Abstract A mathematical model of Green–Naghdi photothermal theory is given to study the wave propagation in a two-dimensional semiconducting material due to moving heat source. By using the Fourier and Laplace transformations with the eigenvalues method, the physical quantities are obtained analytically. Initially, it is assumed that the medium is at rest and it is subject to a heat source in motion

Abstract In this work, a simple technique is suggested applying the simple models for Young’s modulus of polymer nanocomposites to calculate the Y interphase parameter and interphase modulus for multilayered interphase in polymer nanocomposites. The developed model is compared to the experimental results of several samples to examine its correctness. The effects of Y on the Young’s moduli of interphase

Abstract A model based on the concept of interface crack bridging and thermofluctuation theory is proposed for analyzing the efficiency of crack self-healing in composite materials in view of three main stages: (1) crack initiation and growth under external load, (2) self-healing activation, and (3) self-healing with partial or complete bond recovery between crack faces. A system of singular integro-differential

Abstract The present paper deals with the study of the wave propagation in a homogeneous transversely isotropic magneto-thermo-piezoelectric cylindrical material, under the influence of rotation, in the context of the linear theory of thermoelasticity. The displacement, electric potential, magnetic potential, electrostatic displacement, and magnetic induction functions are introduced to uncouple the

Abstract The plastic flow behavior of tensile specimens of ultrafine-grained 08G2B steel prone to strain aging was studied using digital image correlation, electron backscatter diffraction, and microindentation. Standard flat tensile specimens were tested with a constant strain rate in the initial state (after controlled rolling) and after controlled rolling + heating to 680°C for 30 min followed by

Abstract A model of in-plane graphene deformation is developed by considering a linear chain of atoms with regard to the independent moment interaction and noncentral force interaction between atoms. A discrete and continuous beam models of the linear chain of atoms are constructed. Assuming that each graphene atom interacts only with its nearest neighbors, the atomic system is replaced by a beam system

Abstract The paper analyzes the nucleation and growth of bainite in low-carbon low-alloy 09Mn2Si steel doped with titanium carbonitride nanoparticles in impact toughness testing. The analysis shows that such particles segregate at low-angle boundaries, retarding the formation of high-angle ones, and when impacted into the steel, they curve the lattice and generate a new bainite phase at the curvature

Abstract This study explores the effect of the radius of silver nanospheres and temperature on the total potential energy of the system as well as on the surface energy and energy of bulk atoms and binding energy of surface and bulk atoms. An approach is developed for calculating the surface energy of spherical nanoclusters. The investigation is performed for silver nanospheres with a radius of 2 to

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 investigates whether the Weibull parameters of the new local approach model for cleavage fractures are affected by the geometric size of the specimen. Based on the fracture test data of A508-C steel, low temperature round notched bar tensile specimens of A508-C steel with two different notch sizes are numerically simulated by using finite element analysis software ABAQUS, and the

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

AbstractIn this study, the conventional Chow model for the tensile modulus of polymer composites containing fully aligned particles is simplified and developed for polymer nanocomposites, taking into account the effects of interphase and particle arrangement. The results obtained from the developed model are compared to the experimental results of several samples containing spherical, layered, and

AbstractAdditive manufacturing techniques are known for the unrivalled geometric freedom they offer to designers. It is one of the mainstays of “metal 3D-printing”, compared to casting, which, in contrast, implies more restrictions because some shapes do not cool evenly or may need moulds or forms. Despite the possible presence of defects inside additive manufactured components, such as oxide films

AbstractThe paper investigates a model simulating crustal fault dynamics and strain wave generation in a fault block geological medium, the parameters determining sliding regimes in faults, and the physics of transitions between different deformation regimes. The model comprises the most important mechanisms responsible for the interaction of fault walls: friction, geometric irregularities (roughness

AbstractThis paper examines the distribution of the tangential and normal components of the magnetic leakage fields in pole-magnetized sheet materials, such as cold-worked structural steels St3, 09G2S, and 08G2B, as well as electrical steel with different grain structure and coarse-grained magnetically soft alloy Alfer, which have different types of texture induced by rolling and uniaxial tension.

AbstractIn the paper, the plastic deformation of heterogeneous materials is analyzed by direct numerical simulation based on the theory of an elastic-plastic orthotropic Cosserat continuum, with the plasticity condition taking into account both the shear and rotational mode of irreversible deformation. With the assumption of a block structure of a material with elastic blocks interacting through compliant

AbstractThe deformation behavior of St3 steel was studied to show that the stress-strain state of a structure can be estimated using Rayleigh surface waves in both the elastic and plastic region. The most informative parameters in the analysis of the limit state associated with the onset of plastic deformation are the dispersion and shape of the probing signal. If the processes governing the effect

AbstractThreshold modes of multiscale dynamic deformation were identified for 1561 aluminum alloy by conducting two series of impact tests in the velocity range of 250–750 m/s: under uniaxial deformation and with high-speed penetration of elongated impactors. It was found that the scale of deformation changes at the same strain rate in the spall fracture zone under uniaxial deformation and on the lateral

AbstractA discrete model in a generalized rectangular-pulse space is proposed for dislocation cores in a crystal with its undeformed perfect structure taken as a Hilbert space of Schrödinger wave functions and with the core of a dislocation as a rigged Hilbert space of step functions of opposite sign separated by a time interval. The model suggests Vlasov equations for cation and electron distribution

AbstractThe paper considers the problem of elastic wave reflection from a free surface moving with a constant velocity. Analytical expressions in the approximation of geometrical acoustics are derived for the frequency shifts, angles of reflection, and reflection coefficients of P, SV, and SH waves to estimate the strain state at the free surface. Based on respective calculations, the reflection coefficients

AbstractThis paper is an experimental and theoretical study of changes in a laser-induced photoacoustic signal near a hole in metal plates of D16 aluminum alloy. The process of photoacoustic signal generation from metals is analyzed within the classical thermoelasticity framework, with account for only the thermal effect of laser irradiation on metal lattice deformation. A comparison is made of photoacoustic

AbstractThe paper analyzes how the elastic properties of titanium and its alloys vary as their structure is transformed from coarse- to ultrafine-grained under severe plastic deformation. The analysis includes acoustic measurements of the elastic modulus of Ti materials with a piezoelectric composite oscillator over a wide amplitude range, a detailed examination of their microstructure by electron

AbstractA method based on molecular dynamics and embedded atom potential is proposed for estimating the Laplace pressure, thermal expansion coefficient, and surface tension coefficient in spherical nanoobjects in relation to their size and temperature. The method is applied to silver nanospheres of radius 2–8 nm for analyzing their size and temperature effect on the thermodynamic parameters.

AbstractIn this work, the interphase in polymer nanocomposites is modeled as a multilayered part in which the Young’s modulus of each layer Ek continuously changes from nanoparticle surface (xk = 0) to polymer matrix (xk = t). The dependency of Ek onxk is analyzed by linear, exponential and power functions. The average interphase modulus is determined by the Ji model for several samples and the accurate

AbstractThis work suggests a modeling method based on micromechanical models such as Pukanszky one to determine the interphase properties in ternary polymer nanocomposites containing two nanofillers. The developed models can calculate the volume fraction, thickness and strength of interphases between nanoparticles and polymer matrix using the experimental data of Young’s modulus and yield strength

AbstractAttempts to improve the osteointegration, fixation and stability of Ti-base implants have been focused by producing a significative surface roughness that enhances the surface area available for bone/ implant apposition. In this research study, it shows the experimental data by synchrotron radiation X-ray diffraction (SR-XRD) of the main material surface properties (residual stress and cold

AbstractIn this article, the generalized model for photothermal wave under dual-phase-lag model is utilized to compute the increment of temperature, the components of displacement, the carrier density and the stress components in a two-dimension semiconducting media. By using Fourier and Laplace transformations with the eigenvalue techniques methodology, the exact solutions of all physical quantities

AbstractThe paper proposes a finite element approach with a mathematical model and an algorithm for simulating the wear of polymer composites in friction joints with account of temperature. The polymer interaction with a counterpart is modeled by solving a stress-strain contact problem with regard for the physical nonlinearity of deformation in polymer composites. The contact temperature is estimated

AbstractThis paper numerically investigates the mechanical behavior of an aluminum specimen with a TiC–Al6061 composite coating. The strain localization and fracture patterns are determined for different scale levels. The effects of the loading type, distance between titanium carbide particles, and metal matrix coating thickness are studied. A numerical method based on the experimental data is proposed

AbstractThe present paper deals with the development of dense Fe–Ag and Fe–Cu high-strength nanocomposites from blends of nanocomposite powders employing cold sintering (high-pressure consolidation). Nanocomposite powders were obtained by high-energy attrition milling of micron-scale powder of carbonyl iron (Fe) and nanosized silver oxide powder (Ag2O) as well as of nanopowders of Fe and cuprous oxide

AbstractA closed system of differential equations has been derived to describe thermal processes in a one-dimensional harmonic crystal on an elastic foundation. It is shown that the evolution of thermal perturbation in such a crystal is described by a discrete unsteady-state equation, a special case of which is the hyperbolic equation of ballistic heat conduction. This equation remains valid with negative

