International Journal of Mechanics and Materials in Design最新文献

This study proposes a robust mathematical and computational framework for investigating the dynamic response of multidirectional functionally graded viscoelastic beams (MDFGVBs) on elastic foundations under moving loads. To capture the time-dependent behavior of viscoelastic materials, the Kelvin–Voigt constitutive model is adopted to capture both stiffness and damping effects. The beam's material properties vary continuously and independently along the axial, transverse, and thickness directions, governed by a generalized spatial gradation function, reflecting realistic material heterogeneity. The governing equations of motion are systematically derived using both Euler–Bernoulli and Timoshenko beam theories, incorporating bending, shear deformation, and rotary inertia effects. The Ritz method is employed for spatial discretization under various classical boundary conditions, whiletransient dynamic responses are computed using the unconditionally stable Newmark-β scheme. Model accuracy and numerical stability are validated through rigorous comparisons with established benchmark solutions. A comprehensive parametric study is conducted to explore the influence of foundation stiffness, viscoelastic damping coefficients, and material gradation indices on both free and forced vibrations. The results reveal significant coupled effects between the foundation parameters and the spatially varying viscoelastic and elastic properties. These findings provide practical guidance for designing functionally graded beam components, for instance in aerospace wing structures and precision robotic arms, where controlling vibration amplitudes and dynamic deflections is critical for structural integrity and operational accuracy. The study also aids in selecting appropriate material gradation profiles and foundation stiffness to achieve targeted dynamic performance.

The current study presents a significant advancement in the elastic bending analysis of hybrid composite sandwich curved beams with re-entrant auxetic cores by introducing a general beam model that more accurately reflects straight and curved beams. The main contribution of this study is the use of a computationally efficient 2D higher-order shear deformation theory without thickness-stretching effects, that develops a reduced kinematic representation through integral expressions of the three displacement variables for the mechanical analysis of hybrid sandwich curved beam with FG face sheets and re-entrant auxetic core. In this study, a new configuration of curved sandwich beam structures with a re-entrant auxetic honeycomb core is presented. In which the negative Poisson’s ratio behavior, promotes transverse expansion during axial extension, providing enhanced mechanical performance compared with traditional sandwich beam systems with core materials that have a positive Poisson’s ratio, while the virtual work principle is used to obtain the equilibrium governing equations. A closed-form solution is used to determine the transverse and axial displacements and internal forces of the composite sandwich beams. The accuracy and strength of the proposed mathematical model were validated through a comparison study with existing numerical results. A detailed parametric study was conducted to examine the effects of different parameters, including material gradation, length-to-thickness ratio, sandwich configuration schemes, and geometric properties of the auxetic core, on the bending behavior of curved beams. The numerical results provide new insights into the elastic bending characteristics of hybrid sandwich beams with re-entrant auxetic cores, highlighting the significant role of auxetic cores in the bending behavior of curved beams.

Thermal performance is significantly better in hybrid nanofluids compared to traditional nanofluids and leading to advancements in industrial processes, medical equipment, and nanomaterials engineering. The ongoing study explores the hybridized fluid flow dynamics over a bidirectional stretching surface, emphasizing their thermal flow properties under various impacts. The study explores not only achieving higher heat conduction compared to traditional nanofluids but also highlights the shape effects capabilities offered by the single-walled and multi-walled carbon nanotube nanoparticle combination in water. The partial differential equations concerning momentum and energy transport have been rendered into a set of ordinary differential equations using a similarity transformation. The transformed nonlinear dimensionless ODEs were solved using the bvp5c solver, a boundary-value problem tool available in MATLAB, and the obtained profiles were further refined and validated using MATLAB’s bvp5c solver. The visualizations represent the results for flows, heat transmission characteristics, which are obtained via the utilization of many important physical features. The present numerical data were validated by comparing special cases of the model with former published results, and display admirable agreement. Outcomes reveal that both hybrid volume fraction and nanoparticle rotation strengthen the axial velocity but damp transverse motion, showing a directional partiality in momentum transport. The temperature fields are remarkably raised by increasing the Biot number, radiation, hybrid nanoparticle concentration, and heat source factor, depicting the hybrid nanofluid’s thermal performance. These findings are applicable in the cooling of rotating machinery, microchannel thermal systems, solar collectors, and nano-manufacturing technologies.

