In a geometrically linear formulation based on the use of variation principles of elasticity theory, the twodimensional equations of statics and the boundary conditions at the edge of an orthotropic bending plate are obtained within the framework of the classical theory and two low-order nonclassical theories: Reddy–Nemirovskii and Margueere–Timoshenko–Naghdi ones. It is shown that using the hypotheses

An attempt has been made to perform a comparative study on advances in the shear deformation theory for analyzing the statics and dynamics of different plates with the use of numerical examples. Initially, shape functions for the displacement field across the plate thickness are compared, and then, the stresses, deflections, and natural frequencies of laminated composite plates are also compared.

The influence of imperfect contact conditions between layers of a hollow sandwich sphere on its natural frequencies is studied. It is assumed that the materials of face layers are the same, but different from the core layer material. Each layer is made of a homogeneous isotropic material and has a constant thickness. Investigations are performed using a piecewise homogeneous body model with the use

A linear free vibration analysis is presented for computing the natural frequencies of a grid-stiffened carbon-nanotube-reinforced composite cylindrical shell. The carbon nanotubes (CNTs) are supposed to be oriented unidirectionally across the shell thickness, and the elastic moduli of the CNT-reinforced polymer composite are calculated using a modified rule of mixtures. In order to obtain the equivalent

The stochastic eigenvalue problem for free vibrations of functionally graded beams with a random elastic modulus is investigated. The effective material properties and beam cross section are assumed to vary continuously in different directions according to the exponential law. The governing equations for the natural frequency of the functionally graded beams are derived from Hamilton’s principle. In

For a carbon-fiber-reinforced plastic made of an ELUR-P unidirectional tape and an ХТ-118 cold-cure binder, specimens with a ±45° stacking sequence were tested for cyclic tension. The total axial strain was considered as the sum of nonlinearly elastic, viscoelastic, and irreversible creep strains. Using the Abel creep kernel, it was found that, at instants of time shifted by values multiples of the

The main features of physical modeling of the delamination growth rate in layered composites in tensile loading are considered. To estimate this rate, an equation in the form of the well-known Collipriest equation, which is widely used in estimating the crack growth rate in metal materials, is proposed. The values of empirical constants of the equation for a quasi-isotropic [45/90/-45/0]S XAS/914 carbon/epoxy

The hoop tensile strength of a composite pipe was measured experimentally using the split-disk test method. Then, a finite-element modeling was performed to simulate the split-disk test, and the progressive damage modeling was carried out to predict the maximum load the ring specimen representing the hoop tensile strength can carry. The progressive damage modeling was utilized in the context of continuum

A method for the ultrajet diagnostics of products made of composite materials is presented. It makes it possible to simulate, in an accelerated regime, the fatigue tests of materials and to estimate the adhesion strength of the fiber-filler bond under alternating loads. A hydroerosion model of the diagnosed surface under the operation of sequentially conjugate ultrajet actions by various working hydraulic

The improvement of Mode I fracture toughness of epoxy by the addition of single-walled carbon nanotubes (SWCNTs) is considered. To prepare nanocomposites, chemical-vapor-deposition-grown SWCNTs noncovalently functionalized with an ethoxylated alcohol was used as the additive and a diglycidyl ether of bisphenol-A-based epoxy as the matrix material. The SWCNTs were dispersed in the epoxy matrix via a

Structural models of hybrid fiber composites orthogonally reinforced in the plane are constructed. They allow one to calculate the yield loci taking into account the plane stress state in all composition components with different tensile and compressive yield stresses. Materials of the components are homogeneous and isotropic, and their mechanical behavior is described by the associated flow rule for

The role of fiber reinforcement architecture in adjusting the mechanical properties of glass-fiber-reinforced epoxy composite materials is studied. Fibrous E-glass unidirectional (UD) and 3-dimensional (3D) samples with an identical fiber volume fraction were prepared. The UD composites displayed excellent properties along the fiber direction, but the 3D ones showed excellent properties in all three

