Mechanical Displacement Research Articles

Dispersive and attenuation behavior of Love wave in a non-local highly heterogeneous media with imperfect contact condition

Abstract The primary aim of this study is to explore the impact of different physical parameters on the propagation of Love waves in non-local media. This study considers heterogeneous orthotropic viscoelastic properties within a layer and the variation of sandy medium properties with exponential depth, representing the half-space. Furthermore, the interface between the layer and the half-space is considered mechanically imperfect and perfect. The solutions of mechanical displacement of the layer and half-space are derived separately by solving the second-order hyperbolic type differential equation with the help of a variable-separable technique. A closed form of the dispersion relation is obtained using appropriate boundary conditions involving the medium's non-local elasticity and inhomogeneity parameters. Verification of the dispersion relation is shown by deriving some particular cases and comparing them with the classical dispersion relation of Love wave. The effects of physical parameters (like viscoelasticity, inhomogeneity, interfacial imperfection, sandy, non-locality, and \textcolor{blue}{thickness of the layer}) on the phase and attenuation phenomena of Love wave are investigated through numerical calculations and graphical representation. Furthermore, it is observed that the particle displacement in the layer decreases with depth, while in the half-space, the amplitude decreases oscillatory with depth, and the displacement gradually converges towards zero. A comparative graphical analysis of these parameters on the phase and attenuation characteristics of Love wave through the stratified Earth's structure with imperfect and perfect interfaces has been accomplished.

Geometric nonlinear analysis of smart composite laminates

Abstract In order to create an adaptable system, active piezoelectric layers are fused or inserted into a host structure to create smart composite laminates (SCLs). SCL’s prospective applications in form modification, self-health sensing, and active vibration control demonstrate how important it is. In this paper, the static deformation characteristics and dynamic properties of SCL under voltage and mechanical loads are investigated. A completely coupled field program for SCL is constructed using Matlab. It describes mechanical displacements based on the shear deformation assumption and compares two displacement-strain models: linear and von K´arman nonlinear. The coupled nonlinear electromechanical equations are reduced to a finite element form that can be solved with convenience. Based on the program written, we have done a comparative study of linear and geometric nonlinearities of the SCL plate and also compared it with the existing articles. The results of the geometric nonlinear model of the SCL plate are quite different compared to linear and the nonlinear model results are more accurate.

Quantum effect in a hybrid bose-einstein condensate opto-magnomechanical system

Abstract We present a hybrid opto-magno-mechanical cavity system consisting of an optical cavity that creates an opto-mechanical cavity with a fixed mirror, a magnon mode in a ferrimagnetic crystal linked to the movable mirror and an intracavity Bose–Einstein condensate. The mechanical displacement is coupled to the magnon by the magnetostriction force and to the optical cavity by the radiation pressure, and the latter is also weakly coupled to a Bose–Einstein condensate. We provide a strategy to measure and quantify entanglement using logarithmic negativity. In addition, we study the quantum or EPR steering in order to present the stationary quantum steering. We consider that all composite modes in our model are given in a Gaussian state described by a covariance matrix. In these studies, we focus on the interaction between the Bose–Einstein condensate and the magnonic modes in a ferrimagnetic crystal. It is important to note that we use experimentally controllable realizable parameters to observe the interaction of modes at temperatures in the microkelvin range.

Creep stress analysis of functionally graded transversely isotropic piezoelectric disc with variable thickness under rotation

Materials exhibiting different piezoelectric properties throughout their volume are referred to as functionally graded piezoelectric materials (FGPM). Due to their graded composition, the characteristics of these materials can be customized to fit particular needs in a variety of applications. Functionally graded piezoelectric materials are beneficial in many technical applications because of their versatility that enables increased performance, efficiency, and adaptability in a variety of disciplines. The objective of the current study is to analyse creep stresses in an annular disc composed of transversely isotropic, functionally graded piezoelectric material with varying thickness parameters. Creep stresses are evaluated analytically using the approach of Seth's transition theory. By using the stress-strain relations, the equations for mechanical stresses and electrical displacement are determined. Substituting these relations into the equilibrium equation a nonlinear differential equation is obtained. The findings are presented both numerically and graphically, demonstrating how the thickness parameter affects the circumferential stresses in the intermediate surface of the rotating disc. The disc made of transversely isotropic piezoelectric material PZT-4 exhibits higher creep stresses than other materials under consideration according to all of the numerical discussions and calculations. This work may provide an effective methodology for the analysis of functionally graded piezoelectric rotating discs and contribute to theoretical research and engineering applications.