Fins are essential components in many thermal management systems due to their flexible geometry and high efficiency in heat transfer. They are used in applications such as electronic devices, nuclear reactor cooling, and solar energy systems. Among various fin shapes, pyramidal spine fins received attention because of their capacity to improve CPU heat sink performance. Motivated by these applications, the present study investigated the thermal characteristics of an inclined pyramidal spine fin subject to a convective-radiative environment. Additionally, the spine is considered a porous surface, and its interaction with the surrounding fluid is demonstrated using Darcy’s model. By introducing suitable non-dimensional terms, the governing heat equation is transformed into a dimensionless ordinary differential equation (ODE). The resultant equation was solved semi-analytically using a shifted Vieta-Pell polynomial collocation method (SVP-PCM). The novel SVP-PCM approach is distinguished by its close agreement with results from known numerical techniques, showing its robustness and reliability when compared with existing data. Key thermal parameters and their effects are shown graphically. The outcomes reveal that the enhancing values of radiation parameter (from 0 to 3) and convection-conduction parameter (from 2 to 4) improve heat transmission efficiency by 29.82% and 69.28% respectively. Conversely, an increase in the ambient temperature parameter (from 0.2 to 0.5) leads to a decrement of heat transfer rate by 37.5%.

Isaac Newton's contributions laid the foundation for modern mechanics, science, and engineering. This paper explores the historical context in which Newton developed his theories, particularly his three laws of motion, and highlights how they reshaped the scientific understanding of nature and progress. In this paper. we first introduce Newton’s key contemporaries during that era of ground-breaking scientific advances, whose work greatly influenced his discoveries. Then, we focus on the contributions of Newton’s laws of motion to modern mechanics, especially in fields that have received less attention in previous studies. For example, in continuum mechanics, Newton’s laws describe the equilibrium state, dynamic behavior and interactions of particles/systems under external forces. Newton’s contribution also extends to atomistic mechanics. In molecular dynamics simulations, Newton’s second law governs the motion of atoms, which allows us to examine the system behavior under load at the atomistic scale. Furthermore, the paper examines the evolution of classical mechanics into more general formulations, namely Lagrangian and Hamiltonian mechanics, which are central to modern physics. These energy-based approaches provide a more flexible framework to analyze complex systems and serve as a bridge to advanced topics such as statistical mechanics and quantum mechanics. Finally, we examine the limitations of Newtonian mechanics in problems involving relativistic effects, quantum phenomena, and non-inertial reference frames. We briefly introduce the corresponding theories that extend Newton’s framework to address these problems.

A three-dimensional constitutive model considering the effects of grain size, porosity, and temperature on the macroscopic behaviors of nanoporous Shape Memory Alloys (SMAs) is developed. A finite three-phase model containing a spherical pore, a shell-mounted grain boundary phase, and a shell-mounted grain-core phase, is firstly applied to nanoporous NiTi SMAs. By using the composite Eshelby tensor to homogenize, the overall stress–strain relationship of nanoporous NiTi SMAs are then obtained. In order to verify the correctness of the constitutive model, the molecular dynamics simulations of the superelastic behavior of nanoporous NiTi SMAs are also investigated in this paper. By comparing the numerical simulation results with the experimental results and molecular dynamics simulations, it is verified that the constitutive model proposed in this paper can better describe the superelastic behavior of nanoporous NiTi SMAs. Finally, the effects of grain size, porosity, and temperature on the superelastic behavior of nanoporous NiTi SMAs are analyzed by combining numerical and molecular dynamics simulations. This study will contribute to the theoretical basis for the application of nanoporous NiTi SMAs.

