International Journal of Mechanics and Materials in Design最新文献

Graded cellular structures have attracted increasing attention for lightweight and multifunctional applications. However, most existing gradation definitions are qualitative, limiting systematic exploration of their potential in multifunctional design. This study proposes a function-based parametric strategy to tailor the mechanical and thermal performance of two-dimensional (2D) graded cellular structures. By parameterizing key geometric features of regularly patterned structures with mathematical functions, both the dimensionless elastic modulus (E*) and the dimensionless thermal conductivity (K*) can be effectively tuned at a fixed overall infill porosity (P). Comparative analyses highlight the critical roles of porosity and the gradation function form. At P = 40%, quadratic gradations expand the tunable performance range by up to 50% relative to linear gradations. Furthermore, quadratic-graded structures achieve up to 2.1-fold wider tunability in E* and 3.7-fold in K* compared with randomly patterned counterparts, which exhibit narrower, near-normal performance distributions. To address trade-offs in multifunctional design, the Non-dominated Sorting Genetic Algorithm II (NSGA-II) is used to optimize the gradation coefficients. The resulting Pareto fronts show an approximately linear trade-off between E* and K* under the same gradation strategy, revealing promising sub-regions for high-stiffness, low-thermal-conductivity designs. Overall, this work offers a computationally light, physically interpretable approach for the multifunctional design of graded cellular structures, with strong potential for applications in thermal protection, energy absorption, and architected metamaterials.

Magneto-electro-elastic (MEE) materials with integrated sensory and actuation functions have promising application potentials in the spacecraft and automotive engineering. The deformation of MEE structures in temperature varying environments leads to a thermo-magneto-electro-elastic coupled problem. However, most studies considered temperature changes as a thermal load. This unidirectional coupling misses thermal changes due to structural deformations. This study establishes a thermo-magneto-electro-elastic fully coupled finite element (FE) model for MEE plates based on the first-order shear deformation (FOSD) theory. The proposed eight-node Serendipity plate/shell elements for MEE structures incorporate five displacement DOFs per node, and one electric, one magnetic and one temperature DOF per element. The present FE model is first analyzed for mesh convergence. Subsequently, the static and dynamic responses of MEE plates under mechanical, electric, and magnetic loads are investigated. The numerical results, including displacements and temperature fields, are compared with COMSOL simulations. The comparative results indicate that the model has good accuracy in predicting the impact of structural deformations on the temperature field.

The propagation of Love-type waves in composite structures has significant implications for wave-based sensing, energy harvesting, and structural health monitoring. This study investigates the effect of an electric membrane and a classical spring on Love-type wave propagation at the common interface of a piezoelectric fiber-reinforced composite (PFRC) layer comprising a PZT-5A-epoxy combination and a piezoelectric substrate. Utilizing a mathematical model incorporating interface conditions, the wave dispersion characteristics are examined under different bonding scenarios, such as perfect, spring-type, membrane-type, and combined spring-membrane type interfaces. Numerical analysis is conducted to elucidate the influence of material properties, bonding parameters, and interface stiffness on phase velocity. The results show that the presence of a thin electric membrane and a classical spring significantly alters Love-type wave behavior, providing opportunities for optimizing wave control in smart materials and non-destructive evaluation systems. These findings contribute to the advancement of wave manipulation techniques in engineered composite structures and the design of surface acoustic wave (SAW) devices like Love wave sensor, which have gained traction in advanced defence systems due to their robustness, sensitivity, and passive operation.

This study aimed to enhance the tribological and corrosion-resistance properties of copper-tin (Cu–Sn) alloy substrates by developing multilayer diamond-like carbon (DLC) coatings with different modulation periods. Gradient transition layers (Cr and Cr-WC composite) were first deposited, followed by WC-DLC/DLC coatings with four modulation periods (1, 2, 3, and 4) on the Cu–Sn substrates. The microstructure, tribological behavior, and corrosion resistance of the coatings were systematically investigated. Results indicate that the modulation period significantly affects both tribological and corrosion properties. The coating with two modulation periods demonstrated the best performance, exhibiting high bonding strength and a low friction coefficient of 0.044. This tribological improvement is attributed to an optimized internal structure, which, despite a slightly lower sp³ content (38.8%), effectively resists wear and spalling. Additionally, its corrosion current density is only 9.16 × 10^–8 A/cm², two orders of magnitude lower than the other coatings, indicating superior corrosion resistance. These results suggest that DLC coatings with appropriately designed modulation periods develop a dense microstructure with minimal defects, which is a key factor in enhancing corrosion resistance.

This study presents a multi-channel design and optimization framework for active vibration control of ring shell structures using flexoelectric actuators. The novelty of this work is three-fold: (i) a coupled electromechanical dynamic model that captures both membrane and bending responses of a freely floating ring under localized flexoelectric actuation; (ii) a practical actuation mechanism based on AFM-probe–generated nonuniform electric fields to produce highly localized converse-flexoelectric driving forces; and (iii) a multi-objective Sequential Quadratic Programming (SQP) procedure that simultaneously optimizes actuator positions and drive voltages to minimize a physically motivated roundness function measuring deviation from circularity. Numerical case studies for a ring (radius 0.05 m, thickness 0.001 m; flexoelectric patch thickness 50 μm; AFM tip radius 50 nm; actuation voltages up to 10 V) demonstrate that the SQP routine robustly identifies actuator configurations that cancel overall vibration across multiple excited modes, yielding near-zero residual deformation where single-channel schemes fail. We further show that the optimal actuator distributions obey cyclotomic-polynomial symmetry and that control benefit saturates as the actuator count increases (computational cost also rises), indicating an effective practical range for actuator number. The approach offers a systematic route for precision deformation control in ring-shaped micro- and nano-devices and informs design choices for multi-actuator flexoelectric systems.

