundation on a specific example. Structural solutions of the reinforced concrete monolithic foundation of the silo, the main defects and damages determined by the technical condition of the structure are given. For further safe operation of the structure, it is recommended to reinforce the wall foundations by gluing composite tapes and perform reinforcement of the foundations by controlling the growth of piles in accordance with the additional working design of the structure reinforcement. If the latest recommendations on strengthening and adhering to the safe and reliable operation of construction and structures are followed, further operation of building structures will be safe.

Design and Analysis of a Novel 2T2R Parallel Mechanism with the Closed-loop Limbs

This paper presents a novel four degrees of freedom (DOF) parallel mechanism with the closed-loop limbs, which includes two translational (2T) DOF and two rotational (2R) DOF. By connecting the proposed parallel mechanism with the guide rail in series, the 5-DOF hybrid robot system is obtained, which can be applied for the composite material tape laying in aerospace industry. The analysis in this paper mainly focuses on the parallel module of the hybrid robot system. First, the freedom of the proposed parallel mechanism is calculated based on the screw theory. Then, according to the closed-loop vector equation, the inverse kinematics and Jacobian matrix of the parallel mechanism are carried out. Next, the workspace stiffness and dexterity analysis of the parallel mechanism are investigated based on the constraint equations, static stiffness matrix and Jacobian condition number. Finally, the correctness of the inverse kinematics and the high stiffness of the parallel mechanism are verified by the kinematics and stiffness simulation analysis, which lays a foundation for the automatic composite material tape laying.

Thickness effect of anisotropic conductive behavior of carbon fiber/polyetheretherketone unidirectional tape

The conductive anisotropic polymer composites (ACPC) have important applications like field emission devices and electronic sensors. Conventional ACPC are difficult to obtain large conductive anisotropy coefficients and present limited mechanical properties. In this paper, novel technology integrated carbon fiber (CF) spread, surface modification with stacking thermoplastic film was used to prepare CF reinforced polyetheretherketone (CF/PEEK) composite unidirectional tape with thicknesses of 0.04 mm and 0.1 mm. CF/PEEK composite unidirectional woven cloth was prepared with PEEK fiber was used as a binder weft, and CF/PEEK composite unidirectional laminate was prepared by thermoforming process. The in-plane and the thickness directional resistivities of unidirectional laminate were measured by digital multimeter and in-plane electron mobility was tested by Hall effect system. The fiber arrangement within in-planes along the fiber direction and the thickness direction of CF/PEEK composite unidirectional laminate were observed with an ultra-depth microscope. The results show that the in-plane (fiber direction to transverse direction) conductivity ratio of ultra-thin CF/PEEK composite unidirectional laminate reaches to 377, while conductive ratio in the transverse direction to the thickness direction is close to 1, indicating that thin CF/PEEK composite unidirectional laminate presents transverse isotropic electric performance. The results of electron migration also indicate in-plane huge anisotropic conductivity. The results are important for CF/PEEK composite to be used in field emission devices and electronic sensors.