Conical pin fins significantly enhance heat transfer through optimized flow dynamics and increased surface area. This study provides a detailed analysis of rate of thermal transfer and temperature profile of a conical pin fin constructed from a functionally graded material (FGM) with linear, quadratic, and exponential profiles, and the fin is infused with a trihybrid nanofluid comprising MWCNT, silver, and copper in an (EG-{H}_{2}O) base fluid. The governing equation after being nondimensionalized was solved by employing the efficient Fibonacci wavelet technique. This approach facilitated a thorough investigation of the key parameters including the Peclet number, the generation number, the convection parameter, the radiation parameter, power index, thermogeometric parameter, the internal heat generation parameter, and the wet parameter. The results indicate that a 100% increase in the inhomogeneity coefficient (grading parameter) significantly enhances thermal profiles, raising temperatures by 4.8, 4.3, and 6.5% for the linear, quadratic, and exponential FGM profiles, respectively. Furthermore, a 400% elevation in internal heat generation levels induces a proportional rise in fin temperature, with increases of 3, 3.1, and 2.5% for the linear, quadratic, and exponential FGM profiles, respectively. A critical analysis of contour plots for the heat transfer rate reveals that each FGM distribution exhibits distinct characteristics. The exponential profile provides the highest thermal performance and the most favorable temperature distribution, thereby offering significant benefits for applications in electronics cooling, heat exchangers, and aerospace systems.

The free vibration characteristics of two-dimensional (2D) decagonal quasicrystal (QC) cylindrical shell panels hold significant promise for advancing sensor technologies, energy harvesting systems and lightweight structural components in aerospace and mechanical enginee3ring. To address this need, this work presents the Hamiltonian-based analytical solution for free vibration of 2D decagonal QC cylindrical shell panels with Lévy-type boundary conditions. By introducing a full-state vector as the fundamental unknown, the governing equations are formulated in the Hamiltonian form, which are simplified into a set of low-order ordinary differential equations. This approach enables the direct derivation of analytical solutions for free vibration of 2D decagonal QC cylindrical shell panels. Comparison studies validate the accuracy of the proposed symplectic model. Through a comprehensive parametric analysis, it is found that the geometric parameters, elastic constants of the phonon and phason fields, material parameters of the phason field are the key influencing factors on the natural frequencies and modal deformations of the QC cylindrical shell panels.

This study investigates the thermal behavior of a radial porous fin influenced by a magnetic field and internal heat generation. The nonlinear governing ordinary differential equation (ODE) is solved using two advanced methodologies: The Taylor wavelet method and the physics-informed neural networks (PINNs). The Taylor wavelet method provides a semi-analytical solution by converting the ODE into algebraic equations, ensuring accuracy and computational efficiency. PINNs integrate physical laws directly into the neural network framework, employing automatic differentiation to minimize residual errors while solving the ODE. A comparative analysis of the fin’s thermal performance with and without the magnetic field is conducted. The results demonstrate that the Hartmann number ((H)) significantly enhances the heat transfer rate. Furthermore, higher values of the heat generation parameter ((Q)) lead to elevated temperature profiles, as increased internal heat production slows the rate of temperature decay along the fin’s length. This trend is consistent across both scenarios. The PINN approach offers a notable advantage by embedding physics equations within its architecture, eliminating the need for extensive mathematical computations often required by traditional numerical methods. This capability ensures accurate results with minimal training data, making it a time-efficient and resource-saving solution for complex thermal analyses. This approach effectively addresses complex nonlinear thermal problems with high precision and reliability.

The article addresses the nonlinear stability problem of internally hinged arches. Formulation for uniform and non-uniform arches are both given. In latter case, the stiffness of the cross-section at the sides of the internal pin can be different through the geometry and material, causing asymmetry. An analytical model is derived as per the Euler–Bernoulli hypothesis with von Kármán nonlinearity accounted. For uniform arches, generally higher internal forces rise in the arch-half, which is closer to the pinned end. The slenderness ratio affects lower arch angles more drastically. With non-uniformity introduced, a less stiff left side affects negatively the buckling load. Extreme cases are also addressed.