Solid State Phenomena Vol. 208

Abstract: The paper presents the methodology and the results of determination of emissivity coefficient for nickel alloy Inconel 718 in the temperature range predicted for thermomechanical processing of these alloys and its application for correction of temperature during cooling and modeling. The idea presented in the paper is an iterative use of automatic system of temperature measurement and control, facilitated with thermocouples and pyrometer gauge to provide temperature dependent characteristics of the alloy. In addition to estimation of temperature dependence of the emissivity coefficient, the results of cooling tests for simple and complex geometry of nickel alloy forgings are contained, obtained with modeling based on assumption of the determined characteristics. To verify obtained characteristic, they were used in modeling of cooling and compared to those obtained in measurements based on assumption of constant value of emissivity coefficient. Measurement errors obtained were used to indicate show the significance of application of functional dependence in comparison with constant value, as well as, magnitude of error made during temperature measurement or modeling, when neglecting the temperature dependence.

Abstract: The paper considers the task of using computational fluid dynamics in order to upgrade a hydraulic directional valve, which works in mining powered roof support. The modernization is focused on changing the design parameters of the valve so as to reduce pressure drop and thus increase its capacity. In addition emphasis was placed on verifying the simulation results in transient states with the results obtained on the research station.

Abstract: In the paper localised disturbances propagating along the cables are modelled by wave packets. The motion of the cable was described in relation to its equilibrium state. The linear equations were used. Typically disturbances associated with sudden gust of wind are modelled by kinematic generator exciting oscillations in the specified frequency range, concentrated around the central frequency. The packet of binormal waves and coupled packets of normal and tangent waves were considered. The description of the evolution of the wave packets during their motion was presented analytically and numerically in the form of plots.

Abstract: A paper presents analysis of dynamic similarity between full-scale wind turbines tower-nacelle system and its laboratory model. As a reference real-world structure, Vensys 82 wind turbine was assumed. Complete and partial similarity criteria were both introduced. Considering laboratory model to be equipped with tuned mass damper horizontally arranged at the top, partial similarity of one pair of points (tower tips) motions will be satisfactory. On the basis of similarity conditions, laboratory model parameters were determined so that data acquired for the model may be referred to real-world structure.

Abstract: The paper addresses the consecutive development stages of laboratory model of wind turbines tower-nacelle system with horizontally aligned tuned vibration absorber at its top. To cope with system uncertainties and possibly multiple modes of vibration, tuned vibration absorber is equipped with MR damper instead of passive viscous one. Several laboratory model constraints have to be fulfilled. Discrete frequency-based and Comsol-Simulink analyses were conducted to determine and verify model parameters. Finally, sketch of laboratory test rig design was presented.

Abstract: nvestigations of filling the model mould cavity (with perpendicular walls) of the casting die by model liquids of various density and viscosity are presented in the paper. Influence of localisation of the inlet system and inlet velocity on the flow character of model liquids of different viscosity in the system of a cold-chamber casting die was tested. Calculations performed by means of the calculation module NOVACAST (NOVAFLOW&SOLID) for the selected models of cavities cast by the pressure method are also presented in the paper.

Abstract: The study covers the modeling three-layered beam incorporating a magnetorheological (MR) fluid. The beam finite element model was created using the ANSYS software. The beam comprises two outer layers made of aluminium and MR fluid layer in between, sealed with silicone rubber. Interactions of the magnetic field are taken into account by varying the parameters of the finite elements. Data required for identification were collected from results of measurement of the beams free vibrations. The identification procedure assumes the good agreement between the frequencies of the beams free vibrations and dimensionless damping coefficients obtained from research and computation data. The validity of proposed beams finite element model was also investigated. Finally some numerical results were presented.

Abstract: This paper concerns the idea of using magneto-mechanical effects in prophylactic activities to reduce the risk of occurrence of an extensive blackout on high voltage (HV) lines. The subject matter of the paper is related to the event from April 8, 2008, which deprived approximately 600,000 recipients from 18 cities of the West Pomeranian voivodeship of power and caused millions in losses for the national economy. In theoretical considerations, the idea of diagnosing the technical state and level of effort of steel power line towers using the metal magnetic memory method (MMM) is presented, with a consideration of the methodology for obtaining a reference signal from the external magnetic field. The capabilities of the MMM method have been illustrated by examples of active and passive experiments. Finally, the authors indicated the need of IT support of MMM data analysis using a 3D model of the predicted distribution of the magnetic field in the vicinity of the tested object.

Abstract: This document deals with the results of laboratory tests of an experimental electromechanical transducer for supplying an magnetorheological (MR) damper. The aim of the tests was to determine: the electromotive force induced in the sectionalized coil, the voltage and the current strength in the control coil of the damper as well as instantaneous power. The results provided are based on the tests of the transducer under periodic kinematic excitations and are compared with those achieved in numerical calculations.