Multilayer Composite Materials Research Articles

Comparative Analysis of the Selection of Lay-Up Stacking of Polymer Composite Load-Bearing Elements for the Tail Section of Fuselage Structure of the Light Aircraft

The problem of the selecting the optimal lay-up stacking of polymer composite materials for the load-bearing elements of the rear part of fuselage structure is considered. The comparison of two approaches to the design of the load-bearing elements is carried out. The first of them is the use of multilayered composite material for the load-bearing elements, the stacking angles of which is selected from a given discrete set, and the second is the use of composite material with a continuous range of variables in fabric lay-up angles. As a result design optimization, it is shown that using an optimization method with a continuous range of lay-angles allows reducing the weight of the load-bearing elements by 12.79%

Three-dimensional damage quantification of low velocity impact damage in thin composite plates using phased-array ultrasound

The evaluation of internal damage in multilayered composite materials is of great importance for high reliability-demanding applications, and remains a challenge due to the complex failure modes and mechanism of composite materials. This study presents a volumetric method of three-dimensional size quantification and prediction for low velocity impact damage in thin composite plates using phased-array ultrasound. A set of low velocity impact damages are induced in thin carbon fiber/epoxy resin matrix composite plates using quasi-static indentation tests. A volumetric reconstruction method is proposed to reconstruct a three-dimensional volume from the raw data, allowing for direct damage identification, localization, and quantification. Using the echo amplitude feature of the reconstructed volume, the 6 dB-drop method is employed to characterize the damage size in terms of volumes and areas. An impact size prediction model is established to correlate the impact energy and the damage volume/area. Comparisons are made between the microscopy measurement of the damage cross-section and results obtained using the developed method.

Analytical Solution to the Plane Bending Task of the Multilayer Beam with a Circular Axis under Normal Uniform Loading

Circular bars are widespread elements in building and mechanical engineering. They allow one to enhance the strength of the multilayer composite materials along with their weight reduction. However, their analytical modeling is developed rather poorly, which creates additional obstacles in their efficient design. The paper presents the results of the exact analytical solution to the plane bending task of elasticity theory for the multilayer beam with a circular axis under normal uniform loading on its longitudinal surfaces considering the cylindrical orthotropy of its layers’ materials. The problem has been solved using the methods of linear elasticity theory based on the continual approach where the circular bar is considered as a solid with the elastic characteristics varying in the radial direction. The solution for the shear stresses is assumed using the known distribution in the cross section. Therefore, the solution to the problem is reduced to the determination of two unknown functions of stress distribution throughout the section height. The system of linear differential equations has been obtained for the determination of the sought functions and unknown functions of integration in the process of the solution to the equations of plane theory considering the variable elastic characteristics. General analytical solutions for uniform and discontinuous-nonuniform layers from cylindrically orthotropic and isotropic materials have been developed. The influence of transverse shear deformation and compression on the characteristics of the stress-strain state of a cantilever three-layer beam with a semicircular axis is theoretically investigated. The obtained relations allow us to predict the stress-strain state of circular multilayer beams, as well as to build applied methods for solving problems of strength, rigidity, and optimal design of such structural elements.

