International Journal of Mechanics and Materials in Design最新文献

Auxetic cellular structures have attracted considerable attention for impact energy-absorption applications because their negative Poisson’s ratio (NPR) promotes deformation-induced densification and improved energy dissipation. However, the coupled influence of loading velocity and unit-cell geometry on the dynamic crushing behaviour of auxetic lattices remains insufficiently understood, particularly for hybrid re-entrant–chiral configurations. In this study, the dynamic compression behaviour of a re-entrant auxetic (REA) structure and a re-entrant chiral auxetic (RCA) structure is investigated using analytical modelling and finite element simulations. Both lattices are modelled as a 6 × 4 unit-cell assembly and compressed between rigid platens at impact velocities ranging from 5 to 200 m/s. The analytical model is developed to estimate the Poisson’s ratio and energy absorption capacity of the unit cells based on ligament bending and rotational deformation mechanisms. The numerical model is validated at both unit-cell and multi-cell levels by comparing deformation modes, Poisson’s ratio, and energy absorption with analytical predictions and published studies. A parametric investigation is then conducted to evaluate the influence of key geometric parameters, including internal angle, horizontal strut length, inclined strut length, and ring radius. The results show that deformation in the REA structure is primarily governed by ligament bending, which leads to localised collapse bands under dynamic loading. In contrast, the RCA structure exhibits a combined ligament-bending and node-rotation mechanism that promotes more distributed deformation. Increasing impact velocity increases plateau stress and specific energy absorption by inertia-induced stabilisation of ligament deformation. Geometric parameters strongly influence both auxetic response and specific energy absorption by controlling ligament slenderness and rotational kinematics. In particular, horizontal strut length significantly increases the energy absorption capacity, while inclined strut length and ring radius exhibit non-monotonic behaviour, suggesting the existence of favourable geometric configurations. These findings provide mechanistic insights and design guidelines for tailoring auxetic lattice geometries for impact-energy-absorption applications.

This research introduces an approach, denoted as the Natural Coordinates Lagrangian Algorithm using the Steepest Descent Method ((NCLA_{sdm})) for the dimensional synthesis of planar mechanisms with the objective of determining the required geometric dimensions for the generation of a desired path. The proposed approach utilizes a Lagrangian optimization method that employs the Steepest Descent Method and natural coordinates related by the constraint equations defining the admissible configurations of the mechanism. The proposed method is validated through the synthesis of four mechanisms of varying complexity. The numerical examples shown are slider-crank mechanisms with and without slider eccentricity, a four-bar mechanism, and the Theo Jansen linkage. The results demonstrate a strong agreement between the desired paths and those generated by the synthesized mechanisms, even in highly complex mechanisms such as those of Theo Jansen.

In the various manufacturing processes as well as field of engineering, the flow of non-Newtonian nanofluid has tremendous effect because of its physical significance. Particularly, in recent scenario, the implementation of carbon nanotubes (CNT) presents its greatest impact in energy storage, chemical sensors, and structural composite materials. The ongoing analysis delves into the movement of a methanol-based SWCNT/MWCNT Maxwell nanofluid over an expanding sheet with a permeable surface. This work assesses the outcomes of thermal radiation and a magnetic dipole, focusing on the interaction of Darcy-Forchheimer drag force and its impact on inertial drag behavior. The convective condition in thermal boundary condition serves as novel approach for the enhanced thermal performance attributes. The specific transformation rules are adopted for the proposed designed model to get its standard non-dimensional form. Further, a shooting-based Runge–Kutta technique is employed for the solution of the transformed system of equations using MATLAB software. The major conclusions of the research demonstrate that that fluid speed declines as the ferromagnetic parameter gradually rises, while temperature field gradually intensifies with increasing Biot number and thermal radiation parameter. Furthermore, when the Biot number and thermal radiation parameter rise, so does the rate of heat transmission. The surface drag force falls with the augmentation in the viscous dissipation parameter and rises with greater solid volume fraction values.

This study presents a comprehensive hydrodynamic and transport analysis of the blade coating process involving shear-dependent non-Newtonian nanofluid. The model incorporates interfacial nonlinear slip, temperature-sensitive viscosity, Magnetohydrodynamics (MHD), and the coupled influences of Brownian motion and thermophoresis effects to capture realistic thin-film flow behavior and to improve coating uniformity in industrial applications. Lubrication Approximation Theory (LAT) simplifies mathematical governing expressions after non-dimensionalization and solved by numerical boundary value solver (bvp4c) alongwith fourth order Runge–Kutta method. The impact of non-Newtonian fluid rheology, velocity slip, viscosity variations, magnetic field, thermophoresis and Brownian motion on the heat transfer, uniform film thickness and blade load is discussed in detail. Findings reveal that Brownian motion enhances the temperature by 2% and substantially improves nanoparticle redistribution, homogenizing the concentration field. While thermophoresis drives nanoparticles toward cooler regions, resulting a 2% increase in temperature but leading to concentration depletion relative to normalized wall concentration at y = 1. While viscosity variations and shear-thinning behavior reduce coating thickness by 40.5% and 26.8%, the interplay of nanoparticle migration provides a mechanism for coating film stability. These results offer analytical guidance for the design and optimization of coating system under various operating conditions. Query ID="Q2" Text="Please check and confirm if the author names and initials are correct."

