Papers by Author: Roland Pawliczek

Abstract: The paper describes a control and measurement system for controlling and analysing operation of a stepper motor. The system design is based on the concept of virtual instrument, where data acquisition and transmission use standard solutions, whereas software serves both as a generator and a measurement system – an oscilloscope. The generator allows efficient control of motor operation in the following control modes: wave, full-step and half-step control. There were no winding powering sequence errors observed. The measurement system allows presenting and analysing voltage waveforms in individual windings with possibility to detect couplings and overvoltages. It was also shown that it is possible to detect locking of rotor rotation.The proposed virtual instruments have open structure, which enables extended analysis based on available measurements or expand range of measurements as long as measurement and control system instrumentation allows that.

Abstract: The paper presents comparison of the mathematical models for fatigue life calculations including influence of the mean load value. Several model based on stress analysis on the critical plane and energy density parameter were investigated. In this paper three types of materials were tested and subjected to bending, torsion and combination of bending with torsion loading with the participation of mean value of the load. It was found, that the best fatigue life estimations obtained by models taking into account changes of the material behavior under fatigue loading related to the specified numbers of cycles of the load.

Abstract: The paper presents application of the mechatronic concept for laboratory test to support a research activity. Laboratory test is taken into account as set of processes for which some number of environmental parameters must be controlled. This paper describes the laboratory stand for investigations of airflow phenomena, where modern data acquisition system is applied to control pressure, temperature and velocity of the air stream. To acquire and process a large number of data, the idea of virtual instruments is introduced to control system. Modern, high-level graphical language was used and the author’s program was developed. The presented solution of the laboratory stand allows increasing the accuracy of measurement, it is possible to observe all necessary parameters as rescaled to standard units and use this information in process steering. All technical solutions applied in the system assume flexibility for changes because of additional sensors, actuators and new signal processing and steering procedures.

Abstract: This paper presents the results of the fatigue tests of the specimens made from S3555 steel and aluminum alloy AlCu4MgSi subjected to bending block loading with mean load value. The influence of the changes of the mean load conditions was investigated. During the tests strains were registered and relation between the load and the strains was analyzed. In the case of S355 steel it was observed, that additional hardening occurs when higher value of the mean load is applied at the beginning of the block loading. Other case, when the mean load was increased from zero to maximum, a creep effect of the material was registered. For the specimens made from aluminum alloy similar processes were not observed. The strain levels are almost the same apart from changes of the mean load in load sequence and the fatigue life of the specimens is the same.

Abstract: The paper presents a definition of a new energy based parameter which allows to better describe fatigue proprieties of materials, especially cyclically unstable materials in comparison with the Lagoda-Macha parameter. The proposed parameter distinguishes positive and negative work of external force and depends on the sign of the stresses in paths of strain in materials. It is used in laboratory tests for control of a fatigue process on hydraulic stand. A close-loop control system has been equipped with computer program based on MATLAB/Simulink module.