Applied Mechanics and Materials Vol. 816

Abstract: This paper presents the results of the investigation of the causes of the occurrence and the influence of the dynamic effects in the couplers of the remotely controlled electric shunting locomotives and a set of fully loaded rail cars. These are typical rail-road sets, working at the logistic area of the central ore trans-shipment of large steelworks with heavy rail traffic. The stated effects lead to excessive deterioration of the supporting structure of the locomotives, axle gripping, drive mechanisms and braking systems. To achieve the desired goal, the methods and means of numerical and experimental modelling have been used. Based on the performed numerical and experimental analyses were then specified the recommended design and operational measures to prevent the failures mentioned above.

Abstract: The Francis turbine in water power plant station is positioned at top and bottom axial hanging bearings. During reparation work the turbine was disassembled and during assembling the adjusting segments in the hanging bearings were released. In the paper are described procedures that are necessary in order to provide correct distribution of axial forces in twelve segments of upper axial hanging bearing by strain-gages applied on elastic pipes positioned under individual bearing segments.

Abstract: Nowadays, the most spread method for the solution of contact problems is based on numerical modelling. The bolted joints belong to the complex contact problems. In the paper is given methodology for the stress analysis of bolted joints with modification in the area of the first threads on the nut by the optical method. The stress analysis has been accomplished for the bolted joint without as well as with modification. The results of experimental measurements were verified by numerical modelling by the finite element method.

Abstract: This paper is focused on usability of multiestimation scheme approach in the area of identification and control of nonlinear systems. A multiestimation scheme is introduced and subsequently used for the adaptive control of real-time nonlinear system. The multiestimation scheme integrates on-line identification of suitable models of a controlled system and a controller synthesis on base of the identified model. The real-time testing has been carried out by the control of nonlinear laboratory model of interconnected tanks (DTS200 by Amira company).

Abstract: Test results of axial shift of “technical ceramics - glass” parts in taper interference fit joint under axial loading are presented. The load-carrying capacity was tested under normal conditions; a servo press was used to load the test samples. The tested samples were assembled by thermal method.

Abstract: This paper reports on the application of experimental optical methods to study vibration of the centrally clamped disc. The natural frequencies and mode shapes with zero rotational speed are analyzed. Influence of rotational velocity to shifting natural frequencies was investigated with optical derotator. To evaluate shifting of natural frequencies run up analysis were measured. In run-up analysis the frequencies of centrally clamped disc considering increased rotational speed are obtained. Obtained waterfall plots show vibration behavior of spinning disc.

Abstract: This paper deals with the use of classical experimental technique of photoelasticity as well as modern one – digital image correlation by stress analysis. Both mentioned methods were used to compare the corresponding stress fields obtained on a sample with stress concentrators loaded by bending. The paper contains the basic principle of photoelasticity, methodology of static analysis with polariscope and briefly describes the measurement with low-speed digital image correlation system. Taking into account that the used correlation system does not allow to evaluated stress fields, calculation and visualization of stress fields were realized in program Q-STRESS v.1.0 developed at the authors department.

Abstract: The improvement of the main monitored technical parameters of the production devices is connected with the optimization of the individual structural components and construction nodes of these devices. Mainly those critical structural nodes of the devices that have a significant impact on the quality of the products manufactured by this device and its service life are studied. This paper briefly presents the results of experimental and numerical analysis of stresses and strains of selected structural components of the injection device, such as the connecting and guiding columns and the adjustable push plate. The relevant analyses of stresses and strains have been connected with the performance of a series of experimental and computer simulations. The results of these simulations then became an important basis for further optimization of selected structural parts of the injection device.

Abstract: This paper presents the results of static compression tests of concentrated crystallized carbon dioxide. The test results obtained under this research describe the relationship between the compressive stress and strain allowing to estimate the proportionality ratio, limit stress and critical stress values. Special test methods were used due to low temperature of crystallized carbon dioxide (minus 78.5°C) and its sublimation under standard testing conditions. The results of the mechanical properties of agglomerated CO₂ were compared with the mechanical properties of other known materials. This allowed us to derive assumptions, which can become the starting point of the process to build a mathematical model describing the dry ice compaction and granulation processes.

Abstract: The paper presents the results of experiments and measurements of the stress of a pipeline located on a pipe bridge. The experiment was carried out by means of resistance strain gages for two modes, which were the stress changes upon pressure changes in the pipes and at the driving in of sheet pilings in the immediate vicinity of the pipeline. On the basis of measurements, the impact of these changes on the operational safety of the pipeline in the renovation process of old above ground and the realization of new underground pipeline solutions. Polynomial regression models were applied for the prediction and a statistical analysis of residuals was applied for the quality assessment of selected models.