Wireless programmable patterns of electro-hydraulic haptic electronic skins able to create surface morphology

Haptic feedback technology represents a frontier with revolutionary potential, particularly in virtual and augmented reality. Skin, as an underexplored sensory interface, holds tremendous potential to significantly enrich our perceptual experiences while directly impacting the fields of communication, entertainment, and medicine. This article presents a programmable, ultra-lightweight, and ultra-thin wireless wearable haptic electronic skin that achieves rapid response and large mechanical feedback force and deformation displacement output. The electronic skin comprises a series of haptic electro-hydraulic actuators, each with the weight of 0.023 g and the thickness of 199 μm. Each actuator can be independently regulated and produce a maximum normal force of 150 mN and a normal displacement of 0.58 mm, simultaneously achieving the haptic presentation of textures. Relying on a portable multi-channel control circuit system designed, each electro-hydraulic actuator of the haptic electronic skin can be precisely control to achieve various haptic patterns. Showcasing its potentials, the haptic technology aids visual-impaired individuals in reading books, provides ground navigation instructions, and enhances gaming experiences, contributing to a more immersive and authentic artificial intelligence environment.

Research on Decision-Making and Control Technology for Hydraulic Supports Based on Digital Twins

To further enhance the intelligent construction of coal mines and improve the control accuracy of hydraulic support displacement straightness, a digital twin control method for hydraulic support displacement has been proposed. First, a dataset related to hydraulic support is established, and a ridge regression prediction model is developed to achieve digital twin-based displacement decision analysis. Next, by analyzing the mechanical structure and displacement principles of the hydraulic supports, a hydraulic cylinder mathematics model is established, leading to the state-space representation of the controlled object. This study focuses on error control during the multi-agent operation of the hydraulic supports, designing a corresponding controller and using discretization methods to verify the consistency of output displacement between followers and leaders. Finally, simulation experiments based on the digital twin model of hydraulic supports are conducted, validating that the hydraulic supports can be controlled in formation according to actual production requirements. The digital twin control method enables the precise adaptive displacement control of hydraulic supports and provides valuable insights for the intelligent construction of mining faces.

Magnon squeezing via reservoir-engineered optomagnomechanics

We show how to prepare magnonic squeezed states in an optomagnomechanical system in which magnetostriction induced mechanical displacement couples to an optical cavity via radiation pressure. We discuss two scenarios depending on whether the magnomechanical coupling is linear or dispersive. We show that in both cases the strong mechanical squeezing obtained via two-tone driving of the optical cavity can be efficiently transferred to the magnon mode. In the linear coupling case, stationary magnon squeezing is achieved, while in the dispersive coupling case, a transient magnonic squeezed state is prepared in a two-step protocol. The proposed magnonic squeezed states find promising applications in quantum information processing and quantum sensing using magnons.

Flexoelectronics of a centrosymmetric semiconductor cylindrical nanoshell

Cylindrical shell-type semiconductors are essential for sensing and energy harvesting when integrated into surfaces of certain equipment, such as spacecraft, marine devices, and portable electronics, where mechanical forces play a significant impact on charge transport. Traditionally, such functionalities are only manifested in piezoelectric or pyroelectric crystals that possess non-centrosymmetry. Here, we theoretically investigate electronic behaviors driven by strain gradient-induced flexoelectric polarization in a centrosymmetric semiconductor cylindrical nanoshell, expanding the flexoelectronics in shell structures. The governing equations and accompanying boundary conditions are formulated simultaneously using the principle of virtual work and the fundamental lemma of the calculus of variation. Electromechanical interactions through static bending and forced vibration analyses of the newly developed model are systematically investigated. Under localized force excitation, the distribution of mobile charges is manipulated by tuning loading magnitudes and areas. The effects of doping levels on electric potentials and mobile charges are explored to show the interaction mechanism between flexoelectric and semiconducting properties. Moreover, the natural frequencies and modes of all mechanical displacements, electric potentials, and carrier concentration perturbations within the shell are identified. This paper provides a new approach for designing shell-shaped sensors and energy harvesters specifically for centrosymmetric semiconductors.

