Maciej Kachniarz

Influence of Stresses on Magnetic B-H Characteristics of X30Cr13 Corrosion Resisting Martensitic Steel

Paper presents the frame-shaped cores based methodology of testing of magnetoelastic characteristics of energetic steels such as X30Cr13 steel, subjected to tensile stresses. In presented method, the magnetic circuit of the sample is closed. For this reason, the results of magnetoelastic investigation are independent of the shape of the sample. To validate the proposed method, the influence of tensile stresses on B(H) hysteresis loop of X30Cr13 martensitic corrosion resistant steel was carried out. On the base of these result, clear criteria for non-destructive assessment of mechanical stresses in the material were determined.

Two-Channel MEMS Gravimeter of the Automated Aircraft Gravimetric System

A new two-channel gravimeter of the automated aircraft gravimetric systems (AGS), the design of which is based on MEMS technology, was considered. It was established that the accuracy and speed of the new gravimeter is higher as compared to the currently known counterparts. A new two-channel gravimeter operating principle was described and its main advantages were shown, i.e. the lack of the error signals in the two-channel gravimeter output signal from the impact of vertical acceleration and residual nonidentity of the structures of two capacitive elements. The issue of filtering the output gravimeter signal from high-frequency noise was solved. It was established that the AGS accuracy with a two-channel MEMS gravimeter to measure the anomalies of gravity acceleration is 1 mGal.

Temperature Influence on the Magnetic Characteristics of Mn-Zn Ferrite Materials

The subject of this paper was to investigate the temperature influence on the magnetic characteristics B-H of crystalline soft magnetic materials. Four different Mn-Zn ferrite material were investigated. The investigated ferrites were formed into ring-shaped cores with closed magnetic circuit and magnetizing and sensing windings were coiled on them. All cores were placed in the cryostat which was used to set temperature. Magnetic B-H characteristics was measured by computer controlled hysteresis graph. The results of the investigations were presented in the paper and analyzed. On the basis of presented results, the conclusions were formulated, which are also included in the paper.

Magnetoelastic Characteristics of Constructional Steel Materials

Paper presents the methodology and results of magnetoelastic characteristics investigation of three types of constructional steels. Investigated steels were formed into frame-shaped samples with both magnetizing and sensing windings coiled on their columns. Magnetic characteristics of materials were measured by computer controlled hysteresisgraph. In order to apply tensile stresses in material of the sample, special force reversing system was used. The tested samples and the procedure of their investigation were described. Obtained results were processed and presented in the paper as charts, which were analyzed and discussed. On the basis of the results, the conclusions were formulated, which are also included in the paper.

New Methodology of Testing the Stress Dependence of Magnetic Hysteresis loop of the L17HMF Heat Resistant Steel Casting

This paper presents the results of investigation on the tensile stresses dependence of magnetic characteristics of the L17HMF steel casting. To ensure uniform stress distribution in the sample for this investigation and the closed magnetic circuit, the frame-shaped samples were used. This is very important because it provides results independent of the shape and dimensions of the sample. On the columns of the sample both sensing and magnetizing windings were made. It is highly recommended to wound magnetizing and sensing windings on both columns. Due to the specialized force reversing system, compressive force generates the uniform tensile stresses in the sample. Magnetic characteristics are measured under these stresses by digitally controlled hysteresis graph. On the base of results of measurements the magnetoelastic characteristics of L17HMF steel casting were determined. Determined this characteristic is necessary to developed nondestructive testing method for monitoring of industrial and energetic constructions with elements made by L17HMF steel casting.

Investigation of the Magnetoelastic Villari Effect in Steel Truss

The following paper presents results of investigation of the magnetoelastic Villari effect in steel truss. Construction of the specially developed steel truss allowed to investigate three identical steel elements at the same time, where one element was subjected to the tensile stress and two elements were influenced by the compressive stress. For all three elements the magnetic characteristics for different values of applied mechanical stress were measured. Purpose of the performed investigation was experimental validation of the theory of magnetoelastic Villari effect for steel. For tensile stress initial increase of the magnetic flux density was observed up to the Villari reversal point and then values of magnetic flux density started to decrease. For compressive stress only decrease of the magnetic flux density was observed. Obtained experimental results confirmed theoretical description of the Villari magnetoelastic effect.

Test Stand for Investigating of Giant Magneto-Impedance

The paper presents a test stand that will be used in study of Giant Magneto-Impedance (GMI) effect. Measuring system is based on primary electric law and basic instruments used in electrical metrology. GMI phenomena occurs when a magnetic material is subjected to a DC axial magnetic field and a high frequency AC current. It results in large impedance changes (up to 300%) depending on the value of magnetic field. GMI effect sensors are widely used in weak magnetic field detection. Results of the first experiment that proves proper operation of the test stand are presented. Construction of a test bench is the first step to perform extensive study on this promising technology.

Active LR Integrator Circuit for Drift-Free Fluxmeter

The following paper presents the idea of the active integrator circuit based on inductive and resistance components. Such design allows to eliminate the time drift of the circuit, which is undesired phenomenon resulting from capacitive components utilized in classic constructions. This type of integrator circuit can be used to develop the drift-free fluxmeter for investigation of ferromagnetic hysteresis phenomenon in soft magnetic materials. The paper presents concept of the integrator circuit. The SPICE simulations was performed to validate the presented idea. Finally the developed solution was tested and obtained results confirm the correctness of the integrator circuits operation.

Synthesis of Optimal Robust Regulator for Food Processing Facilities

Food processing facilities operate under permanent perturbations. Their nature may be different: change of facility input load; external facility perturbations that change within wide limits; interference in communications lines; in-service evolution of internal facility parameters. These factors lead to a shift of optimum regulator settings and, consequently, deterioration in the quality of transients in regulation system. If perturbation uncertainty range is substantial, control system should imply modification of regulator setting, i.e. development of adaptive system. However, there is another approach, in which regulator settings are not changed. It is called a robust control system. Today there are various methods developed for determining a robust regulator, but they have significant drawbacks limiting and slowing their use in industrial environments, e.g. high-order regulator. The synthesis of matrix linear regulator for multivariable systems based on minimizing H∞-test has all the advantages of robust regulator and reduces interaction of contours. The paper studies and simulates an optimal robust control system for evaporation plant of sugar factory with a linear array regulator based on LMI-approach.

Graphene Joule Heating Measurements in Environmental Chamber

The paper presents results of Joule heating measurements in graphene samples performed in a specially designed environmental chamber. The experimental stand was designed and described in the paper, paying particular attention to the project of the environmental chamber. The graphene samples preparation process was also discussed. Results of the testing were presented and analyzed and the conclusions are formulated, which are also included in the paper.