The static performance of a composite type 4 CNG cylinder was investigated using a finite-element simulation and experimental validation. This cylinder involved a liner hoop wrapped with a fiber impregnated by a suitable resin. Tensile tests were performed on standard specimens to examine the mechanical properties of the composite material. Next, a finite-element simulation was performed to determine

In a geometrically linear formulation based on the use of variational principles of elasticity theory and the generalized Galerkin method, three approaches to constructing equations of static bending of orthotropic plates with a constant thickness are considered. The displacements of plate points are approximated by polynomials in the transverse coordinate with unknown coefficients of expansion. The

The impact behavior of hybrid composite plates cured at 120°C were examined by dropping weights on them for three hours. Two groups of hybrid composite plates were considered. In the first group (TYPE1), all plies were staked symmetrically or antisymmetrically with orientation angle 0°, but in the second group (TYPE2), plies were staked symmetrically or antisymmetrically with orientation angles 0°

The effect of nanosize alumina (Al2O3) concentration on the morphology and mechanical properties of microfibrillar composites obtained by processing the thermodynamically incompatible polypropylene/ copolyamide (PP/CPA) blend was studied. It was established that composite monofilaments exhibited a selfreinforcing effect due to the in situ formation of PP fibrils (microfibers) in the CPA matrix. The

Drop-weight tests were conducted to investigate the impact responses of carbon-fiber-reinforced composite laminates under low-velocity impacts. A finite-element model is proposed to describe the failure during impacts. The impact damage behavior of composite laminates with different thicknesses were simulated to analyze their energy absorption ability, and a method for its prediction is presented.

Results of experimental investigations into a unidirectional composite of basalt fibers and epoxy resin used as part of high-voltage electric wires are presented. Tensile tests of BFRP specimens previously held wrapped around a transportation drum during 10 h were carried out. The influence of the keeping time of the BFRP core in the composition of a high-voltage electric wire on drums of diameter

Experimental results are presented on the onset and propagation of local delaminations caused by the interaction between specimen edges and intralaminar cracks in fiber bundles of 90° layers in quasi-isotropic [–45/90/45/0]s CF/EP noncrimp fabric (NCF) laminates subjected to tension-tension fatigue loadings. It is confirmed that the first damage mode is intralaminar cracking in 90° layers, which consists

For the first time, the influence of microwave radiation on the structure of a three-dimensionally cross-linked, plasticized, filled polymer composite material based on low-molecular rubbers — a polydivinyl epoxyurethane rubber of grade PDI-3B and a divinyl rubber of brand SKD-KTR — was investigated. It is shown that variations in the mechanical characteristics of the composite material during irradiation

The effects of metakaolin (MK) and basalt fiber (BF) on the performance of gypsum-based composites were investigated. BFs 6 and 12 mm long were used in concentrations of up to 0.8 wt.%. Mechanical tests were conducted on both dry and water-saturated specimens. It was found that their flexural and compressive strengths increased with content of BFs to 0.6%. However, the mechanical and durability properties

The conventional wood-based composites contain an unreacted free formaldehyde, which causes a cancerous effect on humans. To overcome this problem, citric-acid-modified corn and oil palm starches are proposed as ecobinders for wood-based composites in this study. Experimental rubber-wood panels were made using the ecobinders. The panels were subjected to FT-IR, TGA, DSC, and X-ray diffraction analyses

The classical methods of surface damping of bending vibrations of thin-walled structures and a promising integrated version with a damping coating consisting of two layers of a material with pronounced viscoelastic properties and an intermediate thin reinforcing layer of a high-modulus material are discussed. A four-layer finite element for an elongate plate with an integral damping coating is developed