EXPERIENCE OF USING ACOUSTIC FLAW DETECTORS ID-91M AND AD-60K IN ASSESSING THE QUALITY OF MULTILAYER STRUCTURES

The article considers the experience of using acoustic flaw detectors ID-91M and AD-60K for non-destructive control of the continuity of filling gaps with Vixint-K18 sealant, quality control of composite material based on organoplastics and construction of boroaluminium composite materials. The analysis of publications on the issue under consideration is performed. A list of publications from 15 sources is presented. An analysis of the continuity of filling gaps with a sealant was carried out with the construction of diagrams of the distribution of signal amplitudes across the scanning zones. The measurement results are presented in the figures in the form of a color scheme by selected amplitude scale. The effect on the results of changes in the edge effect is shown, insufficient locality of the sensors used is noted. For structures made of composite materials based on organoplastics and boroaluminum material, dependences of signal amplitudes on the depth of imitators of defects of various sizes are constructed. A static analysis of the measurement results from each of the defect simulators is performed. Good reproducibility of the acoustic signal for specific simulators is shown. The dependences of the signal amplitudes on the layer thickness to the defect simulator are constructed for two different transducers (RSP-60 and SP-60). It is proposed that the SP-60 transducer with less sensitivity but with a monotonic characteristic will be used for a rough estimation of measurement results, and the RSP-60 transducer, with a higher sensitivity but with non-monotonic characteristic, will be used to refine the results. Studies have shown the effectiveness of using acoustic flaw detectors ID-91M and AD-60K with non-destructive testing of the quality of manufacturing a number of structures from multilayer composite materials. Based on the results of the studies, the optimal settings for flaw detectors for various types of controlled parts were selected, a non-destructive testing method for structures by the acoustic method was developed and certified, and metrological parameters of the method were evaluated.

Absorption of Water Vapor Using Superabsorbent Polymer Composite Material

The ability of superabsorbent polymers (SAP) to absorb water vapor was studied. A multilayer composite material was prepared where SAP particles were spread in the fluffy fibrous layer located in the middle of the composite structure. Distribution of SAP within the composite material permits air to pass through its porous structure effectively hence allowing efficient contact of air with SAP. SAP was able to decrease the relative humidity of air of a 3-L cabinet from 96% relative humidity (RH) to 52% and 49 % (RH) in 18 hours using 2 g and 4 g of SAP respectively. Study on the water vapor absorption ability of SAP placed together with pure water in a closed cabinet was conducted with and without convective air transport effect. Convective air transport was done by activating the 12 V fan allowing air recirculation speed at rates corresponding to constant voltage settings of 6 V and 12 V. Higher SAP water vapor absorption rate was obtained at higher air recirculation speed. SAP particles swelled after water vapor absorption with slight decrease in the porosity of composite material as observed through the digital microscope.

A reduced-order modelling for real-time identification of damages in multi-layered composite materials

This work is focused on the detection of interlayer damages in multi-layer composite materials, which use the inverse analysis approach based on the reduced-order models (ROMs). Direct problems including heat conduction through the solid and heat radiation to the space are solved by finite element method (FEM), and the solutions of transient nonlinear analysis are collected to build the snapshot data matrix. The Proper Orthogonal Decomposition (POD) method coupled with two surrogate models are utilized to construct a low dimensional model which can be used to rebuild physical fields. By minimizing the discrepancy of measured and simulated temperatures using ROMs, the optimal parameter values related to damages can be estimated efficiently. Results prove that an excellent estimation on the position of damages can be obtained in the multi-layer materials. The computational efficiency and solution accuracy of two ROMs are compared, which proves that the POD-Kriging method has faster convergence speed than the POD-RBF method, with the same fitness value. Moreover, noise analysis validates that two ROMs have similar stability, whereas the POD-Kriging method is easier to achieve convergence in this type of problems.

Numerical and Experimental Analysis of Stacking Sequences Effects in Composite Mechanical Joints under Impact Loadings

Composite structures in the field of advanced and modern structures in engineering design and according to high specification of composite materials such as high strength to weight ratio use in various industries such as aerospace, marine. One of the most important fields that Researchers have paid less attention to that is to investigate the effect of stacking sequence on the strength of mechanical joints under impact loading. In view of changing the mechanical properties of composite materials by changing the arrangement of layers, in this study, the effect of different orientation of layers on the strength of pin joints in glass-epoxy composites under low-velocity tensile impact has been investigated. Using the Abaqus software and the finite element method, the impact simulation and the force applied to the mechanical joint were analyzed. To evaluate the simulations, the results of the finite element method have been compared with the experimental results. By observing the results, the introduced finite element model is well-considered and is well-matched with the result of the experimental dataset, which made it a valuable tool for predicting the strength of multi-layer composite materials under impact loadings. Using the results of the model, one can analyze the distribution and type of stress and strain in each layer of composite.

