Thermal response of a dynamically loaded viscoelastic rod with variable properties

AIAA Journal ◽  
1990 ◽  
Vol 28 (1) ◽  
pp. 173-175 ◽  
Author(s):  
Mehdi Pourazady ◽  
Harish Krishnamurty
Keyword(s):  
Thermal Response ◽  
Variable Properties ◽  
Dynamically Loaded ◽  
Viscoelastic Rod

Thermal Response of a Viscoelastic Rod Under Cyclic Loading

1974 ◽  
Vol 41 (1) ◽  
pp. 229-233 ◽  
Author(s):  
S. Mukherjee
Keyword(s):  
Cyclic Loading ◽  
Thermal Response ◽  
Time History ◽  
Thermomechanical Coupling ◽  
Large Strains ◽  
Driving Frequency ◽  
Wide Range ◽  
History Of ◽  
Complex Young’S Modulus ◽  
Viscoelastic Rod

Thermal response of a viscoelastic rod under cyclic loading is discussed by determining the stresses and temperature in a viscoelastic rod insulated on its lateral surface and driven by a sinusoidal stress at one end. Temperature dependence of the complex Young’s modulus of the rod and the effect of thermomechanical coupling are included in the analysis. A method of finite differences is used to directly determine the steady-state stresses and temperature without obtaining the complete time history of the process. The iterative algorithm used is very efficient and converges rapidly for a wide range of driving stress amplitudes and frequencies. It is found that rapid rise of temperature to dangerous levels occurs for relatively low values of driving stress amplitudes, especially if the driving frequency is close to one of the critical frequencies of the rod. Drastic softening of the rod leads to large strains. Thus failure of the rod could occur at low values of the driving stress.

Critical frequencies of a dynamically loaded viscoelastic rod

1988 ◽  
Vol 29 (4) ◽  
pp. 657-660 ◽  
Author(s):  
Harish Krishnamurthy ◽  
Mehdy Pourazady ◽  
Ronald L. Huston
Keyword(s):  
Dynamically Loaded ◽  
Viscoelastic Rod

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Numerical simulation of the tree higro-thermal response in forest fire environment

2020 ◽  
pp. 57-65
Author(s):  
Eusébio Conceiçã ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Jorge Raposo ◽  
Domingos Xavier Viegas ◽  
...  
Keyword(s):  
Forest Fire ◽  
Numerical Study ◽  
Thermal Response ◽  
View Factor ◽  
Tree Model ◽  
Pine Tree ◽  
Surface Temperatures ◽  
Fire Environment ◽  
Fire Front ◽  
Heat Exchanges

This paper refers to a numerical study of the hypo-thermal behaviour of a pine tree in a forest fire environment. The pine tree thermal response numerical model is based on energy balance integral equations for the tree elements and mass balance integral equation for the water in the tree. The simulation performed considers the heat conduction through the tree elements, heat exchanges by convection between the external tree surfaces and the environment, heat exchanges by radiation between the flame and the external tree surfaces and water heat loss by evaporation from the tree to the environment. The virtual three-dimensional tree model has a height of 7.5 m and is constituted by 8863 cylindrical elements representative of its trunks, branches and leaves. The fire front has 10 m long and a 2 m high. The study was conducted taking into account that the pine tree is located 5, 10 or 15 m from the fire front. For these three analyzed distances, the numerical results obtained regarding to the distribution of the view factors, mean radiant temperature and surface temperatures of the pine tree are presented. As main conclusion, it can be stated that the values of the view factor, MRT and surface temperatures of the pine tree decrease with increasing distance from the pine tree in front of fire.

A New Scanning Thermal Microprobe

1997 ◽  
Vol 503 ◽  
Author(s):  
Yongxia Zhang ◽  
Yanwei Zhang ◽  
Juliana Blaser ◽  
T. S. Sriiram ◽  
R. B. Marcus
Keyword(s):  
Thin Film ◽  
High Resolution ◽  
Thermal Response ◽  
Temperature Sensing ◽  
Thermal Sensor ◽  
Atomic Force ◽  
Thin Film Thermocouple ◽  
Processing Steps ◽  
Thermocouple Junction

ABSTRACTA thermal microprobe has been designed and built for high resolution temperature sensing. The thermal sensor is a thin-film thermocouple junction at the tip of an Atomic Force Microprobe (AFM) silicon probe needle. Only wafer-stage processing steps are used for the fabrication. The thermal response over the range 25–s 4.5–rovolts per degree C and is linear.

MIXED-CONVECTION FLOW IN A LID-DRIVEN SQUARE CAVITY FILLED WITH A NANOFLUID WITH VARIABLE PROPERTIES: EFFECT OF THE NANOPARTICLE DIAMETER AND OF THE POSITION OF A HOT OBSTACLE

2014 ◽  
Vol 45 (6) ◽  
pp. 563-578 ◽  
Author(s):  
Mohammad Hemmat Esfe ◽  
Seyed Sadegh Mirtalebi Esforjani ◽  
Mohammad Akbari ◽  
Arash Karimipour
Keyword(s):  
Mixed Convection ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Variable Properties ◽  
Square Cavity ◽  
Nanoparticle Diameter

SEEPAGE HEAT TRANSFER BETWEEN CLINKER AND COOLING AIR WITH VARIABLE PROPERTIES OF THE GRATE COOLER

2017 ◽  
Vol 48 (3) ◽  
pp. 263-281 ◽  
Author(s):  
Meiqi Wang ◽  
Bin Liu ◽  
Yan Wen ◽  
Haoran Liu
Keyword(s):  
Heat Transfer ◽  
Variable Properties ◽  
Grate Cooler ◽  
Cooling Air
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