In this work, transmission electron microscopy (TEM) and Raman spectroscopy were used to assess the dispersion quality of carbon nanotubes (CNTs) in an epoxy matrix. Its ultimate tensile strength (UTS), engineering strain, local strain, and the elastic tensile modulus were determined experimentally. The effect of CNT sonication time in an ethanol medium was also evaluated. A statistical analysis using

A method is proposed for calculating the near-surface effect in piecewise homogeneous bodies under large deformations based on a combined use of one-level applied and two-level carcass theories. The applied theory is used for a macromechanical continuation of the solution of the problem, but the carcass theory is used in the final part of the loading path or directly at the final loading of the body

For the real time characterization of pultrusion processes with a complex temperature control, two finite-element modeling approaches utilizing a continuous model with lumped material properties for a cured composite have been developed. The first procedure, based on the mixed time integration scheme and the nodal control volumes method, is working in the ANSYS Mechanical environment, but the second

A finite-element (FE) model simulating the elastic behavior of anisotropic glass/epoxy composite laminates subjected to a biaxial tensile loading is proposed. A progressive failure prediction and analysis are performed in the ABAQUS FE code by using user-defined constitutive equations. A numerical analysis is performed for different loading ratios and ply angles. Gradual failure patterns of fiber and

An acoustic method for a quantitative assessment of the volume content of a polymeric matrix in CFRPs is proposed and realized experimentally. For this purpose, a laser-ultrasonic method based on the thermo-optical excitation of broadband pulses of longitudinal acoustic waves is used. A formula for calculating the volume content of the polymeric matrix in a CFRP from experimentally measured phase velocities

The present paper deals with the four-point bending of polyvinyl chloride beams reinforced with glass fiber clusters. The clusters, treated as orthotropic materials, were arranged periodically along the longitudinal axis of beams. The load-carrying capacity of the beams was estimated by two methods. In the first method, the beam strength was assessed using the Max-Stress, Max-Strain, Tsai–Wu, Inverse

Various composite materials used as biomaterials were tested by 20-, 50-, and 80-N chewing forces in distilled water and a poppy seed medium by using a computer-controlled chewing simulation procedure. In each chewing test, steatite balls 6 mm in diameter were used as an antagonist material. The mean volume loss of worn surfaces and the surface roughness of the composite materials was measured with

In this review, the characteristic temperatures for epoxy polymers and epoxy matrices of fiber-reinforced composites in the glass-transition ( α-transition) range determined using different methods of thermal analysis (DSC, DMA, and TMA) are compared. The influence of loading frequency in the DMA method and of uniformity of heating and postcuring of specimens in all the methods is revealed. The agreement

The results of studies into the influence of the thickness of a polystyrene shell applied to surfaces of dispersed corundum (Al2O3) filler particles on the structure and mechanical properties of the composition of an acrylonitrile butadiene styrene plastic are presented. It is shown that the mechanical properties of the composition depend at least on two factors: the interaction between shell molecules

Commercial γ − Al2O3 particles, Al2O3 n, and synthesized Al2O3 doped with iron oxide (Al2O3 Fe) were used as reinforcements to enhance the toughness of an unsaturated polyester resin (UPR). Alumina modification with vinyl, Al2O3 (n, Fe)–VT, and methacryloyl, Al2O3 (n, Fe)–ME functionalities contributed to the increase in the extent of covalent binding at the UPR/filler interface. Tensile tests showed

An exact analytical solution of the problem on plane elastic bending of the segment of a narrow multilayer beam under the action of arbitrary normal loads distributed over its longitudinal faces is presented. It is assumed that the beam deforms elastically, its layers are made of orthotropic materials homogeneous or continuously heterogeneous across the thickness of layers, which are rigidly connected

A lateral buckling analysis of simply supported web- and/or flange-tapered I-beams made of axially functionally graded materials and subjected to a uniformly distributed load is performed. The properties of beam material vary continuously along the beam axis, depending on the volume fraction of constituent materials, according to an exponential or power law. Considering the coupling between the lateral

