This study presents a generalized theoretical framework for analyzing wave propagation in a semiconductor medium within the context of nonlocal photo-thermoelasticity. The model incorporates bi-fractional dual-phase-lag (DPL) heat conduction, a multi-temperature formulation distinguishing between thermodynamic and conductive temperatures, and temperature-dependent thermal conductivity under ramp-type thermal loading. Nonlocal elasticity is introduced to account for size-dependent mechanical behavior, which becomes significant in micro- and nanoscale semiconductor structures. The governing equations, describing the coupled interactions among displacement, temperature fields, and carrier concentration, are formulated in a two-dimensional setting and reduced using the normal mode method to obtain a characteristic equation governing wave propagation. The influence of the nonlocal parameter, fractional orders, and phase-lag times on the attenuation and dispersion characteristics of thermoelastic waves is examined. The results reveal that nonlocality significantly smooths stress distributions and reduces wave amplitudes, while the bi-fractional DPL model introduces pronounced memory effects that delay thermal responses and modify phase behavior. Furthermore, ramp-type thermal loading leads to more gradual stress development compared with instantaneous heating. The proposed model provides a comprehensive framework for understanding coupled wave phenomena in semiconductor media and offers new insights into the role of size effects and thermal memory in advanced solid-state systems.
The electroplastic effect (EPE) is used in metal forming, reducing the forces required to shape metals without significant heating, minimizing tool wear, and producing parts from difficult-to-deform alloys. However, the physical nature of EPE remains insufficiently understood, necessitating fundamental research to uncover the mechanisms of interaction between high-density electric current and a sample. Most EPE studies are conducted by passing an electric current through a sample undergoing plastic deformation, monitoring the movements of the grips, and recording the changes in stresses in the sample. This paper discusses a different deformation scheme, in which a wire sample is loaded with a dead weight and a current pulse is passed through it, causing its plastic deformation. With this deformation scheme, for a sufficiently long sample, Joule heating can be accurately determined from its thermal expansion. This is important for the separation of the thermal and athermal effects influencing electroplastic deformation. The nearly instantaneous heating of a sample when passing a current pulse lasting approximately 10–4 s results in its thermal expansion, triggering oscillations in the sample-weight system. A condition for the specimen temperature increase, when it appears in a compressed state, is obtained, and Euler critical loads are calculated. For the case where the specimen remains in a stretched state after passing the current pulse, weight oscillations are analyzed for both linear-elastic and elastic-plastic samples. It is shown that, under experimental conditions, the weight oscillation period is significantly longer than the time it takes for a longitudinal sound wave to pass through the specimen, allowing the sample-weight system to be considered a single-degree-of-freedom system. The obtained results demonstrate that experiments studying EPE must take into account the dynamic effects caused by the nearly instantaneous release of Joule heat.
Currently, although the plasticity framework has been proposed for the numerical modelling of pile-sand interface, the application of anisotropic hypoplasticity framework is very rare. The hypoplastic models do not need to consider the traditional plastic theory, so have been attracted wide attention. In this paper, an anisotropic hypoplastic interface model is improved by considering the plane strain state and roughness precisely, the relation between the fabric tensor and anisotropic parameters. The applicability of the improved model is validated by comparing the simulation results of existing model and the experimental data. The results indicate that the modified model can be utilized to reflect the mechanical response of sand-pile contact surface.
The concentric cable-driven manipulators have attracted considerable attention for its applications in confined spaces. However, a major challenge lies in accurately determining its configuration owing to the absence of robust visual information and configuration detection methods. To address this limitation, this paper proposes a vector construction method based on binocular vision for the configuration detection of concentric cable-driven manipulators. Firstly, the markers that are easily identifiable and do not interfere with the manipulator’s functionality are attached to the concentric cable-driven manipulator. Subsequently, a binocular vision system is designed to obtain real-time images of the concentric cable-driven manipulator. Finally, based on the binocular vision system and markers, the vector construction method is proposed to detect configurations of the concentric cable-driven manipulator. Extensive experiments show that the configuration detection accuracy of the proposed method for the concentric cable-driven manipulator is more than 94
This study is devoted to factorization of the characteristic polynomial of the quadratic energy form of a hemitropic micropolar elastic medium. The strain energy is considered as a function of the nonsymmetric strain and wryness tensors, which are interpreted as thermodynamic state variables. The A-representation is provided for the strain energy of the hemitropic micropolar elastic medium, characterized by nine isentropic mechanical moduli. The characteristic polynomial of algebraic degree 18 is obtained for the considered quadratic form, and its multiplicative decomposition into four polynomials of lower algebraic degree is carried out. The eigenvalues are obtained and their algebraic multiplicities are determined. The unilateral constraints, imposed on the constitutive constants that ensure the positive definiteness of the quadratic form, as well as three essential constitutive inequalities, that guarantee the equilibrium stability of the hemitropic micropolar elastic solid, are obtained.
The present study examines the reflection and transmission of elastic waves at a plane interface between two perfectly bonded, dissimilar nonlocal elastic solid half-spaces containing voids. The analysis is carried out for the oblique incidence of coupled longitudinal (dilatational) waves and a lone transverse wave within the framework of Eringen’s nonlocal elasticity, considering both Voigt and non-Voigt models. By applying suitable nonlocal boundary conditions, closed-form expressions for the reflection and transmission coefficients, together with the associated energy ratios, are derived. Numerical results illustrate the influence of nonlocality, porosity, angle of incidence and frequency on wave propagation characteristics. The results reveal significant mode conversion and energy redistribution, particularly near critical angles. Increasing nonlocality enhances impedance mismatch at the interface, leading to increased reflection and reduced transmission, while favoring mode preservation for the incident coupled longitudinal displacement waves. For transverse wave incidence, nonlocal effects enhance reflection and redistribute energy toward reflected modes. Energy conservation is verified through reflected and transmitted energy ratios. Some new as well as previously known results are also successfully recovered as special cases of the present formulation.
This research presents an alytical and machine learning approach for the prediction and optimization of fundamental frequencies in functionally graded material (FGM) – porous – FGM sandwich plates resting on a Pasternak elastic foundation. The analytical model is developed based on the First-Order Shear Deformation Theory (FSDT) to derive the governing equations of motion, which are solved using the Navier solution method. The influence of FGM volume fraction, porosity, aspect ratio, side-to-thickness ratio, and foundation parameters on the fundamental frequencies is systematically investigated. To enhance computational efficiency and improve predictive capabilities, different machine learning models are trained to predict the frequency over a wide range of input parameters. It is shown that the Artificial Neural Network model can predict the dimensionless fundamental frequency with a very strong effectiveness (R2 = 1.0000, RMSE = 2.2034 and MAE = 1.0309 using testing dataset). Furthermore, optimization studies are also performed to determine the optimal input parameters corresponding to a desired value of frequency. Pros and cons of analytical and machine learning models are also revealed during the optimization process, for instance in order to carry out just 1 iteration optimization, the analytical model needs on average 1958s while the Artificial Neural Network model needs on average only 0.1039 s.
We develop a unified dynamic formulation for nonlocal functionally graded magneto-electro-elastic (MEE) sandwich plates of irregular boundary based on the Yan-Dowell sandwich theory extended within Eringen’s differential nonlocal elasticity framework. The derived sixth-order governing equation consistently incorporates thickness-wise material gradation, size-dependent stiffness effects, and linear magneto–electro–mechanical coupling in a multi-field continuum setting. A generalized dimensionless transformation is introduced to obtain closed-form dispersion relations, stability admissibility conditions, and explicit expressions for phase and group velocities. The formulation captures the transition from classical bending-dominated behavior to microstructure-sensitive nonlocal regimes and predicts finite high-frequency saturation limits absent in local models. Parametric analysis quantifies the coupled influence of wave number, nonlocal parameter, gradient index, effective MEE stiffness, together with external electric and magnetic potentials on dispersion characteristics. The results demonstrate broadband stiffness amplification under MEE activation, curvature-enhanced wave modulation at short wavelengths, and well-defined electromagnetic stability boundaries. The proposed model establishes a predictive mechanics framework for tunable wave propagation and regime-classified design of smart graded sandwich nanostructures.
This study investigates SH-wave scattering phenomena in prestressed elastic bi-materials containing cylindrical cavities. The analytical framework involves four key components: First, Tensor formulation of wave equations in prestressed media, where coordinate transformations convert variable-coefficient Helmholtz equations to standard forms; Second, Development of scattering solutions through hybrid analytical techniques combining conformal mapping with image methods, rigorously satisfying half-space boundary conditions; Third, Implementation of Green’s function methodology via domain decomposition and equivalent loading systems to establish Fredholm integral equations; Fourth, Derivation of complete stress fields using elasticity superposition principles, with numerical solutions obtained through spectral expansion methods. Comparative validation against finite element simulations confirms solution accuracy, particularly regarding dynamic stress concentration effects near cavity boundaries.
The current study discusses the effect of an inclined load and magneto-elastic coupling on thermoelastic behavior solid and its microtemperatures and temperature-dependent properties of the material. The refined-phase-lag (RPL) is used to tackle the issue. The normal mode method was introduced to determine the governing equations and acquire analytic representations of the electromagnetic, thermal, and elastic fields. Matlab software is exploited to do simulation based analysis. The numerical physical fields are obtained as graphical displays. Figures are used to compare data and illustrate the interaction between the temperature-dependent, inclined load, and magnetic field. The isotropic thermoelastic solid is sensitive to tilted load effects additionally Regarding the magnetic field. Comparative results to the previous results obtained to reveal external parameters influence on the phenomenon of a refined-phase-lag model on thermoelastic solids with magnetic field considering inclined load.
This study investigates elastic wave propagation and attenuation in a saturated porous ground incorporating a wave-impeding barrier within the framework of nonlocal elasticity theory. A nonlocal wave-propagation model for the barrier-saturated porous medium system is established, and transmission amplitude ratios are employed to characterize the reflection, transmission, and mode conversion behaviors of fast compressional (P1), slow compressional (P2), and shear (S) waves at the interfaces. The proposed formulation is validated through comparison with available results in the literature. A systematic parametric investigation is then conducted to examine the effects of the nonlocal parameter, barrier thickness, incident angle, and barrier material properties (elastic modulus and density) on elastic-wave transmission and attenuation. The results indicate that nonlocal effects are negligible at low frequencies but become increasingly pronounced at medium-to-high frequencies, leading to significant modifications of peak-valley transmission patterns and even simultaneous suppression of multiple wave modes at specific nonlocal parameter values. The barrier thickness exhibits a strong tuning effect on compressional-wave transmission, producing quasi-periodic peak-valley structures, while the incident angle markedly influences energy partition and mode-conversion efficiency. Moreover, tuning the barrier density alters the dynamic impedance mismatch and further affects compressional-wave attenuation. The findings demonstrate that effective attenuation of elastic waves in saturated porous grounds can be achieved through coordinated tuning of the barrier nonlocal parameter, geometric configuration, and material impedance, providing theoretical guidance for the design and optimization of wave-impeding barriers for vibration mitigation.
In this work, a rotating hollow cylinder subjected to thermal shock is analyzed in the context of Ezzat-type fractional thermoelasticity and fractional order strain theory. The governing equations are nondimensionalized and solved via Laplace transform and an eigenvalue procedure. To validate the theoretical derivation, a reduced case is employed and the results show close agreement with prior literature. Then, the influence of fractional order, strain relaxation coefficient, acting time, and rotating speed on physical quantities are analyzed respectively. Numerical results show that the decreasing fractional order parameter strengthens memory effects and suppresses instantaneous response amplitudes; increasing strain relaxation coefficient reduces displacement and stresses; and increasing rotating speed monotonically elevates stress amplitudes while exerting only minor influence on temperature.
The main objective of this paper is to investigate the deformation behavior in a two-dimensional homogeneous, isotropic thermo-elastic half-space subjected to an external heat source applied at its boundary and electro-magnetic field, within the framework of the Lord-Shulman theory. The novelty of this work lies in formulating a new coupled dynamic model that integrates mechanical stresses with temperature interactions in an elastic medium. The Lame’s potential method and normal mode analysis method is applied to solve the resulting coupled differential equations, obtaining both deterministic and solutions. The temperature, displacement component and stress components of these waves are obtained analytically with the use of suitable boundary conditions. Focusing on aluminium epoxy-like material, graphical representations of numerically simulated findings using MATHEMATICA software show how time, magnetic field and permeability of electric field. The work includes detailed graphical representations of crucial discoveries such as temperature distributions, stress components, and displacement components which provide amazing visual insights into the complex interactions that occur within thermo-elastic systems. From the distributions, it can be found the wave type heat propagation in the medium. A comparison is made with the results obtained in the presence and absence of the electro-magnetic field. By forging a link between theoretical insights and practical applications, this study stands to make a significant contribution to the field of materials science, providing a solid foundation for subsequent inquiries within this rapidly progressing arena. A graphic comparison of our physical quantity accuracy results with earlier studies shows the significant influence of electro-magnetic field on thermoelastic phenomena. The analysis of thermoelastic problems with electro-magnetic field benefits from the study.
In this work, the investigation of a non-linear thermo-mechanical disc, which is made of Ti−6Al − 4V/GFRP nanomaterial, has been done. The main feature of such a disc is the presence of a rigid central shaft and an exponentially varying thickness that can be extended outward. B.R. Seth’s transition theory is used to establish the compatibility and equilibrium conditions under various mechanical and thermal conditions. This theory helps to analyze the large deformations that the disc experiences in such conditions. The numerical results for radial, hoop stresses and the displacement occurring at the radius of the disc are generated using MATLAB software. The obtained results are presented graphically to investigate how the rigidity of the disc is affected by the exponential thickness and stiffness of the nanomaterial. Moreover, some nano-additives, such as CNTs, Al2O3, SiC and graphene nano-plates, have been incorporated with Ti − 6Al − 4V/GFRP to observe the strength and thermal performance of the nano-material used. This proposed approach is a powerful tool for designing components of remove the space discs, aircraft blades, compressor rotors, etc., which rotate at very high speed and exhibit thermo-mechanical environments.
This study develops a hydro-mechanical (HM) multi-field coupled model to track stress evolution in reactive materials like cementitious composites. These materials exhibit highly non-steady-state bulk and interfacial stresses during the transition from liquid to porous solid. Unlike conventional structural analyses, our model accounts for phase transition processes and dynamic boundary conditions. It specifically highlights how material strength development drives load transfer and how endogenous volumetric strain redistributes system stress. By incorporating nonlinear constitutive parameters correlated with the degree of reaction, the model achieves a precise description of the spatiotemporal mechanical response of the sheath system under annular confinement. Validation results demonstrate that the calculated values are in high agreement with experimental pressure evolution trends. The findings reveal that internal volumetric shrinkage is the core driver for the reduction of radial compressive stress and the generation of circumferential tensile stress. Furthermore, the interplay between initial hydrostatic pressure and the evolution of skeletal stiffness dictates the medium-to-long-term evolution path of interfacial stress. This research elucidates the mechanical pathways of stress redistribution in reactive materials during constrained phase transitions, providing a theoretical framework for the structural integrity assessment of heterogeneously evolving materials under complex constraints.
For a triaxial satellite with a spherical damper, the equations of rotational motion in an elliptical orbit in the Biletskii–Chernousko variables are derived. On their basis, for the case of a circular orbit, averaged equations of the second approximation over a small parameter were constructed, describing the evolution of non-resonant rotations of the satellite. Bifurcation curves in the space of phase variables of the system are investigated, at the intersection of which the nature of the rotational motion of the satellite changes significantly.
The paper presents a review of the sampling surfaces method for solving three-dimensional problems of elasticity, thermoelasticity, electroelasticity and thermoelectroelasticity for layered elastic and piezoelectric shells. According to this method, the sampling surfaces parallel to the middle surface and located at the nodal points of Chebyshev polynomials are introduced in each shell layer, in order to choose displacements, temperatures and electric potentials of these surfaces as unknown functions. This choice of unknown functions allows representation of governing equations of the higher-order shell theory in a sufficiently compact form and obtaining strain-displacement relations that correctly describe displacements of the shell as a rigid body in both geometrically linear and nonlinear formulations.
This article develops a nonlinear mathematical model of the resonator dynamics of a wave solid-state gyroscope in slow variables, taking into account the high angular velocities of moving objects. A case is considered in which the cubic nonlinearity inherent in the equations of the resonator dynamics of wave solid-state gyroscopes is taken into account. Mathematical modeling of the resonator dynamics at high angular velocities is performed, demonstrating the adequacy and sufficient accuracy of the proposed mathematical model. It is shown that in addition to the constant angular drift velocity of the wave solid-state gyroscope, caused by the nonlinearity of oscillations and independent of the angular velocity of the moving object, an additional constant component of the angular drift velocity appears, which depends on the angular velocity of the moving object.
The ability of composite structures incorporating flexible metamaterials with a cell-based structure in the form of a convex or concave hexagon to mechanically resist penetration by a rigid spherical striker was experimentally studied. In some experiments, solid layered samples with layers having different internal structures were penetrated. In other cases, the penetrated samples consisted of separate, unconnected layers. The samples were 3D-printed from flexible TPU 95A plastic (thermoplastic polyurethane) and represented metamaterials with various mechanical properties, including auxetic ones. The prepared barriers, similar in total mass, differed in the sequence of laying solid or separate layers and were compared for their ability to reduce the kinetic energy of strikers at a speed of approximately 190 m/s and a temperature of 25°C. Under the chosen experimental conditions, it was found that separate layers better reduce the kinetic energy of the striker. The most efficient order of laying layers in barriers was also determined.
This paper is devoted to the study of a mixed problem in a half-strip for a hyperbolic second-order system of partial differential equations, which can be used to model vibrations of finite Timoshenko beams. The solution to the problem is constructed in an implicit analytical form as a solution to a system of some integro-differential equations. The solvability of these equations, as well as the dependence on the initial data and the smoothness of their solutions, is studied. For the problem in question, the uniqueness of the solution is proved and the conditions under which its classical solution exists are established.
