Nonlinear dynamic modeling of ionic polymer conductive network composite actuators using rigid finite element method

Ionic polymer conductive network composite (IPCNC) actuators are a class of electroactive polymer composites that exhibit some interesting electromechanical characteristics such as low voltage actuation, large displacements, and benefit from low density and elastic modulus. Thus, these emerging materials have potential applications in biomimetic and biomedical devices. Whereas significant efforts have been directed toward the development of IPMC actuators, the establishment of a proper mathematical model that could effectively predict the actuators' dynamic behavior is still a key challenge. This paper presents development of an effective modeling strategy for dynamic analysis of IPCNC actuators undergoing large bending deformations. The proposed model is composed of two parts, namely electrical and mechanical dynamic models. The electrical model describes the actuator as a resistive-capacitive (RC) transmission line, whereas the mechanical model describes the actuator as a system of rigid links connected by spring-damping elements. The proposed modeling approach is validated by experimental data, and the results are discussed. © 2014 Elsevier B.V. All rights reserved.

Electromagnetic receiving properties of overhead power line

This paper examines the use of overhead power transmission lines as electromagnetic sensors for detecting electric discharges caused by defective power transmission equipment. The experimental study involved the use of a spark gap (point-point configuration) and two HV conductors of different lengths to simulate electric discharge that takes place on transmission line. The experimental results show that large amount of energy are coupled onto the conductors and the amount of electromagnetic energy is dependent on the length of the conductor and the distance between the source and the conductor.

Parametric investigation and measurement of near end and far end crosstalk in multiconductor microstrip transmission lines

This paper investigates and measures the near end and far end crosstalk in the multiconductor transmission line (MTL) mounted on the PCB by varying the parameters which are associated with physical dimension, characteristic of the substrate and the nature of input signal. With the variation of these factors, the coupling inductance and capacitance vary causing crosstalk. By using the method of moment (MoM), the per unit length parameters are calculated for microstrip lines. Subcircuit model is used to investigate the time domain and frequency domain analysis of near field and far field crosstalk. This parametric investigation is very useful for designing high speed interconnectors on PCB substrates. Some experimental results are presented to validate the analytical findings.

Pi-shaped MEMS architecture for lowering actuation voltage of RF switching

A wide band low actuation capacitive coupling electrostatic RF MEMS switching device is presented in this paper. The device includes a pi-shaped matching architecture containing two switches connected by a high impedance short transmission line. The device can act as a switch for any desired frequency whilst requiring only 12volts for actuation. By optimizing the length and the characteristic impedance of the transmission line, the switch can be tailored for desired frequency bands. The switch is calculated and simulated for Ka to V frequency bands demonstrating excellent improvements of RF characteristics.

Design and simulation of a tunable MEMS filter for wireless biomedical signal transceivers

This paper presents a new architecture for a high quality tunable MEMS filter that can be used in wireless biomedical signal transceivers. It consists of a π match circuit with two shunt capacitive coupling switches separated by a piece of high impedance short transmission line, and also a series switch placed at the quarter wavelength distance away from the π match circuit. The low actuation voltage and also tunability are important features of the design objective. All portions of the filter can be realized simultaneously. Thus, the filter docs not require any extra steps during its fabrication, and is not costly. The simulation results confirm the good performance of the filter.

RF techniques for lowering the actuation voltage of RF MEMS shunt capacitor switch for C-K band

Increasing the capacitance ratio in RF MEMS shunt capacitive switch will increase its RF performance but also raise its actuation voltage. To improve the RF performance of the switch without increasing its capacitance ratio, this paper explores two methods: reducing the LC resonance from the mm-wave into the X-band by using an inductive bridge, and using two short high impedance transmission lines at both ends of the CPW line. Accordingly, this paper presents the design and simulation of an electro-static low actuation voltage and a very high isolation multipurpose switch with a very large bandwidth. The simulation results are presented and discussed.

Applying inverse just-noticeable-differences of velocity to position data for haptic data reduction

ust-Noticeable-Differences (JND) as a dead-band in perceptual analysis has been widely used for more than a decade. This technique has been employed for data reduction in hap tic data transmission systems by several researchers. In fact, researchers use two different JND coefficients that are JNDV and JNDF for velocity and force data respectively. For position data, they usually rely on the resolution of hap tic display device to omit data that are unperceivable to human. In this paper, pruning undesirable position data that are produced by the vibration of the device or subject and/or noise in transmission line is addressed. It is shown that using inverse JNDV for position data can prune undesirable position data. Comparison of the results of the proposed method in this paper with several well known filters and some available methods proposed by other researchers is performed. It is shown that combination of JNDV could provide lower error with desirable curve smoothness, and as little as possible computation effort and complexity. It also has been shown that this method reduces much more data rather than using forward-JNDV.

