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This paper investigates the dynamic behavior of micro/nanobeams made of two-dimensional functionally graded porous material (2DFGPM) under accelerated, decelerated, and uniform moving harmonic load, using surface elasticity and modified couple stress theories. The key feature of this formulation is that it deals with a higher order shear deformation beam theory. The non-classical equilibrium equations are developed using Lagrange's equation and the concept of physical neutral surface. The equations of motion are derived using the same approach, accounting for the porosity effect and the modified power-law distribution of material properties. The trigonometric Ritz method is used with sinusoidal trial functions for the displacement field, and the Newmark method is applied to obtain the dynamical response of 2DFGPM nanobeams. The results are compared with previous studies, and the impact of critical parameters such as gradation indices, volume fraction ratio, pattern of porosity, velocity, frequency, and motion type of the applied force are explored. This study highlights the importance of considering the porosity effect, as neglecting it can lead to significant errors in the predicted results. Additionally, the study found that the accelerated and decelerated motions of the applied load have a greater impact on the dynamical deflection of 2DFGPM nanobeams than the uniform motion. The findings of this study can provide guidance for the optimal design of micro/nanobeams subjected to a moving force with multifunctional properties. [ABSTRACT FROM AUTHOR]

This paper analyses the effects of a non-uniform laminar flow past a circular cylinder using the direct numerical simulation approach. Compared to the cylinder immersed in a uniform flow case, modifications caused by the non-uniform approaching flow on the evolution of the flow and sound fields are studied in detail in the present work. The prescribed non-uniform velocity profile at the inlet has a Gaussian distribution and imitates a jet or a wake flow velocity profile. The sound is generated due to periodic vortex shedding behind the circular cylinder. The frequency of vortex shedding and the strength of the shed vortices depend on the inflow velocity profile. Hence, variation of the inflow velocity profile alters the shed vortices, changing the generated sound field. It is observed that the amount of gain or deficit present in the prescribed inflow velocity profile compared to the uniform inflow profile alters the sound field information. The jet kind of inflow profile creates a sound of higher frequency and intensity in contrast to the wake kind of inflow profile. The presence of shear in the inflow velocity profile is also expected to change the sound propagation direction. However, in present simulations, the distance over which sound propagation is considered is small compared to the wavelength of the sound waves, and sound beam drift effects are not observed much. [ABSTRACT FROM AUTHOR]

In this paper, an equivalent imperfect interface model of PN homojunction/ heterojunction of piezoelectric semiconductor for the multi-field coupled wave propagation is proposed firstly. PN junction is a special structure formed by the contact of two different types of doped semiconductors, which has been used extensively in semiconductor devices. Due to the gradient distribution of the electric potential and carrier concentration in PN junction of finite thickness, the reflection and the transmission will arise when the coupled waves propagate through PN junction. The effects of the PN junction on the wave propagation will be much more complicated by the accurate estimation. An equivalent imperfect interface model without thickness but with seven interface parameters is established to simulate the effects of PN junction which largely reduces the calculation cost. The numerical examples are provided and compared with the state transfer matrix method and the piecewise homogenization method. Energy flux of the reflected and transmitted waves are estimated, and the energy conservation is checked to verify reliability of the numerical results. [ABSTRACT FROM AUTHOR]

Interference fit is a classic issue in mechanical engineering. In this paper, under the axial/spherical symmetrical assumption, the analytical solutions for the interference fit problem of the internal and external functionally graded materials (FGMs) hollow cylinder/spherical shell are obtained. Herein, the unified form of the FGMs hollow cylinder/spherical shell basic equation is given by introducing a geometric parameter. The degradations of the analytical solutions in this paper are consistent with the corresponding results in the existing work. The effects of interference value, structural material parameters, and geometric dimensions on the displacement and stress distribution of FGMs structures are analyzed numerically. [ABSTRACT FROM AUTHOR]

Surface texturing is an efficient approach for boosting the performance of bearing. In this paper, a vein bionic texture has been applied to the surface of hydrodynamic journal bearing in order to improve its bearing performance. The bionic texture is inspired by the pattern of a peepal (ficus religiosa) leaf and optimized by a bio-inspired genetic algorithm technique. In this study, the use of bionic texture without GA optimization has been observed to increases the value of stability parameter by 13.08% and reduces the value of friction torque by 21.17%, while the use of the GA-optimized vein-bionic texture resulted in a significant improvement in bearing performance, with the stability parameter increases by up to 18.24% and friction torque being reduced by up to 46.66%. This class of surface texture improves both static and dynamic characteristics of the bearing. Further, the bifurcation diagram has been plotted to examine the system's stability. The findings of this study should prove useful for rotor-dynamic researcher in their efforts to stabilize systems with the use of GA-optimized vein-bionic textured journal bearings. [ABSTRACT FROM AUTHOR]

