Solid State Phenomena Vol. 240

Abstract: In the paper dynamic electromechanical coupling between the structural model of the rotating machine drive system and the circuit model of the asynchronous motor has been investigated. By means of the computer model of the rotating machine drive system the results of experimental testing have been confirmed. From the obtained results of computations and measurements it follows that the coupling between the considered rotating system and the installed rotary dampers with the magneto-rheological fluid (MRF) results in effective energy dissipation leading to significant reduction of undesired torsional vibrations.

Abstract: The paper presents a selected example of investigations, carried out by the author, on complex thin-walled structures [3] that were designed based on the method of statically admissible discontinuous stress fields (the SADSF method, [1,2,4,5]) with the condition of equalized effort in the limit state. The SADSF method is substantiated based on the conclusions that follow on the lower bound theorem of limit analysis, and is an approximate method. The aim of the investigations was practical verification of solutions of the SADSF method in elasto-plastic and elastic range of stress, because these ranges are not taken into account in the method. The existing application software of the SADSF method allows one to design very complex thin-walled structures which are free of cardinal errors. Moreover, the method can be easily used by practically any engineer.

Abstract: Thin-walled structures are widely used in building structures such as thin-walled vessels or storage tower, beam-columns of houses and halls, as components for cars, boats or airplanes and in sport industry. These types of structures are made not only as steel, but nowadays of composite materials.This paper deals with buckling and postbuckling behaviour and presents the experimental results for thin-walled composite columns with channel cross-section subjected to compression.

Abstract: In the time of the exploitation of building structures frequently situations do occur, in which due to failures they are exposed to much higher loads than has been originally predicted. In a state of emergency due to overloading of the structure, significant reserves of load capacity may be appear in the case of a self-acting tension member work. The aim of the paper was to demonstrate the influence of reinforced steel parameters and its quantity on the mechanism of destruction of four three-span models of reinforced concrete strips with the dimensions 7140×500×190 mm. The paper contains the description of the test stand and test models and the results of experimental tests which were compared with the results of the calculations based on traditional methods.

Abstract: The paper presents a proposed theoretical-strength destruction model of the corner of a slab-column structure at 1:2 scale. The theoretical destruction model was developed on the basis of laboratory tests of a reinforced concrete slab with the dimensions 4000×4000×100 mm. The assumptions of the proposed theoretical model were based on a traditional theory of behaviour of reinforced concrete constructions. The method for calculating the strength of reinforced concrete sections is based on interaction graphs of the load capacity N_Rd, M_Rd,x and M_Rd,y. The calculation method takes into account the influence of changes in the shape of the cross-section of the analysed element on its limit load capacity in every load step.

Abstract: The paper reports experimental results from tests carried out at room temperature on servo-hydraulic system dedicated for examination of the exploitation properties of rocker arms. The ball joint of this element was modified by an application of composite coating such as the tungsten carbide (WC). To apply cyclic loading to rocker arms the griping system was designed and elaborated. Results from tests performed on the composite coated ball joints were compared with data obtained for typical elements. Variations of the following parameters versus time i.e. force, temperature and surface topography of balls were analysed with respect to exploitation properties of the modified ball joints. An increase of the wear coefficient was achieved for sliding joints of the steel ball-steel cups coated by the WC.

Abstract: Magnetorheological elastomers (MREs) belong to the group of so-called smart materials, which respond to an external stimulus by changing their viscoelastic properties.The vibration head will be modified with the MRE regulation system. The elastomer pillows will be enhanced with MRE and the regulation system (coils).The main idea of the modification is to increase an effectiveness of the vibrator work by the regulation that will stable the vibrations in the resonance frequency. It will be caused by the changeable stiffness of MRE elements under magnetic field.The aim of presented study is to research the influence of MREs cured under the magnetic fields on the strength properties of the elastomer pillow.

Abstract: The aim of this article is to present the results of experimental studies on protection systems of military vehicles against RPG type missiles. The paper presents the research methodology of rod armours and active protection system. On the basis of the presented methodology, both a rod armour and an active protection system were investigated. The effectiveness of these solutions reaches 70% in the rod armour and about 80% in the case of the active protection system.

Abstract: Most incidents, serious incidents, accidents and disasters (catastrophes) connected with the irregular work of technical devices is caused by mechanical damage. Despite this, responses originating from the fields of psychology, sociology and medicine prevail in practical approaches to preventing accidents. In the author’s opinion this is the result of the low level technological knowledge amongst those involved in safety engineering. Technical education in the area of the mechanics is indispensable. A key part of this education, not just for engineers but also lawyers and others who work in safety regulation services, is explanatory experiments. In this article, the particular significance of scientific experiments in decreasing all factors posing a threat is shown. This article does not report concretely performed research, but rather attempts to propose a program of cooperation between different areas of the engineer’s art.

Abstract: Ring-shaped specimen is commonly used in tests for determination of mechanical properties for arteries in hoop direction, especially for small mammals such as rats or mice. Although ring test is a lot more convenient than the tests concerning strip specimens, interpretation of the experimental data might be inconclusive – it is difficult distinguish whether it's still straightening up or the actual tension begins. The basic problem is to properly define initial length of specimen, which is essential for strain calculation. The purpose of this study was to evaluate various methods for strain evaluation. Ten Wistar Albino Glaxo male rats (3 months old, body weight about 200g) were sacrificed by decapitation and arteries were immediately removed. Three specimens, each approximately 2–3mm long, from each rat were excised adjacent to the aortic arch. Couple different initial lengths, as well as Digital Image Correlation based extensometer results were used for strain-stress response calculations. In addition a 3D Finite Element model, with an Ogden constitutive model based material, was made for deeper investigation of specimen behavior. This study has shown that the testing procedure for determination of mechanical properties of arteries, based on ring-shaped specimen, is prone to errors. Stiffness calculations are very sensitive to the choice of initial length of the specimen. As the use of DIC proved to give very good correlation with experimental data this method will be used in further studies.