Investigation of a cascaded piezoelectric transducer with cone horn for multi-mode power ultrasound application

To meet the ultrasonic application requirement of high power intensity and large mechanical displacement, a new theoretical method is used to study the multi-mode characteristic of the cascaded piezoelectric transducer with cone horn in this paper. Based on equivalent circuit and Kirchhoff’s law to obtain the frequency equation and vibration velocity expression of the transducer, then the resonance frequency and effective electromechanical coupling coefficient can be calculated, the velocity amplification ratio can be obtained in the meantime. This method is distinguish from traditional theoretical analysis, which avoids complex transformation of the multi-excitation sources in cascaded structure, and can calculate more performance parameters. The relationships between these performance parameters and the excitation position of the piezoelectric stack, the length and output end radius of the cone horn are analyzed and compared with the numerical simulation, and the optimized parameters of the transducer size are given. A transducer is manufactured for experimental test, the results show that the experimental value is in good agreement with theoretical calculation and finite element simulation. This work is expected to be used in the optimal analysis of the multi-mode transducer in high power ultrasonic field.

Semi-analytical layerwise solutions for FG MEE complex shell structures

This paper presents a unique analytical layerwise solution for functionally graded magneto-electric-elastic shell with complex geometry. The middle surface of the shell is modeled by a parametric equation and the Lamé parameter and radii of curvature is modeled by Differential Geometry. The mechanical displacements, electrical and magnetic potentials are written in term of a simple cosine layerwise based on a unified formulation. The highly coupled differential equations are discretized by the Chebyshev-Gauss-Lobatto grid points and solved numerically via the Differential Quadrature Method (DQM). Lagrange interpolation polynomials are employed as the basis functions. The highly coupled differential equations are solved for shells subjected to different loads and boundary conditions. Since extremely few results on this topic is available in the literature, benchmarks complex shell problems and their solutions are introduced in this paper for the very first time.

Design and performance analysis of an embedded amplified piezoelectric jetting dispensing valve

Abstract In order to satisfy the market's demand for high-consistency, micro-dispensing of colloids, an embedded lever-amplified piezoelectric dispensing valve based on flexure hinge is designed. This structure has stable jetting performance, strong reliability, and can achieve micro-dispensing of medium and low viscosity glue. Theoretical analysis shows that the output displacement of the piezoelectric stack can meet the displacement requirement of dispensing after being amplified by this amplification mechanism. And the output displacement and mode of the amplification mechanism are calculated and analyzed by simulation. The rationality of the simulation model is verified by experiments, and the effect law of driving voltage, signal duty cycle and working frequency on the mass of glue droplets is obtained. The results show that under the conditions of driving voltage 100 V, duty cycle 50%, glue supply pressure 0.6 MPa, working frequency 100 Hz, the consistency deviation of single dispensing amount is ± 2.01%, as a whole, 0.34-0.38 mg of uniform tiny glue dots can be obtained. The experimental results have verified the stability and micro-dispensing performance of the embedded lever amplification piezoelectric dispensing valve, providing reference for the subsequent application and research of jet dispensing.

Enhancing Ultrasonic Echo Response of AlN Thin Film Transducer Deposited by RF Magnetron Sputtering.

Accurate measurement of the pretightening stress for bolts has great significance for improving the assembly quality and safety, especially in severe environments. In this study, AlN thin film transducers were deposited on GH4169 nickel base alloy bolts using the RF magnetron sputtering, enabling a systematic investigation into the correlation between structures and the intensity of ultrasonic echo signals. Employing the finite element method resulted in consistency with the experimental data, enabling further exploration of the enhancement mechanism. With the increasing thickness of both the piezoelectric layer and the electrode layer, the intensity of the ultrasonic echo signals saw a great enhancement. The maximum-intensity observed increase is 14.7 times greater than that of the thinnest layers. Specifically, the thicker piezoelectric layer improves its mechanical displacement, while the increased thickness of the electrode layer contributes to better densification. An electrode diameter of nearly 4 mm is optimal for an AlN thin film transducer of M8 bolts. For pretightening the stress measurement, the sample with a strong and stable echo signal shows a low measurement error of pretightening below ±2.50%.

An existence result for accretive growth in elastic solids

We investigate a model for the accretive growth of an elastic solid. The reference configuration of the body is accreted in its normal direction, with space- and deformation-dependent accretion rate. The time-dependent reference configuration is identified via the level sets of the unique viscosity solution of a suitable generalized eikonal equation. After proving the global-in-time well-posedness of the quasistatic equilibrium under prescribed growth, we prove the existence of a local-in-time solution for the coupled equilibrium-growth problem, where both mechanical displacement and time-evolving set are unknown. A distinctive challenge is the limited regularity of the growing body, which calls for proving a new uniform Korn inequality.

