Analysis on heat source of abnormal temperature rise of composite insulator housings

2017 ◽  
Vol 24 (6) ◽  
pp. 3578-3585 ◽  
Author(s):  
Zhikang Yuan ◽  
Youping Tu ◽  
Yongfei Zhao ◽  
Han Jiang ◽  
Cong Wang
Keyword(s):  
Heat Source ◽  
Temperature Rise ◽  
Composite Insulator ◽  
Abnormal Temperature

Detection of grouting defects in prestressed tendon ducts using distributed fiber optic sensors

2019 ◽  
Vol 19 (4) ◽  
pp. 1273-1286
Author(s):  
Shilin Gong ◽  
Xin Feng
Keyword(s):  
Thermal Conductivity ◽  
Temperature Rise ◽  
Fiber Optic ◽  
Detection Efficiency ◽  
Fiber Optic Sensors ◽  
Detection Methods ◽  
Experimental Program ◽  
Accurate Identification ◽  
Equivalent Thermal Conductivity ◽  
Abnormal Temperature

To compensate for the shortcomings of the existing point detection methods for grouting defects in prestressed tendon ducts, such as low detection efficiency, stringent detection environment, and easy omission of grouting defects, this article presents a distributed detection approach to detect the grouting defects in tendon ducts. The main objective of the research pertained to the development of a method for accurate identification and location of grouting defects and qualitative evaluation of the size of grouting defects using distributed fiber optic sensors with active heating. Using the thermal analysis of grouting defects in the tendon duct and the research on distributed fiber optic sensors measurement characteristics, our work proposed a method for identifying and locating grouting defects and explored the effect of the grouting defect length and the grouting compactness on the temperature rise of distributed fiber optic sensors. The feasibility of the proposed approach is evaluated through an experimental program. The experimental program involved use of heating distributed fiber optic sensors for the distributed measurement of temperature after the heating and detection of grouting defects in tendon ducts in a concrete beam. The results indicate that distributed fiber optic sensors can monitor the temperature distribution of the tendon duct during a temperature rise in real time. Grouting defects in the tendon duct can be quickly detected and located by identifying temperature anomalies in the temperature contour of the distributed fiber optic sensors. Furthermore, there is a linear relationship between the defect length and the abnormal temperature length on the distributed fiber optic sensors, and the defect length can be identified based on the abnormal temperature length obtained by the measurement. Plane-equivalent thermal conductivity can be used to evaluate the grouting compactness of the tendon duct. When the grouting compactness is greater than 70%, the smaller the plane-equivalent thermal conductivity is, the lower the grouting compactness is. The plane-equivalent thermal conductivity is basically the same when the grouting compactness is less than 70%.

Modeling of Cutting Temperature in Near Dry Machining

2005 ◽  
Vol 128 (2) ◽  
pp. 416-424 ◽  
Author(s):  
Kuan-Ming Li ◽  
Steven Y. Liang
Keyword(s):  
Heat Source ◽  
Heat Loss ◽  
Temperature Rise ◽  
Flank Wear ◽  
Cutting Temperature ◽  
Heat Sources ◽  
Dry Machining ◽  
Machining Processes ◽  
Tool Flank Wear ◽  
Dry Cooling

Near dry machining refers to the condition of applying cutting fluid at relatively low flow rates, on the order of 2-100ml∕h, as opposed to the conventional way of using either a large quantity, typically of about 10l∕min, as in wet machining; or no fluid at all, as in dry machining. One important expectation of applying fluids is to control the cutting temperature, which is an important parameter for tool life and part dimensional accuracy in machining processes. In this context, the understanding of cutting temperature variation corresponding to the near dry cooling and lubrication is of interest. This paper models the temperature distributions in the cutting zone under through-the-tool near dry cooling condition. The heat source method is implemented to estimate the cutting temperatures on the tool-chip interface and the tool-workpiece interface. For the temperature rise in the chip, the effects of the primary heat source and the secondary heat source were modeled as moving heat sources. For the temperature rise in the tool, the effects of the secondary heat source, the heat loss due to cooling, and the rubbing heat source due to the tool flank wear, were modeled as stationary heat sources. For the temperature rise in the workpiece, the primary heat source, the heat loss due to cooling, and the rubbing heat source due to the tool flank wear were modeled as moving heat sources. The model describes the dual effects of air-oil mixture in near dry machining in terms of the reduction of cutting temperature through the cooling effect, as well as the reduction of heat generation through the lubricating effect. To pursue model calibration and validation, embedded thermocouple temperature measurement in cutting medium carbon steels with uncoated carbide insets were carried out. The model predictions and experimental measurements show reasonable agreement and results suggest that the combination of the cooling and the lubricating effects in near dry machining reduces the cutting temperatures on the tool-chip interface by about 8% with respect to dry machining. Moreover, the cutting speed remains a dominant factor in cutting temperature compared with the feed and the depth of cut in near dry machining processes.

