We study the vibration and acoustic responses of the ABH-type FG sandwich plates with dynamic resonators. Based on the first-order shear deformation theory and the acoustic theory, the dynamic governing equation and the acoustic formula of the structure are derived. The Rayleigh-Ritz method is used to solve the vibro-acoustic responses. The accuracy of the theory is proved by the finite element results, and then the effects of variable thickness forms and the parameters related to additional oscillators on the acoustic responses of ABH-type superstructure plates are discussed. It is shown that the single-layer variable thickness and the placements, numbers, connections of additional oscillators cause the acoustic response curves greater changes. The research advances the comprehension of localized responses, and vibro-acoustic response of the system can be adjusted by changing the oscillators of the superstructure, especially the parallel oscillator.
In order to explore the influence of combined effects of shear lag and shear deformation on the bending deformation and stress of thin-walled box girders, the energy variational principle and Timoshenko beam theory are applied to establish governing differential equations. Deflection curve equation, bending stress expressions and calculation formulas for shear lag coefficients are given respectively. With an increase in n, the deflection of the box girder decreases instead. It is recommended that n = 5 when analyzing the bending deformation and stress of simply supported thin-walled box girders. The smaller the span-width ratio, the more obvious shear lag effect. Shear lag effect is more significant under the concentrated load. Compared with the shear lag effect, the influence of shear deformation on the bending deformation of box girders is more prominent. The investigation results provide a simple and effective analytical calculation method for solving the bending problems of thin-walled box girders.
The bone scaffold needs to balance mechanical properties and biological properties, but traditional methods struggle to achieve efficient collaborative optimization. This study is based on a data-driven framework integrating active learning with generative adversarial networks and finite element simulations for multiobjective design of modified face-centered cubic bone scaffolds. We address the critical challenge of simultaneously optimizing mechanical properties (elastic modulus, yield strength) and partial biological performance indicators (porosity and specific surface area) in bone scaffold design. Through a novel combination of convolutional neural networks for property prediction and variational autoencoders for structural generation, our approach explores a significantly expanded design space compared to conventional methods. The framework successfully identified Pareto-optimal solutions that achieve: (1) 11.7% increase in yield strength with only 0.55% porosity reduction and 4.1% specific surface area enhancement (Yj solution), (2) 4.78% porosity improvement with 28.5% specific surface area increase despite 19.2% strength decrease (Pj solution), and most remarkably (3) concurrent 10.1% strength enhancement and 2.24% porosity increase while maintaining near-baseline specific surface area (Cj solution) in 75% porosity systems. These results demonstrate a 69% variation range in specific surface area (3.23-5.47 m(2)/kg), revealing that these biological indicators can be precisely tuned without necessarily compromising mechanical integrity. Experimental validation confirmed the accuracy of finite element simulations (deviation < 10%) and demonstrated the method's capability to precisely match target elastic modulus while overcoming inherent material limitations. This study can be used for the design of other bone scaffold structures and different bone tissues, and can efficiently explore breakthrough structures with collaborative optimization of mechanical properties and key biological indicators.
We investigate a novel meticulous heat transfer model to capture the photo-thermal-elastic interactions efficiently inside a nonlocalized semiconductor material affected from a dynamic thermal loading. For the purpose of apprehending memory and nonlocal effects during complex diffusion processes inside the semiconductor, the Atangana-Baleanu fractional derivative is established on the linearized coupled thermoelastic theory which involves thermal displacement gradient and temperature gradient among the constitutive variables. Laplace transform methodology is acquired for solving the problem. Later on, a suitable algorithm of numerical inversion of the Laplace transform is employed for achieving the computational results in physical domain. As per the graphical results, conclusions about the influences of significant parameters such as fractional parameter, photo-generated carrier life-span and the velocity of dynamic heat source on the dimensionless physical fields like temperature, displacement, stress and carrier density are constructed. Further, the utility of the current advanced heat transfer model is established by comparing the graphical results of physical fields under the current heat transfer theory with the old developed theories of heat transfer models having two phase lags and single phase lag parameter. All the graphical results are evaluated against distinct values of depth of the semiconductor media. We believe that this fine study will support researchers for obtaining promising and optimum results of real world problems where the photo-thermal effects inside the semiconductor are taken into account.