Modeling the flow behavior, recrystallization, and crystallographic texture in hot-deformed Fe-30 Wt Pct Ni Austenite

The present work describes a hybrid modeling approach developed for predicting the flow behavior, recrystallization characteristics, and crystallographic texture evolution in a Fe-30 wt pct Ni austenitic model alloy subjected to hot plane strain compression. A series of compression tests were performed at temperatures between 850 °C and 1050 °C and strain rates between 0.1 and 10 s⁻¹. The evolution of grain structure, crystallographic texture, and dislocation substructure was characterized in detail for a deformation temperature of 950 °C and strain rates of 0.1 and 10 s⁻¹, using electron backscatter diffraction and transmission electron microscopy. The hybrid modeling method utilizes a combination of empirical, physically-based, and neuro-fuzzy models. The flow stress is described as a function of the applied variables of strain rate and temperature using an empirical model. The recrystallization behavior is predicted from the measured microstructural state variables of internal dislocation density, subgrain size, and misorientation between subgrains using a physically-based model. The texture evolution is modeled using artificial neural networks.

Statistical analysis of finite element modeling in sheet metal forming and springback analysis

This work focuses on development of a method to statistically study forming and springback problems of TRansformation Induced Plasticity (TRIP) through an industrial case study. A Design of Experiments (DOE) approach was used to study the sensitivity of predictions to four user input parameters in implicit and explicit sheet metal forming codes. Numerical results were compared to experimental measurements of parts stamped in an industrial production line. The accuracy of forming strain predictions for TRIP steel were comparable with conventional steel, but the springback predictions of TRIP steel were far less accurate. The statistical importance of selected parameters for forming and springback prediction is also discussed. Changes of up to ±10% in Young's modulus and coefficient of friction were found to be insignificant in improving or deteriorating the statistical correlation of springback accuracies.

Improving casthouse throughput using discrete-event modeling

The scheduling of metal to different casters in a casthouse is a complicated problem, attempting to find the balance between pot-line, crucible carrier, furnace and casting machine capacity. in this paper, a description will be given of a casthouse modelling system designed to test different scenarios for casthouse design and operation. Using discrete-event simulation, the casthouse model incorporates variable arrival times of metal carriers, crucible movements, caster operation and furnace conditions. Each part of the system is individually modelled and synchronised using a series of signals or semaphores. in addition, an easy to operate user interface allows for the modification of key parameters, and analysis of model output. Results from the model will be presented for a case study, which highlights the effect different parameters have on overall casthouse performance. The case study uses past production data from a casthouse to validate the model outputs, with the aim to perform a sensitivity analysis on the overall system. Along with metal preparation times and caster strip-down/setup, the temperature evolution within the furnaces is one key parameter in determining casthouse performance.

X-ray diffraction line broadening from gold and platinum thin films

X-ray diffraction line profile analysis has been used to study the microstructure of (Ill) oriented gold and platinum thin films deposited by thermal evaporation and DC magnetron sputtering. In addition to crystallite size broadening, the profiles from these films displayed broadening arising from dislocations. A parallel investigation, using transmission electron microscopy (TEM) was undertaken to study the nature of dislocations formed, and to provide information on the dimensions of the crystallite columns in the films. X-ray data were collected at room temperature to determine the anisotropy of the broadening with (hkl), using a Siemens D5000 powder diffractometer (CuKa radiation) and two high-resolution synchrotron instruments (BM 16 at the ESRF [A=0.35A] and station 2.3 at the Daresbury laboratory. Two approaches to instrument deconvolution were investigated; Fourier deconvolution and fundamental parameters profile fitting, using Lab6 as a reference material to determine the instrument profile function. After removal of the crystallite size broadening contribution from the measured integral breadths, the residual microstrain broadening was modelled assuming dislocations based on a FCC a/2<110>{ Ill} slip system. The results of the X-ray analysis agreed with dark field TEM micrographs, which showed that many of the crystallites contained dislocations of mixed character (screw- edge).