Solid State Phenomena Vol. 198

Abstract: The paper presents new method, which enables measurement of magnetic characteristics of amorphous alloy ribbons in two directions. In presented method a frame shaped core is placed in middle layer of PCB (Printed Circuit Board). Magnetizing and measuring coils on every side of core enable measurements of both axis of tape. The results show, that differences in magnetic properties in two directions of tape caused by anisotropy are limited. Research opens possibility to develop two axis fluxgate sensors and miniature cores for power conversion devices.

Abstract: The bearingless systems are a key technology in many power mechatronic applications. The topic of the paper reports the original, very relevant and very timely research. The methods of numerical and experimental testing of the bearingless induction motor, presented in the paper revised, are convergent with the directions of up-to-date research in this domain.

Abstract: Paper discusses the possible of application of iron-based amorphous Fe₇₇Cr₂B₁₆Si₅ alloys for tensile force sensors. In proposed sensor uniform stresses were generated in direction of the ribbon ring core axis. As a result stresses were perpendicular to the magnetizing field direction, what increases sensor sensitivity as well as simplified analyses. The results show high magnetoelastic sensitivity of Fe₇₇Cr₂B₁₆Si₅ amorphous alloy. Moreover, this magnetoelastic sensitivity increases during the annealing process, which is connected with thermal relaxation of amorphous alloy.

Abstract: This study focuses on the rubber material behaviour assessment under dynamic loading using numerical methods. Consequently, dynamic simulations of the rubber structural coupon subjected to dynamic velocity loading were performed using the explicit integration procedure with central difference scheme with modified time integration of the equation of motion implementation. During investigations two impulse velocities were used and compared for two different constitutive materials: Mooney-Rivlin without rate-dependency and Mat 181 Simplified Rubber which includes strain rate effects. From the obtained results it was noticed that material behaviour in both cases is different and along with different values of velocity the strain rate sensitivity changes.

Abstract: In the paper is presented model of the passive magnetic bearing. The response of bearing is approximate by second order model. There are presented the damping and stiffness coefficient of suspension. The coefficients derived from Biot-Savards law, Ohms law and Lorenzs force. There is presented loop with molecular current as a model of magnet, final formula of damping and stiffness coefficients and static characteristic of passive magnetic bearing.

Abstract: The paper presents a model of the 10-coil launcher, which can be used as a catapult of micro aerial vehicles (MAVs). The main advantage of such a device is the possibility of controlling its acceleration. We have also shortly described main disadvantages of pneumatic and rubber launchers and compared them to our solution which involved magnetic phenomena. The history and the classification of magnetic launchers were also mentioned. The investigated magnetic system was described in details. The system voltage equations and energetic conversions which take place during the launch were presented. With the use of finite element method we calculated the lumped parameters of the system (self-and mutual inductances). Nonlinear model was implemented in the MATLAB packet. Launch operation was divided into an acceleration and a braking phase. Thus, nine coils operated as accelerators and the last one was employed as a magnetic brake. The system was controlled by means of PID regulators which were tuned manually. Current values in the modelled coils were also limited by bang-bang controllers. In the last part of the paper we presented results of simulations and discussion about possible improvements of the model in the future.

Abstract: The thermal field model of the linear oscillating actuator [5, has been presented in the paper. The calculated temperature has been taken into account to obtain the correct characteristics of the permanent magnets, which are operating in raised temperature (above 293 K). The parameters of the NdFeB magnets change significantly with temperature increasing (the magnets are weaker). Thus, the phenomenon should be included in the designing of the actuators. We have determined the highest current density of the actuator winding, for which the actuator still operates properly. Using the thermal field analysis, the temperature of the whole actuator construction has been obtained. Using the correct parameters of the hot magnets in the calculation model, the static electromagnetic parameters of the actuator have been determined. They were compared with those obtained for the actuator, which is operating in the room temperature (T_o=293 K). It has been proved, that the parameters of the actuator are going down under the increasing of the temperature.

Abstract: The aim of this research was to discuss the possibilities of inertial load control and stabilization and investigate the arm muscle loading when exercising upper limb on an inertial-load type simulator. Arm muscle activities have been investigated using computer simulation by software LifeMOD at different modes of exercising.

Abstract: The paper presents the problem of vibration reduction in designed discrete mechanical systems. The method of reduction has been based on active synthesis, which makes it possible to obtain the desired mechanical effect through the proper selection of dynamic properties of the system, including the calculation of the active force as a function of the system force feedback.

Abstract: Mechanical structures are spatial, three-dimensional (3D) systems of distributed parameters. They present quite complicated plants, if methods of control systems theory are applied. The design process of the vibration control system for such plants is extremely difficult and requires an extensive heuristic knowledge. The subject of the control system is to eliminate the vibrations of the free end at the plane parallel to the foundation Similar problems are met, when the stabilization of robot arms, antennas, satellite solar batteries or slender skyscrapers is considered. In the paper we have presented the 3D bar structure with sticked parallel two piezo-stacks into bars. Recall piezo-elements are actuators, but sensors are two eddy-current sensors located in near free end the structure in perpendicular directions X and Y. Thus the whole structure is TITO (Two Input Two Output) system. For such system the control law was designed with used LQR controller. Above controller was designed for coupled and decoupled system also. In both case a correct damp and very short period of the vibration were criteria to choose the controller parameters. All investigations were carried out in two steps. In the first step control laws were designed in computer simulation. In the second step these control laws were verified experimentally on the laboratory stand by using DSP. Finally, desired control laws were compared.