Using the complex variable formulation developed by Suo (1990), we derive an explicit closed-form expression for the compressibility of a quasihypotrochoidal pore in an infinite degenerate orthotropic elastic material. The shape of the pore boundary is hypotrochoidal in the z1-plane where z1 is the single complex variable appearing in Suo's formulation. The pore compressibility is defined as the fractional decrease in the area of the pore due to a remote hydrostatic pressure of unit magnitude. The compressibility is independent of the rotation of the pore boundary in the z1-plane for all cases except pores of fourfold symmetry in the z1-plane. The compressibilities of pores having fourfold symmetry in the z1-plane vary with cos 49, where 9 is the rotation angle of the pore boundary in the z1-plane. We also derive a closed-form expression for the compressibility of a pore having an (n+1)-fold axis of quasisymmetry with n >= 2 in an infinite degenerate orthotropic elastic material. The pore, which is described by a three-term mapping function, has an (n+1)-fold axis of symmetry in the z1-plane.
We investigate the rheological behavior of nanosilica/PEG200-based shear thickening fluids (STFs), focusing on their temperature-dependent characteristics over the range of 5-50 degrees C. Results show that increasing temperature significantly reduces both the peak viscosity and shear stress while raising the critical shear rate. At 5 degrees C, the STF transitions into a gel-like state. Mechanistic analysis confirms that solvent viscosity is not the dominant factor; instead, interparticle interactions and temperature-induced evolution of the solvation layer are identified as the key mechanisms. This work quantitatively reveals how solvation layer thickness varies with temperature: a thicker layer at low temperatures promotes the formation of stable force chains, leading to high friction and shear stress, whereas a thinner layer at high temperatures allows hydrodynamic clusters to dominate, resulting in a weaker stress response. The peak viscosity follows the Arrhenius model. These findings elucidate the temperature-dependent link between macroscopic properties and microstructure in STFs, providing a theoretical basis for designing STFs for use in varying thermal environments.
A novel Trefftz function is employed in this study to address the inverse Cauchy boundary value problem arising in thin plate bending. The Trefftz functions are constructed by applying the method of separation of variables to the governing equilibrium equation of the plate. Due to the ill-conditioned nature of the resulting matrix equations, the Kozlov iterative method is introduced to transform them into two well-posed problems, which are subsequently solved using the collocation approach. The effectiveness of the method is demonstrated through numerical experiments involving both smooth and piecewise smooth domains, with scenarios considering exact as well as noisy boundary data. A comprehensive investigation is conducted into how the algorithm's performance is influenced by key parameters, including the number of series terms, collocation points, iterations, and noise levels. The results suggest that the proposed numerical scheme attains good accuracy and stable, convergent performance across the tested cases while maintaining practical computational cost, indicating promise for inverse Cauchy problems in isotropic thin plate bending.
Understanding the mechanical and contact behavior of hyperelastic materials under complicated boundary conditions holds significant importance for soft material design. In this study, the indentation contacts problem of a rigid spherical indenter on a semi-infinite elastic solid under prestretching are analyzed. An incompressible hyperelastic material is applied to describe the mechanical behavior of the elastic solid. A theoretical model for accurately determining the contact radii and forces is developed by introducing the neo-Hookean strain energy function and the instantaneous elastic modulus based on the small deformation assumption. Finite element method is then used to compare to theoretical results. To efficiently process simulation data in batches, we present an automatic process based on the secondary development of Python. Such theoretical model and automatic process have potential applications in many fields such as biological tissues and the automotive industry.
This study investigates the effective properties of periodic array nanocoated fiber composites through theoretical analysis. Based on the Gurtin-Murdoch surface elasticity theory, an analytical solution for the effective anti-plane shear modulus of periodic nanocoated fiber composites is derived using the unit cell functional variation method for periodic microstructures. The obtained solution is validated against existing results, demonstrating the accuracy and effectiveness of the proposed approach. Furthermore, the influences of coating thickness, material properties, and surface property on the nanocomposites' effective properties are systematically examined. Additionally, the study reveals the impact of microstructure periodicity ratio and fiber/matrix stiffness matching on the effective modulus.
In this paper, the continuum damage mechanics (CDM) with the classical jump cycle algorithm is used to study the fatigue fracture problems of bone in clinical analysis. The fatigue experiments have demonstrated that the initiation and growth of microcracks in bones is the key factor to premature fracture of bones. To describe the evolutions of microcracks, continuum damage mechanics is used. Based on the definition of bone damage due to microcracks evolution, a novel damage accumulation model is developed to predict the long-term mechanical performance of cortical bone. The developed damage model predicts the fatigue performance of bones by assessing damage development and elastic modulus degradation in bones of various ages. The correctness of the proposed model is validated by comparing it with the experiments' results. Based on the jump cycle algorithm method, distributions of the cortical bone damage can be obtained according to the finite element method. This work uses a mechanical method that can quantitatively describe the performance degradation of materials or structures and a commonly used fatigue algorithm to solve the fatigue problem of bone fracture across disciplines.
