Rafał Mech

Magnetomechanical Properties of Terfenol-D Powder Composites

In this work the methodology of determining mechanical and magnetomechanical properties (mainly magnetostriction) of original composite material on epoxy resin matrix and powdered Giant Magnetostrictive Material (Terfenol-D) has been presented. Researches were carried out in order to differentiate properties of the GMM composite with two different volume fraction of Terfenol-D powder (35% and 45%) in comparison with bulk Terfenol-D. Results show that composites magnetostriction highly depends on volume fraction of Terfenol-D powder, and it is few times lower than in monolithic material. Moreover a possible ways of application were indicated.

Power generating by high pulse mechanical stimulation of magnetic coupled NdFeB and Terfenol-D

Rising requirements for a new constructions, devices and machines force engineers to monitor them all day long. An attractive solution seems to be applications of wireless sensors. However, there is a barrier limiting their application, which is the need to supply them with an electrical power over extended period of time without using additional wiring or batteries. The potential solution of this problem seems to be an energy harvesting. Most methods of obtaining the energy from the external sources e.g. vibrations, is to use piezoelectric materials. However, the amount of energy generated by piezoelectric materials is smaller than most electronic devices need. Therefore a new method for generating a pulse of energy and conditioning for other loads devices must be developed. This paper proposes a new energy harvesting device based on magnetostrictive material. In the course of the experiments with using Terfenol-D rods as actuators and sensors it has been observed interesting phenomenon. Mechanical impact (e.g.energy between 1J and 10J in infinite time) to magnetic core based on Terfenol-D rod (diameter 5mm, length 10 mm), NdFeB permanent magnets and coil allowed get electric power signal enough to supply device of 100 Ohm load on their active state (typical low power controller). In comparison to the same magnetic circuit built with other typical ferromagnetic materials e.g. Armco iron, showed effect 10 times lower or none. Tests and experiments showed the important role of coupling Terfenol-D and NdFeB permanent magnets, their configuration and variable coil parameters determined this effect. In regard to the results the authors proposed the construction of a new impulse harvesting method based on Terfenol-D material for low impedance load.

The Use of Magnetostrictive Cores for the Vibrations Generation and Energy Harvesting from Vibration, in the Selected Frequencies of Work

The paper presents research on use of magnetostrictive cores for the recovery of energy from vibrations and its use to power low-power electronics. To achieve this goal a test stand was constructed to generate and to receive the vibrations in the measurement system at the same time. Selection of an appropriate magnetomechanical parameters of the system was an important element influencing end results. The most important were values of the prestress and magnetising field for actuators and harvesters. As a result of the investigation the device operating in a wide frequency range (up to 40 KHz) and a system for energy transportation through mechanical vibrations were developed. Moreover it was shown that the proposed solution allow information transfer in a short bursts over the same system as energy transfer.

Magnetomechanical properties of magnetostrictive composites with high volume of fraction Terfenol-D powder

The role of Smart Magnetic Materials (SMM) is still increasing. One type of SMM are Giant Magnetostrictive Materials (GMM) which can be represented by i.e. Terfenol-D. The biggest difficulty with mechanical application of GMM is its brittleness. On the other hand, increase of frequency generate meaningfully eddy currents. These disadvantages tend to search new solutions in a form of composite materials with giant magnetostriction (GMMC). The matrix for GMMC most often is an epoxy resin with magnetostrictive material inside (in a form of powder, flakes or tiny rods made of i.e. Terfenol-D). Several composites, with outstanding magnetostrictive properties, have been synthesized combining an epoxy resin with polycrystalline powders of Terfenol-D. Application of appropriate way of compression allowed to achieve composites consisting near 70% volume fraction of Terfenol-D powder in comparison with about 48% volume fraction of reinforcement in traditional production way. Composites had random and preferential grain orientation which was obtained by curing the material respectively with or without a magnetic field. The quasistatic magnetomechanical properties of the composites were investigated and compared with monolithic Terfenol-D alloy. The highest response was obtained for a perpendicular polarized composite. Investigated composite are promising magnetostrictive material enable to create a new type of actuators and magnetic field sensor.