Diverse loads frequently damage concrete when it is in use. However, it might be challenging to immediately identify the stress and damage of concrete in actual engineering situations. In order to predict the stress and damage of concrete, a deep learning (DL) model based on the convolutional neural network (CNN) is proposed in this paper. To provide the training and validation data, a finite element (FE) model of uniaxial compression of concrete specimens based on the concrete damage-plasticity (CDP) model is constructed. The DL model is trained with the strain contours with a specified range provided by the FE model as the inputs and the stress and damage assessment of concrete as the outputs. The prediction of the stress and damage of concrete materials was effectively realized by the trained DL model, and it was verified in a larger range of working conditions distinct from the training and verification sets. The results show that the DL algorithm has good accuracy and reliability. By efficiently and correctly recreating the FE prediction results, the DL model offers a method for promptly evaluating the stress and damage of concrete structures under complicated stress circumstances in actual engineering. [ABSTRACT FROM AUTHOR]

In this paper, a novel locking-free finite beam element is proposed utilizing the absolute nodal coordinate formulation. By incorporating a gradient vector along the transverse direction at the boundary points, the linear interpolation of the gradient vector field within this element is achieved. Consequently, the problem of constant transverse strain distribution, which is observed in the Omar–Shabana beam element, is effectively addressed. Building upon this concept, this study further extends the proposed element from two dimensions to three dimensions. Additionally, it analyzes and compares the locking alleviation mechanism of the newly developed element and Patel–Shabana beam element. The analysis aims to provide insights into the factors contributing to the locking alleviation of different absolute nodal coordinate formulation (ANCF) elements. Furthermore, to demonstrate the effectiveness of the new element, six numerical simulation examples are designed, comprising three and three dynamic examples. These examples encompass small deformation statics, large deformation statics, small-scale motion, large-scale motion, and rotational motion problems. Finally, the results indicate that the proposed ANCF beam element can effectively alleviate the locking problem. The element exhibits robust adaptability, rationality, and effectiveness when subjected to complex mechanical characteristics by comparing the numerical results of this element with the classical Omar–Shabana, high-order Shen, and Patel–Shabana elements. [ABSTRACT FROM AUTHOR]

In this paper, an exact elasticity solution of functionally graded material (FGM) rectangular plate under cylindrical bending is presented. The formulation is based on the displacement approach in which 3D elasticity equations are reduced to 2-D equations using plane-strain conditions. In the present formulation, an exact elasticity solution is feasible due to the consideration of simply supported boundary conditions with applied loads expressed in harmonic forms. Functionally graded material (FGM) infinite rectangular plate subjected to realistic transverse normal loads are analyzed. Solutions have been presented for FGM plate with various aspect ratios and gradation factors. Variation of displacements and stresses through the thickness has been investigated for the FGM plate subjected to single sinusoidal load, uniformly distributed load, hydrostatic load, and strip load. Validation of results is presented using reference results in the literature. The extensive results presented in this paper can be served as benchmark solutions for the assessment of improved plate theories. [ABSTRACT FROM AUTHOR]

In this paper, transient dynamic responses and frequency characteristics of a rotating internally connected laminated piezoelectric beam are analyzed and studied. Since the beam is compressed by the centrifugal force, frequencies decrease with the increase in the rotating speed (and centrifugal force), which can be called as the dynamic softening effect. When the frequency of increasing speed is gradually close to the decreasing the first frequency, the system resonance will occur. Nevertheless, the resonant rotating speed was rarely accurately calculated in the previous studies owing to ignoring the foreshortening effect that plays a significant role in the dynamic softening. To this end, a novel dynamic model of rotating internally connected laminated piezoelectric beams is developed. In this model, constitutive equations for metallic and piezoelectric material are considered, and the axial shortening displacement caused by the bending deformation is calculated for the foreshortening effect. The buckling rotating speeds obtained from the presented model show good agreement with those presented by the research considering the foreshortening effect, which well validates the model. Several examples are presented for investigating effects of radius, foreshortening effect, rotating speed on transient dynamic responses and frequency characteristics. The results show that beat and resonant vibrations can be orderly observed when the rotating speed is gradually close to the resonant speed. The resonant rotating speed is smaller than the buckling one. The simplified model ignoring the foreshortening effect leads to imprecise results including dynamic responses, buckling and resonant speeds. [ABSTRACT FROM AUTHOR]

This paper presents a data-driven solver (DDS) for the growth-induced deformation problems of soft materials. Contrary to the over-reliance of traditional numerical methods on material constitutive models, the DDS requires only a discrete material dataset of stress–strain pairs to describe the stress–strain relationship. With the multiplicative decomposition of the gradient tensor, the growth effects are introduced. The growth-induced deformation problems are then solved as the pre-strain problems. To overcome the difficulty in determining the growth-induced pre-stress without an explicit constitutive model, a strain-driven searching scheme is thus proposed. Several numerical examples demonstrate the robustness and its good performance of the proposed DDS. In particular, the reason for choosing the strain-driven searching scheme is also illustrated according to the numerical example results. [ABSTRACT FROM AUTHOR]