AbstractThe paper analyzes the scale hierarchy of transitions from very high to high and low cycle fatigue which are taken as fatigue limit according to the Wöhler concept. The analysis shows that the life distribution in the transition range 106–108 cycles is multimodal. From relations between the fatigue limit σ–1 and mechanical characteristics σU and σ0.2 in aircraft materials based on Fe, Al, Mg

AbstractControl over the inelastic deformation of polycrystals aimed at achieving desired performance characteristics of finished products is impossible without analyzing the structural evolution of the material at different scale levels. A major task in this respect is to develop physically sound mathematical models for describing the internal structure evolution as it determines the material properties

The use of NiBrAl casting alloy for the construction of marine propellers is expanding due to the resistance to fatigue, corrosion and wear under the effect of particles suspended in fluid. In this study, the nanostructure of the Ni-B coating is created by the electroless plating method on the NiBrAl alloy surface. After plating, the specimens are heat-treated, and the temperature and optimum time

A simple methodology is suggested to examine the roles of interphase characteristics in the shear, bulk and Young’s moduli of polymer nanocomposites containing spherical nanoparticles such as SiO2 and CaCO3. A core-shell structure is presumed for nanoparticles and surrounding interphase, and then the shear and bulk moduli of supposed particles are calculated. Subsequently, simple equations predict

This paper presents a higher-order shear and normal deformation theory for the static problem of functionally graded porous thick rectangular plates. The effect of thickness stretching in the functionally graded porous plates is taken into consideration. The functionally graded porous material properties vary through the plate thickness with a specific function. The governing equations are obtained

A new hybrid discrete-continuum cellular automata approach is proposed to simulate the process of new phase/grain nucleation and growth. The method couples classical thermomechanics and the logics of cellular automata switching. Within the framework of the hybrid discrete-continuum cellular automata method, the space occupied by the simulated specimen is represented as a cellular automaton—a set of

The prime objective of the present paper is to analyze the propagation of thermoelastic waves in a homogeneous isotropic elastic semi-infinite space that is exposed to a magnetic field at initial temperature T0 and whose boundary surface is subjected to the moving heat source and load moving with finite velocity. Temperature and stress distribution occurring due to heating or cooling have been determined

The stochastic structure of polycrystalline materials causes a high inhomogeneity of the kinematic and force fields in grains of materials and large fluctuations of these fields. The inhomogeneity and fluctuations are insignificant in some cases, but they become crucial in the study of various critical phenomena whose occurrence strongly depends on the type of material microstructure. Fluctuations

In this paper, we report the experimental data of the elastic properties of the Young’s modulus and shear modulus based on the variation in the ultrasonic velocity parameter during the microstructural evolution in a Ti-6Al-4V alloy with two—bimodal and Widmanstätten—varying microstructures. The two different initial microstructures were treated thermally by aging at 515, 545, and 575°C at different

Real mechanical assemblies favor the initiation and propagation of fatigue cracks due to stress concentration phenomena arising from the geometrical features such as notches, corners, holes, welding toes, etc. Classical fatigue analysis of notched specimens is done using an empirical formula and a fitted fatigue strength reduction factor, which is experimentally expensive and lacks physical scene.

In this work, the current state of understanding of grain structure evolution during friction-stir welding is briefly reviewed. The broad aspects of this process and experimental techniques for its examination are critically addressed. The specific character of the microstructural evolutions in body-centered cubic, face-centered cubic and hexagonal close-packed metals are considered in details. In

Thrust faulting has been studied within the framework of a tectonic wedge model. A variant of the model was proposed which accounts for changing friction between the wedge bottom and a rigid foundation during irreversible deformation. Some specific deformation structures typical for thrust zones were revealed; their formation conditions were estimated. The range of friction coefficient values was determined

In the work, we develop and implement force and deformation models of the strain and damage accumulation rates in creep with the use of the ANSYS finite-element analysis software. Numerical calculations are performed on a plane plate with a rectilinear through crack under biaxial loading and on a three-dimensional compact specimen under eccentric tension. The obtained stress-strain fields are used

Inclined multiple cracks may appear in composite laminates and sandwich structures. In this paper, we solve the fracture problem of a three-layer sandwich structure which contains multiple inclined cracks in the central layer under tension and antiplane shear. Three types of crack configurations are considered: an isolated crack, a periodic array of inclined cracks with the same length, and two parallel

The problem of the strength of a plate made of a brittle material with through mode I cracks is discussed. In contrast to the approach based on the singular solution of the classical theory of elasticity for a plane with a crack and on linear fracture mechanics, we propose to use nonsingular solutions obtained within the generalized elasticity theory and, as a result, to implement a method, conventional

