International Journal of Mechanics and Materials in Design最新文献

Many experiments have shown that micro-particle reinforced metal matrix composites (MPMMCs) display a strong particle size effect on mechanical behavior. Meanwhile, the stress concentration near the particle phase leads to matrix damage and interface debonding for composites in service. In this research, a modified conventional theory of mechanism-based strain gradient plasticity (CMSG) considering the damage effect, and a cohesive zone model are used to predict the mechanical behaviors of MPMMCs. The particle size effect and matrix damage behavior are characterized by modified CMSG while the interface debonding is controlled by the cohesive zone model. Details about the local distributions of strain, strain gradient and stress fields have been captured. An interesting phenomenon is found that matrix damage enhances the strain and strain gradient of the matrix, but interface debonding does the opposite. Both the interface debonding and matrix damage weakened the strength of composites. As a result, the numerical predictions agree well with both uniaxial tension and compression experiments. Furthermore, this work finds interface debonding takes the dominant role of damage mechanisms in uniaxial tension cases. However, matrix damage is dominated in compression cases. The present research should provide a comprehensive understanding of the mechanical behaviors of MPMMCs in service, which is also helpful for optimal designs of such advanced composites.

In this paper, the wave finite element (WFE) method is briefly presented and applied in order to extract the dispersion curves. The formulation of the laminated structure is detailed through the Timoshenko theory. The finite element technique is used to model the laminated beam and extract the mass and stiffness matrices for the bending vibration. The bending vibration of the laminated beam is simulated and discussed. The travelling and evanescent modes are illustrated to characterize the flexural wave propagation in laminated structure. The resolution of the equilibrium equation leads to the extraction of the analytical wave number as a function of the frequency in order to validate the dispersion curves simulated through the WFE method. The question of the influence of the layers thickness on the wave propagation is detailed. An uncertainty is introduced in the thickness as a Gaussian variable and the mean and the standard deviation of the dispersion curves are extracted through the Monte Carlo simulation. Among the contributions of this article, the laminated structures are modeled through the Abaqus software and the mass and stiffness matrices are extracted for the multimodal propagation. The multimodal wave number is presented and discussed for the travelling and evanescent modes.

Origami, the ancient Japanese art of paper folding, has evolved beyond its cultural origins to inspire innovations in engineering and design. By transforming a simple sheet of paper into complex three-dimensional structures, origami offers solutions where flexibility and structural efficiency are paramount. This work explores the application of these principles in origami structures, focusing on their development and optimization using shape memory materials and 4D printing. The study highlights the Miura-ori and Triangular Cylindrical Origami structures, both renowned for their mechanical properties and adaptability, making them ideal for various applications in mechanical engineering, aerospace engineering, robotics, and biomedicine. Using finite element numerical modeling, these structures were parameterized for optimization. A multi-objective optimization approach was adopted, aiming to reduce mass and internal stresses while maximizing material strength and efficiency. Graded structures were introduced, varying their geometric characteristics throughout the volume to explore optimized distributions of material and mechanical properties in response to loads. These variants represent a significant advancement in customizing functional properties, enabling structures to meet specific performance requirements with even greater precision. The optimization algorithms employed include particle swarm optimization, genetic algorithms, and the Sunflower algorithm, all applied to refine structural parameters and identify the best solutions in multi-objective optimization. This study also underscores the emerging importance of shape memory materials in additive manufacturing, particularly for applications that benefit from inherent structural adaptability. The integration of graded origami structures with advanced material technologies represents a promising frontier for future innovations in engineering and design, with the potential to revolutionize how functional structures are conceived and implemented across various fields. Quantitatively, the study achieved a hypervolume of 0.88 using the MOPSO algorithm for mass minimization, indicating a broad and effective search for optimal solutions. Additionally, experimental results demonstrated a 99.3% height recovery in the Miura-ori structure after deformation and heating, confirming the robustness and applicability of these structures in real-world scenarios.

Structural optimization has emerged as a fundamental pillar of modern engineering design, propelled by the imperative to augment structural performance while minimizing material consumption and weight. While topology optimization (TO) has demonstrated efficacy in fulfilling stiffness and dynamic requisites, extant methods reveal substantial lacunae in concurrently handling multi-material designs and buckling constraints, particularly when geometric fidelity and stability are of paramount significance. Although prior investigations have independently advanced iso-geometric analysis (IGA), multi-phase TO, and buckling-aware optimization, their isolated evolution gives rise to unresolved predicaments in circumstances demanding unified geometric resolution, material hybridization, and compressive stability. To bridge this chasm, this study proffers an integrated framework that synergizes a novel buckling-constrained topology optimization framework for multi-phase materials, integrating Iso-geometric Analysis (IGA) to enhance computational accuracy and geometric representation. This unified methodology addresses a critical constraint in conventional TO–the incapacity to co-optimize geometric precision, material heterogeneity, and stability constraints–enabling lightweight designs with assured manufacturability and resistance to failure under compression. The proposed approach harnesses the high-order continuity and precise geometry modeling capabilities of IGA to optimize material distribution while ensuring structural stability under compression. By incorporating critical buckling load constraints alongside compliance minimization, the framework achieves an optimal balance between stiffness, stability, and material efficiency. Numerical case studies validate the effectiveness of the proposed method, demonstrating significant improvements in buckling resistance, structural efficiency, and manufacturability. The results highlight the potential of IGA-based topology optimization in advancing stability-driven structural design, particularly for multi-phase material systems.

