scholarly journals Experimental studies of heat dissipation by a stream of dressing products during dry dressing of conventional ceramic grinding wheels

2018 ◽  
Vol 35 ◽  
pp. 735-745
Author(s):  
Ryszard Dębkowski
Keyword(s):  
Heat Dissipation ◽  
Experimental Studies ◽  
Grinding Wheels ◽  
Ceramic Grinding

Experimental and Numerical Modal Analysis of Composite Laminated Shells

2019 ◽  
Vol 161 (A1) ◽  
Keyword(s):  
Heat Dissipation ◽  
Mass Matrix ◽  
Experimental Studies ◽  
Free Vibration Analysis ◽  
Mode Shapes ◽  
Radius Of Curvature ◽  
Lumped Mass ◽  
Auxiliary Equipment ◽  
Mass Model ◽  
Laminated Shells

The presence of cut outs at different positions of laminated shell component in marine and aeronautical structures facilitate heat dissipation, undertaking maintenance, fitting auxiliary equipment, access ports for mechanical and electrical systems, damage inspection and also influences the dynamic behaviour of the structures. The aim of the present study is to establish a comprehensive perspective of dynamic behavior of laminated deep shells (length to radius of curvature ratio less than one) with cut-out by experiments and numerical simulation. The glass epoxy laminated composite shell has been prepared in the laboratory by resin infusion. The experimental free vibration analysis is carried out on laminated shells with and without cut-out. The mass matrix is developed by considering rotary inertia in a lumped mass model in the numerical modeling. The results obtained from numerical and experimental studies are compared for verification and the consistency between mode shapes is established by applying modal assurance criteria.

scholarly journals Numerical and experimental studies on a novel magneto-rheological fluid brake based on fluid–solid coupling

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041987900 ◽  
Author(s):  
Shujun Li ◽  
Wenjun Meng ◽  
Yao Wang
Keyword(s):  
Heat Dissipation ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Test System ◽  
Structure Design ◽  
Brake Disc ◽  
Braking Torque ◽  
Braking Process ◽  
Magneto Rheological ◽  
The Impact

The previous work of the authors indicated that the fluid–solid coupling effect of the magneto-rheological fluid and the brake disc is a necessary focus during braking process. In this study, a novel design of magneto-rheological fluid brake was proposed and studied theoretically and numerically, aiming to solve the prominent problem of heat dissipation, especially in the case of single emergency braking. First, based on the modified Bingham model, a parameter defined as the apparent equivalent viscosity was utilized to represent the relationship of magnetic field, flow field, and temperature field. The braking torque and the formula for calculating the impact factor of fluid–solid coupling employed for characterizing the associations among the thermal field and the stress field were established based on fluid–solid coupling. With a detailed explanation of simulation method, the distribution disciplinarian’s numerical simulation of each field was analyzed using COMSOL software. To validate the accuracy of the established model on the designed magneto-rheological fluid brake, the prototype was also manufactured, and results achieved experimentally which were measured on inertia test system of brake, for braking torque, motion parameters, and surface temperature in braking process, were compared with simulations. Simulation results manifested that the designed magneto-rheological fluid brake’s magnetic circuit structure is feasible based on magnetic induction intensity distribution. Finally, it has been shown that the simulations appear to be basically consistent with the experimental results, and the heat dissipation of the designed magneto-rheological fluid brake is partially improved. These results might contribute to the structure design, optimization, and improvement of magneto-rheological fluid products, extending the previous work on fluid–solid coupling analyses.

A Novel Magnetorheological Concentric Spiral-Flow Damper

2015 ◽  
Author(s):  
Kai Hsiang Chang ◽  
Jing Long Tong ◽  
Chou Min Chia ◽  
Kuang Yuh Huang
Keyword(s):  
Heat Dissipation ◽  
Experimental Studies ◽  
Low Frequency ◽  
Mr Damper ◽  
Flow Channel ◽  
Spiral Flow ◽  
Damping Force ◽  
Fixed Space ◽  
Novel Design ◽  
High Range

In this article, a novel design of MR damper, concentric spiral flow MR damper, is proposed. It could improve the heat dissipation problem which is usually found in traditional MR damper. The proposed MR damper has a concentric spiral flow channel around the cylinder which not only separates coils from MR fluid, but also increases the length of flow channel in a fixed space. Experimental studies has been conducted to demonstrate the performance of the proposed MR damper, the result shows the MR damper generates the maximum damping force of 188 N without applying magnetic field and 1251 N when inputting 1.5 A at low frequency, which means the damper has high range of adjustable damping force. The CSF-damper can be used to systems or structures with low dynamic response.