In this article, the thermomechanical wave propagation analysis of sandwich nanocomposite plates with a triply-periodic-minimal-surface (TPMS) core layer and magneto-electro-elastic (MEE) surface layers are evaluated using the high-order shear deformation theory (HSDT). MEE surface plates are composed of a mixture of cobalt ferrite (CoFe₂O₄) and barium titanate (BaTiO₃) according to the rule of mixture, while the TPMS core layer is SUS304. Three different TPMS cells are considered for the core layer: Gyroid (G), Primitive (P), and Wrapped package-graph (IWP). It is assumed that the material properties of both MEE and TPMS plate structures exhibit temperature-dependent variations. The equations of motion for the sandwich structure are established using HSDT and nonlocal strain gradient elasticity theory (NSGT), while the wave equations are obtained through analytical solutions. The study explores the effect of nonlocal parameters, wave number, TPMS cell pattern, CoFe₂O₄ and BaTiO₃ mixture ratio, temperature increase, and thermal and electrical load parameters on the phase velocity and wave frequency of the sandwich plate. Based on the results, it is concluded that the parameters which are addressed significantly affect the wave propagation phase velocity and frequency of the sandwich plate, and that sandwich plates can be modeled to adapt to variable environmental conditions and tune the desired properties with appropriate parameter selection. It is aimed that this study will contribute to advanced aerospace studies where the effect of temperature change is significant, and where both lightweight and high strength and energy absorption capabilities are prominent.

Transport phenomena in rotating disk systems play an important role in many engineering applications such as rotating disk reactors, disc drilling bits, and bio-microfluidic devices; therefore, this article evaluates the electrically conducting Carreau nanofluid motion between rotating disk surfaces, integrating motile microbes and bidirectional reactions, with regard to the influence of nonlinear radiation, thermal diffusion, and Ohmic dissipation. The intricate nature of the PDEs is framed in consideration of boundary layer approximations by utilizing a similarity transformation. The appropriate conversions of transformation functions are specified and executed to recast the set of PDEs into highly nonlinear ODEs (Ordinary Differential Equations). Then, the Spectral Quasi-Linearization Methodology (SQLM) is adopted to numerically describe the dimensionless expressions of the ODEs. Graphic representations for liquid flow, temperature, concentration, and microbial concentration distributions are plotted. Computational and semi-analytical results detailing the parametric influences on physical variables are presented in a tabular format. A comparison with a literary work is also undertaken to ensure the validity of the modeled system. The results show that the primary velocity decreases with the magnetic field parameter but increases with the rotation and stretching parameters. The temperature rises with Brownian motion and thermophoresis, while the concentration decreases with higher Lewis number and chemical reaction parameter.

This paper introduces a novel Monte Carlo–Levenberg–Marquardt neural network (MCS-LMNN) framework for efficient stochastic buckling and vibration analysis of tri-directional functionally graded porous (3D-FGP) microplates under material uncertainties. Deterministic frequencies and buckling loads are obtained via higher-order shear deformation theory (HSDT), modified couple stress theory (MCT), and Ritz method with hybrid orthogonal polynomial shape functions, achieving convergence with only five terms. The MCS-LMNN surrogate achieves R = 0.99 correlation to Ritz-MCS benchmarks (2000 samples) at 44% of the computational cost, representing a 2.25 × speedup. Parametric studies reveal that porosity degrades stiffness, steeper gradients amplify size effects, and boundary conditions significantly modulate dispersion (COV = 10–15%). Statistical analysis shows positive skewness (0.2–0.4) from lognormal stiffener dominance and kurtosis > 3 from porosity-induced heavy tails. New stochastic benchmarks for 3D-FGP microplates across porosity patterns, gradation profiles, and material length scale parameter ratios provide essential design data, validating the framework’s accuracy and efficiency for microplate analysis.

