Acta Mechanica

The authors present a numerical investigation of laminar natural convection flow past a moving semi-infinite vertical cylinder subjected to constant heat flux. The transformed governing equations are obtained and solved using an implicit finite difference scheme of Crank-Nicolson type. Numerical results for the transient velocity, the temperature and the concentration profiles are shown graphically. It is observed that there is a rise in temperature due to the presence of mass diffusion. The local as well as average skin friction, and the rate of heat and mass transfers are shown graphically.

In the presented paper the nonlinear response of doubly curved layered panels subjected to time-varying lateral loads is studied. The considered panels are composed of three thick perfectly bonded isotropic layers, which are symmetrically arranged with respect to the middle surface. The structural model utilized to analyze the panels is based on a first-order layerwise theory, which includes transverse shear flexibility, initial geometric imperfections, and Berger-type geometric nonlinearities. The boundaries of panels with polygonal planform are modeled as simply (hard hinged) supported edges with the displacements normal to the edge face fully restrained.

The charge-free zone model for electrically conductive cracks in dielectric and piezoelectric ceramics is reviewed with the simplified constitutive equations and the regular constitutive equations and then applied to interpret the experimental results on window ceramic glass and poled lead zirconate titanate PIC 151 ceramics. A good agreement is found between the experimental results and the theoretical predictions from the charge-free zone model, which indicates that the concepts of fracture mechanics can be applied to the failure of conductive cracks in dielectric and piezoelectric ceramics.

Existence, uniqueness and dissipativity is established for a class of nonlinear dynamical systems including systems with fractional damping. The problem is reduced to a system of fractional-order differential equations for numerical integration. The method is applied to a non-linear pendulum with fractional damping as well as to a nonlinear pendulum suspended on an extensible string. An example of such a fractional damping is a pendulum with the bob swinging in a viscous fluid and subject to the Stokes force (proportional to the velocity of the bob) and the Basset-Boussinesq force (proportional to the Caputo derivative of order 1/2 of the angular velocity). An existence and uniqueness theorem is proved and dissipativity is studied for a class of discrete mechanical systems subject to fractional-type damping. Some particularities of fractional damping are exhibited, including non-monotonic decay of elastic energy. The 2:1 resonance is compared with nonresonant behavior.

A thick-shell hollow piezoceramic sphere electroded completely on both inside and outside surfaces and radially polarized can be used as a source and receiver of underwater sound. Restricting the analysis to moderately thick shells the electromechanical equations of displacement are solved to generate the frequency equation for the pure radial modes. The frequency equation is specialized to reflect the behavior of a barium-titanate shell and numerical values are tabulated for the first three frequencies for a broad range of shell thicknesses.

This study presents the vibroacoustic analysis of a hybrid epoxy composite panel reinforced with advanced multi-walled carbon nanotubes (MW-CNTs) and luffa fibre. The vibroacoustic responses were obtained numerically, and the model validity was verified with experimental values. The responses were analysed under the stimulus of harmonic point excitation, considering ambient conditions, using a coupled finite element–boundary element (FE–BE) model. To ensure the accuracy and stability of the numerical model, the different structural responses, including natural and thermal frequency, of hybrid composite plates, were evaluated and compared with data from published literature. In addition, experimentation was conducted, and the results were compared with the numerically derived model to demonstrate the model’s effectiveness. Furthermore, several numerical examples were solved using the numerical model to illustrate its applicability and enhance understanding. The results obtained from the experimental investigation showed that adding luffa fibre and MW-CNTs to the composite panel improved its sound transmission loss and absorption coefficient. Overall, the results suggest that the hybrid composite panel has excellent vibroacoustic performance and can be used in various engineering applications that require lightweight, high-strength materials with good damping and noise reduction properties.

The investigation of a wide class of time-dependent gas flows with heat addition is reduced to consideration of a single partial differential equation. Solutions are derived corresponding to assigned forms of the entropy distribution.

By gradually changing the compositions, functionally graded materials (FGMs) are constructed and possess comprehensive performance. In this paper, based on the micromechanics, the thermo-elasto-plastic behaviors of FGMs are studied with consideration of the pairwise particle interaction, where the graded microstructures of the FGMs are represented by employing a particular representative volume element (RVE). Based on the assumption that the matrix dominates the plastic behavior of the FGMs while the particles stay in their linearly elastic state, the von-Mises yield function is extended to solve FGMs problems. By employing the backward Euler’s method, the overall effective thermo-elasto-plastic behavior of FGMs can be numerically obtained. When eliminating the plastic or thermal effect, the proposed model can be downgraded to the thermoelastic model or the elastoplastic model of the FGMs, respectively. In addition, the proposed model is validated with available experimental results. Finally, the effects of temperature changes, particle distributions, volume fractions, and material properties on the effective thermo-elasto-plastic properties of FGMs are studied.

The sand accumulation on a flat plate in flows around a near-wall circular cylinder has been mainly investigated by the method of numerical simulation at the sub-critical Reynolds number1200 (based on the diameter of the circular cylinder) and the gap ratio G/D (ratio of the gap between the circular cylinder and the plane wall to the diameter of the circular cylinder) 1.0, 0.5 and 0.25. The standard k− ε turbulent model and the vorticity-stream function formulation are adopted to analyze the wake characteristics. The lift and drag coefficients of the circular cylinder and the pressure pulsation on the wall are solved. The simulation of streak-lines for the flow visualization and PIV experiments are detailed carried out to analyze the sand accumulation phenomenon on the plane wall, and a possible mechanism has been proposed. Results of the numerical simulation indicate that the effect of the cylinder results in flow separation from the plane wall. Separations occur about 1 to 2 cylinder diameters behind the cylinder, where the particles in the flow near the plane wall accumulate gradually.