Effect of a Surface Film on the Surface Temperature of a Rotating Cylinder

1986 ◽  
Vol 108 (1) ◽  
pp. 92-97 ◽  
Author(s):  
B. Gecim ◽  
W. O. Winer
Keyword(s):  
Thermal Properties ◽  
Heat Source ◽  
Film Thickness ◽  
Surface Temperature ◽  
Temperature Rise ◽  
High Speed ◽  
Integral Transform ◽  
Heat Conduction Problem ◽  
Surface Film ◽  
Layer Effect

Solution to the steady heat conduction problem of a rotating layered cylinder is presented. The governing differential equations (for the film and the substrate) are solved by using an integral transform technique. It is shown that the presence of a surface film measured in micrometers can substantially change the level of the surface temperature. The effect of the surface film on the surface temperature depends on: respective thermal properties of the film and the substrate; relative surface speed; heat source (contact) size; and surface film thickness. However, the range in which the effect of the film on the surface temperature is dependent on these parameters is limited. Outside this range (i.e., thin film/low speed or thick film/high speed) the surface temperature rise is determined by the thermal properties of the substrate, or by the properties of the film alone, respectively. Hence, outside this range, a further change in the film thickness does not influence the surface temperature rise. Dimensionless plots showing the change in surface temperature rise as a function of material thermal properties, surface speed, heat source size, and film thickness are presented. Behavior for specific material combinations are also presented. The present information can be utilized to predict the layer effect on the partition of heat between the layered cylinders.

scholarly journals Temperature Rise of a Spur Gear Tooth Due to Repeated Action of a Moving Heat Source

1986 ◽  
Vol 29 (258) ◽  
pp. 4403-4408 ◽  
Author(s):  
Fumio OBATA ◽  
Komei FUJITA ◽  
Masahiro FUJII
Keyword(s):  
Heat Source ◽  
Temperature Rise ◽  
Gear Tooth ◽  
Spur Gear ◽  
Moving Heat Source

Prediction and Measurement of Surface Temperature Rise at the Contact Interface for Oscillatory Sliding

1995 ◽  
Vol 209 (1) ◽  
pp. 41-51 ◽  
Author(s):  
X Tian ◽  
F E Kennedy
Keyword(s):  
Heat Source ◽  
Surface Temperature ◽  
Temperature Rise ◽  
Frictional Heating ◽  
Temperature Model ◽  
Contact Interface ◽  
Simple Method ◽  
Sliding Motion ◽  
Thin Film Thermocouple ◽  
Temperature Solution

Surface temperature rise due to frictional heating in oscillatory sliding is studied using Green's function method and a recently developed temperature model for finite bodies. The surface temperature solution in oscillatory sliding differs in two respects from that in unidirectional sliding: the heat source is time varying and the sliding motion is periodic. The magnitude of the heat flux determines the local or flash temperature rise, which is cyclic owing to the time-dependent nature of the heat source. The periodic sliding movement of the heat source is found to be responsible for an additional surface temperature increase which can be considered as a nominal temperature rise. Based on a new surface temperature model for a finite contacting body, a relatively simple method for predicting the maximum surface temperature rise for an oscillatory sliding system is presented. Experimental measurements of surface temperature rise during oscillatory sliding were carried out using thin-film thermocouple (TFTC) techniques. The measured surface temperature rise at the contact interface agrees well with the model's predictions.

Plastic Dissipation and Temperature Field around a Steady Running Crack

2006 ◽  
Vol 324-325 ◽  
pp. 895-898
Author(s):  
Wen Bo Luo ◽  
Ting Qing Yang
Keyword(s):  
Temperature Field ◽  
Heat Source ◽  
Plastic Zone ◽  
Temperature Rise ◽  
Heat Dissipation ◽  
Crack Tip ◽  
Maximum Temperature ◽  
Growth Speed ◽  
Density Distribution Function ◽  
Plastic Dissipation

Temperature field is formed due to heat dissipation when material is subjected to irreversible deformation. In this paper, the heat dissipation in the crack-tip plastic zone was considered. By considering the propagating crack-tip plastic zone as a running heat source and constructing a reasonable heat source density distribution function, the temperature field around a steady running crack was obtained. It is shown that temperature rise is dependent on the crack growth speed and the material parameters. The maximum temperature rise reaches to >50 oC in our example calculations for a steady running crack in PMMA.

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