Двухслойный композит, армированный базальтовыми волокнами различной длины

The article considers the issues of creating composites using long, continuous structures along the entire length of the structure, and short basalt fibers, and, based on them, multilayer composite materials as reinforcement. A mathematical description of the strength properties of multilayer composite materials based on layers of composites using long, continuous along the entire length of the structure, and short basalt fibers as reinforcement is considered. The results of theoretical studies showed that the multilayer composite material has improved properties. The first layer of material, which is a layer of reinforcement made of continuous fibers, provides tensile and bending strength. The second layer of composite material provides thermal insulation properties and compressive and deformation strength. This layer consists of a composite whose reinforcement is short fibers. It is shown that a multilayer composite material, which is a combination of composites created on the basis of long continuous and short fibers, works as a single system. The first layer of the composite, created on the basis of continuous fibers, works in tension and bending, the second layer, created on the basis of short fibers, determines the strength characteristics during compression and deformation. In order to confirm the theoretical results, work was carried out to create composites based on long and short basalt fibers. When creating a layered composite, a heat-insulating plate was used as the first component, which was reinforced with pieces of basalt fiber. For the production of such plates, a plant was developed to obtain pieces of basalt fiber and further uniform distribution of these pieces in a composite plate. A multilayer composite material with improved properties based on long and short basalt fibers is obtained. The composite slab was reinforced with a mesh assembled from continuous basalt fibers.

A Simple High-Resolution Near-Field Probe for Microwave Non-Destructive Test and Imaging

Non-destructive tests working at lower microwave frequencies have large advantages of dielectric material penetrability, lower equipment cost, and lower implementation complexity. However, the resolution will become worse as the work frequencies become lower. Relying on designing the structure of high field confinement, this study realizes a simple complementary spiral resonators (CSRs)-based near-field probe for microwave non-destructive testing (NDT) and imaging around 390 MHz (λ = 769 mm) whereby very high resolution (λ/308, 2.5 mm) is achieved. By applying an ingenious structure where a short microstrip is connected to a microstrip ring to feed the CSR, the probe, that is a single-port microwave planar circuit, does not need any extra matching circuits, which has more application potential in sensor arraying compared with other microwave probes. The variation of the electric field distribution with the standoff distance (SOD) between the material under test and the probe are analyzed to reveal the operation mechanisms behind the improved sensitivity and resolution of the proposed probe. Besides, the detection abilities of the tiny defects in metal and non-metal materials are demonstrated by the related experiments. The smallest detectable crack and via in the non-metal materials and the metal materials are of a λ/1538 (0.5 mm) width, a λ/513 (1.5 mm) diameter, a λ/3846 (0.2 mm) width and a λ/513 (1.5 mm) diameter, respectively. Moreover, to further evaluate the performance of the proposed probe, the defects under skin layer in the multilayer composite materials and the defects under corrosion in the carbon steel are inspected and imaged. Due to lower work frequency, high resolution, outstanding detection abilities of tiny defects, and large potentials in sensor arraying, the proposed probe would be a good candidate for microwave NDT and imaging.

Regulation of Mechanical Properties of Advanced PCM Products with the Aid of Catalysts

The article considers the problem of the effect of uneven curing caused by the temperature gradient across the thickness of the material on the anisotropy of the strength properties of polymer composite materials. The effect of catalysts on the curing of the epoxy binder EDT-69N, used for the manufacture of multilayer polymer composite materials, was studied. According to dielectric spectrometry, the accelerating effect of the selected compounds on the curing process of the EDT-69N epoxy binder during fiberglass molding has been proved. The possibility of controlling the curing process using catalysts to reduce the influence of the temperature gradient on the anisotropy of the strength properties of the matrix in the manufacture of polymer composite materials is shown.

Research and modeling of a multilayer composite material using basalt fabric

Introduction . The range of use of composite materials (CM) is constantly expanding, finding application in many areas of mechanical engineering, agricultural technology, aircraft manufacturing, instrumentation, shipbuilding, in the manufacture of high-pressure containers, etc. Quite often, multilayer composites consisting mainly of one type of reinforcing material and a binder are used. Of particular interest is the use of various types of reinforcing materials – more durable in the places of maximum stress in the cross section – in a single composite. As an example, we can use glass and basalt fabrics and fibers using one type of binder. The work objective is to study properties of such a material and to model it using the finite element method. Materials and Methods . The components used are commercially available. BT-11 basalt fabric, TR-0.5 fiberglass, as well as glass mat with a density of 300 g/m2 were used as reinforcing materials. An epoxy resin of the ED-20 grade with a PEPA hardener was used as a binder. Two types of material were also manufactured for tensile and bending tests, respectively, the differences of which consisted in the number, type and layer sequence. For modeling, CAD COM-PASS 3D, APM-FEM module was used. Results . Basalt fabric is used in the outer layers of the composite material, fiberglass – in the inner layers. This approach provides increasing the tensile strength of the composite during tensile and bending; however, critical failure leads to an instant loss of the bearing capacity of the material. The use of glass mat as the core of the composite material showed lower allowable stresses, both tensile and bending; but in case of bending, it turned out that when the material was delaminated, the load-bearing capacity of the material was about 10% of the maximum. Modeling of the material is possible with some assumptions, in view of the size of the final elements. Discussion and Conclusions . The use of basalt fabrics as a reinforcing material provides obtaining products with the properties of both glass and carbon plastics. Such a CM will be slightly more expensive than fiberglass and much cheaper than carbon fiber. Products made of composite materials (equivalent to isotropic materials) can be modeled in computer-aided design systems using the finite element method. It is important to consider the type of loading on the product, since CM mainly have anisotropic properties (the load is applied taking into account the direction of fibers). In multilayer CM from structural fabrics, it is necessary to direct the loads along the fibers. In addition, it is necessary to consider the interlayer shear, different adhesion between the layers, etc. The main assumption of this method is the “constancy” of the material thickness, the number of layers and the order of their location.

Sound absorption properties for multi-layer of composite materials using nonwoven fabrics with kapok

Kapok fiber with high degree of hollow and small fiber diameter has excellent sound absorption. To optimize the sound absorption characters at the low frequency, sound absorption coefficients and specific surface impedance of two-layer, three-layer, and four-layer materials as polyethylene film-reinforced kapok fiber nonwoven fabrics have been studied by using the impedance tube method in the frequency range of 100–2500 Hz. The layering sequence, the polyethylene films thickness, and the gradient thickness structure of nonwoven fabrics affected the sound absorption properties at the low frequency for multi-layer materials that have been analyzed. The results show that the multi-layer composite materials have better sound absorption than a single-layer nonwoven fabrics at the low frequency. The elastic vibration of polyethylene film contributes to sound absorption improvement at the low frequency. The sound absorption at the low frequency of multi-layer materials can be further improved by changing polyethylene film position or increasing polyethylene film thickness. In addition, the gradient thickness structure of nonwoven fabrics can effectively improve sound absorption at the low frequency, and the gradient change direction also exhibits remarkable effects on the sound absorption of multi-layer materials.

The effect of cutting tool coating on the form and dimensional errors of machined holes in GLARE\xae fibre metal laminates

Fibre metal laminates (FMLs) are multilayered metal composite materials currently used in aeronautical structures, especially where fatigue and impact resistance are required. FMLs are produced in large panels and often require assembly using the drilling process for riveting purposes. Hole making is a critical machining process in the joining and assembly of aeronautical components, which has to meet stringent tolerance requirements. This paper reports a systematic analysis of hole integrity when drilling an FML known as GLARE®. In particular, the primary objective is to investigate the impact of three different drill coatings (TiAlN, TiN and AlTiN/TiAlN), against several important hole parameters: thrust force, hole size, circularity, cylindricity and perpendicularity. The results show that TiAlN-coated drills produced the highest thrust force, while TiN-coated drills produced holes with the lowest deviation between the hole diameter measured at the entry and the exit and that the drill coating was the most influential parameter for the resulting hole size. TiAlN-coated drills resulted in the highest circularity at the upper part of the hole, while hole cylindricity tended to be best when using AlTiN/TiAlN- and TiN-coated drills. The ANOVA analysis shows that the drill coating and the spindle speed had a significant influence on hole size and circularity, while drill coating was the only influential parameter on hole cylindricity, and spindle speed was the only contributing parameter on hole perpendicularity. Finally, scanning electron microscopy analyses showed two distinct hole wall surface damage phenomenon due to broken fibres and evacuated metallic chips.

Regulation of Mechanical Properties of Advanced PCM Products with the Aid of Catalysts

The article considers the problem of the effect of uneven curing caused by the temperature gradient across the thickness of the material on the anisotropy of the strength properties of polymer composite materials. The effect of catalysts on the curing of the epoxy binder EDT-69N, used for the manufacture of multilayer polymer composite materials, was studied. According to dielectric spectrometry, the accelerating effect of the selected compounds on the curing process of the EDT-69N epoxy binder during fiberglass molding has been proved. The possibility of controlling the curing process using catalysts to reduce the influence of the temperature gradient on the anisotropy of the strength properties of the matrix in the manufacture of polymer composite materials is shown.

The Preparation and Characterization of Cu/AA6061 multi-layer Composte produced by Accumulated Roll Bonding

The present study focuses on the preparation and characterization of Cu/AA6061 multi-layer composite materials produced by accumulated roll bonding (ARB). The bonding between metallic layers and the microstructure of samples was characterized by optical and scanning electron microscopy and tensile testing which were used to characterize the mechanical properties. After four ARB cycles, the interface only displays a little bit, showing that the good contact between layers were formed and the mechanical properties were improved. The both materials have a fine microstructure with grain sizes decreased with increasing cycles of ARB.

Synthesis of graphene-siloxene nanosheet based layered composite materials by tuning its interface chemistry: An efficient anode with overwhelming electrochemical performances for lithium-ion batteries

Owing to its high theoretical storage capacity, two dimensional (2D) silicon nanosheets is the one among the most exciting anode material for the next generation lithium ion (Li-ion) batteries. However, deprived electrochemical properties due to the huge volume expansion resulting in rapid capacity decay, thereby hindering its commercial application aspect of silicon nanosheet based materials. The present work proposes a novel concept of synthesizing graphene-siloxene (SiG) based multi-layered structures by tuning the interface chemistries of graphene oxide and siloxene sheets derived from topochemical transformation of calcium silicide (CaSi2). Morphological characterization using Field emission scanning electron microscopic and transmission electron microscopy reveal the successful formation of few- to multi-layered SiG composite materials with intercalated/surface grafted siloxene nanosheets on the graphene layers. Owing to its hierarchical composite structure, SiG as anode delivers the first discharge and charge capacity values as high as 3880 mAhg−1 and 3016 mAhg−1 respectively measured at the current rate of 205 mAg−1. Even at high current rate (4.1 Ag-1), SiG composite materials delivers first charge capacity of 1480 mAhg−1 with good cycling performance (1040 mAhg−1) after 1000 cycles. Due to its enhanced lithium storage, cycling stability and rate capability, synthesized SiG composites could be a potential anode candidate for Li-ion batteries.

Sound absorption properties of multi-layer structural composite materials based on waste corn husk fibers

In order to find a reasonable way to use the waste corn husk, waste degummed corn husk fibers were used as reinforcing material in one type of composite material. And polylactic acid particles were used as matrix material. The composite materials were prepared by mixing and hot-pressing process, and they were processed into the micro-slit panel. Then, the multi-layer structural sound absorption composite materials were prepared sequentially by micro-slit panel, air cavity, and flax felt. Finally, the sound absorption properties of the multi-layer structural composite materials were studied by changing flax felt thickness, air cavity depth, slit rate, and thickness of micro-slit panel. As the flax felt thickness varied from 0 to 10 mm in 5 mm increments, the peak of sound absorption coefficient shifted to low frequency. The sound absorption coefficient in the low frequency was improved with the air cavity depth varied from 0 to 10 mm in 5 mm increments. With the slit rate increased from 3% to 7% in 2% increments, the peak of sound absorption coefficient shifted to high frequency. With the thickness of micro-slit panel increased from 2 to 6 mm in 2 mm increments, the sound absorption bandwidth was broaden, and the peak of sound absorption coefficient was increased and shifted to low frequency. Results showed that the highest sound absorption coefficient of the multi-layer structural composite materials was about 1 under the optimal process conditions.