The paper analyzes the microstructure and phase state of magnetron-sputtered nanocomposite Ti-C-Ni-Cr coatings based on Ni- and Cr-doped amorphous carbon by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. The analysis shows that the coating structure comprises an amorphous carbon matrix and nanosized TiC and Ni particles with relatively low lattice bending-torsion

The paper studies the effect of the annealing temperature on microstructural transformation and micro-hardness variation in an internally oxidized vanadium alloy V—Cr—ZrO2 deformed by high-pressure torsion in Bridgman anvils. It is shown that the development of large plastic strains and subsequent annealing of the particle-reinforced V—Cr—ZrO2 alloy lead to the formation of a fine-grained structure

The paper analyzes the applicability of available nonlocal and gradient fracture criteria to brittle, quasi-brittle, and ductile fracture in notched materials. All chosen criteria use an internal size parameter as a material structure characteristic, which makes it possible to describe the scale effect under stress concentration and to extend the range of their application compared to conventional

The paper discusses fracture processes occurring under compressive loads. The processes are considered from two points of view: (i) compression fracture mechanisms and their effect on the strength and fracture resistance of the material, and (ii) the effect of geometric constraints on the stress-strain state and fracture conditions of bodies (natural objects) with cracks and crack-like defects. These

The paper proposes a Lagrangian formalism for describing the space-time dynamics of complex continuum motion with addition variables—non-Eulerian dynamic degrees of freedom. The new variables are interpreted in terms of mechanics and geometry, and principles are suggested for their tracking in experiments. The formalism offers invariant tensor representations of Lagrangians in a system with an extended

A new concept in mechanics is proposed based on the notions of space, time, and energy. The energy is represented by the sum of thirteen terms expressed as products of invariants of the Lagrangian equations of motion and scalar factors corresponding to the physical properties of materials. Differential equations of motion and equilibrium are derived from the frame indifference condition for energy

Ultrasonic and electron beam treatment of commercial titanium VT1-0 and its alloy VT6 (Ti-6Al-4V) produces a nonequilibrium grain-subgrain hierarchical substructure in the surface layer, which causes a multiscale fragmentation of the material and reveals a damping effect. When cooled in the gradient temperature field (during electron beam treatment) and when the β phase of the initial alloy is destroyed

Molecular dynamics simulations have been performed to investigate the defect structure evolution at different development stages of atomic displacement cascades with energies up to 50 keV in iron crystallites in the temperature range from 300 to 900 K. The number of surviving radiation defects in iron crystallites increases according to a power law with increasing energy of the primary knocked-on atom

The paper reports on a molecular dynamics simulation of plastic deformation in polycrystalline titanium under scratch testing with explicit account of crystallographic orientations determined by electron backscatter diffraction for individual Ti grains. The simulation shows that the presence of a grain boundary breaks the lattice translation invariance and induces a constrained strain zone in which

The paper analyzes the redistribution of atomic displacements in an initially defect-free copper crystallite after shear deformation with emphasis on the evolution of dynamic structures formed by self-consistent collective atomic rotations. The analysis is based on an original technique which allows one to identify vortex motion in a vector variable space with a discrete step. The results of research

The paper explores the effect of high-temperature cross rolling followed by cold rolling on the internal structure of metastable Fe-Cr-Mn austenitic stainless steel, formation of nonequilibrium martensite ε and α′ phases in it, dynamic rotations on fracture surfaces, fatigue life under alternating bending, and wear resistance. Scratch testing revealed a strong increase in the damping effect in the

Superplastic forming is promising for the manufacturing of complex-shaped metal parts and components. Superplastic conditions allow one to produce unwelded parts, to reduce the number of technological operations and forming forces, and thus to reduce tool wear. Optimal processing modes can be determined using mathematical models based on constitutive equations. However, there are serious difficulties

Molecular dynamics simulations were performed to investigate the effect of the size of the simulated nanoscale system on energy absorption under cyclic loading, as well as on further damage and failure of the system. Two copper nanorods with perfect crystal structure were considered: a base rod measured 50 × 5 × 5 lattice cells and a larger nanorod measured 200 × 20 × 20 cells. It was found that energy

In the paper, inelastic strain localization in homogeneous specimens and mesovolumes of a polycrystalline material is modeled based on the asymmetric theory of an elastoplastic Cosserat continuum in a two-dimensional formulation for plane strain. It is assumed that rotational deformation in loaded materials occurs due to the development of localized plastic deformation as well as bending and torsion