Abstract A multilevel mathematical model is proposed for studying the technological processing of metals and alloys by severe plastic deformation. The model is based on crystal elasto-viscoplasticity and can describe the evolving structure as well as predict crystallographic texture formation. A geometrically nonlinear nonstationary boundary value problem of quasi-static elasto-viscoplastic deformation

Abstract The present study is devoted to tensile modulus of recycle PET/clay nanocomposites based on the various conventional models. Some models such as Paul and Takayanagi provide good results, when compared with the experimental data. Hirsch model predicts more accurate data by the x value of 0.1 revealing that the tensile modulus of current nanocomposites conforms to the inverse rule of mixture

Abstract Although fracture mechanics offers a way to assess the probability of fracture in materials with critically stressed notches, its criteria can hardly account for complex configurations of structures (e.g., welded ones), residual stresses, and inhomogeneity of material properties. Besides, the use of strength criteria accounting for local plasticity requires special tests. Therefore, strength

Abstract In this work, Reddy beam theory is used with the nonlocal differential constitutive relations of Eringen, and the equations of motion of the protein microtubules in terms of the generalized displacements are presented. Analytical solution of bending the protein microtubules is presented to bring out the effect of the nonlocal behavior on deflections. The theoretical development as well as

Abstract In this study, the ability of two criteria, the maximum tangential strain energy density criterion and the maximum tangential strain criterion for sharp V-shaped notches, were evaluated. These two criteria in the crack can be employed within the entire range of the mixed-mode loading from pure mode I to pure mode II and provide acceptable results. However, these criteria have been less examined

Abstract This paper aims to present free vibration of porous functionally graded thick rectangular plates using a quasi-3D refined theory. This theory considers the thickness stretching effect for vibration analysis of porous plates. It is assumed that the material properties of the porous plate are varying across the plate thickness according to a modified polynomial material law. The equations of

Abstract The paper proposes a simple two-layer model to assess the behavior of a heat-loaded thermal barrier coating–substrate system with neglect of thermally grown oxide and bond coat. The model includes solutions of boundary value problems of thermal conduction, thermoelasticity, stability, and stress-strain state after stability loss, and it also provides for coating delamination from the substrate

Abstract Fracture behavior of VT22 near β titanium alloy produced by radial shear rolling and subsequent aging was studied in very high cycle fatigue tests with ultrasonic vibration frequency. This type of processing was shown to significantly increase the static and fatigue strengths of the alloy. According to fractographic analysis, the transition from very high cycle to high cycle fatigue failure

Abstract In this article, the effect of the magnetic field, initial stress, rotation, and nonhomogeneity on the radial displacement and the corresponding stresses in orthotropic material is investigated. The analytical solution for the elastodynamic equation is solved in terms of displacements. The variation of stresses, displacement, and perturbation magnetic field have been shown graphically. Comparisons

Abstract The constitutive equations of strain gradient plasticity were applied to numerically analyze the combined effect of material plastic properties, the type of stresses, and the Taylor parameter of material structure on the stress fields and dislocation densities at the crack tip. It was found that taking into account the influence of the intrinsic length scale parameter leads to different levels

Abstract Epoxy resins are one of the most commonly used class of materials in polymeric composite industry. One of their main weak points is their vulnerability to moist and hot environments. In this paper, the effect of hydrophilic Fe2O3 nanoparticles, hydrophobic graphene-oxide nanoplatelets (GONPs) and a hybrid of both was experimentally studied on the moisture absorption and mechanical properties

Abstract Mechanical properties of multidirectional fiber-reinforced composite laminates are dispersive and random, and these uncertainties cause difficulties in safety design of structures. So, it is necessary to analyze the sensitivity of uncertain material properties on failure of structures. In this paper, sensitivity analysis of uncertainties for composite laminates with different stacking sequences

Abstract Previously, an algorithm based on two control parameters was applied to computer aided design of materials, and here the algorithm is extended to three parameters controlling the effective physicomechanical properties of polymer matrix composites: (i) the average particle size of a polymer powder, (ii) the length of reinforcing fibers, and (iii) the level of fiber–matrix adhesion. The use

Abstract In the framework of the theory of anisotropic elasticity, a theoretical analysis of the out-of-plane extension of thin two-layered plates of hexagonal crystals is carried out. The six-fold axes of all pairs of crystals are assumed to be perpendicular to the plane of the plates. Formulae for effective Young’s modulus and effective Poisson’s ratio are obtained. It is shown that in most cases

Abstract Researchers have investigated the effects of different nanoenhancers on the physical properties of polymer-based nanocomposites. However, the effect of resin type on the properties of nanocomposites reinforced by multiwalled carbon nanotube (MWCNT) has not been studied very well. This study aims to understand the link between the nature of polymer as the base material for nanocomposite and

Abstract Doppler laser interferometry is used to measure the transient time between the slow quasi-stationary stage of damage accumulation in rock samples to the ultrafast catastrophic stage of failure as well as the duration of the autocatalytic stage of macroscopic fracture. Small rock samples are tested for compression and three-point bending, and the velocity of displacement of their lateral surfaces

Abstract This work is an overview of studies on the determination of the elastic characteristics of nanomaterials published over the past 20 years in peer-reviewed Russian journals. It is known from the literature that changes in the characteristic size of nanomaterials lead to multiple changes in their properties, which must be taken into account when creating specific nanoparticle-filled structures

Abstract The paper proposes a thin shell model based on moment elasticity with independent displacement and rotation fields for shear-plus-rotation deformation. Assuming that the shell walls are thin and that all displacement and rotation vector components through the shell thickness are constant, the model gives a uniform through-thickness distribution of the main stress and couple stress tensor components

Abstract Deformation behavior of polycrystalline titanium was studied by numerical simulation in the micromechanical and crystal plasticity frameworks. A three-dimensional model of a polycrystalline structure was generated by the step-by-step packing method based on experimental data. The constitutive equations describing the deformation behavior of grains were derived on the basis of crystal plasticity

Abstract The change in the spectra of elastically and discretely scattered electrons in Ti–6Al–4V alloy subjected to radial shear rolling at T = 1000°C was studied in comparison with the initial state. Interatomic bonds in the equilibrium α phase of the alloy are formed by Al sp electrons, and their contribution is small. Quenching after radial shear rolling at T = 1000°C causes the formation of a

Abstract TEM and X-ray diffraction studies were carried out to examine changes in the structure, phase composition, and defect substructure in the head of a differentially hardened rail after 691.8 and 1411 million gross tons (MGT) of traffic. The rail material was examined along the central axis of the head and along the gauge corner radius at distances of 0, 2, and 10 mm from the tread surface. The

Abstract The present paper analyzes the tensile modulus in a toughened ternary nanocomposite containing a thermoplastic, an elastomer and nanoclay. The unsuitable predictions by simple models reveal the effect of various parameters on the modulus of nanocomposites such as the size and shape of nanofiller and the characteristics of interphase section. Therefore, the effect of interphase is taken into

Abstract Many models are used for the analysis of tensile modulus in cross-linked polyethylene/clay shape memory polymer nanocomposites. The conventional models such as modified rule of mixtures, Guth, Paul, Counto, Kerner–Nielsen, etc. underestimate the modulus exhibiting that the reinforcing effect of nanofiller should be considered for the estimation of tensile modulus in the shape memory nanocomposites

Abstract The fracture behavior of Ti0.45Al0.55N coatings under uniaxial tension was investigated at different scale levels. The coatings were deposited on 12Cr18Ni9Ti steel substrates by direct current reactive magnetron sputtering. According to molecular dynamics simulation, the nonuniform distribution of aluminum in the coatings affects the initiation and growth of cracks in them. It was found experimentally

Abstract After hot rolling and multipass cold rolling experiment, the hot rolled sheet and the sheets with reduction ratios of 20% and 40% of 301L stainless steel were obtained. The effect of cold rolling reduction ratio on microstructure of 301L stainless steel was investigated by metallographic analysis, XRD analysis and TEM analysis. The research shows that carbides precipitate along the austenite

Abstract The current paper studies the development of new models for the prediction of tensile modulus in metal/carbon nanotubes (CNTs) nanocomposites. Several composite models such as the Hirsch, Hui–Shia, developed Halpin–Tsai for 3D fillers and Lewis–Nielsen models can present appropriate predictions compared to experimental results of a Cu/multiwalled CNTs (MWCNTs) sample. Furthermore, Takayanagi

Abstract The effect of the interface on the fracture of metal heterostructures under constant-rate uniaxial tension was investigated by molecular dynamics simulations. It was found that the presence of an interface aligned in the direction of the tensile loading axis leads to the strengthening of the sample. A cause of the observed strengthening is the inflow of atoms of one metal into the voids in

Abstract The paper analyzes the plasticity of deformed solids as a hierarchical translational-rotational system. The analysis shows that accounting for plastic rotation in addition to plastic translation, which is conventionally related to dislocation motion, radically changes the description of plasticity as a displacement gauge potential. With both deformation modes, and hence, with two-component

Abstract The paper provides a fractographic analysis of fatigue cracking in D16T aluminum alloy under very high cycle fatigue at a frequency of 20 kHz. The analysis shows that in the range of 2.8 × 108 to 5.1 × 109 cycles to failure, the material reveals cracks on and beneath its surface with their subsurface site developing through intergranular fracture at triple junctions or smoothly faceted transgranular

Abstract The study investigates an electron beam cladded coating of nitrogen-alloyed austenitic steel (24.4Cr, 16.4Mn, 0.18Ni, 1.1Si, 0.57С, 0.7N, rest Fe (wt %)). Cladding was performed by a continuous low-energy (27 keV) and low-current (0.02–0.04 A) focused electron beam on an electron beam system at a residual pressure of 0.1 Pa. The microstructure, phase composition, and chemical composition of

Abstract Mechanics of defects in solids across a wide span of length scales is commonly formulated using the dislocations theory. This paper revisits the classical problem of interaction between an elastic edge dislocation and a circular cavity. A heuristic, yet, mechanistic approach is taken to obtain the stress solution to this problem. The approach uses complex variable theory of elasticity, along

Abstract The paper discusses the basic principles underlying a new approach to the control of seismic activity in tectonic fault zones. A key component of the approach is the use of controlled man-made impacts on highly stressed fault segments. The applicability of the approach was verified in field experiments on seismically active fault segments of the Baikal rift zone and collision structures of

Abstract This paper numerically investigates the stress-strain behavior at the scale of the dendritic structure in an aluminum-silicon alloy additively manufactured by selective laser melting. The stress-strain state in the eutectic phase is studied under the assumption that the continuum mechanics principles are applicable on the scales considered. The averaged characteristics of the eutectic phase

Abstract The objective of this study is to improve the detection capability of eddy current testing by developing a novel eddy current probe. The developed probe is composed of six excitation coils made at different areas and suitably aligned with a single-axis sensitive DRV425EVM fluxgate sensor. The distribution of magnetic field intensity and eddy current density of the developed probe were calculated

Abstract Concrete is known for its low tensile strength. The difference between its compressive and tensile strengths can reach a factor of 15–20. Therefore, it is important to predict the behavior of concrete structures under various operating conditions and unexpected loads. This paper reports the numerical results on the fracture behavior of a high-strength concrete target struck by an ogival-nosed

Abstract Sandwich composites with nanoreinforced polypropylene core and aluminum face sheets were studied under low velocity impact using a finite element model. A three dimensional quarter model was implemented to simulate the drop weight impact response of sandwich structures. In order to consider the strain rate dependent behavior of the core and face sheets, the Johnson–Cook material model was

Abstract Recent experimental studies on spall fracture show that the impact parameters can lead to instabilities in the strain rate dependence of the dynamic strength of the material. Here we consider the effect of the dynamic impact parameters on the time dependences of the material ultimate stress. Numerical modeling of spall fracture is conducted for ultrapure aluminum. The stress-time relations

Abstract In this paper, the influence of graphene-oxide nanoplatelets (GONPs) on the response of the glass laminate aluminum reinforced epoxy (GLARE) under high-velocity impact loading was investigated. Different weight percentages of nanofillers including 0.25, 0.50 and 1.00 wt % GONPs and a hybrid of 0.25 wt % GONPs and 0.25 wt % multiwalled carbon nanotubes (MWCNTs) were used for reinforcing GLAREs

Abstract The main aim of this paper is to define the interfacial stress transfer parameter s in the Callister model using the Pukanszky model. The parameter s is expressed by the polymer strength, carbon nanotube (CNT) size, and interfacial shear strength. The developed equation is applied to plot the roles of all parameters in the value of s. The reasonable outputs of the developed equation show its

Abstract The abnormal behavior of monotonic stress-strain curves of aluminum alloys induced by the yield drop with increasing strain rate or decreasing temperature is considered based on the relaxation model of plasticity. The plastic deformation of 2519A and 2519A-T87 aluminum alloys within the strain rate range from 0.001 to 6000 s–1 and temperature range from –45 to 450°С is analyzed from the standpoint

Abstract The study explores the effect of helical rolling on the low-temperature impact toughness of pearlitic steel 09G2S. Helical rolling in two modes was performed at T = 850°C in six passes through rolls of varied diameters with air cooling (mode I) and water quenching (mode II). The tensile σ–ε curves at room temperature are characterized by parabolic strain hardening, without any specific behavior

Abstract The operating conditions of current highways require the development and implementation of new testing standards for pavement materials with regard to dynamic impact. Pavement materials have a complex hierarchical structure exhibiting a self-consistent response to load at different scale levels. The corresponding parameters of the phenomenological models used for macroscopic objects essentially

Abstract This paper deals with a mesomechanical modeling of fracture in concrete like quasi-brittle materials. The paper seeks to provide insight regarding the variation of the fracture process zone (FPZ) length during the cracking process. The correlation between the FPZ length and the crack extension is also investigated. The FPZ variation is investigated through the evolution of cohesive tangential

Abstract The paper studies the effect of the temperature of helical rolling, which creates nanoscale mesoscopic structural states in lattice curvature zones, on the low-temperature impact toughness of Ti–6Al–4V alloy. The polymorphic transformation temperature Tс = 950°C is shown to play the decisive role in this effect. The impact toughness is very high at helical rolling temperatures above Tс, while

Abstract The work studies the mechanical properties of chiral metallic nanotubes by the molecular statics method. The atomic structure of nanotubes was obtained by rolling up thin nanoplates from cubic crystals of copper, iron, aluminum, and cobalt with the (010) orientation at various chiral angles. It is shown that such nanotubes can experience torsion under tension and their Poisson’s ratio decreases

Abstract This study examines TiAlN and CrAlSiN coatings with a thickness of 0.8–4.0 μm deposited by plasma-assisted physical vapor deposition in vacuum on nitrided and carburized steel substrates. The coatings have different structural morphologies: a homogeneous monolayer structure, a multilayer structure with different-thickness layers, and a heterogeneous multiphase structure. A range of coating

Abstract The paper is a theoretical study of mechanically activated processes in tribocontact, which lead to the formation of a lubricating film between rubbing bodies. The adhesive aspect of tribofilm formation is considered using the condition of the mechanical activation of the friction surface. This condition is satisfied when the adhesion energy becomes greater than the cohesion energy. The Hamaker

Abstract The paper analyzes the evolution of microcracks in austenitic and carbon steels on evidence from our studies and literature data. The well-known Lotka–Volterra model, applied to competing processes of various nature, and the percolation model are used to describe the alternation of microcrack formation, growth, and coalescence providing a hierarchical damage structure.

Abstract The ball on beam system is a highly nonlinear laboratory model which helps to understand the modern and classical control theory. This paper emphasizes the position control of a ball on beam system which is actuated by shape memory alloy wires in an antagonistic configuration. The shape memory alloy actuator provides the necessary force to actuate the beam in the left and right directions

Abstract Equal channel angular extrusion is an extrusion to refine the microstructure of metals and alloys. This paper presents for the first time the experimental results on effects of the equal channel angular pressing (ECAP) on tensile mechanical properties and ductile fracture strength of 7075 Al alloy. The 7075 Al was subjected to equal channel angular pressing after solution treatment, and significant

Abstract Nonlocal elasticity assumes integral stress constitutive equation, takes into account interatomic long-range forces, reduces to the classical theory of elasticity in the long wave-length limit and to the atomic lattice theory in the short wave-length limit. In this paper, we propose the nonlocal elasticity theory with the kernel (the weight function in the integral stress constitutive equation)

Abstract In this study, the thermal stress distribution surrounding a quasi-triangular hole within a symmetric composite laminate made of various composite materials was investigated. A composite laminate exposed to uniform heat flux was analyzed using the complex variable method as a thermo-elastic two-dimensional problem under a steady state condition. The analytical solution was achieved with the

Abstract Acoustic emission activity under static loading of Pb–Sn alloys was studied in a wide range of alloy element concentrations. The strain rate dependences of the acoustic emission count rate were plotted in mechanical tests. The obtained experimental data revealed a significant change in the type of recorded acoustic emission signals depending on the alloy structure, determined by the content

Abstract Frictional damping in elastic contact of a parabolic indenter subjected to a combination of oscillations in normal and tangential directions is numerically simulated. The dissipated energy first increases linearly with coefficient of friction, then decreases linearly, and finally reaches a constant value. These three regions correspond to the states of complete slip, partial slip and complete

Abstract In this article, several models are applied to reveal the effects of volume fraction, thickness, strength and modulus of interphase region between polymer matrix and nanofiller on the Young’s modulus and yield strength of polymer nanocomposites. The properties of interphase are calculated for several samples by experimental data of mechanical properties. It is found that the concentration

Abstract This paper investigates the bending, buckling and free vibration behaviors of porous functionally graded curved nanobeams with different boundary conditions via a nonlocal strain gradient theory. The stresses are dependent on the strain gradients according to the nonlocal strain gradient theory. This theory contains both nonlocal and material length-scale parameters. The three-variable sinusoidal

Abstract In this research, the prevalent mode fracture of V-notches with end holes (VO-notch) in tungsten–copper functionally graded material (W–Cu FGM) was studied experimentally and theoretically. W–Cu FGM specimens were made by powder metallurgy technique in the experimental part. Several fracture tests were done on VO-notched W–Cu FGM specimens under prevalent mode loading for different notch tip

Abstract The possibility of the structural turbulence of plastic flow and ductile fracture in low-carbon and low-alloy steel 09Mn2Si is shown by fracture toughness measurements and uniaxial tension of chevron-notched specimens at 20°C. The conditions for the structural turbulence of plastic deformation of solids are determined which provide high fracture toughness. The decisive functional role is played

Abstract This paper studies the formation of cermet coatings by a combined additive manufacturing technology on the basis of cold gas dynamic spraying and subsequent laser irradiation. The coatings are made of titanium and nickel metal powders with ceramic particles of tungsten carbide and boron carbide. Optimal energy parameters are determined for coating deposition by cold gas dynamic spraying and

The effect of hydrogen charging, ultrasonic treatment, and hydrogen charging after ultrasonic treatment on the fatigue life of VT6 alloy is investigated. Ultrasonic treatment causes the formation of a continuous nonetching α2(Ti3Al) layer within the surface layer, which reduces the fatigue life. Below this layer there are bands of the α2(Ti3Al) phase which, on the contrary, increase the fatigue life