Investigation on Properties of Magnesia Grinding Wheels Used in Silicon Wafer Grinding

2014 ◽  
Vol 1017 ◽  
pp. 273-278
Author(s):  
Bing Jun Hao ◽  
Zhi Gang Dong ◽  
Shang Gao ◽  
Ren Ke Kang ◽  
Dong Ming Guo
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Integrated Assessment ◽  
Experimental Studies ◽  
Molar Ratio ◽  
Rockwell Hardness ◽  
Grinding Wheels ◽  
Curing Conditions ◽  
Molar Ratios ◽  
Scanning Electron

This paper presents the results of an experimental investigation on molar ratios of MgO/ MgCl2 affecting the hardness of magnesia grinding wheels, which is one of the most important properties. Magnesite grinding blocks of different ratios of MgO/MgCl2 were prepared. The surface Rockwell hardness of which was tested under the same curing conditions. By an integrated assessment of the experimental studies of hardness and component, it is recognized that the molar ratios of MgO/MgCl2 can significantly affect the properties of magnesia grinding wheels. With the increase of MgO/MgCl2 molar ratio, hardness of the specimens increases. Scanning electron microscopy (SEM) studies on grinding blocks of different ratios indicated that micro needle shaped crystal structure of phase 5 are mainly responsible for hardness development. Finally the optimal recipe was selected in consideration of the characteristics of the silicon mechanical chemical grinding (MCG), which was verified to be effective by the following grinding experiment.

scholarly journals THERMOELECTRIC SEMICONDUCTOR DEVICES FOR THERMAL STABILISATION OF REA POWERFUL TRANSISTORS

2020 ◽  
Vol 47 (1) ◽  
pp. 30-38
Author(s):  
T. A. Ismailov ◽  
A. R. Shakhmaeva ◽  
A. M. Ibragimova
Keyword(s):  
Heat Dissipation ◽  
High Efficiency ◽  
Solid Phase ◽  
Electronic Devices ◽  
Experimental Studies ◽  
Thermoelectric Module ◽  
Optimal Designs ◽  
Excess Heat ◽  
Power Transistors ◽  
Low Energy Consumption

Abstract. Aim. The aim of the study is to analyse the problem of heat dissipation in high-power transistors and develop devices for their thermal stabilisation when used in electronic equipment. Method. A method is proposed for testing power transistors using a device to to ensure thermal stabilisation in the stating volume by means of a two-position temperature controller along with a model for the use of these components in electronic devices. The proposed devices support high thermal stabilisation accuracy of power transistors in a radioelectronic device system allowing temperature to be maintained at a given level with high accuracy by means of a thermoelectric battery. Results. Device designs were developed for increasing the accuracy of thermal stabilisation of power transistors with high efficiency, low energy consumption and small size. Conclusion. Based on the results of experimental studies, optimal designs for devices for the thermostabilisation of radioelectronic device components that dissipate significant power during their operation are presented. The devices can be used to increase the accuracy of thermal stabilisation of the radioelectronic device element by means of a working substance whose melting point coincides with its thermal stabilisation temperature. The developed devices have the following functions: the thermoelectric battery sections of the thermoelectric battery will be sequentially disconnected depending on the electrical signals from the temperature sensors to which the solid phase of the working substance has moved. The battery of the thermoelectric module (TEM) removes excess heat from the heat-stabilising substance while maintaining the required temperature of the radioelectronic device element. Excess heat from the heat-generating junctions of the TEM battery is removed by the heat exchanger. During melting of the working substance, the temperature of the thin-walled metal container – and, accordingly, the temperature of the CEA element – can be maintained at a constant value equal to the melting temperature of the working substance. 

scholarly journals POLYMINERAL COMPOSITE BINDERS FOR FOAM CONCRETE: FEATURES OF HYDRATION AND HARDENING

2020 ◽  
Vol 17 (1) ◽  
pp. 122-135
Author(s):  
V. V. Voronov ◽  
E. S. Glagolev
Keyword(s):  
Electron Microscopy ◽  
Portland Cement ◽  
Building Materials ◽  
Heat Dissipation ◽  
Experimental Studies ◽  
Foam Concrete ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Mineral Additives ◽  
Scanning Electron

Introduction. The paper devotes to the features of hydration and hardening of polymineral composite binders. The authors carry out the complex research of the phase composition, hydration and structure formation processes of hardened composite binders with active mineral additives by X-ray phase analysis, differential scanning calorimetry and electron microscopy. The study using a Tescan MIRA 3 scanning electron microscope reveals differences in the microstructure of hardened binders and the authors confirm the results by microprobe studies. The authors study the hydration of the composite binder prepared on the basis of Portland cement and mineral components. Moreover, the paper demonstrates the dynamics of the system’s heat dissipation from the moment of mixing with water and hardening up to 24 hours and up to 72 hours by the expressed bond of dQ / dt = f (t) using a differential calorimeter.Methods and materials. The authors carried out experimental studies at Belgorod State Technological University named after V.G. Shukhov, at the Department of Building Materials, Products and Structures, at the High Technology Center and “BelGTASM-Certificate” Test Center. Therefore, the authors used the existing basic research methods, including modern physicochemical methods of analysis: X-ray phase, scanning electron microscopy, etc. The paper determined the main characteristics of raw materials, composite binders and foam concrete using standard methods and regulatory requirements.Results. The authors obtained the results that testified the peculiarities of hydration and hardening processes of polymineral composite binders on the basis of Portland cement and mineral additives: opoka marl and fly ash.Conclusion. The research establishes the hydration and hardening processes of polymineral composite binders. As a result, the authors demonstrate that the opoka marl introduced into the cement leads to the increased hydration in the induction and accelerated periods and also increases the hydration completeness of the main clinker minerals due to the manifestation of the pozzolanic reaction and the active binding of blocking Portlandite, as well as to the higher concentration of accumulated neoplasms, second generation calcium hydrosilicates.Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.

scholarly journals Exploitive properties of ceramic grinding wheels with cBN abrasive grains of differential construction

Mechanik ◽  
2016 ◽  
pp. 1530-1531
Author(s):  
Andrzej Gołąbczak ◽  
Tomasz Pobol ◽  
Daniela Herman ◽  
Ryszard Dębkowski
Keyword(s):  
Grinding Wheels ◽  
Abrasive Grains ◽  
Ceramic Grinding ◽  
Differential Construction

Energy Model in Laser Processing of a Cylindrical Grinding Wheel

2006 ◽  
Vol 304-305 ◽  
pp. 33-37 ◽  
Author(s):  
Xu Yue Wang ◽  
Yong Bo Wu ◽  
Ren Ke Kang ◽  
Dong Ming Guo ◽  
Wen Ji Xu ◽  
...  
Keyword(s):  
Laser Processing ◽  
Laser Energy ◽  
Experimental Studies ◽  
Incident Beam ◽  
Processing Parameters ◽  
Balance Model ◽  
Grinding Wheel ◽  
Grinding Wheels ◽  
Cylindrical Grinding ◽  
Mechanical Methods

Laser processing of abrasive grinding wheels is paying a great role in a truing technique to complement mechanical methods. An energy balance model was adopted that took into account the space modes of laser energy absorbed/scattered by the wheel (circular profile). Both geometric and mathematic models were developed to reveal laser processing mechanism and predict various processing parameters, such as incident position, focal offset, and incident power, to perform material removal during laser processing a cylindrical grinding wheel. Moreover, the incident angle for laser processing of small-vitrified CBN grinding wheels was optimized. Further theoretical analysis and experiments determined the focal position of the incident beam with respect to the wheel profile. Experimental studies were carried out using different processing parameters and grinding wheels to test the effects of laser space properties on processing quality. The experimental results were shown to be in reasonable agreement with predicted results.

scholarly journals Experimental Studies on the Centrifugal MQL-CCA Method of Applying Coolant during the Internal Cylindrical Grinding Process

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2383 ◽  
Author(s):  
Krzysztof Nadolny ◽  
Seweryn Kieraś
Keyword(s):  
Hybrid Method ◽  
Experimental Studies ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Grinding Wheels ◽  
Cylindrical Grinding ◽  
Minimum Quantity ◽  
Dry Grinding ◽  
Internal Cylindrical Grinding ◽  
Cooling And Lubrication

This paper presents the results of experimental research concerning the possibility of supporting the cooling function during internal cylindrical grinding using the minimum quantity lubrication (MQL) method by additional delivery of a compressed cooled air (CCL) stream. The article presents a description of a hybrid method of cooling and lubrication of the grinding zone integrating centrifugal (through a grinding wheel) lubrication with the minimum quantity of lubricant and cooling with a compressed cooled air stream generated by a cold air gun (CAG). The methodology and results of experimental studies are also presented in detail, with the aim of determining the influence of the application of the hybrid method of cooling and lubrication of the machining zone on the course and results of the internal cylindrical grinding process of 100Cr6 steel in comparison with other methods of cooling and lubrication, as well as compared with dry grinding. The research results obtained using the described hybrid method of cooling and lubrication of the grinding zone are related to the results obtained under the conditions of centrifugal MQL method, cooling with a stream of CCA, cooling and lubrication with a stream of oil-in-water emulsion delivered using the flood method, and dry grinding. The efficiency of the grinding process is evaluated (based on the average grinding power Pav, grinding wheel volumetric wear Vs, material removal Vw, and grinding ratio G), along with the thermal conditions of the process (based on the analysis of thermograms recorded by infrared thermal imaging method), the textures of machined surfaces (based on microtopography measured by contact profilometry), the state of residual stress in the surface layers of workpieces (determined by X-ray diffraction method), and the state of the grinding wheels’ active surfaces after grinding (based on microtopography measured by laser triangulation and images recorded with a digital measuring microscope). The obtained results of the analyses show that the application of the hybrid method allows for the longest wheel life among the five compared grinding methods, which is about 2.7 times the life of grinding wheels working under the flood cooling and centrifugal MQL methods, and as much as 8 times the life of grinding wheels working under the conditions of CCA only and dry grinding.

scholarly journals Experimental Study on Heat Loss of a Single Screw Expander for an Organic Rankine Cycle System

2020 ◽  
Vol 8 ◽  
Author(s):  
Wei Wang ◽  
Li-li Shen ◽  
Ru-meng Chen ◽  
Yu-ting Wu ◽  
Chong-fang Ma
Keyword(s):  
Heat Loss ◽  
Output Power ◽  
Heat Dissipation ◽  
Experimental Studies ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Experimental Period ◽  
Experimental Results ◽  
Lubricating Oil ◽  
Single Screw

For displacement expanders, the irreversible losses include leakage, friction, heat dissipation, and flow resistance. Currently, the research on the heat loss of expanders is scarce, especially with regards to experimental studies. In this paper, the experimental research on the heat loss of the single screw expander (SSE) for the Organic Rankine Cycle was carried out under different working conditions, in the summer and winter, respectively. In each set of experiments, there were five cases, and the temperatures of the working fluids at the inlet of the expander were 83, 93, 103, 113, and 123°C, respectively. The heat removed by the lubricating oil was also measured throughout the experimental period. The experimental results showed that the amount of heat loss was not comparable to the output power and enthalpy difference between the inlet and outlet of the SSE. The proportion of the heat dissipated by the casing was only 30% ranging from 0.11 to 0.28 kW. Comparing the experimental results in summer and winter, the heat loss in summer was lower than in winter, but the variation in output power showed an opposite trend. It was also shown that heat loss was not a main factor affecting the performance of SSEs.

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