In this paper, a continuum mathematical electro-mechanical model of ultrasonic Langevin transducers has been developed by considering three factors: 3D vibrations, piezoelectric effects, and elements damping. Since the equivalent-circuit methods simulate a continuous system with discrete components, they are valid near one resonance frequency. However, a continuum model is valid in broader frequency ranges. It can also describe the effect of geometries and material properties on the frequency response of transducers. By using the mathematical model, the amplitude of vibrations, mode shape, resonant and anti-resonant frequencies, mechanical quality factor, and frequency response can be achieved for a transducer with a specific geometry and m

In this paper, a new bulk magnetostrictive bending actuator is presented using a permendur rod. By applying an axial magnetic field in a thin layer of the magnetostrictive rod, the tensile deformation of the layer would cause bending of the actuator. The generation of the magnetic field in the layer is carried out by coils and a comb-shaped magnetic core. The Comsol software is used to calculate the magnetic field. Following the fabrication of the actuator, deflection values are measured at different currents and compared with results of the simulation. The actuator has been tested with constant and alternating magnetic fields. The actuator is excited with an alternating magnetic field at the resonance frequency of the actuator to increase

In this paper, a vibrational drilling tool using a magnetostrictive torsional transducer is designed and fabricated. The torsional transducer is a hollow cylinder, which is made up of “2 V permendur.” Passing an alternating current through the material creates a variable circular magnetic field and exciting a coaxial coil with a direct current generates a constant axial field in the material. According to the Wiedemann effect, the magnetic domains of the material rotate helically in the direction of the external field and cause a shear strain in the material. To utilize the maximum torque and amplitude of the transducer as well as to maintain the transducer’s resonance conditions, a wave transmitter is designed to connect the transduc

In this paper, contributions of the mechanical and electric power losses have been studied in a typical piezoelectric ultrasonic transducer under free conditions. The losses in a Langevin ultrasonic transducer can be divided into three parts: dielectric loss of piezoelectric, structural damping loss of the transducer’s mechanical components, and losses due to the friction of contact surfaces. In order to estimate dielectric losses, loss factor or t a n δ of the piezoelectric ceramic have been measured. Dielectric power loss is obtained by calculating the electrical energy stored in a piezoelectric and using the loss factors. The structural damping of the mechanical components of the transducer is calculated using the mechanical quality f

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This paper presents a theoretical study of nonlinear dynamic behavior of a dielectric elastomer minimum energy structure (DEMES). While planar Dielectric Elastomer Actuators (DEA) solely poses material nonlinearity in their model, geometrical nonlinearity imposes additional challenge to model DEMES. Considering dielectric elastomer and bending frame, respectively, as a hyper-elastic film and an elastic beam, Euler–Lagrange equation is employed to derive the equation of motion of actuator subject to a harmonic voltage. Fixed point analysis of the equation of motion demonstrates supercritical pitchfork bifurcation with respect to film pre-stretch as bifurcation parameter. It is shown by simulation results that the system poss

For detecting cells by Surface Acoustic Wave sensors, a sacrificial layer with antigens is usually used to trap cells. This paper introduces a new idea where Dielectrophoresis force traps target cells instead of a sacrificial layer that reacts with target cells and sensed by the surface acoustic wave. Therefore, one can use the sensors more than once, and it is possible to trap different types of cells with different dielectric properties. The device is simulated, and the main parameters of a Dielectrophoresis trapping system and Surface Acoustic Wave sensor, have been introduced and optimized. The effects of focused and unfocused electrode are studied numerically on the displacement of the sensor. Eventually, the feasibility of using the h

In this paper, a hybrid sensor to measure the torque and axial force using a magnetostrictive hollow rod is presented. The magnetostrictive material is made up of vanadium permendur alloy. Axial and circular magnetic fields are used in order to excite the sensor. An axial coil and a single wire passing through the material are used in order to generate axial and circular magnetic field, respectively. In order to detect axial and circular flux changes, two orthogonal pickup coils are used. Theoretical modeling of the sensor has been done using piezomagnetic equations of magnetostrictive materials. In order to achieve an estimation of applied magnetic fields to the material, the sensor has been simulated numerically. Then, the sensor has been

In this study, high-temperature tensile behavior of Al-3 vol% SiC nanocomposite is investigated. To fabricate the samples, SiC nano reinforcements and Al matrix were mixed using an attrition milling. The mixed powders were then subjected to cold pressing and hot extrusion at temperature of 500? C. Tensile behavior at different temperatures along with density measurement and microstructural examinations were studied. The results represent a 40% improvement in ultimate tensile strength of Al-3vol% SiC nanocomposite in comparison with non-reinforced sample at ambient temperature. Also, a rise in temperature up to 270 ? C during the tensile test led to an increase of the maximum elongation. Moreover, this temperature rise caused to 50% and 44%

In this paper, a hybrid damper is developed to achieve lower stiffness compared to magneto rheological dampers. The hybrid damper consists of an eddy current damper (ECD) and a Magneto Rheological Damper (MRD). The aim of this research is to reduce the stiffness of MRDs with equal damping forces. This work is done by adding an eddy current passive damper to a semi-active MRD. The ECDs are contactless dampers which show an almost viscous damping behavior without increasing the stiffness of a system. However, MRDs increase damping and stiffness of a system simultaneously, when a magnetic field is applied. Damping of each part is studied theoretically and experimentally. A semi-empirical model is developed to explain the viscoelastic behavior

The paper provides a comprehensive procedure for the mechanical and magnetic design of Langevin transducer based on giant magnetostrictive material. The the transducer is designed to work at its second mode of vibration, having high mechanical quality factor and low damping coefficient. The design procedure is based on an analytical model and it is verified by finite-element analysis. Experimental tests based on impedance response analysis in first and second modes are carried out on the prototype. Results confirm the appropriate design of this transducer, demonstrating the highest mechanical quality factor between the resonant transducers in the literature.

In the present paper, classical and excess eddy currents losses of Terfenol-D are studied and effects of magnetic field frequency, peak of magnetic flux density and diameter of Terfenol-D on the eddy currents losses are investigated. To provide reliable data for the purpose of the paper, an experimental laboratory is fabricated and used to obtain major and minor hysteresis loops of Terfenol-D at different frequencies. In theoretical study, initially an analytical model based on uniform distribution of magnetic flux is developed which yields to calculation of classical eddy currents losses. Then, another eddy currents model based on non-uniform distribution of magnetic flux and nonlinear diffusion of electromagnetic fields is presented. The

In case of human bone fracture, the best way to better and faster knitting is when a traumatologist fixes the fractured bone ends by drilling and setting the immobilization plates by screws. Heat generation during bone drilling may result in thermal injury due to exposure to elevated temperatures, with potentially devastating effect on the outcome of orthopedic surgery. A recent and promising method for reducing temperature in bone drilling is the use of ultrasonic assistance, where high-frequency and low-amplitude vibrations are added in feed direction during cutting process. In this research, experimental tests are carried out in five cutting speeds and three feed rates. The results demonstrate that ultrasonic-assisted drilling offered lo