Averaging the viscoelastic properties of rubber-cord composites is of interest from both theoretical and practical points of view. For example, the viscoelasticity of rubber leads to heat release in rolling tires, which affects their rolling resistance and the fuel-efficiency. This work focuses on two interrelated aspects: the experimental determination of viscoelastic parameters of the rubber and

The work aims to generalize the existing theoretical studies into the influence of geometrical dimensions of the Maddock element installed on the extruder screw on the mixing quality of polyethylene composition with a silicone rubber in order to establish theoretical laws of the process and to verify them experimentally. A mathematical model of the flow of polymer melts in the working gaps of a single-extruder

S-glass-fiber-reinforced plastic layered composites were prepared by the vacuum-assisted resin transfer molding, and their mechanical properties in relation to different layering types were studied. The effects of layering type and off-axis angle on the tensile and flexural strengths of the composites were clarified. In addition, variations in the intelaminar shear strength and bearing strength by

Thermoplastic vulcanizates based on an ABS-plastic and a nitrile butadiene rubber blend filled with fluorinated carbon were considered and their stress–strain properties, resistance to aggressive liquids and thermal-oxidative aging were investigated. Fillers of PKF-MS, PKF-2V and FUP-NK-S grades were used as the modified carbon black. It was found that they increased the stress–strain properties of

The impact behavior and energy absorption of two types of composite tubes, fabricated from carbon fabrics by the resin transfer molding and from carbon prepregs by the lay-up method, were investigated experimentally and numerically. In impact tests, outward-splaying crush caps with different fillet radii were used. Different types of crushing behavior of the tubes were simulated by the finite-element

The effect of Al2O3 and B4C nanoparticles on the quasi-static penetration test (QSPT) and Charpy impact test of glass-fiber-reinforced polymer composite plates has been studied with the aim to clear up whether there is a correlation between results of these two tests. Punch shear tests on the plates were carried out. The data for the absorbed energy obtained from the Charpy impact test were feasible

The mechanical properties of sandwich panels with a polyurethane core and fiberglass face layers produced by a continuous lamination process have been studied. Tensile, compression and shear tests were performed on isolated face layer materials. Using a nonlinear finite-element model, the mechanical behavior of the sandwich panels in flatwise compression, edgewise compression, and bending was simulated

The initial-boundary value problem of thermoelastoplastic deformation of flexible reinforced plates is formulated. The possible weak resistance of such structures to the transverse shear is taken into account within the framework of Ambartsumyan theory. The geometric nonlinearity is taken into account in the Karman approximation. The temperature across the thickness of the plates is approximated by

The rubber-cord layers in passenger car tires are usually calculated assuming that deformations in them are small. However, rubber-cord layers can experience deformations of up to 15%. In calculations, the rubber-cordis usually replaced by an effective material. In this work, a phenomenological approach is used to construct a model of the effective material, where the inhomogeneous rubber-cord layer

A new approach to the analysis of the stress-strain state of adhesive joints and the transverse strength of layered composites is proposed. It consists in a combined use of finite-element and contact layer methods. Based on this approach, the problem of the long-term strength in normal separation of two adhesively bonded disks glued together by an epoxy resin, which was previously considered by R.

To assess the stability and postbuckling behavior of thin composite panels with additional repair lap plates, it is proposed to use relations that consider the unsymmetry of the structure. An analytical solution of the geometrically nonlinear problem is presented for smooth composite panels, whose shape is close to a square, loaded by tangential flows. The initial relations of the problem consider

To meet the aviation and aerospace requirements for detachability and load-carrying capacity, a novel connecting structure — a carbon-fiber-filament-wound composite tube with grooved metal inserts has been developed. The tensile behavior of the structure was investigated experimentally and by the finite-element method. The finite-element method was used to simulate the damage process. The failure load

The present study aims to design stacking sequences of dimensionally stable symmetric balanced laminated carbon/epoxy composites, with different numbers of layers, with a low coefficient of thermal expansion and high elastic moduli. To avoid excessive interlaminar stresses in the composites, the contiguity constraint for plies is also taken into consideration. In the design process, both single- and

Curved continuous fiber trajectories for composite plates with a bolted joint corresponding to the lines of maximum principal stresses were designed using the iterative finite-element modeling. On their basis, variable stiffness composite structures were modeled by the finite-element method, when each element was assigned variable material properties depending on the distribution of fiber trajectories

The effective elastic modulus of composites with network microstructures is studied by micromechanics methods. Based on their network morphology, a mesoscopic model for them is developed. The predictions found by the model are compared with previous experimental results, and a good agreement between them is found to exist. The effect of some parameters, including the particle size, volume fraction

