Journal of Mechanics of Materials and Structures最新文献

A multilayer approach is developed to solve the moving Hertzian contact problem involving a circular punch and a functionally graded multiferroic coating. The mathematical model constructed consists of arbitrary numbers of multiferroic layers and elastic interlayers, and a half-plane substrate. The formulation is based on wave equations of plane elastodynamics and Maxwell’s equations. The problem is reduced to a singular integral equation by applying Galilean and Fourier transformations. The integral equation is solved numerically through an expansion-collocation technique. A convergence analysis is performed to determine the number of homogeneous multiferroic layers required to simulate the behavior of functionally graded coatings. Presented parametric analyses illustrate the influences of coating type, punch speed, kinetic friction coefficient, and coating thickness upon contact stresses, electric displacement, magnetic induction, and the required contact force. Magnetoelectricity of the system is shown to be significantly coupled with mechanical parameters such as the kinetic friction coefficient and coating thickness.

This paper describes the laboratory experiments conducted on specimens with artificially created internal structure produced by drilling a regular pattern of circular holes in an alumnium matrix. The specimens are subjected to four-point bending and the protocol is described in detail with emphasis given on the top-edge and bottom-edge axial-strain measurement and processing in the zone of pure bending. An increase in stiffness is observed with the reduction in the characteristic specimen dimension (size effect), which may be explained by the micropolar theory of elasticity. A methodology is suggested for establishment of the effective Young’s modulus and the characteristic bending length of a homogenised substitute micropolar material, which is entirely based on a known closed-form pure-bending solution. The results are compared with those obtained using an alternative protocol from the literature.

Due to their versatile mechanical qualities, metal matrix composites (MMCs) are explored for usage in a wide variety of structural applications, including those in the aerospace/aviation, transportation, defense, and sports sectors. Al6092/SiC 17.5% by volume particle composites are investigated to determine the effect of Al matrix anisotropy on their mechanical properties under a range of loading, strain rates, and heat treatments with the goal of improving metal matrix composite performance and design. This work examines the effects of anisotropy and loading conditions at a $10^{-4}{�\mathrm{\text{ s}}}^{-1}$ strain rate on the deformation and damage behavior of composites made of Al6092 and SiC particles in three orientations ($0^{\circ }$, $45^{\circ }$, and $90^{\circ }$). To gain a fundamental understanding of the heat treatment effect on the fracture mechanism, the microstructural changes, and the interface between the Al-matrix and SiC particles, as well as to establish a correlation between strain rate and heat treatment and anisotropy effect, it is necessary to examine the influence of heat treatment (T6 and O-condition) on the microstructure, deformation, and damage behavior of metal matrix composites under various loading conditions. The mechanical properties were evaluated by tensile stress, and shear stress. In order to characterize the precipitate and intermetallic compounds generated at the Al/SiC interface, changes in the microstructure of the Al/SiCp and the topography of the fracture are examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed in parallel $(0^{\circ })$ to the rolling axis was observed to be the preferred orientation of the Al matrix over the perpendicular $(90^{\circ })$ and $45^{\circ }$ orientations. In the longitudinal direction (parallel to the rolling axis), Young’s modulus and ten

A functionally graded porous beam is engineered to have various material properties and porous characteristics in a controlled and deliberate manner. The tailored material properties can help optimize structural performance, improve energy absorption, and enhance the overall efficiency and safety of engineered systems. Adapting the higher-order shear deformation theory, this paper investigates the buckling behavior of two-directional functionally graded porous beams (FGPB). The development of a mathematical model that incorporates material properties with a power law distribution and polynomial functions for axial and transverse deflections. The critical buckling analysis is undertaken using the Kuhn–Tucker analytical solution approach with the R-program. On the behavior of buckling, the influences of aspect ratio, gradient index, porosity index, and even/uneven porosity distributions are investigated. Comparisons with established numerical methods are used to validate the accuracy of the suggested analytical methodology. The effect of various parameters on the critical buckling response is investigated by means of a parametric investigation. The results contribute to the comprehension of the buckling behavior of FGPB and shed light on the optimization of their design. The proposed methodology provides a valuable instrument for analyzing these structures under various boundary conditions.

In this paper, for the first time, a safety assessment process is proposed for predicting fatigue crack extension remaining life and crane load reduction use. The method is based on fracture mechanics to establish a simulation model of the main girder of a crane using on-site strain-gauge tests and related crack extension test results. Establishing a statistical model based on the real work experience of a crane, obtaining the stress-time history and load spectrum at the fatigue calculation point on the crane girder through dynamic simulation. Expansion simulations of a single initial crack with different deflection angles show that crack deflection slows down the crack expansion rate, i.e., the smaller the deflection angle, the smaller its lifetime. Expansion analyses of coplanar and adjacent parallel surfaces multicracks were also performed to investigate the effects of crack morphology changes during crack coalescence and coplanar crack interactions on crack coalescence, as well as the effects of defect spacing on fatigue life. For the single crack with a width of 4 mm, a load reduction analysis is performed, and the simulation results indicate that the load reduction range is $20\%$–$30\%$, the fatigue remaining life of the crack is increased to $2.05$–$3.08$ times the original value, the degree of load reduction and the remaining life is compliant with the GB/T 41510-2022 Safety Assessment Rules for LiftingAppliances-General Requirements general requirements for crane safety evaluation, indicating that the proposed approach in this paper for estimating fatigue crack growth life and crane load reduction is viable and offers the benefits of a short cycle and low cost.