A Molecular Dynamics Study on Polycaprolactone -Metal Oxide Interactions

In order to realize the macroscopic features of a number of chemically bonded multi-layer dielectric and composite materials, interactions of metal oxide surfaces, polymer surface atoms, and near-surface atoms are very beneficial. The simulation study of polymer-metal oxides interfaces is of great importance in investigating the adhesion and miscibility features of these systems that are inherently challenging to obtain experimentally or for which there is no experimental data, even if some low data exist, they are not reliable. Polycaprolactone (PCL) is biocompatible, biodegradable, non-toxic and hydrophobic polyester that has been used in tissue engineering, such as a bioactive implant. Hence, the molecular dynamics simulations of PCL are carried out to investigate its surface interaction with metal oxides as ZnO, CuO, Fe2O3, NiO and SiO2. The force field of COMPASS is applied to simulations in order to compute interfacial and solubility parameters. Molecular dynamics approach to investigate the interaction and adsorption manner of PCL with metal oxides. Whereas investigations are useful in exploring polymer composites. Much better adhesion is achieved by the calculations between the PCL oligomer and the metal oxides under investigation. The negative values of interaction energy have to be forecasted despite the presence of acid-base or hydrogen-bonding interactions.

Математические модели для проектирования композиционных материалов с барьерными свойствами

Одним из важных направлений обеспечения химической безопасности являются разработка и совершенствование средств индивидуальной защиты для персонала химически опасных объектов и аварийно-спасательных подразделений МЧС. Современные средства индивидуальной защиты от опасных веществ выполняются на основе многослойных полимерных композиционных материалов с барьерными свойствами. Обоснована актуальность математического моделирования процессов тепломассопереноса при проектировании этих изделий и материалов для них, с учетом широкого набора воздействующих токсичных и агрессивных сред и различных по мощности и природе тепловых факторов. В статье представлен обзор математических моделей для описания тепло- и массопереноса через полимерные (в том числе композиционные) материалы, теплозащитные покрытия, поглощающие системы. Приведены наработанные к настоящему времени приемы решения входящих в них уравнений, которые успешно используются в смежных областях инженерной деятельности и могут быть рекомендованы для проектирования новых защитных материалов и покрытий. One of the most urgent tasks of ensuring chemical safety is the development and improvement of personal protective equipment required for the work of the staff of chemically hazardous facilities and emergency rescue units of the Ministry of Emergencies. Modern personal equipment for protection against hazardous substances is based on multilayer polymer composite materials with barrier properties. The relevance of mathematical modeling of heat and mass transfer processes used for designing these products and materials is justified, taking into account a wide range of toxic and aggressive environments and thermal factors of different types and origin. The article provides an overview of mathematical models describing heat and mass transfer through polymeric (including composite-based) materials, heat-protective coatings, absorbing systems, etc. A series of developed to date techniques for solving the appropriate equations are summarized, which have been successfully used in related engineering fields and can be recommended for designing novel protective materials and coatings for the corresponding purpose.

Comparative structural analysis of advanced multi-layer composite materials

Generally, an integrated effect of a composite depends on reinforcement and its load transformation characteristics. In this regard, research about fiber and its orientation are emerged to fulfill the requirements of Structural Engineering. Hence in this paper analyzes the orientation of reinforcement on multi-layer composite structures composed of a variety of materials. Structural-geometrical classifications of multi-layer composite test specimens are suggested, in which it having multiple layers of various fabrics such as Glass, Carbon, and Kevlar are coupled with the matrix. Finalized layers in this paper are advanced layers in the perspective of stronger, lighter and more flexible than currently available vests. Finite element models of the tensile test against the multi-layer composite structures have been developed in Ansys ACP-Pre 17.2. The reference components' design is based on ASTM D3039 and the entire comparative analyses have been carried out with the help of Ansys ACP-Post 17.2. Finally, stress variation and displacement of various combinations of multi-layer composites have been analyzed and the suitable material is optimized.