A technique for the numerical homogenization of plastic deformation of unidirectionally reinforced composites is developed. A modification of Prandtl–Reuss theory that takes into account the influence of the first invariant of stress tensor is used as governing relations for an equivalent orthotropic material. The isotropic hardening is described by a function depending on the work of plastic deformation

The internal friction spectra λ = f (T) were obtained experimentally and the frequency of the free damped vibrational process v = f (T) was determined for an excited polyvinyl alcohol-chitosan system on the temperature interval of –150-250°C. Theoretically analyzed is the possibility of using the Maxwell function to describe the local dissipative processes observable on different temperature ranges

The self-heating effect occurs during cyclic loadings or vibrations of composite elements, which may significantly intensify their structural degradation due to a rapid temperature increase. For minimizing this influence, the air cooling can be used. In this study, the influence of air cooling on the fatigue and residual life of a cyclically loaded structure was investigated by analyzing the self-heating

Considered are two types of multistage cyclic block loading rather common in the practice of fatigue tests and fatigue life predictions for layered polymer composite materials: block loading by four-stage cyclic regular zero-tension loads and block loading by multistage (8-10 levels) asymmetric cyclic loads. In order to improve the prediction accuracy for the fatigue life of carbon-fiber-reinforced

The low-velocity impact behavior of polypropylene- core-based sandwich composites reinforced with basalt/epoxy facesheets was investigated by drop-weight impact tests. The impact resistance of composite samples was characterized for various impact energies according to ASTM standards. Also, the effect of facesheet thickness was explored, and the failure and fracture surfaces around the impacted region

The necessary composition and content of fillers of a multicomponent extrudable composition based on an ultrahigh-molecular polyethylene (UHMPE) with specified mechanical and tribotechnical characteristics are determined. For the purpose of effective and operational development of extrudable composites based on an UHMPE, a minimum amount of experimental data and an algorithm for determining the governing

This work is the result of experimental research conducted to determine the contribution of a composite material to improving the mechanical behavior of old, full-size reinforced T-beams in operation conditions under the action of short-term loads. The tension side of their ribs were strengthened by carbon strips of different lengths. Then, they were tested in loading by concentrated and uniformly

The aim of this study was to experimentally determine the creep and shrinkage properties of plain geopolymer and carbon-fiber-reinforced geopolymer concretes. The creep properties of concrete specimens were determined by loading them by 20% of their ultimate stress. The specific creep of the geopolymer concrete was in the same range as that of the ordinary Portland cement — 0.00065 1/MPa. New information

The purpose of this pilot study was to create a mathematical model for the composite rotor blade of a light multipurpose helicopter by using an optimum combination of known solutions and to perform static and dynamic tests on prototypes of the blade for validation of the model. The emphasis is on some solutions used in designing the blade and on their reflection in the model. The article describes

A refined formulation is presented for linearized problems on internal multiscale spatial buckling modes of a fiber or fiber bundle — the structural elements of fibrous composites — that is in a subcritical (unperturbed) state under the action of shear and tensile (compressive) stresses in the transverse direction. Such an initial stress state is formed in fibers and fiber bundles in tension and compression

The problem of local buckling delamination around interface edge cracks in a sandwich PZT/Metal/PZT rectangular thick plate is studied within the scope of the 3D linearized buckling instability theory. Crack faces have an insignificant initial imperfection, and the plate is compressed by uniformly distributed normal forces acting on two opposite ends of the plate. The evolution of the initial imperfection

The nonlinear buckling and postbuckling of eccentrically oblique-stiffened doubly curved shallow functionally graded shells is investigated based on improved Donnell equations. The improved Lekhnitskii smeared stiffeners technique is employed to found the stiffness matrix of the stiffened shells. The shells are reinforced by eccentrically oblique stiffeners with an arbitrary inclination angle. Using

Models for unidirectional fiber-reinforced hybrid composites of a regular periodic structure that allow one to determine the yield loci for fibrous composites are constructed. The plane stress state in all components of compositions having different tensile and compressive strengths is considered. Components of the compositions are homogeneous and isotropic, and their mechanical behavior is described

In the first part of this survey, T. D. Shermergor’s works on the use of the confluent hypergeometric function of the first kind for describing asymmetric relaxation spectra are considered. The second part is devoted to the works of Soviet authors of the past (20th) century on this topic.