Softening and toughening size-dependent axisymmetric elastic buckling and free vibration of functionally graded porous (FGP) Kirchhoff microplates with two different porous distribution patterns are investigated through strain-driven ($𝜀$D) and stress-driven ($\sigma$D) two-phase local/nonlocal integral polar models (TPNIPM), respectively. The Hamilton’s principle is used to derive the differential governing equation and boundary conditions. A few nominal variables are introduced to simplify the differential governing equation and boundary conditions, and equivalent differential constitutive relations and constitutive constraints are expressed in united nominal forms. The general differential quadrature method is applied to discretize differential governing equation and constitutive relations as well as boundary conditions and constitutive constraints. L’Hospital’s rule is applied to deal with the boundary conditions and constitutive constraints at center for circular microplate. A general eigenvalue problem is obtained in matrix form, from which one can determine buckling loads and vibration frequency for different boundary conditions. The effects of nonlocal parameters, FGP distribution patterns, geometrical dimensions and buckling/vibration order on the buckling load and vibration frequency are investigated numerically for different boundary conditions, and consistent size-effects are obtained for $𝜀$D- and $\sigma$D-TPNIPMs TPNIPMs, respectively.

The extended boundary element method (XBEM) is employed to calculate the whole displacement and stress fields of the plane V-notched/cracked structure in a bonded bimaterial under different elastic modulus ratios. Firstly, the V-notched/cracked structure is divided into two parts, which are a small region around the notch tip and the outer region without the tip region. Then, the asymptotic series of the singular stress fields in the notch tip region are embedded with the boundary integral equation for the outer region without stress singularity. Numerical examples show the accuracy and effectiveness of the XBEM for obtaining the whole displacement and stress fields of the V-notched/cracked structure in bonded bimaterials. It is demonstrated that the notch/crack tip region of the V-notched/cracked structure in bonded bimaterials should choose reasonable eigen-pairs.

The research on the electromigration behavior of inclusions has a significant impact on extending the lifespan of interconnects and tuning the required nanopatterns or nanostructures. The electromigration behavior of conductive inclusions in highly symmetric oriented single crystal metal interconnects is studied in this paper utilizing phase-field simulation combined with adaptive mesh technology and the finite element method. Facet-central-cubic metal allows us to investigate the effects of misorientation and anisotropic strength on the morphological evolution of inclusions under highly symmetric orientation. Meanwhile, the relationship between the above two parameters is explored by establishing the morphological evolution maps. The results indicate that three main evolution patterns and their combination patterns emerge during the electromigration process: steady migration, complex splitting, oscillation, splitting before steady migration and splitting before oscillating. Furthermore, the velocity of a steady migration of inclusions, the frequency of oscillation, and the number of splitting generation inclusions decrease as anisotropic strength increases.

We study the problem of a spherical elastic inhomogeneity with simultaneous interface slip and diffusion embedded in an infinite elastic matrix subjected to a uniform deviatoric far-field load. The inhomogeneity and the matrix have separate elastic properties. Using the representations for displacements and tractions given by Christensen and Lo (1979), the original boundary value problem is ultimately reduced to a state-space equation which is then solved analytically. The field variables in the inhomogeneity and the matrix decay with two relaxation times. As time approaches infinity, the stresses inside the spherical inhomogeneity are completely relaxed to zero. Our solution recovers existing solutions in the literature when the inhomogeneity is rigid or when the inhomogeneity and the matrix have the same elastic properties. The internal spatially uniform and time-decaying stress field inside the spherical inhomogeneity is achieved when the radius of the spherical inhomogeneity is appropriately designed corresponding to interface diffusion and drag parameters.

Biomaterials such as bone and dentin have hierarchical heterogeneous structure and display remarkable damage tolerance, toughness, and strength. The recent challenge is to imitate these structural properties in synthetic materials such as superior nanocomposites. Simulation studies in composites typically focus on simulation of damage propagation due to material heterogeneity such as reinforcements or defects. This paper shows the utility of the mass spring system (MSS) proposed in our previous work in effective simulation of stress distributions in various composite structures. For bench-marking, we compared simulation results of the MSS model for composites with finite element simulations and validated the model using the experimental data for in-plane tension and in-plane shear tests. Thereafter, we applied the model to investigate behavior of composite materials. The results obtained using the MSS model emphasize that stress distributions and subsequent probable crack propagation in composite structures depend on dispersion, geometry and properties of reinforcements and matrix properties as well.