An Electrical Method for Failure Prediction in Ductile Machine Elements at Elevated Temperatures

1978 ◽  
Vol 100 (4) ◽  
pp. 614-618
Author(s):  
G. M. Kurajian ◽  
T. Y. Na
Keyword(s):  
Electrical Resistivity ◽  
Critical Stress ◽  
Elevated Temperatures ◽  
Failure Prediction ◽  
Electrical Method ◽  
Conservation Of Energy ◽  
Ductile Metals ◽  
Machine Element ◽  
Machine Elements ◽  
Good Agreement

This paper provides the designer with an electrical method for failure prediction in ductile machine elements operating at elevated temperatures from room through the creep range. The law of conservation of energy, electrical considerations, and electrical properties are employed to result in a formulation. The formulation enables the designer to obtain, or verify, and then employ the critical stress value he requires in the design of a particular machine element operating at a given elevated temperature. It is shown that this critical stress value may be calculated simply by knowing the electrical resistivity value at the operating temperature, and the critical stress and electrical resistivity values at a datum (room) temperature. Specific applications are taken for various categories of steels with very good agreement between the theory and experimental data. The formulation is deemed to be applicable to other ductile metals as well.

Prediction of Failure in Ductile Machine Elements Operating at Elevated Temperatures

1976 ◽  
Vol 98 (3) ◽  
pp. 1062-1065
Author(s):  
G. M. Kurajian ◽  
T. Y. Na
Keyword(s):  
Elevated Temperatures ◽  
State Of The Art ◽  
Design Practice ◽  
Ductile Metals ◽  
Ductile Materials ◽  
Machine Element ◽  
Distortion Energy ◽  
Machine Elements ◽  
Sound Theoretical Basis ◽  
Good Agreement

This paper provides the designer with formulations and data so that he can more confidently design a ductile machine element, operating at elevated temperatures, by employing obtainable strength data at those temperatures. The paper begins by taking a panoramic view of the state of the art regarding a procedure for designing such elements, under such conditions, on the basis of stress vs. strength. Then, the paper combines the basic principle of the distortion-energy theory of failure, long recognized as the best theory of failure for ductile materials by well documented experiments, with thermodynamic behavioral and mechanical properties. This combination and accompanying study result in formulation, information and data so that the validity of the aforementioned design practice is given a sound theoretical basis. Specific applications are taken for various categories of steel with very good agreement between the theory and experimental data. However, with necessary data, the procedure can be applied to other ductile metals as well.

Prediction of Yield in Ductile Materials Operating at Creep Temperatures

1977 ◽  
Vol 99 (3) ◽  
pp. 425-428
Author(s):  
G. M. Kurajian ◽  
T. Y. Na
Keyword(s):  
Experimental Data ◽  
Elevated Temperature ◽  
Yield Strength ◽  
Yield Point ◽  
Room Temperature ◽  
Ductile Metals ◽  
Ductile Materials ◽  
Machine Element ◽  
Creep Temperature ◽  
Good Agreement

Utilizing a thermodynamic approach, this paper provides the designer with formulations and data so that he can obtain or verify, and then employ, the yield strength (or yield point) value he may desire in the design of a particular ductile machine element operating in the creep temperature range. A previous paper by the authors [1] dealt with the prediction of failure of such elements in the range between room temperature and the lower creep temperature. Thus, the present paper in conjunction with [1], and the references in both, is to provide a thermodynamic explanation for failure of such elements operating in elevated temperature environments ranging from room through creep temperatures. Specific applications are taken for three selected categories of steel with good agreement between the theory and experimental data. However, with necessary data, the procedures in this paper, as it was in [1], is expected to be applicable to other ductile metals as well.

A LOW-COST RESISTIVIMETER FOR USE IN PRACTICAL LECTURES OF APPLIED GEOPHYSICS

2016 ◽  
Vol 34 (1) ◽  
Author(s):  
Walter Sydney Dutra Folly ◽  
Aracy Sousa Senra
Keyword(s):  
Electrical Resistivity ◽  
Low Cost ◽  
Test Area ◽  
Vertical Electrical Sounding ◽  
Applied Geophysics ◽  
Resistivity Profile ◽  
Electrical Sounding ◽  
Good Agreement

ABSTRACT. We describe the construction and testing of a simple and efficient low-cost resistivimeter designed for use in practical classes in Applied Geophysics. The equipment was successfully tested in a vertical electrical sounding (VES) performed on sandy terrain within the campus of the Universidade Federal de Sergipe, Brazil. The VES results were in good agreement with the profiles obtained from two boreholes located approximately 500 m from the test area, clearly demonstrating the efficiency of the equipment and the adopted methodology.Keywords: vertical electrical sounding, electrical resistivity, resistivity profile. RESUMO. Neste artigo, descrevemos a construção e o teste de um resistivímetro de baixo custo, simples e eficiente, concebido para ser utilizado em aulas práticas de Geofísica Aplicada. O equipamento foi testado com a realização de uma sondagem elétrica vertical (SEV) em um terreno arenoso localizado no campus da Universidade Federal de Sergipe, Brasil. Os resultados obtidos nesta SEV apresentaram boa concordância com os perfis observados em dois poços de sondagem localizados a 500 m da área de teste, fato que comprovou a eficiência do equipamento e da metodologia adotada.Palavras-chave: sondagem elétrica vertical, resistividade elétrica, perfil de resistividade. 