Morphological analysis of a novel scissor-type deployable cable dome structure

A novel deployable scissor-type strut cable dome structure was proposed, which can improve the lateral stiffness of the traditional cable structure and achieve the characteristics of fast unfolding and closing during construction. However, the geometric stability and optimal initial prestressing theory of traditional cable dome structures cannot be applied to the new structure. Based on the equilibrium matrix theory, the geometric stability analysis was conducted and the number of self-stress modes, mechanism displacement modes, and feasible prestress modes was calculated. Then, the formula for the initial prestress distribution of the structure was derived based on the node equilibrium equation. Furthermore, the geometric stability and initial prestress distribution of the structure with different rise-to-span ratios, number of circumferential struts, and hoop cables were studied. Finally, the dynamic properties of the structure are explored by finite element simulation. The analysis results show that the structure has excellent structural stability. The rise-to-span ratios, the number of circumferential struts, and hoop cables are the important factors affecting the geometric stability and the initial prestress distribution. The rise-to-span ratios have no effect on the number of structural modes, while the number of circumferential struts and cables will cause significant changes in the number of self-stress modes. The internal force of the structural members decreases with the rise-to-span ratio and the number of circumferential struts increases, and the number of circumferential struts has the greatest influence on its internal force. The structural natural frequency exhibits a dense distribution, which indicates that the structure has good stiffness. In summary, the research has provided an idea for the application of the deployable scissor-type strut cable dome structure as a new structural system in the field of structural engineering.

Electromagnetic–Structural Finite Element Analysis of Copper and Aluminum Windings in Power Transformers under Short-Circuit Conditions

Electromagnetic forces can lead to the structural failure of power transformers due to extreme loading conditions, vibration, and/or fatigue. Therefore, studying the nature and the magnitude of these forces is a key task in the design and failure analysis of such important equipment. Keeping this issue in mind, this work aims at conducting a numerical analysis in order to evaluate the mechanical stresses and displacements of windings in power transformers due to the action of electromagnetic forces. With this purpose, a finite element model is developed considering electromagnetic and mechanical effects assuming short-circuit conditions. The study compares the cases employing copper and aluminum windings with header tap, in different temperatures. The model developed in this work is verified against analytical solutions. The numerical calculations allow for performing a detailed analysis in terms of the distribution of both displacements and stresses along the windings, which is of great relevance for identifying critical structural points and avoiding structural failure. Overall, the obtained results demonstrate that the finite element model is a useful tool for the structural design of power transformers that allow for investigating and optimizing key aspects before manufacturing.

Real, imaginary and complex branches of Lamb waves in p-type piezoelectric semiconductor GaAs plate: Numerical and experimental investigation

First, we experimentally measure the concentration of holes of the piezoelectric semiconductor (PSC) Gallium arsenide (GaAs) material based on the Hall effect measurement. We then numerically calculate the Lamb wave characteristics in a p-type PSC GaAs plate using this measured value of the concentration of holes (estimated at approximately p0=3.5431×1025m−3). To guarantee the coupling effect that makes the Lamb wave a piezo-active wave, the GaAs crystal is oriented in a specific orientation of (110) plane. Ordinary differential equation (ODE) method is employed to calculate the dispersion curves, 3D view of the mechanical displacements, 3D view of the electric potential and 3D view of the concentrations of holes. Results show that the appearance of the complex branches of the Lamb modes coincides with the vanishing of the imaginary part of the wavevector (Im(k1)) to zero, which is a very remarkable finding that has not been discussed in previous studies. Meanwhile, these complex branches start exactly at the point of Zero-group-velocity (ZGV). Moreover, the present work highlights the hole drift characteristics of PSC GaAs and provides a critical comparative discussion with those published by (Zhu et al., 2018) for the PSC ZnO plate. Accordingly, the “Screening effect” phenomenon that is based on the positive holes in the negative electric potential region is discussed. The present results provide a theoretical and fundamental guidance on the development of smart devices based on the PSC GaAs material.