To achieve ultra-low-frequency broadband vibration isolation in space-constrained systems, this study proposes a sandwich shell metastructure (SSM) tuned via prescribed pre-displacement. A stability-aware framework is developed to determine band gaps under geometric nonlinearity, eliminating ambiguities introduced by unstable eigenbranches. The pre-displaced equilibrium configuration is used as the reference state, and dispersion relations are obtained via small-on-large linearization. Band gaps are extracted exclusively from stable branches to avoid spurious predictions. Increasing pre-displacement shifts the stable band gaps toward lower frequencies and broadens the effective isolation bandwidth to 7.6–395.7 Hz. In the QZS regime, the first stable band gap reaches a maximum relative width of 64.7%. When pre-displacement exceeds 3.2 mm, the first three eigenbranches become unstable, defining a critical design boundary. The widening of the first band gap is attributed to a transition from global bending to shell-dominated local resonance, accompanied by increased frequency separation between adjacent stable modes. Parametric analysis of the SSM shows that orifice diameter, neck length, and cavity diameter govern local stiffness and effective inertia. Approaching critical geometric limits degrades low-order band gaps. A practical guideline is to reduce the orifice diameter while maintaining sufficient neck length and cavity size, thereby preserving stable band gaps and broadening the isolation bandwidth. Finite-structure simulations confirm that transmissibility attenuation coincides with predicted stable band gaps, with localized vibration occurring within these ranges. Experiments on additively manufactured thermoplastic polyurethane samples demonstrate a 76% increase in effective isolation bandwidth (from 158.3 to 279.3 Hz). This study provides a mechanics-based framework for tunable metastructures, offering explicit design guidelines and stability-informed operating boundaries.

It is a very interesting problem to study the effects of aerodynamics pressure load of supersonic airflow and thermal loads of thermal environment on the plates-shells structure of thick-laminated functionally-graded material (FGM). The motivation comes from a chosen model of aerodynamics pressure load by using the third-order piston of pressure mode with respect to the based first-order piston mode for the supersonic airflow flow over the outer surface of FGMs. A computational approach method can be used to obtain solution for differential motion equation is the generalized-differential quadrature (GDQ) approaching. There are many parameters used in the study for third-order shear-deformation theory (TSDT), temperature-dependent power-law FGM, applied-heat loads, aerodynamic pressure load and advanced shear correction factor. The typical materials SUS304 and Si₃N₄ used for the FGMs to obtain the key findings with quantitative results of displacement and stress on dynamic-convergence study, time response study, environment temperature study, power-law indices study, and compared data curves study. The main conclusions are the external load including uniform pressure load for the third-order piston model and first-order piston model are in small different values. The environment temperature value can affect the convergence of grids in TSDT case. The plate center displacement values of metal behavior, e.g., power-law index = 10 case are greater than ceramic behavior, e.g., power-law index = 0.1 case. The genuine academic novelty of this paper is to provide a preliminary basic data for the future possible studies in the coupled fields of supersonic aerodynamics and thermal loads.

This research delves into the complex interactions of plasma and acoustic wave propagation within a thermoelastic semiconductor material. The semiconductor is characterized by double porosity, indicating two distinct pore structures, and by volume fraction fields that describe the spatial distribution of different phases within the material. The study also considers the influence of moisture diffusion, acknowledging the potential impact of water content on the material's properties and wave behavior. To model the thermoelastic heat conduction within the semiconductor, a three-phase-lag model is employed. This model accounts for the time delays among heat flux, temperature gradient, and thermal displacement gradient, providing a more refined description of heat transfer than simpler models. The analysis relies on harmonic wave solutions, which assume that the waves propagate as sinusoidal functions in space and time. This approach allows for a detailed investigation of the wave characteristics, such as their velocity and attenuation. A key aspect of the study is to highlight the influence of plasma waves on the overall wave propagation phenomena. Plasma waves are collective oscillations of charge carriers within the semiconductor, and their interaction with acoustic waves can significantly affect the material's behavior. The research presents numerical results to illustrate these interactions. The numerical analysis considers two different values for both gravity and time, allowing for an assessment of how these parameters affect the wave propagation. The findings reveal a significant positive correlation between gravity and plasma waves, indicating that stronger gravitational forces enhance the plasma wave activity. Furthermore, the numerical results demonstrate the variations in field quantities, such as temperature, displacement, and stress, within the semiconductor material. These variations provide insights into the spatial distribution of energy and forces associated with the wave propagation. The overall results of the study support existing research in the field, providing further evidence for the complex interplay between plasma waves, acoustic waves, and thermoelastic effects in semiconductor materials.

Graphical abstract

This graphical abstract illustrates that the thermodynamic response of a semiconductor thermoelastic medium with double porosity was affected by the moisture and the acoustic wave pressure. Central icons depict interacting thermal and microthermal fields. 2D representations on the right highlight the influence of gravity on strain, temperature variation, and stress.

The alternative text for this image may have been generated using AI.