scholarly journals Classification and examples of next generation machine elements

2019 ◽  
Vol 84 (1) ◽  
pp. 21-32 ◽  
Author(s):  
G. Vorwerk-Handing ◽  
T. Gwosch ◽  
S. Schork ◽  
E. Kirchner ◽  
S. Matthiesen
Keyword(s):  
System Analysis ◽  
Signal Transmission ◽  
Main Research ◽  
Related Data ◽  
Research Areas ◽  
Machine Element ◽  
Machine Elements ◽  
Technical Systems ◽  
Key Aspects ◽  
Sensory Functions

Abstract In order to fully exploit the potential of the rapidly progressing digitalisation of technical systems, it is necessary to provide reliable and significant process and condition related data. In this context, solutions are especially aspired to allow a simple integration into the surrounding system and to influence it as little as possible. The main challenges regarding the measurement of process and condition data in the operation and control of technical systems as well as in test environments are identified and presented at the beginning of this article. A promising approach to meet the resulting requirements is the integration of sensory functions into simple standardised machine elements. In order to facilitate the discussion and interdisciplinary development of machine elements with sensory functions, an extension of the existing classification of mechatronic machine elements is introduced and illustrated with examples. The introduced classification takes into account the classification according to Stücheli and Meboldt and is based on a comparison of conventional and mechatronic machine elements on a functional level with regard to the function structure. As a result, the three classes sensor carrying machine elements, sensor integrating machine elements and sensory utilizable machine elements are introduced and subsequently discussed in more detail on the basis of examples. Finally, an outlook is given on the main research areas with regard to the development of mechatronic machine elements. Key aspects include working principles and effects for application in mechatronic machine elements, system analysis with regard to load conditions, power supply of sensor and data processor in the environment of the machine element as well as data processing and signal transmission under typical environmental conditions of mechanical engineering.

Heat Dissipation and Temperature Distribution of Brake Liner Using Steady State Analysis

2012 ◽  
Vol 249-250 ◽  
pp. 712-717
Author(s):  
M.P. Natarajan ◽  
B. Rajmohan
Keyword(s):  
Heat Dissipation ◽  
Friction Material ◽  
Automotive Application ◽  
Element Analysis ◽  
Slowing Down ◽  
Drum Brake ◽  
The Coefficient Of Friction ◽  
Machine Elements ◽  
Braking Process ◽  
Good Agreement

Brakes are machine elements that absorb kinetic energy in the process of slowing down or stopping a moving part. Brake capacity depends upon the unit pressure between the braking surfaces, the coefficient of friction, and the ability of the brake to dissipate heat equivalent to the energy being absorbed. In braking system, drum brake is used mostly for automotive application. During the braking process, the forces and pressures in a drum brake are difficult to determine because of the manner in which the shoe contacts the drum. Finite Element analysis has been used to predict interface temperatures and heat flows and the results have been compared with experimental measurements made using fine thermocouples. Good agreement has been achieved, showing that the proportion of heat which flows into the friction material varies with time and temperature.

scholarly journals Curie Temperature and Microstructural Changes Due to the Heating Treatment of Magnetic Amorphous Materials

2016 ◽  
Vol 61 (1) ◽  
pp. 451-456 ◽  
Author(s):  
J. Gondro ◽  
K. Błoch ◽  
P. Brągiel ◽  
M. Nabiałek ◽  
M. Szota
Keyword(s):  
Amorphous Materials ◽  
Elevated Temperatures ◽  
Great Influence ◽  
Soft Magnetic ◽  
Transmission Electron ◽  
Heisenberg Type ◽  
Heating Treatment ◽  
Magnetic Hardening ◽  
Curie Temperatures ◽  
Good Agreement