SMART composite high pressure vessels with integrated optical fiber sensors

In this paper application of integrated Optical Fiber Sensors for strain state monitoring of composite high pressure vessels is presented. The composite tanks find broad application in areas such as: automotive industry, aeronautics, rescue services, etc. In automotive application they are mainly used for gaseous fuels storage (like CNG or compressed Hydrogen). In comparison with standard steel vessels, composite ones have many advantages (i.e. high mechanical strength, significant weight reduction, etc). In the present work a novel technique of vessel manufacturing, according to this construction, was applied. It is called braiding technique, and can be used as an alternative to the winding method. During braiding process, between GFRC layers, two types of optical fiber sensors were installed: point sensors in the form of FBGs as well as interferometric sensors with long measuring arms (SOFO®). Integrated optical fiber sensors create the nervous system of the pressure vessel and are used for its structural health monitoring. OFS register deformation areas and detect construction damages in their early stage (ensure a high safety level for users). Applied sensor system also ensured a possibility of strain state monitoring even during the vessel manufacturing process. However the main application of OFS based monitoring system is to detect defects in the composite structure. An idea of such a SMART vessel with integrated sensor system as well as an algorithm of defect detection was presented.

High Power Actuator Based on Magnetostrictive Composite Core with Temperature Drift Compensation

The paper presents an actuator based on a coil placed in the casing, with specially prepared connection rods. The construction allows installation of the fiber Bragg grating sensors inside the coil. It allows to measure deformation of the composite that is located in the core of the coil. Thanks to the signal generation with use of DASYLab software, it is possible to precisely control the frequency, value of amplitude excitation and to send the signal to the system with use of the measurement card. The main goal of the experiment is to keep constant value of deformation, by means of a feedback loop with use of PID control, and to change the initial conditions of the test by change of the external force. The system is designed to return to the initial settings by appropriate control of the intensity of magnetic field, and thus the deformation of the sample.

GENERATING OF ELECTRICITY FROM MAGNETOELECTRIC COMPOSITE WITH USE OF CHANGES IN DIRECTION OF MAGNETIC FIELD VECTOR

Currently, the research on new materials exhibiting cross effects, coupled by the mechanical and magnetic fields are directed to combine these materials with other materials which exhibit completely different properties. The most promising of these additional materials tend to be those which are characterized by an electric properties. Usually in the literature a combination of these two kind of materials is known as hybrid material. They can be characterized by the capability to work under the influence of various external factors. Most of these new materials are based on polymer matrices. Polymer-based magnetoelectric (ME) materials are one of the most interesting, Summary:

Influence of Terfenol-D Powder Volume Fraction in Epoxy Matirx Composites on their Magnetomechanical Properies

Abstract In this paper the investigations of magnetostriction as well as DC magnetic properties for composites doped with Terfenol-D particles are presented. All investigations were performed for the materials with 35%, 46% and 70% volume fraction of the Terfenol-D particles surrounded by epoxy matrix. Moreover, the bulk Terfenol-D alloy was tested. The obtained results show that the magnetization of the composite materials increases with increasing the volume fraction of Terfenol-D particles. Similar dependence as for magnetization was observed for the magnetostriction measurements. Although the magnetostriction of composite material is smaller than for solid Terfenol-D it is still tens of times bigger than in case of traditional magnetostrictive materials. Obtained results gives opportunity to use these materials for variety applications such as actuators and sensors.

Investigations on Magnetoelectric Composites Based on Terfenol-D & PZT in an Alternating Magnetic Field Conditions

In this paper a study on the magnetostrictive-piezoelectric composite material with different configuration in a variety of external magnetic field changes was presented. An experimental setup for investigation of properties of magnetostrictive-piezoelectric materials was prepared. The hybrid structure was made of magnetostrictive composite (based on Terfenol-D) and piezoelectric materials. Experimental results shown the response of prepared hybrid material to the rate of magnetic field changes at the same direction of magnetic field vector. Based on the obtained results, it was found that the prepared composite material exhibits magneto-electric effect in the case of work in a variable magnetic field. This phenomenon could be used as a support for the tensiometers during measurements of deformation or cracks propagation of the samples during fatigue tests.

INFULENCE OF RECRYSTALLIZATION ON DAMPING PROPERTIES OF ALLOY Fe75Zr4Ti3B17Cu1

Internal structure of metal alloys has strong influence on their mechanical properties. It can be observed even during conventional heat treatment of metals [3, 4, 6]. Nowadays advanced technologies combined with specific metal alloys allow us to obtain amorphous structure, under condition cooling rate exceeds the limits for specific alloy [1]. Such structure should poses interesting mechanical properties [5]. Paper is conAbstract: