Papers by Keyword: Dynamics

Abstract: For a regulation of moulding cooling time course in a mould it is necessary to derive an equation of the mould temperature dependence on the moulding temperature as the equation of the regulation system. Amplitude, phase and transition characteristic are for R=1 and P=1 identical as for the action quantity. Amplitude, phase and transition characteristic of the action quantity and the control of the regulation circuit at use of the proportional regulator show that the circuit is stable a periodic. From the amplitude, phase and transition characteristic of the regulation circuit defect it is seen that the defect in the regulation circuit is relatively fast lowered. From the mentioned conclusions it is seen that the moulding cooling in the mould at injection of plastics with the proportional regulator introduces the regulation with relatively favourable regulation properties.

Abstract: The knowledge of classical mechanics gives deeper insight into the Herbert hardness tester applicability for material testing. Elastic materials with low friction presence between contact surfaces are supposed to be investigated in this study. Firstly the dynamics approach is used to obtain simplified solution of swing angle. Then a new solution of the problem is gained by means of an energy approach. Slight decrease of the swing angle is predicted by the new solution as also shown in experiments. After comparison of both solutions a new formulae useful for evaluation of rolling resistance coefficient is applied for measurements performed on some metallic materials and artificial sapphire. Rolling resistance coefficients obtained by the way are always less than maximal estimated value.

Abstract: The dynamic simulation of a reactive distillation process developed with the aid of CHEMCAD for the production of n-butyl acetate has been carried out in this research work. Originally, the by-product of the process was water. The developed model of the system was first simulated for steady state using a reflux ratio of 3 and a reboiler duty of 1.4 kW in order to have initial values for the mole fractions of the components involved. The model was converted to a dynamic type by activating the “Dynamics” in the “Convergence” tab of the “Run” menu of CHEMCAD. The dynamic model of the system was run using different (positive and negative) step changes applied to the input variables, which were reflux ratio and reboiler duty, of the process. The results obtained from the steady-state simulation showed that only n-butyl acetate and unconverted acetic acid were existing in the reboiler section of the column initially. The dynamic simulation of the process showed that the system was a stable one because it could get settled after some running time of its dynamic model for all the step changes in the two input variables considered. It was also discovered from the simulations carried out that the dynamic responses of the system to negative step changes in reflux ratio were smoother than those obtained when positive step changes were applied to the same input variable. Moreover, the applications of negative step changes to the reboiler duty resulted in decreases in the mole fractions of n-butyl acetate present in the bottom section of the column while the applications of positive changes to the same reboiler duty gave rise to increases in the mole fraction values of the desired product that was collected through the reboiler section of the column. It was discovered from the results obtained that the higher the reboiler duty of the system that was applied in the production of n-butyl acetate from the esterification reaction involving acetic acid and n-butanol, the faster the system was approaching its dynamic steady state.

Abstract: With the rail vehicle industry development and increasing request to the riding comfort, to reduce the structure vibration and noise caused by the gearbox is increasingly valued. Multibody dynamics method is proved to be very effective to structure optimization for noise control in gearbox design process. This paper aims to find an optimization way for the gearbox structure to increase the structure noise performance. Initially gear shafts and the casing were discretized using the finite element method, subsequently the multi-flexible body of low floor gearbox was established in the SIMPACK which considering the time-varying mesh stiffness and backlash, bearings were modelled via radial, axial and rotational stiffness elements, then the multi-flexible body dynamic response were analyzed and the structure noise was predicted. Finally, optimization schemes, in terms of gear modification and structure improvement, were proposed to improve the structure noise performance.

Abstract: Bio-templates such as proteins, lipids offer rich structural and functional diversity for the synthesis of nanoparticles by controlling their shape, size and orientation. In this work we have exploited a pH dependent folding-refolding feature of Horse Spleen Apoferritin (HsAFr) to synthesize copper and manganese oxide nanoparticles in a controlled manner. Two methods of preparation were used in this study. In the first method, Copper Sulphate (100 mM) and Manganese Chloride (4.8 mM) have been incubated with the protein and the pH dynamically adjusted for homogeneous incorporation of the metal ions into the HsAFr shell. The second study involved the incorporation of Cu²⁺ and Mn²⁺ inside HsAFr cavity and subsequent designing of nanoclusters of the respective oxides. UV, fluorescence and far-UV circular dichroism (far-UV CD) spectroscopic techniques have been used to study the mineralization effect of the metal inside the HsAFr cavity. Size determination carried out using XRD suggested an average size ranging from 20-30 nm. The EPR of the nanoclusters show that incorporation of Mn²⁺ leads to a characteristic magnetoferritin behavior.