Three distinct alloys: Fe86Zr7Nb1Cu1B5, Fe82Zr7Nb2Cu1B8, and Fe81Pt5Zr7Nb1Cu1B5were characterized both magnetically and structurally. The samples, obtained with spinning roller method as a ribbons 3 mm in width and 20 μm thick, were investigated as-quenched and after each step of a multi steps heating treatment procedure. Each sample was annealed at four steps, fifteen minutes at every temperature, starting from 573K+600K up to +700K depending on type of alloy. Mössbauer spectroscopy data and transmission electron microscope (HRE M) pictures confirmed that the as-quenched samples are fully amorphous. This is not changed after the first stages of treatment heating leads to a reduction of free volumes. The heating treatment has a great influence on the magnetic susceptibilities. The treatment up to 600K improves soft magnetic properties: an χ increase was observed, from about 400 to almost 1000 for the samples of alloys without Pt, and from about 200 to 450 at maximum, for the Fe81Pt5Zr7Nb1Cu1B5. Further heating, at more elevated temperatures, leads to magnetic hardening of the samples. Curie temperatures, established from the location of Hopkinson’s maxima on the χ(T) curve are in very good agreement with those obtained from the data of specific magnetization, σ(T), measured in a field of 0.75T. As a critical parameter β was chosen to be equal 0.36 for these calculations, it confirmed that the alloys may be considered as ferromagnetic of Heisenberg type. Heating treatment resulted in decreasing of TC. These changes are within a range of several K.

Effects of Gravity on Rewetting of Capillary Groove Surface at Elevated Temperatures—Experimental and Theoretical Studies

1995 ◽  
Vol 117 (4) ◽  
pp. 1042-1047 ◽  
Author(s):  
S. H. Chan ◽  
J. D. Blake ◽  
T. R. Shen ◽  
Y. G. Zhao
Keyword(s):  
Elevated Temperatures ◽  
Liquid Films ◽  
Thin Liquid Films ◽  
Experimental Investigations ◽  
Plate Temperature ◽  
Groove Surface ◽  
Grooved Surface ◽  
The Difference ◽  
Experimental And Theoretical Studies ◽  
Good Agreement

Theoretical and experimental investigations of the rewetting characteristics of thin liquid films over heated and unheated capillary grooved plates were performed. To investigate the effect of gravity on rewetting, the grooved surface was placed in upward and downward-facing positions. Profound gravitational effects were observed as the rewetting velocity was found to be higher in the upward than in the downward-facing orientation. The difference was even greater with higher initial plate temperatures. With either orientation, it was found that the rewetting velocity increased with the initial plate temperature. But when the temperature was raised above a rewetting temperature, the rewetting velocity decreased with the initial plate temperature. Hydrodynamically controlled and heat conduction controlled rewetting models were then presented to explain and to predict the rewetting characteristics in these two distinct regions. The predicted rewetting velocities were found to be in good agreement with experimental data with elevated plate temperatures.

Open Applicator Analysis For Material Joining And Dielectric Measurements

1996 ◽  
Vol 430 ◽  
Author(s):  
S. P. Chen ◽  
W. R. Tinga ◽  
F. E. Vermeulen
Keyword(s):  
Steady State ◽  
Dielectric Properties ◽  
Elevated Temperatures ◽  
Field Measurements ◽  
Steady State Solution ◽  
Dielectric Measurements ◽  
External Electromagnetic Fields ◽  
Quarter Wave ◽  
Planar Materials ◽  
Good Agreement

AbstractResonant internal and radiated external electromagnetic fields of an open coaxial structure are analyzed using FDTD. These fields are characterized for two structures, with and without a quarter-wave choke. Techniques utilized to obtain a steady state solution are discussed. Good agreement with field measurements is obtained. This moveable open applicator is convenient for creating intense hot zones as required in ceramic joining. It is also suitable for the measurement of surface dielectric properties of planar materials at room or elevated temperatures.

Design, Preparation and Microwave-Absorbing Properties of Sandwich-Structure Radar-Absorbing Materials Reinforced by Glass and SiC Fibres

2014 ◽  
Vol 788 ◽  
pp. 573-579 ◽  
Author(s):  
Hai Tao Liu ◽  
Hai Feng Cheng
Keyword(s):  
Electrical Resistivity ◽  
Sandwich Structure ◽  
Microwave Absorbing Properties ◽  
Dielectric Layers ◽  
Impedance Characteristics ◽  
Absorbing Materials ◽  
Resistive Sheet ◽  
Microwave Absorbing ◽  
Smith Chart ◽  
Good Agreement

In order to broaden the absorbing bandwidth of radar-absorbing materials (RAMs), a type of sandwich-structure RAMs (SSRAMs) derived from a Salisbury absorber and comprising two dielectric layers and one resistive sheet was investigated. In this paper, the impedance characteristics of the SSRAMs were analysed and the mechanisms of broadening microwave-absorbing bandwidth were interpreted using a Smith chart. In order to realise the study’s SSRAMs, plain-woven glass fibre fabric and silicon carbide (SiC) fibre fabric with low electrical resistivity were employed as reinforcements of the dielectric layers and lossy layer, respectively. The microwave-absorbing properties of the SSRAMs were measured and compared with simulated results. The results showed that the experimental and simulated results were in good agreement, that the SSRAMs had better wideband microwave-absorbing properties and that the microwave-absorbing bandwidth at reflectivity below −10 dB can reach 11.6 GHz.

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