This study investigates a novel energy harvesting approach using flex tensional piezoelectric bridge structures integrated with auxetic metamaterials. Auxetic structures, characterized by their unique negative Poisson’s ratio, offer a distinct advantage for energy harvesting applications by generating favourable strain distributions that enhance the output of piezoelectric materials. A finite element model is developed to analyse the electromechanical functionality of a bridge structure utilizing an auxetic substrate with PZT-5A piezoelectric material. Key geometric parameters, including cavity height, cavity length, thickness ratio, end cap thickness, and apex length, are optimized to maximize energy output while mitigating potential mechanical failures. The study's findings reveal significant improvements in energy harvesting efficiency due to the auxetic design, highlighting its potential for applications under dynamic loading conditions, such as in roadways, tiles and smart wearables. This research presents an extensive exploration of auxetic structures in piezoelectric energy harvesting, opening new pathways for smart, adaptive energy solutions.

This study employs the high-order shear stress theorem and nonlocal strain gradient elasticity theory to foresee and evaluate the heating and buckling behavior of sandwich nanoplates featuring a hexachiral auxetic core layer and magneto-electro-elastic surface layers. This study examines the influence of electroelasticity and magnetostriction for the magnetic electroelastic surface layers, as well as the mechanical impacts on the hexachiral structure of the primary layer, to obtain the equations of motion for the sandwich nanoplate. Separate studies are performed to assess the influence of the core layer and the surface layers on the thermal buckling performance of sandwich smart nanoplates, with the findings of these analyses recorded. The analysis reveals that the auxetic structure in the core layer significantly influences the thermal buckling behavior inside the sandwich nanoplate. Furthermore, studies indicate that the buckling behavior of a sandwich nanoplate is considerably influenced by external electric and magnetic potentials applied to the surface layers. Generally, applying of an external electric potential induces a softening reaction in the surface layer of the sandwich nanoplate, thus reducing the buckling temperatures. Conversely, the magnetostrictive material on the surfaces induces a hardening effect contingent upon the introduction of a magnet outside, hence elevating the buckling temperatures.

This study primarily investigates the thermo-electro-magneto-mechanical free vibration characteristics of sandwich plates with a core layer made of graphene oxide powder-reinforced nanocomposite (GOPRC) and two outer face sheets composed of magneto-electro-elastic functionally graded materials (PoFGMEE). For convenience, this structure is referred to as PoFGMEE-GOP. The plate is considered to be supported by a three-parameter Kerr elastic foundation. The magneto-electro-elastic properties of the face sheets vary through the thickness following a modified power-law rule that accounts for both even and uneven porosities, while the GOPRC core’s material properties are determined using the Halpin–Tsai model. The magnetic and electric potentials within the PoFGMEE layer are modeled as a blend of cosine and linear functions through its thickness. Additionally, three types of temperature distributions along the plate thickness—uniform, linear, and nonlinear—are also considered. To perform this analysis, a novel model using a four-variable refined plate theory (HSDT-4), combined with the pb2-Ritz method, is developed. Comparative examples validate the accuracy of the model. New numerical findings are provided to assess the influence of temperature, magnetic potential, electric voltage, power-law index, porosity distribution type, porosity coefficient, graphene oxide powder distribution type, thickness ratio of the core to the face sheet, and foundation elasticity on the free vibration response of PoFGMEE-GOP sandwich plates.

This study focuses on an optimization analysis of the nonlinear free vibration of a functionally graded porous micropipe conveying fluid in uniform steady thermal environment using the Timoshenko beam theory. The nonlinear equations of motions are derived based on the modified strain gradient elasticity theory and Von–Kármán’s strain relations. By means of the Galerkin method, the nonlinear partial differential equations of motion are transferred into an ordinary 4^th-order nonlinear ordinary differential equation. An analytical closed-form solution for this nonlinear differential equation has been presented using homotopy analysis method. As a consequent, closed–form expressions for the nonlinear critical flow velocity, time history and n^th nonlinear frequency are obtained. The exact solution for the critical flow velocity of the micropipe resting on elastic foundation has been used to find the optimum pipe length. The results illustrate as the micropipe’s length increases, the nonlinear frequency significantly drops for short micropipes but it decreases slightly for longer ones. Additionally, in high temperatures, the nonlinear frequency is less affected by the variation of the power-law exponent. Furthermore, in the absence of elastic substrate, the critical fluid velocity decreases with increasing the microtube length. However, when the microtube is placed on an elastic substrate, the optimum value of the microtube length is observed in higher mode shapes.

Aerial vehicle electronics, such as inertial measurement units (IMU), are subjected to aerodynamic forces and engine-induced vibrations during flight. Structural vibrations must be attenuated using vibration isolators to ensure these electronic devices operate effectively and the vehicle completes its mission successfully. Passive vibration isolators are typically placed between the vibration platform and the electronic devices to mitigate dynamic responses and prevent resonance. This paper investigates energy dissipation methods in mechanical systems, focusing on viscoelastic damping materials (VDM). These materials are ideal for energy dissipation due to their ability to deform and dissipate energy under load. By optimizing parameters and selecting an appropriate VDM, the performance of isolators can be significantly enhanced. In the study, vibration isolation components are designed for electronic devices, and elastic isolators are produced and validated through static and dynamic load testing. A comprehensive analysis of various material parameters transforms the system’s dynamics and shock level, ultimately enhancing the VDM model for effective vibration isolation and shock absorption. This study aims to provide a clear understanding of energy dissipation methods and required material properties, enabling the design of efficient vibration isolation strategies for IMU and other electronic devices on aerial vehicles.