Using the Cowin-Nunziato model, a coefficient inverse problem for inhomogeneous poroelastic bodies is formulated, and operator equations of the 1st kind for its solution are derived. As an example, an inverse problem for a functionally graded elastic pipe with voids is considered using additional information measured in the domain of transient loading. To solve the direct transient problem, a combined method is used: transition to the Laplace transform space, followed by solution of the boundary value problem using the shooting method and inversion using an expansion in shifted Legendre polynomials. The solution to the direct problem was verified by comparing it with the solution obtained in the finite element package FlexPDE for a homogeneous pipe. The influence of the heterogeneity laws of the Lam & eacute; moduli, coupling modulus, pore diffusion modulus, density, and pore stiffness modulus on the radial displacement was investigated. For reconstruction of physical and mechanical characteristics the iteration approach is applied. Two methods discretization of operator equations (a collocation method and a projection method) are proposed. The initial approximation is defined among the constants as the average of the maximum and minimum values of the material properties. Refinement of physical and mechanical characteristics in projection method was carried out in stages: (1) among constants; (2) linear functions; (3) quadratic functions. Computational experiments were conducted to reconstruct variable properties both at internal points of the pipe and in the class of power functions. A comparative analysis of the effectiveness of the proposed discretization schemes is performed.
External forces generated due to earthquakes, wind, and blasts cause damage to the structure by which its structural integrity gets compromised. A method is to be developed to find the current state of the structure after the damage has occurred. This can be done by finding the natural frequency of the structure using modal analysis. In this study, a two-storey steel frame bolted structure has been studied experimentally on a onedimensional shake table. Results obtained through the experiment have been verified using the numerical study of the same structure. COMSOL Multiphysics was used for additional numerical analysis, and the various eigenfrequencies and mode shapes were identified. Additionally, numerical research was carried out to simulate damages ranging from 10 mm to 20 mm, and the findings indicate that the natural frequencies decrease as the damage increases. Thus, Modal analysis can be used to determine the current state of the structure. For various mode shapes, the experimental and numerical frequency variations are 0.37, 1.61, and 3.16 %, respectively.
This study investigates the mechanical, moisture resistance, and thermal behavior of hybrid flax/hemp/glass fiber reinforced epoxy composites incorporated with TiO2 and SiC nanoparticles. The composites were fabricated using compression molding with different stacking sequences and varying nanofiller contents to evaluate their influence on tensile strength, flexural strength, microhardness, fracture toughness, water absorption, and thermal stability. The results indicate that both fiber stacking configuration and hybrid nanoparticle reinforcement significantly influence the performance of the composites. Among the tested configurations, the Sequence-3 laminate containing 2 wt. % SiC and 3 wt. % TiO2 exhibited the best overall performance. Compared with the baseline composite, this optimized structure demonstrated a 33 % increase in tensile strength, 18 % improvement in flexural strength, 22 % enhancement in microhardness, and 9 % increase in fracture toughness, indicating improved load transfer and crack resistance. In addition, the incorporation of hybrid nanoparticles reduced water absorption by approximately 18 %, enhancing moisture resistance of the composite system. Thermogravimetric analysis further confirmed improved thermal stability, with delayed degradation temperatures attributed to the barrier effect and strong interfacial bonding provided by SiC and TiO2 nanoparticles. Overall, the synergistic interaction between hybrid fibers and nanofillers significantly improves the structural, thermal, and environmental performance of the composites, demonstrating their potential as sustainable lightweight materials for advanced engineering and structural applications.
This study investigates the flexural behavior of mortars modified with recycled polyethylene terephthalate through numerical simulations developed in SolidWorks Simulation using a linear dynamic approach. Prismatic specimens measuring 40 & times; 40 & times; 160 mm3 with recycled polyethylene terephthalate contents of 10 and 20 % were evaluated under three temperature levels (20, 150, and 350 degrees C) and two curing conditions: ambient and water curing. A linear dynamic finite element model was developed in SolidWorks Simulation to reproduce the bending response and analyze the temporal evolution of Von Mises stresses, principal stresses, and stress distribution patterns. The numerical model incorporated experimentally determined mechanical properties and breaking loads as input parameters. The results indicate that increasing recycled polyethylene terephthalate content reduces the stiffness and load-bearing capacity of the mortar, particularly at elevated temperatures, due to the thermal softening of the polymer and the weakening of the interfacial transition zone. Water curing enhances mechanical performance by promoting matrix hydration and improving the capacity for stress redistribution, thereby mitigating the adverse effects of thermal exposure. The numerical simulations showed strong agreement with experimental observations and successfully captured the evolution of stress localization and failure mechanisms under different thermal and curing conditions. These findings highlight the combined influence of recycled polyethylene terephthalate content, curing regime, and temperature on the structural performance of modified mortars and confirm the suitability of linear dynamic finite element analysis for investigating bending behavior in polymer-modified cementitious materials.
X-ray diffraction and temperature-dependent dielectric measurements were used to examine the structural and dielectric characteristics of Bi2Te2.8Se0.2, a promising thermoelectric material. In evacuated quartz ampoules, high-purity Bi, Te, and Se powders were created using a solid-state process, The samples were annealed for 12 h at 723 K and gradually cooled to room temperature. A highly crystalline rhombohedral structure (space group R3m) with little lattice distortion (microstrain similar to 3.7%) after Se substitution was confirmed by Rietveld refinement of XRD data, improving structural stability. Because Se has a larger atomic radius than pure Bi2Te3, the unit cell volume increased slightly. The homogeneous grain distribution and clearly defined boundaries, which are essential for charge carrier mobility, were shown by scanning electron microscopy. At about 10 Hz, dielectric loss (tan delta) showed a Debye-type peaks signifying the greatest amount of energy released by polarization processes. At the peak frequency, the imaginary electric modulus verified relaxation dynamics with relaxation time tau = 0.016 s. The dielectric constant epsilon' rose gradually (by around 20%) at higher temperatures, indicating better polarizability for thermoelectric applications. In comparison to undoped versions, this work demonstrates the originality of Se-doping in Bi2Te3 for adjustable dielectric characteristics, attaining better efficiency (potential ZT > 1.2) with reduced synthesis costs. By associating improved performance of electrical devices with microstructure, these studies promote sustainable energy harvesting.