The interface/interphase is modeled by distributed springs, and the degree of interface damage is characterized by the flexibility coefficient of the springs. Considering different degrees of damage at different interfaces, a general dispersion equation by the transfer matrix method was obtained. For the purpose of application, the transmission coefficient of finite-period phononic crystals is also

Methods of composite mechanics were used to evaluate the effective elastic moduli and Biot’s parameter of porous media. Natural composites — dolomites and hyaloclastites — were considered as examples, which were also examined experimentally. The microscopic structure of the rocks was studied under a microscope, and their mineral composition was determined by the X-ray diffractometry. A comparison of

Basalt-fiber-reinforced epoxy (BFRE) composite laminates fabricated using the vacuum infusion process were subjected to axial compression to assess their buckling behavior. The buckling responses of open-hole specimens were compared with those of plain ones. ABAQUS finite-element predictions of BFRE composite buckling agreed well with experimental results. A validated numerical model was used to perform

Compositions of unidirectional short boron fibers and titanium, magnesium, and aluminum matrices are considered. The Rosen and Kelly parameters (the ineffective and critical lengths) characterizing the interaction of short fibers and the matrix are studied. These parameters as functions of material characteristics of components of the composites are established on rectangular (with a 2D reinforcement)

The paper discusses a method for measuring changes in the electric resistance of a unidirectional carbon-fiber-reinforced plastic (CFRP) to detect an internal delamination. A numerical solution was obtained by the four-probe method for measuring the electric resistance. The influence of distance between electrodes on the efficiency of delamination detection was investigated. The problem was solved

A 3D buckling delamination problem for a simply supported rectangular orthotropic composite thick plate containing a rectangular crack and subjected to an axial compressive force is studied. In the initial state, crack faces have an infinitesimal imperfection. The development of this imperfection caused by an external compressive loading along the crack is investigated within the framework of the 3D

Analytical solutions of the problem on free vibrations of an orthotropic cuboid with free faces, based on the use of trigonometric functions as base ones in all three directions, are constructed. It is established that the solutions obtained describe the purely shearless vibration modes occurring in the body considered at particular ratios between its faces and physicomechanical characteristics of

A plane inverse fracture mechanics problem for a composite in bending is considered. Its binder is weakened by rectilinear cracks located arbitrarily near fibers. To determine the optimum tightness of fiber-binder connection that reduces stress concentrations at the interface of material joints and minimizes the fracture parameters (stress intensity factor) of the composite, a theoretical analysis

Using a system of equations corresponding to the classical theory of orthotropic cylindrical shells, the free vibrations of a thin elastic orthotropic cylindrical panel with free edges is investigated. To calculate its natural frequencies and to identify the respective vibration modes, the generalized Kantorovich–Vlasov method of reduction to ordinary differential equations is employed. To find the

The problem on constructing new time-effective characteristics of a linear viscoelastic body is considered. The initial medium is modeled as a viscoelastic composite. One its part has properties determined by time-effective moduli of the Lagrangian type, but the other part has properties determined by moduli of the Castigliano type. This model makes it possible to employ the methods of mechanics of

The destruction of silicone composites irradiated by accelerated electrons is investigated. Experimental results showed that, at irradiation doses of the order of 103 Gy, the mechanical strength of silicon—organic composites is significantly reduced, and doses of the order of 106–107 Gy, their total destruction occurs. This phenomenon was investigated theoretically using a mathematical model for calculating