A novel capacitive sensor interface based on a simple capacitance-to-phase converter

Abstract A novel room temperature capacitive sensor interface circuit is proposed and successfully tested, which uses a modified All-Pass filter architecture combined with a simple series resonant tank circuit with a moderate Q-factor. It is fashioned from a discrete inductor with small dissipation resonating with a grounded capacitor acting as the sensing element to obtain a resolution of ∆C ~ 2 zF in a capacitance range of 10 – 30 pF. The circuit converts the change in capacitance to the change in the phase of a carrier signal in a frequency range with a central frequency set up by the tank circuit’s resonant frequency and is configured to act as a close approximation of the ideal All-Pass filter. This cancels out the effects of amplitude modulation when the carrier signal is imperfectly tuned to the resonance. The proposed capacitive sensor interface has been specifically developed for use as a front-end constituent in ultra-precision mechanical displacement measurement systems, such as accelerometers, seismometers, gravimeters and gravity gradiometers, where moving plate grounded air gap capacitors are frequently used. Some other applications of the proposed circuit are possible including the measurement of the electric field, where the sensing capacitor depends on the applied electric field, and cost effective capacitive gas sensors. In addition, the circuit can be easily adapted to function with very small capacitance values (1 - 2 pF) as is typical in MEMS-based transducers.

Atomic-scale wear behavior of two-phase TiAl alloys by vibrational horizontal friction

To investigate the influence of vibrational horizontal friction on the microscopic distortion of γ/α2 biphasic TiAl alloys, a molecular dynamics approach was used for simulation by analyzing the mechanical properties, atomic displacements, shear strains, and defect distributions of the substrate in vibrational horizontal friction and conventional friction. The friction force and coefficient of friction in vibrational horizontal friction were found to be less than conventional friction. Vibrational horizontal friction has a shallower depth of abrasion marks and a larger wear area compared to conventional friction. At the same time, this γ/α2 phase boundary changes the direction of motion of the atom so that they move in the same orientation as parallel to the interfacial boundary. Vibrational horizontal friction has a larger strain concentration area than conventional friction. The existent γ/α2 interface impedes the strain transmission so that some of the stresses are concentrated near the interface, and the γ-phase accumulates a large proportion of dislocations, which leads to work-hardening of the material. The slip of the horizontal stacking faults in the vibrational horizontal friction releases internal stresses. The formation of structures such as stacking fault tetrahedrons has a significant strengthening effect on the material.

Temperature Effects on GaN/AlN Heterojunction in a Piezomagnetic and Piezoelectric Semiconductor Composite Fiber

In this article, considering the thermal effects, a PN GaN/AlN heterojunction in a piezomagnetic and piezoelectric semiconductor composite fiber driven by dynamic magnetic loads is studied. The true nonlinear constitutive equations of the electric current density for the composite heterojunction are employed. Thus, a nonlinear finite‐element method (FEM) is adopted to obtain dynamic responses of the composite heterojunction, including the mechanical displacement, electric potential, and electron and hole concentrations. By comparing dynamic responses with those derived by COMSOL Multiphysics, the nonlinear FEM is verified. Based on numerical results, regulation effects of the temperature on distributions of the mechanical displacement, electron and hole concentrations, and temperature–current–voltage characteristics are discussed.

Use of Fibrin Glue as a Surgical Adjunct in Bone Grafting of Fracture Non-unions.

Non-union of long bones is a common challenge in the treatment of fractures. Bone grafting is commonly used to treat atrophic non-union, but mechanical displacement of the graft may occur, resulting in delay or failure of treatment. Fibrin glue has demonstrated positive results in management of bone defects in neurosurgery and oromaxillary facial surgery, however, there has yet to be any study on its use in long bone fractures. We conducted a prospective randomised controlled trial at a single tertiary centre involving adult patients with long bone fractures that had undergone non-union and requiring bone grafting only. Autologous iliac crest bone graft was applied to the debrided non-union site, with additional fibrin glue applied for the intervention arm. Patients were followed-up with serial radiographs until clinical and radiographical union. Ten patients (3 male, 7 female), of mean age 41.7 (19 - 63) were recruited over five years, with one drop out. Eight out of nine fractures united after treatment. One patient underwent hypertrophic non-union requiring re-fixation and bone grafting. There was no difference in the time to union for patients in the fibrin glue group (19.5 weeks) versus the control group (18.75 weeks) (p=0.86). There were no complications sustained from usage of fibrin glue. Fibrin glue appears to be a safe adjunct for treatment of non-union of long bone fractures across varying fracture sites by holding the bone graft in place despite not demonstrating a faster time to union.