In this study, a smart damper based on shear thickening fluid (STF) was developed, and its dynamic mechanical performance was investigated. STFs with various mass fractions were prepared, and their rheological properties were characterized under steady-state and dynamic conditions. These fluids were incorporated into dampers, and dynamic tests were conducted under different frequencies and amplitudes to analyze the variation in damping force. Experimental results suggest that the STF-based damper exhibits effective damping performance. A force-velocity relationship model of the STF damper was established based on the experimental data, revealing that during the compression stage, the behavior conforms to Boltzmann's law, while during the recovery stage, it exhibits exponential behavior. By integrating the relationships among STF mass fractions, loading speeds, and maximum output damping forces, a three-dimensional plot was generated to guide future research and industrial applications.
To investigate the effects of pulsed current on the mechanical behavior of nanocrystalline foil materials, nanocrystalline nickel foils with different characteristic dimensions lambda (thickness/grain size) were prepared and subjected to current-assisted tensile experiments. The experimental results indicate that without the application of current, the Ni foil exhibits a significant size effect. After applying pulsed current, in addition to a decrease in tensile strength and an increase in elongation, the size effect is also weakened. Furthermore, it was also found that the tensile strength, elongation, and size effect of the foil materials are not only related to the current density but are also closely associated with the direction of current application. When the direction of the current is aligned with the deformation direction, the reduction in the size effect of the foil materials is most pronounced, and the electroplastic effect is most significant. Finally, a parameter describing the pulsed current was introduced into the Johnson-Cook constitutive model, and a phenomenological constitutive model capable of describing the size effect of nanocrystalline Ni foils was established.
This study presents a novel investigation of thermal wave propagation in layered phononic crystals (PCs) composed of functionally graded materials (FGMs), revealing unprecedented thermal band gap tuning mechanisms through the Cattaneo-Vernotte and dual-phase-lag heat conduction models. Unlike conventional homogeneous PCs, the FGM-based structure introduces unique gradient-dependent band gap modulation, analyzed via the transfer matrix method and Bloch theorem. The complex dispersion curves of thermal waves are obtained. The first band gap intervals increase with the increase of the gradient change index y0, and the intervals of the first band gap shrink and then become broader a little bit with the increase of parameter /r. Besides, the first band gap intervals decrease with the increase of 5. The intervals of the first band gap increase with the increase of Cpn. The tqn can affect the first band gap width and the number of the band gap.
This paper proposes a phased optimization physical information neural networks (PINNs) method based on the DeepXDE framework, which is used to solve transient heat conduction equations. By combining the Adam and L-BFGS hybrid optimization strategy, this method achieves rapid convergence and demonstrates superior performance in one-dimensional to three-dimensional heat conduction problems. Through comparative experiments, the influence laws of neural network structure parameters (such as the number of hidden layers and the number of neurons) on the solution accuracy are clarified, and the optimal network structure configuration is established. The tanh activation function with second-order derivatives is adopted to avoid the problem of gradient disappearance effectively, and the governing equations and boundary conditions are seamlessly integrated into the loss function, achieving a true meshless solution. The numerical experimental results show that this method can accurately capture the spatiotemporal evolution characteristics of the temperature field.
The coupled dynamics of extremely large deformations and small deformations in tethered satellite towing systems pose significant challenges in dynamic analysis. To address this, the present study develops an MPM-FEM framework by integrating the advantages of the finite element method (FEM) in solving small-deformation problems and the material point method (MPM) in simulating extremely large deformations. This hybrid approach is specifically designed to model the dynamic behavior of tethered satellite towing systems. First, the theoretical framework of the MPM-FEM containing the beam element as well as the rod element is established. In the framework, procedures for incorporating beam and rod elements into the MPM formulation are presented in detail. Subsequently, the validity of the proposed method is rigorously verified through two benchmark cases: a tether oscillation model and a cantilever beam impact dynamics model. Finally, MPM-FEM is applied to simulate the dynamic process of a tethered satellite towing a flexible beam. Key results include time-resolved displacement-deformation profiles of the towing system and the temporal evolution of total energy, kinetic energy, and strain energy. These findings provide critical insights for the design of dynamic systems and control strategies in tethered satellite towing applications.
We explore the effects of curvature-dependent surface tension on the elastic behavior of a line edge dislocation embedded in a free-standing thin film. The dislocation line is assumed to be parallel to the surface of the film, while the entire system is confined to plane strain deformations. The total surface tension is treated as the sum of a constant initial part arising from the originally flat surface of the film and a configuration-dependent part proportional to the curvature of the deformed surface of the film. We employ the complex variable formalism of elasticity and develop a series-based solution procedure to determine the dislocation-induced stress field in the film subjected to the nonclassical boundary conditions related to the curvature-dependent surface tension. The image force, describing the mobility of the dislocation, is also represented in terms of the obtained coefficients of the series. By setting the curvature-dependence parameter of surface tension to zero, our procedure recovers accurately the known analytic results in the literature for an edge dislocation in an elastic half-plane with constant surface tension. Numerical examples are presented for illustrating the influence of the curvature-dependence parameter of surface tension on the local stress field near the surface of the film and the image force. It is shown that as the thickness of the film decreases to a few nanometers, the curvature dependence of surface tension always contributes significantly to the determination of the stress concentration around the surface of the film irrespective of the direction of the Burgers vector of the dislocation. In contrast, however, it is found that even for a few-nanometer-thickness film the influence of the curvature dependence of surface tension on the image force becomes notable only when the Burgers vector is at a large angle to the surface of the film (for example, more than 60 degrees) and simultaneously the distances from the dislocation to the two surfaces of the film differ significantly (for example, by a factor of three or more).
We investigate the contact problem of a functionally graded piezoelectric material (FGPM) under a cylindrical indenter by considering the surface effect. The electromechanical properties of the FGPM coating vary as an exponential function along the thickness direction. The Fourier integral transform method is employed to obtain the fundamental solution of the two-dimensional contact problem of FGPM considering the surface effect. Numerical results are obtained to analyze the effects of the material gradient and surface effect on the distributions of normal contact stress, in-plane stress, and in-plane electric displacement. The results show that surface effect play a crucial role in the contact problem of the FGPM. The contact behavior of the FGPM at micro/nano-scales can be improved by adjusting the gradient index.
Prestrains and residual stresses have certain impacts on the characteristics and functions of soft materials and tissues. Consequently, prestrains and residual stresses also influence the indentation test of soft materials. This paper focuses on the indentation contact of a compressible rubber polymer with prestretching conditions. It derives the semi-analytical expressions for the ratio of the indentation force to the indentation depth and the stress distribution. Subsequently, these semi-analytical expressions can be simplified into analytical expressions in the equiaxial prestretching case. Based on the deduced results, the influences of prestrain, ambient temperature, and indenter parameters on indentation force, indentation depth, and stress distribution parameters are further analyzed. The results indicate that the compressibility of the material makes the surface stiffness of the material increase under the condition of prestretching, resulting in a smaller indentation force or indentation depth during the indentation test. The analytical expressions obtained here in the equiaxial prestretching situation provides a theoretical reference for the indentation test of some soft materials.
To achieve multiple closely spaced natural frequencies in the low-frequency range of piezoelectric energy harvester, a novel three-dimensional braided multi-modal piezoelectric energy harvester (BMPEH) is proposed. The 3D BMPEH is composed of a main beam with piezoelectric layers and multiple branch beams equipped with tip masses. The main beam and the branch beams are employed as the elastic layers, and are made of 3D braided composites with excellent mechanical properties and good design flexibility. The theoretical model of the 3D BMPEH under transverse excitation is established, and the electromechanical coupling equation is derived. The effects of design parameters, including braided angle, tip mass, load resistance, and excitation amplitude, on the output response are examined. Numerical simulations demonstrate that the 3D BMPEH broadens the bandwidth of frequency response in the lower frequency range and shows great potential for powering electronic equipment.
A plane stress nonlinear point load problem is addressed analytically on a half-plane by using a technique based on a one-parameter group transformation that admits a similarity solution. An exact solution for the stress field is expressed in terms of a Jacobian elliptic function. As this stress acts only in the radial direction from the point of application, it parallels the solution found for the linear elastic Flamant problem. The corresponding strain field is composed of both elastic and inelastic components, which collectively satisfy a derived compatibility equation. A possible application for the solution involving residual stress is discussed.