Results of many experimental and numerical studies indicate that, in unidirectionally reinforced composites, plastic deformations do not arise in tension along the reinforcing fibers. CFRPs and boron-aluminum composites with rectilinear fibers deform elastically up to fracture. However, unlike homogeneous materials, such composites deform plastically in hydrostatic loadings. In order to rationally

Results of an experimental study and numerical simulation of the curing kinetics of an epoxy binder under the conditions of violation of the stoichiometric equilibrium of its components are presented. The object of research is a two-component composition of an L epoxy resin and an EPH 161 hardener, certified as a binder for composite materials of aerospace purpose. As the basic model, we used a system

The effect of organomodified montmorillonite (MMT) content and mixing conditions on the mechanical properties, structure, and morphology of a chloroprene rubber was investigated. Nanoparticles were mechanically mixed with a plasticizer, followed by ultrasonic homogenization before compounding of all ingredients of the mixtures in two-roll mills. Mechanical tests were carried out on samples prepared

Quasi-static tests in bending of thin-walled beams with different material design forms and weak link locations have been carried out, and their deformation mode and force responses are investigated by numerical simulations. The influence of some factors, including fiber direction, stacking sequence, and making holes in different positions, on the energy absorption of thin-walled CFRP beams is analyzed

The influence of arrangement of carbon- and aramid-fiber reinforcing layers in a multilayered epoxy composite on its energy absorption at the action of an impactor on it has been investigated. The geometry of the impactor corresponded to a 7.62×51-mm projectile core. Its initial velocity was 250 m/s. The numerical research was carried out using the finite-element method in the LS-Dyna software. Bilateral

The influence of the inhomogeneous initial thermal stresses caused by the heating or cooling of the inner and outer surfaces of a hollow bilayered cylinder on dispersion of torsional waves propagating in this cylinder is studied. The study is performed within the scope of the second version of the 3D linearized theory of elastic waves in initially stressed bodies, according to which the initial inhomogeneous

Equilibrium equations of a rib grid-stiffened composite cylindrical shell reinforced with carbon nanotubes (CNTs) are derived based on the first-order shear deformation theory considering the effect of shear deformation and moment of inertia. The distribution of CNTs across the shell thickness is assumed uniform, and the elastic modulus of the CNT-reinforced polymer is calculated using the rule of

The effects of TiO2 microparticle blending on the mechanical and thermal properties and the water absorption behavior of hybrid Pinus/Shorea robusta wood particulate-epoxy composites have been investigated. The tensile, flexural, impact, microhardness, and water absorption tests and a thermogravimetric analysis were performed for the hybrid composites. The results obtained, in comparison with those

The paper presents results of changes in the extreme values (minimum and maximum possible) of the tensile strength of threads and single filaments of an aramid fiber as a result of its processing by a suspension of carbon nanotubes in the production process. It is shown that the shift in the parameter of the Weibull–Gnedenko distribution for threads, which characterizes the point of fracture onset

A fractal model allowing one to theoretically estimate the shearing strength of the interfacial contact in a polymer-carbon nanotube system is proposed. It takes into account the structure of carbon nanotube surface and describes experimental data accurately enough. This makes the model promising for predicting the polymer/nanofiller contact strength. As a function of nanotube diameter and contact

For the first time, the effect of γ-radiation (with doses of 5, 10, 15, and 20 Mrad) on the structure and mechanical characteristics of a polymer composite material based on low-molecular-weight rubbers has been studied. It is shown that an increased radiation dose increases its breaking stress and decreases the breaking strain. The fracture energies are calculated from experimental values of the breaking

A modified Mori–Tanaka model to predict the average mechanical characteristics for dispersedly reinforced materials considering the physical nonlinearity, especially plasticity, of its constituents is proposed. A comparison of theoretical results with experimental data showed that this modification provides a sufficiently high accuracy of calculated estimates for parameters of the stress-strain state

Results of a work on evaluation of the effectiveness of promising vibration diagnostic technologies on the basis of an operating helicopter with an experimental system for monitoring the state of structures are presented. To move towards a practical application of the monitoring system based on the Operational Modal Analysis (OMA), it is necessary to assess its ability to distinguish actual defects

Aiming at the phenomenon of delamination and serious tool wear when processing carbon-carbon composite materials by traditional mechanical tools, an abrasive water jet reaming process for carbon-carbon composites is proposed. First, the carbon-carbon composite material is prepunched by a certain method, and then the abrasive water jet is used for cutting and reaming. The internal stresses and interlayer

Experimental tests and numerical studies were performed to investigate the burst performance of thermoplastic composite pipes (TCPs) under internal pressure. A progressive damage model is established to predict the burst behavior of TCPs, in which different failure criteria and the damage evolution of a composite material are considered and directly incorporated into the ABAQUS with a user-defined

Fibre-reinforced polymer (FRP) composite materials are widely used in different branches of industry, especially in aerospace, owing to their low mass, high strength and stiffness, and good fatigue and corrosion resistance. However, these materials are prone to the impact damage. Especially dangerous are barely visible impact faults, since it is difficult to detect them. If left unrepaired, they can

The power spectral density (PSD) of an equivalent stress is proposed to analyze the fatigue life of composite laminates under random vibration loadings using the Tsai–Hill criterion. The vibration fatigue life can be estimated based on the rainflow amplitude probability density function p(S) of the equivalent stress, which is obtained from this PSD, combined with the S-N curve of the materials. The

Particleboards based on a mixture of grey alder (Alnus incana (L.) Moench) wood particles (sieve fraction 0.4-2 mm) and 15 or 25% of lignin powder obtained by hot pressing from four different industrial sources were investigated. Their density, thickness swelling, water absorption, modulus of rupture, modulus of elasticity in bending, and internal bond strength were determined. It was founded that

The paper presents a review of Haar wavelet methods and an application of the higher-order Haar wavelet method to study the behavior of multilayered composite beams under static and buckling loads. The Refined Zigzag Theory (RZT) is used to formulate the corresponding governing differential equations (equilibrium/stability equations and boundary conditions). To solve these equations numerically, the

The critical buckling load for a FGM plate under a linearly distributed in-plane load is determined. Material properties of the plate vary exponentially across its thickness. The Ritz method is used to solve the equations formed according to the 3D linear elasticity theory. The effects of different material compositions and dimensions of the plate on its critical buckling load and mode shapes are investigated

The effect of different frequencies on the glass-transition temperature, storage and loss moduli, and damping of untreated and sodium bicarbonate-treated sisal fibers reinforced biocomposites have been analyzed in the temperature range of 30-160°C. In addition, tensile and flexural properties of these composites were also studied as per ASTM standards. On the basis of the results obtained, it is concluded

In the paper, the averaging method was used to determine the effective elastic moduli of dispersed B4C/2024Al composites and porous geomaterials using 2D and 3D X-ray images of their internal structure. A comparison of calculated values of Young’s modulus with experimental data showed that the use of 2D models of the real structure led to underestimated values of Young’s modulus, especially for porous

The analytical solution of the bending problem for a clamped rectangular plate with a variable in-plane stiffness is found by using the method of superposition. The flexural rigidity of the plate varies across its width according to an exponential function. First, the analytical solution for a simply supported rectangular plate with a variable in-plane stiffness is obtained, and then the bending problem

A mathematical model and a technique for evaluating the technological process parameters to obtain superthin prepregs by flattening carbon tows impregnated with an epoxy binder have been developed. It is recommended to simultaneously roll 25-50 carbon tows containing 400-600 monofilaments by rolls 50-100 mm in diameter, which is conceptually and technically consistent with possibilities of the existing

The bending stiffness of carbon/epoxy and glass/epoxy cross-ply laminates with intralaminar cracks in the surface 90° plies and local delaminations were studied experimentally using 4-point bending tests. The bending stiffness is defined as the slope of the relation between the applied bending moment and the corresponding midplane curvature. To measure the midplane curvature of laminates with different

Two types of thin impact indicator films were developed: made of an epoxy composite with hollow glass microspheres and of a selfadhesive thermoplastic with retroreflective microprisms. They are highly sensitive to local impacts and change the intensity of light reflection in damage zones. Experimental investigations into the residual strength of a GFRP plate covered with indicator films and resting

A computational model describing crack formation in a fibrous composite is developed. It is assumed that, upon repeated loading, crack formation in the composite leads to its fracture. Determination of the unknown parameters characterizing an initial crack is reduced to solving a singular integral equation. A closed system of nonlinear algebraic equations whose solution allows one to predict crack

A dynamic analysis of the behavior of sandwich beams with a viscoelastic core under the action of a moving load is performed considering their geometrical asymmetry. The use of viscoelastic materials integrated into structures in front of the moving load is considered as a new suggestion to enhance their stability. A high-order theory, taking into consideration longitudinal and rotational inertias

The work presented is devoted to the axisymmetric contact problems on the interaction of a rigid stamp and an elastic layer fixed on a porous elastic half-space by using the Cowin–Nunziato model. It is assumed that the stamp basis has a flat or parabolic shape and friction is absent in the contact zone. With the help of the Hankel integral transform, the problems stated are reduced to solving integral

