Journal of Engineering and Thermal Sciences
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Vibration measurements for copper ore milling and classification process optimization
Get PDFThe paper presents a new approach to optimize the comminution process by using accelerometer measurements of the mill shell. An installation performed in the KGHM Polska Miedź Division – Ore concentration Plant Lubin – one of the largest producers of copper and silver in the world – has been used. It is shown that the measurements are correlated with the lithological structure of the ore, and they can be used in a control system to improve effectiveness of the milling and classification processes
On an inline conveyor resonantly driven by piezoelectric actuators
Get PDFThis paper aims to propose a novel inline conveyor driven resonantly by piezoelectric actuators, such that its advancing distance can be maximized, and the energy consumption can be reduced. First, the proposed conveyor is presented, and its operating principle is addressed. Then, the optimal dimensional synthesis of the conveyor is conducted. Furthermore, the approaches for resonance analysis and modal analysis by using ANSYS software are presented. In addition, a design example is given for illustration, and a motion simulation with resonance input is conducted by using ADAMS software. Finally, experiments are carried out to verify the effectiveness of the proposed design. The result shows that the advancing distance of the conveyor operating at the resonance frequency can be significantly increased. Therefore the required energy could be reduced
A novel approach to Hurst analysis of motor vibration data in aging processes
Get PDFDetermining age in motors and rotating machinery in general is a serious question. Using the vibration signals collected during motor aging is challenging due to nonlinear and non-stationary nature of these signals. This paper presents a study on applicability of Hurst analysis in motor vibration data collected in an artificial aging process, which at first seems to suggest inapplicability of Hurst Exponents in motor age determinations. Conclusions drawn from the straightforward application of Hurst exponent calculation are used to propose a novel method for Hurst analysis of such signals, named Higuchi-Hurst-Hilbert Vibration Decomposition (H³VD), using Higuchi’s algorithm for Hurst exponent calculation and Feldman’s Hilbert Vibration Decomposition overcoming the shortcomings of the original approach and delivering results that were expected based on previous research on frequency domain features of motor vibration in artificial aging processes. Features of this approach have been presented on both Fractional Gaussian noise model and the real vibration data. Non-accelerated bearing aging vibration data was used to demonstrate practical applicability of this new method
Calculations of electrical fixing device for vibrotesting of electronic components
Get PDFThe description of the device with the electrical sensitive glue to fix components of electronic devices (capacitors, resistors, chips) at their trials on harmonic and shock loads with the aid of shaker table is presented. Based on the polarization forces of interaction of the filler particles in the structure of the electrical glue we have performed a simulation and calculation of the limiting values of fixing forces of the component with the electrode of the mounting devices. Parameters of the electric field corresponding to the utmost full transmission of vibrations to the component are determined
Simulation and stability of multi-port DC-DC converter
Get PDFIn this paper, the simulation and stability of multi-port DC-DC converter will be presented. Traditional DC-DC converter topologies interface two power terminals: a source and a load. The construction of diverse and flexible power management and distribution systems with such topologies is governed by a tight compromise between converter count, efficiency, and control complexity. The DC-DC converter may be considered as an advanced environment-friendly electronic conversion system, since it is a greenhouse emission eliminator. By utilizing the advancement of these renewable energy sources, we minimize the use of fossil fuel and thus contribute to a cleaner and pollution-free environment. Finally, comparison between the averaged model and the actual switching converter model is been studied
Vertical vibration reduction and audible sound analysis in surface grinding with electroplated tools
Get PDFOne of the first approaches to the development of a grinding process monitoring system based on audible sound sensors is presented in the paper. Electroplated diamond tools (abrasive D64 and D107) were used in a modified single-disc lapping machine configuration for flat grinding of ceramics (Al2O3). The main aim of the machine modification was to reduce the vertical vibration in order to decrease the tool wear and to increase the material removal rate. The sound generated by the material processing was analysed in the aspect of actual abrasive ability of the grinding tools. The abrasive properties of the tool are decreasing during machining due to the wear of diamond grains. The results from experiments, such as the material removal rates and waveforms of recorded sound are presented and discussed in the paper
Analysis of camera orientation variation in airborne photogrammetry: images under tilt (roll-pitch-yaw) angles
Get PDFTaking images for airborne photogrammetry, tilt angles (drifts) variations of camera are resulting to objects positions on the images therefore influence to correctness and accuracy of produced geodata. Several experiments have been done for investigation of camera’s roll-pitch-yaw angles determination regarding to technical flying means orientation in the space. Using aerial triangulation technique, exterior orientation parameters of each image from entire flight strip – projection center coordinates and image tilt angles with estimated accuracy are presented. Results show coincidences or discrepancies to requirements specified in aerial photography regulations. In order to investigate deflections of camera’s tilts, stereo pair of images has been processed using airborne photogrammetric approach and different software. Two digital photogrammetric software (DDPS and LISA PHOTO) used in experimental image orientation operates on particular algorithms. Determined values of exterior orientation parameters differ not significantly. Exterior orientation of images gained by Unmanned Aerial Vehicle (UAV) with mounted CCD camera has been done. As shows analysis, images from UAV Photogrammetry are under marketable tilts. Using a certain number of Ground Control Points (GCP) measured by GPS, exterior orientation was not possible; the results not meet the accuracy requirements
Nonlinear vibration modeling and bifurcation characteristic study of a planetary gear train processing device
Get PDFIn this paper, a nonlinear torsional vibration model with meshing errors, time varying meshing stiffness, damping coefficients and gear backlashes was established and dimensionless equations of the system are derived in the planetary gear train processing device. The paper analyzed the nonlinear dynamic behavior of the device which was used to machine the Circular-Arc-Tooth-Trace cylindrical gear. By using the method of numerical integration, the bifurcation diagrams are obtained and the results indicate that the processing device has abundant bifurcation characteristics with the change of the dimensionless speed, and the damping ratios, gear backlashes and meshing errors of meshing pairs could influence the vibration greatly. The bifurcation diagrams reveal that increasing the damping ratios can change the bifurcation and the chaos can be avoid when the damping ratios are bigger enough, reducing the gear backlashes can reduce the dimensionless displacement amplitudes, increasing the meshing errors can make the bifurcation diagrams shift left for a distance, and alternating load torque with large amplitude will cause complex chaos phenomenon. The study can help to avoid the fatigue failure and instabilities caused by chaos and it also contribute to improving the performance of the processing device
An analysis of shock isolation characteristics of a head of a woodpecker and its application to a bionic helmet
Get PDFThe effect of a woodpecker’s head structure on shock isolation was investigated from a dynamic point of view. A simplified multi-degree-of-freedom model was set up to study shock isolation characteristics of a woodpecker’s head. The shock-isolation performance of this model was calculated and analyzed by changing the dynamic parameters. And it was evaluated by two indexes: the absolute acceleration of the skull bone and the relative displacement between the skull bone and the beak. A bionic helmet model subjoining the elastic damping layer and the cushion pad was presented. Calculating the three-dimensional shock response surfaces validated it
Experimental study of the effect of drilling pipe on vortex-induced vibration of drilling risers
Get PDFA vortex-induced vibration experiment considers drilling conditions has not been conducted. A new experimental facility was designed to investigate effect of drilling pipe on vortex-induced vibration. Results show that vortex-induced vibration can be inhibited with the increasing drilling pipe tension. Strain amplitude decrease with the increase in drilling pipe tension and strain amplitude decreases significantly with increasing pipe tension at high current speed. Drilling pipe tension does not affect the dominant vibration frequency. Interaction between the IL and CF vibration and the multi-modal phenomenon are more apparent for the periodically contacting and colliding between the drilling pipe and risers