Mechanics of Solids最新文献

This paper presents a modern comprehensive approach to the analysis and design of reinforced concrete buildings, taking into account soil-structure interaction (SSI) under seismic loading. As a case study, the approach was applied to the seismic analysis of a five-story reinforced concrete building. The external seismic impact was defined using a three-component accelerogram corresponding to a magnitude-9 earthquake. The interaction between the building and the soil foundation was implemented through an SSI interface (soil-structure interaction). To eliminate the influence of wave reflections from the boundaries of the finite soil domain, a perfectly matched layer (PML) was employed. The reinforced concrete structures were modeled using a method that combines solid elements for concrete with beam elements for reinforcement. The simulations were performed using distributed computing technology on a high-performance computing cluster. A study of the failure mechanisms of the structure was carried out. A comparative analysis was conducted between the input accelerogram at the free surface of the soil and the acceleration recorded at the building’s foundation slab. With appropriate adaptation and the use of high-performance computing systems, the proposed methodology can be applied in engineering practice to improve the reliability of seismic analysis of reinforced concrete buildings.

Hallux valgus is a widespread pathology. Osteotomy of the first metatarsal bone is the gold standard for its treatment. The success of this surgical intervention depends, among other factors, on the stability of the “bone-fixation” system. Previous studies assessing the biomechanical properties of various first metatarsal osteotomies have examined the influence of osteotomy type, degree of fragment displacement, as well as the number and positioning of screws. In these studies, the biomechanical properties of bone tissue corresponded to normal values of conventionally healthy patients. Older patients are characterized by a high prevalence of osteoporosis. This disease manifests in reduced mineral density and mechanical properties of bone. The effect of osteoporosis on the biomechanical parameters of first metatarsal osteotomy models has not been previously studied. The aim of this work was to evaluate the stability of first metatarsal osteotomies under normal bone density and osteoporotic conditions, as well as to assess the robustness of biomechanical models of the most common osteotomy types to minor variations in screw positioning and bone-cutting plane geometry. For this purpose, 36 biomechanical models of scarf and chevron osteotomies were created, varying screw placement, bone-cutting plane geometry, cortical thickness, and elastic modulus. Finite element analysis was used to assess the stress-strain state of the osteotomy models. Model validation was performed based on natural cantilever bending tests of first metatarsal osteotomies in universal testing machine. The study demonstrated the robustness of scarf and chevron osteotomy models to minor changes in geometric parameters. Chevron osteotomy proved more stable than scarf. Additionally, scarf osteotomy generated significantly higher bone stresses compared to chevron. It was found that even under osteoporotic conditions, both osteotomy types can provide sufficient stability and strength in terms of screw breakage and bone tissue damage.

The paper is devoted to propagation of time-harmonic mirror wave modes in hemitropic micropolar media. Dynamics equations of a hemitropic micropolar elastic solid are formulated in terms of pseudotensors formalism. Transformation formulae for translational and spinor displacements, differential pseudovector operators and constitutive pseudoscalars for the cases of space inversion and mirror reflection relative to a given plane are obtained. Simultaneous existence of the direct, inverse and mirror reflected wave modes of propagating plane waves is predicted. Plane wave propagating in hemitropic micropolar elastic media comprises the three types of wave modes: direct, inverse and mirror. Algorithm for transformation direct wave modes into inverse and mirror modes of spinor and translational displacements is proposed.

In the approximation of the cylindrical bending model, a solution is obtained for the problem of elastic-plastic deformation of a thin plate bent along a cylindrical surface, taking into account the resulting longitudinal forces, under boundary conditions of the rigid or generalized elastic fixation type. When describing the plate, standard Kirchhoff-Love kinematic hypotheses, which made it possible to reduce the problem to a system of ordinary differential equations, were used. A numerical solution is obtained for this system for rigid and generalized elastic fixation conditions.

This paper is devoted to the description of an automated complex SN-EVM (Complex Loading – Computerized Test) developed for the experimental study of elastic-plastic deformation of structural materials and the response of materials under real operational loads. The article describes the mechanical part of the complex, including an autonomous control unit, the parameters of measuring equipment used to record loads and deformations, the samples used, and the technical requirements for these samples (shape, dimensions, and tolerances). The results of basic experiments on the type of central fan necessary for estimating the initial isotropy or anisotropy of the studied material are presented, as well as some numerical values obtained during the tensile experiment, a method for processing results under complex loading, and the construction of deformation diagrams. Conclusions are drawn regarding the importance of basic experiments and directions for future research development. The results of the study contribute to an understanding of the mechanical behavior of materials beyond elasticity, which is crucial for improving the reliability, durability and safety of engineering structures.

The article is devoted to elastic-plastic torsion of a multilayered rod under torque. It is assumed that the rod consists of several layers. Each layer has its own elastic properties, but the plastic properties of both layers are the same. For simplicity, a three-layer rod is considered. The contact boundaries of the layers are located along the x-axis. The lateral boundary of the rod is free of stresses, the displacements and stresses are continuous at the interlayer boundaries. The stress tensor components at a point are calculated, using the contour integrals obtained from the conservation laws calculated on the edge of the cross section. Then, the second invariant of the stress tensor is compared with the yield strength. At the points where the yield strength is reached, the plastic state occurs, and the remaining parts are elastic. This lets us construct a boundary between the plastic and elastic regions. This method provides a way to calculate the elastic-plastic boundaries for the standard rolled profiles of rods. This issue will be considered in future studies. It should be noted that previously, using the conservation laws, the main boundary value problems were solved for the plastic two-dimensional medium, elastic-plastic torsion of isotropic rods and elastic media for finite-sized bodies.

The Johnson-Cook constitutive model is extensively utilized in numerical simulations of high-velocity impact and penetration scenarios, with its primary material parameters (A, B, n, C, and m) directly governing the material’s flow stress. However, material parameters obtained exclusively through dynamic and static experiments generally prove inadequate for direct application in penetration analysis, necessitating further calibration for penetration studies. To investigate the influence of penetrator core material parameters on computational outcomes—particularly maximum penetration depth—during high-velocity penetration of semi-infinite metallic targets by long-rod projectiles, numerical simulations employing an experimentally validated ANSYS/LS-DYNA model were conducted. These simulations examined 93W alloy penetrator cores with varied material parameters impacting Rolled Homogeneous Armor steel at identical velocities. Results demonstrate that the initial yield strength (parameter A) constitutes the predominant factor influencing penetration depth; within the investigated range (500–2500 MPa), increasing A enhances penetration performance by 15.23%, while penetration depth sensitivity to the remaining parameters (B, n, C, m) remains below 5% across ranges typically covered by most materials.

Auxetic materials, characterized by their negative Poisson’s ratio (NPR), exhibit unique mechanical properties that make them highly desirable for lightweight structural applications. This study introduces a novel 3D double arc star-shaped (3D DASS) auxetic structure and systematically investigates the influence of cross-sectional shape (square vs. circular) and thickness variation on its mechanical behavior. We derive expressions for Poisson’s ratio and Young’s modulus using analytical modeling and numerical simulations and validate them across different geometric configurations. The results reveal that while Poisson’s ratio remains nearly constant for both cross-sections, Young’s modulus is significantly influenced by cross-sectional thickness, particularly in circular configurations. These findings provide valuable insights into the design optimization of lightweight auxetic structures and their potential applications in engineering.

The study examines the effects of point source on SH wave propagation in a functionally graded piezoelectric material layer over a functionally graded piezoelectric substrate. The formulation of dispersion equation for SH wave propagation on a given formation is produced by taking appropriate boundary conditions into account and utilizing the governing equations. Using Mathematica 7, numerical calculations are performed to visually represent the significant influence of the piezoelectric constant, dielectric constant, and functional gradient factors on phase velocity of the SH wave.

The present article indicates a pioneering investigation into the photo-thermal transport processes within semiconductor materials influenced by a mobile heat source. This study addresses critical research gaps by employing an advanced heat transfer theory grounded in fractional derivatives, as formulated by Atangana-Baleanu. This innovative approach incorporates non-singular kernel functions, enabling the derivation of accurate solutions for complex thermal mechanisms. The research makes a significant contribution to the field by providing analytical solutions in the frequency domain through the application of the Laplace transform algorithm and the eigenvalue methodology. Key findings reveal intricate relationships between various field quantities, including temperature, displacement, carrier density, and thermal stress, which are illustrated through the graphical results. These results are analyzed across diverse parameters such as material depth, fractional parameters, the lifetime of photo-generated carriers, as well as the velocity and intensity of the moving heat source. Notably, the inclusion of fractional quantities elucidates the precise and finite nature of photo-thermal waves, distinguishing this work from traditional hyperbolic thermoelasticity theories. The implications of these findings extend to a deeper understanding and optimization of semiconductor materials in practical applications, while also suggesting new avenues for future research in the field of thermal transport.