The application of asymmetric composite materials in such adaptive structures as fan blades, fixed-wing aircrafts, and tilting rotors can lead to more deformation modes and good mechanical properties still remaining hygrothermally stable. But the influence of the extension-bending coupling effect on their mechanical properties is unknown. The wing skin is taken as an example to obtain a variety of

Two optimization problems are formulated to improve the effectiveness and productivity of pultrusion processes, to preserve the quality of pultruded profiles, and to take into account the ambient industrial shop temperature and requirements of process technologists. To solve these problems, an optimization methodology using designed computer experiments and the response surface technique was developed

A progressive interlaminar damage model, based on the Northwestern University theory and a trapezoidal trilinear traction-separation law, is presented to predict the initiation and propagation of delamination in layered composites under Mode I and Mode II loadings. The capability and reliability of the damage model proposed is assessed by comparing its results with experimental data. It was found that

A photo-optical and radiophysical study into the destruction process of the internal structure of plexiglass (PMMA) after its exposure to an ionizing electron irradiation and a subsequent external mechanical point impact was carried out. Enlarged macrophotography of the picture of the radiation-mechanical internal destruction of plexiglass was performed at different shooting modes. An analysis and

During the curing process of thermoset composites, residual stresses inevitably develop in them and lead to their curing deformation after the manufacturing process. This work was aimed at investigating the effect of tool–part interaction and bending stiffness on the curing deformation of L-shaped composite structures. Therefore, a twostep calculation model was developed. It consists of a numerical

Electrorheological elastomers (EREs) have viscoelastic properties controllable by external electric fields. For their application, it is necessary to investigate the rheological properties of EREs under various loading conditions. In this work, anisotropic EREs based on a silicone rubber with 10 wt% of PI-Na polyimide particles oriented in an electric field were first obtained. Their elastic properties

Advances in the additive manufacturing (AM) processes have opened up the possibilities of widely using them in various structural sectors. Since 1980s this technology has been in permanent mutations. The ramification of the AM technology makes it difficult to obtain a clear impression of its potentialities. Predicting and controlling the mechanical characteristics of printed products is crucial for

The analytical solutions of supersonic flutter of porous functionally graded plates are investigated. The material properties of the plates (stiffness and density) vary according to a power law across the thickness and axial coordinates depending on the volume fraction of constituent materials. Their equilibrium and stability equations are derived based on the classical plate theory. The solution of

The static compression of porous aluminum specimens, with free vertical surfaces fixed in a cylindrical holder, was investigated both theoretically and experimentally. Calculation were performed using the principle of 3D similarity of the stress-strain state in structural elements of constructions. Such an approach allows one to take into account the nonuniform distribution of stresses and strains

The optimal stochastic distribution of carbon nanotubes (CNTs) in nanoreinforced polymer composite of a cantilevered microbeam is investigated. Finite-element simulations of the CNT-reinforced microbeams were conducted to obtain data for training an artificial neural network to construct a surrogate model. This model was then used in an optimization routine to determine the optimal CNT distribution

To model the deformation of fabric polymer composite materials highly nonlinear in tension along the warp/weft threads, an analytical approach is proposed. Based on experimental data and the method of a deformable polyhedron, a tool is developed for an efficient selection of parameters for the model of a fabric composite consisting of equivalent orthogonally stacked unidirectional layers. A new version

Based on the method of sampling surfaces, a hybrid finite-element model is developed for a three-dimensional analysis of laminated composite plates with piezoelectric patches. According to this method, the sampling surfaces inside the layers and piezoelectric patches parallel to the middle surface are selected, and displacements and electric potentials of these surfaces are introduced as unknown functions

Systems of equations are obtained to study the onset of panel flutter of a composite shell with a linearly varying thickness. Using a model developed, the critical flow-over speed, corresponding to the onset of flutter, as a function of thickness difference between the left and right ends of the shell is calculated for various values of the axial compressive force and shell length with and without

Based on the classical laminate theory and proceeding from the necessary and sufficient conditions for the hygrothermal stability of materials, interlayer hybrid extension-twisting coupled free-layer laminates are designed. Then, analytical solutions for their yield and buckling strengths are derived. A mathematical model for the optimum design of composite structure is established to realize a synchronous

Up to now, the notched strength of a composite laminate containing an inclined elliptical hole at its center has not yet been predicted by researchers due to the absence of an appropriate failure criterion and an analytical solution. In this study, this problem is tackled by using a finite-element-based procedure, developed previously by the authors, together with a modified point stress criterion

Reliable accelerated testing routines involving tests at enhanced temperatures are of paramount importance in developing viscoelastic models for polymers. The theoretical basis, the time-temperature superposition (TTS) principle, is used to construct master curves and temperature-dependent shift factor, which is the necessary information to simulate the material response in arbitrary temperature and