Abstract: The generalised finite difference method (GFDM) is a mesh-free method for solving partial differential equations (PDEs) in non-structured grids. Due to its strong theoretical background and simplicity, hence efficiency, it has been introduced to handle interesting and sophisticate engineering problems. However, the GFDM has not been applied to problems associated to dynamics of porous media yet. In these problems, the strong coupling between solid displacements and liquid pressures may cause large numerical oscillations if equal order interpolation functions are used for both variables. Nevertheless, some fractional steps techniques can be introduced in order to minimise these problems. In this contribution, a fractional steps scheme is developed and applied to the GFDM in order to model fully saturated porous media dynamics. Simulations of 1D and 2D wave propagation are performed in order to reveal the advantages, drawbacks and capabilities of the proposed method.

Abstract: In this paper, the dynamics of multiple-drive belt conveyors during starting is discussed. The aim of the research is to determine whether the belt sections in a multiple-drive belt conveyor can be viewed as a single-drive belt conveyor, and whether the DIN 22101 standard for the starting of a single-drive belt conveyor can still be used for the starting of a multiple-drive belt conveyor. A finite element model of a belt conveyor system was built in Matlab, consisting of a model of the belt and its support structure, and a model of the drive system. In this work, the simulations were carried out for the starting procedures of empty belt conveyors with varying number of drives. For each simulation case, the linear start-up procedure was tested. The simulations focused on the study of the axial elastic response of the belt. The simulations revealed that, by using more drives, the maximum belt stress during non-stationary as well as stationary conditions decreased. However, when using reduced starting times, negative stresses occur in the system. Overall, it was observed that the behaviour of each section between two drive stations in the multiple-drive belt conveyor differed from those of the single-drive belt conveyor. Therefore, the DIN 22101 guidelines for the start-up of a single-drive belt conveyor cannot be applied directly for the start-up of a multiple-drive belt conveyor.

Abstract: Having a realistic estimate of structural parameters, such as natural frequency and damping is important for design purposes. In this study, available wind and earthquake induced acceleration data from four multi-story reinforced concrete buildings are utilized to examine structural behaviour and system parameters. The buildings measurement systems are described and the recorded structural response data presented. The data stems from two different sources of excitation, i.e. wind and earthquake, and are recorded for various excitation levels and environmental conditions. System identification analyses of the buildings are carried out applying previously verified parametric methods to the recorded data. The natural frequencies and critical damping ratios established from the recordings are compared to values estimated using design guidelines and international data compilations for reinforced concrete structures of similar type. Considerable variability is discovered between the different estimation formulas and the observed natural frequencies of the buildings are found to lie at the upper limit of the prediction formula.

Abstract: This paper deals with the dynamics of face packing seals, in which one of the sealing rings is made of elastic sealant. The study involved analyzing the axial vibration of the flexible ring for two configurations of its housing in the seal and determining the frequency characteristics and the condition of maintaining face-to-face contact between the sealing rings with considerably different elastic properties subjected to two types of external excitations. The derived analytical relationships were verified using a calculation example for real operating conditions of face packing seals in two pumps.

Abstract: The paper presents a method of the kinematic excitation courses’ identification in excitation points, based on the car road test acceleration at different measurement points. For the purpose of the laboratory fatigue life investigation of contemporary complex structures (e.g. cars bodies) and components of these structures (i.e. cars roofs), only a few first vibration modes are usually taken into account. During real life tests (i.e. road tests), accelerations at the selected points and along the defined directions are recorded and preprocessed appropriately. Subsequently, appropriate information about the measured acceleration allows us to identify such kinematic excitation function on the laboratory stand, whose result is the same as during the real road test. Thanks to the proposed approach, further time-consuming fatigue experiments can be performed on the laboratory stand.