In this study, the free vibration behavior of a viscoelastic nanobeam resting in a nonlocal viscoelastic medium is analytically investigated using the Navier solution method. A modified Jeffreys-type viscoelastic model, consisting of one elastic and two viscous elements, is employed to more accurately represent the time-dependent and hereditary mechanical behavior of the beam material. The equations of motion are formulated by combining stress-driven model and, nonlocal elasticity theory for viscoelastic foundation. These are coupled with the modified Jeffreys model to derive a generalized differential equation that captures both stress-driven effects and nonlocal viscoelastic interactions within a unified analytical framework. Unlike conventional studies limited to classical viscoelastic formulations, this work introduces an enhanced viscoelastic model to describe viscoelastic nanobeam dynamics under the influence of a nonlocal viscoelastic foundation, providing a more realistic depiction of nanoscale structural behavior. The analytical closed-form solutions obtained allow a detailed investigation of how scale effects, viscous damping, and foundation parameters influence the dynamic response characteristics of viscoelastic nanobeams. This theoretical contribution highlights that the dynamic behavior of nanobeams is strongly governed by the coupled effects of nonlocal elasticity and advanced viscoelasticity, offering new insights into nanoscale material modeling and providing a valuable analytical benchmark for future nanomechanical system designs.

This study presents a comprehensive investigation into the dynamic stability analysis of laminated composite plates using meshless methods, particularly the Radial Point Interpolation Method (RPIM). Laminated composite plates are widely utilized in civil and aerospace engineering due to their exceptional properties, including high strength-to-weight ratios, lightweight nature, and tailorable anisotropic behavior. However, analyzing their dynamic stability poses significant challenges due to geometric nonlinearities and critical responses under time-varying loading conditions. In this research, RPIM is integrated with higher-order shear deformation theories, specifically the Third-Order Shear Deformation Theory (TSDT) and Classical Plate Theory (CPT), to model complex plate behaviors under diverse dynamic loadings, such as periodic, moving, and combined loads. The influence of critical parameters, including fiber orientation, number of layers, thickness-to-width ratio, boundary conditions, and elastic modulus ratio, on the primary dynamic instability region is thoroughly examined. The results demonstrate that the combination of RPIM and TSDT yields highly accurate predictions of natural frequencies and critical buckling loads, particularly for thick plates where shear deformation effects are pronounced. The primary innovation lies in a robust computational framework leveraging meshless methods for greater geometric flexibility and computational efficiency; benchmark tests show RPIM achieves ~ 20–30% faster computation than FEM for comparable accuracy. Increasing the length-to-thickness ratio and elastic modulus ratio shifts the dynamic instability region to higher excitation frequencies, enhancing structural stability. This work advances the understanding of nonlinear dynamic stability phenomena in laminated composites and offers a robust computational framework for future studies in structural mechanics.

An optimal design study is presented for a stiffened pultruded cable tray beam manufactured from carbon fiber-reinforced epoxy with a 55% fiber volume fraction, subjected to a uniformly distributed transverse load. The objective is to determine the optimal stiffener thickness at the side sections to achieve weight-efficient structural performance. Design constraints include limits on deflection, material failure, and buckling, and the associated structural problem is solved using an 8-noded degenerated shell finite element model. First, the mechanical properties of the composite material are derived analytically, and a mesh convergence study is conducted for the unstiffened tray configuration. In the subsequent optimization phase, the optimal stiffener thicknesses are determined for selected geometries while maintaining a constant structural weight. Comparative results show that the stiffened design achieves approximately a 70% increase in load-carrying capacity relative to the unstiffened configuration of equal weight. Furthermore, the findings indicate that increasing the height of the side sections leads to more structurally efficient and economical designs.

This study presents a semi-analytical framework for the size-dependent free vibration analysis of Timoshenko nanobeams based on nonlocal elasticity theory. The Initial Value Method (IVM) combined with the Approximate Transfer Matrix (ATM) approach is employed to compute natural frequencies. The proposed method captures nanoscale effects with high accuracy and reduced computational effort, eliminating the need for closed-form symbolic expressions and offering a practical alternative to conventional numerical techniques. Convergence analyses and comparison with a benchmark solution confirm the robustness and validity of the solution method. Parametric studies reveal that increasing (mu) reduces the natural frequencies in supported, clamped–simply supported, and clamped–clamped beams, demonstrating the expected softening behavior due to nonlocal effects. For the clamped–free beam, an increase in (mu) leads to a hardening response for the fundamental mode, while higher modes retain the classical softening trend. Additionally, increasing L/h results in higher frequencies, and the influence of nonlocality becomes more pronounced for higher-order modes. The ATM–IVM framework provides a robust and efficient tool for modeling, designing, and optimizing advanced nanostructured materials, where an accurate representation of size effects is crucial.

A tube reinforced hyperelastic gradient porous sandwich structure (TRHGP) for shock isolation of gearbox is proposed based on the principles of bionics. The perfusion–moulding press integrated molding process is developed to prepare the specimens. This process is simple and conducive to industrialization. Moreover, the dynamic responses and shock isolation efficiencies of TRHGPs connected to a gearbox under different shock acceleration amplitudes are investigated experimentally and numerically. The effects of topological configuration, porosity, and impact load on the shock resistance performance of TRHGPs are also explored. The results indicate that, compared with the response under rigid impact condition, the shock isolation efficiency of TRHGPs is more than 40%. Furthermore, it is demonstrated that the TRHGP with triangular tubes exhibits better shock isolation efficiency than those with rectangular or circular tubes. The findings provide a valuable reference for the design of shock isolation structures.