https://cme.hormozgan.ac.ir/ International Journal of Innovative Computational Methods in Engineering Sciences en daily 1 Sat, 06 Sep 2025 00:00:00 +0330 Sat, 06 Sep 2025 00:00:00 +0330 https://cme.hormozgan.ac.ir/article_228594.html In this study, the mechanical buckling of a Timoshenko sandwich microbeam is analysed, where the core is made of functionally graded porous materials, and the facesheets are composed of graphene platelets reinforced nanocomposites. The mechanical properties of the beam layers vary along the thickness direction based on defined functions, and the microstructure is subjected to thermal load. The governing equations are derived using the principle of virtual work and the variational method based on both first-order shear deformation and modified couple stress theories to capture the effect of shear deformation and scale. Navier's method is employed as an analytical solution for simply supported boundary conditions to obtain the critical buckling loads of the microbeam. The effects of various factors such as temperature changes, porosity coefficient, amount and dispersion type of reinforcing nanoparticles in the facesheets, elastic foundation parameters, and other important parameters are investigated and analysed. It is observed that increasing the porosity coefficient of the microbeam's core leads to a decrease in the critical buckling load. Moreover, based on the results, an increase in the mass fraction of reinforcing nanoparticles in the facesheets generally leads to an increase in the critical buckling load. The outcomes of this research can be used in the design of space and innovative structures. https://cme.hormozgan.ac.ir/article_229708.html In this research, an axisymmetric thick hollow cylinder made of functionally graded materials under internal thermal shock based on classical theory of linear thermoelasticity is considered. The cylinder is made of a combined ceramic-metal material and its material is graded through the thickness direction according to a power law distribution. The governing equations are based on 2D-axisymmetric theory of elasticity and graded finite element method based on Rayleigh- Ritz energy formulation is used to model the problem. To obtain transient temperatures, Crank- Nicolson algorithm is used and then Newmark direct integration method is used to obtain time history of displacements and stresses. Distribution of displacements and stresses for different power law exponents is investigated. To obtain transient temperatures, Crank- Nicolson algorithm is used and then Newmark direct integration method is used to obtain time history of displacements and stresses. Distribution of displacements and stresses for different power law exponents is investigated. https://cme.hormozgan.ac.ir/article_231119.html This study presents a comprehensive investigation into the torsional vibration behavior of rectangular microrods using modified couple stress theory (MCST) to capture size-dependent effects. Unlike previous studies focused on circular cross-sections, we develop a novel analytical model for noncircular microrods with clamped-clamped (C-C) and clamped-disk (C-D) boundary conditions. The governing equations are derived via Hamilton’s principle and solved using Galerkin’s method, incorporating the material length scale parameter to account for microscale effects. Key findings reveal that: Increasing the material length scale parameter enhances torsional stiffness, raising natural frequencies by up to 35% for C-C boundary conditions. Aspect ratio significantly influences vibrational response: horizontal configurations exhibit 20% higher frequencies than vertical ones. Attached disk mass reduces frequencies by 50% under C-D boundary conditions, demonstrating critical design implications for MEMS/NEMS applications. Validation using silicon microrods confirms theoretical predictions, bridging the gap between continuum mechanics and microscale behavior. This work provides a foundational framework for optimizing microrod-based sensors and actuators in nanotechnology and biomedical devices. https://cme.hormozgan.ac.ir/article_231900.html Functionally graded materials (FGMs) have a heterogeneous and advanced structure, and their properties change gradually and continuously from one surface to another. This continuous structure eliminates the delamination problems of layered composite materials. These materials, due to their gradual change in properties, are suitable options for withstanding harsh conditions and mechanical and thermal stresses. On the other hand, they perform better under various environmental and operational conditions, especially in applications that require high resistance to temperature and pressure. This article examines the thermoelasticity and creep behavior of functionally graded materials along with their governing structural equations. Creep in functionally graded materials refers to the time-dependent deformation behavior of a material under continuous loading, which is highly important in mechanical engineering and material analysis. In functionally graded materials, due to the gradual spatial variation of material properties, the creep and thermoelastic behavior must be modeled in a more complex and precise manner. https://cme.hormozgan.ac.ir/article_233423.html Microbeams play a crucial role in mechanical processes and in the design of micro- and nanoscale structures. In many engineering applications, these structures are supported by elastic foundations, which can significantly affect their vibrational and stability characteristics. When subjected to external loading and internal fluid flow, the interaction between the microbeam and its elastic support must be accurately modeled to predict realistic dynamic behavior. The mechanical stability analysis of such structures, especially in the presence of internal fluid flow, is of great significance. In this study, the stability of a curved microbeam resting on an elastic foundation and containing an internal fluid flow is investigated. To account for the nanoscale effects, the nonlocal couple stress theory is employed for the solid domain, while the modified velocity theory is adopted for the fluid part. The internal fluid flow is analyzed using the Navier–Stokes equations, and the governing equations of the microbeam are derived from Hamilton’s principle. The fluid–structure interaction is modeled as a two-way coupled phenomenon. The governing differential equations are solved numerically using the Galerkin method combined with Gauss quadrature integration. The results reveal that size effects play a significant role in the stability analysis, and neglecting nonclassical continuum mechanics may result in considerable errors. Small curvatures are found to have a noticeable influence on the vibrational behavior of the microbeam system. Increasing the fluid flow velocity enhances system instability and reduces the natural frequency. Furthermore, the type of fluid and the stiffness of the elastic foundation have a remarkable impact on the system’s dynamic response. Overall, this study demonstrates that accurate mechanical modeling of microbeams, incorporating both size-dependent effects and elastic foundation interactions, can provide valuable insights for the design and optimization of micro- and nanoscale structures.