Fundamental thermo-elasticity equations for thermally induced flexural vibration problems for inhomogeneous plates and thermo-elastic dynamical responses to a sinusoidally varying surface temperature

A numerical model is developed to analyze the influence of thermal deformations on the performance of a radially grooved thrust washer. The analysis couples the flow phenomena (including cavitation) in the lubricant with the heat transfer in both the fluid and solid media, as well as with the thermally induced deformations in the solid parts. The finite element method (both two-dimensional and three-dimensional, with linear and quadratic shape functions) is used to solve the Reynolds equation for flow, the energy equation for temperature and the thermo-elasticity equations for deformations in the solid. Grid coupling is achieved by using a Newton-Raphson iteration. Realistic boundary conditions and geometry are used for the fluid and solid domains. The results show that, for the case of a properly shaped stator, the thermal deformations can lead to an increase in bearing performance.

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The Wave Method for Solving Flexural Vibration Problems

Journal of Applied Mechanics ◽

10.1115/1.4010822 ◽

1954 ◽

Vol 21 (1) ◽

pp. 75-80

Author(s):

R. P. N. Jones

Keyword(s):

Normal Mode ◽

Flexural Vibration ◽

Initial Response ◽

Time Base ◽

Subsequent Response ◽

Mode Solution ◽

Vibration Problems ◽

Wave Methods ◽

Theoretical Results ◽

Good Agreement

Abstract In this paper the use of normal mode and wave methods in problems of dynamic loading on beams is discussed, and the methods are applied to simple problems of uniform beams under a suddenly applied load. For these problems, mathematically exact results have been obtained, enabling a comparison to be made between the two types of solution. Experimental results for these problems also have been obtained, using an apparatus which releases the beam from a deflected position, and displays a record of the resultant response on an oscillograph screen, using a time base synchronized with the release of the beam. Good agreement is obtained between the experimental and theoretical results, and it is shown that the wave solution is useful for determining the initial response of the beam, while the subsequent response can be better obtained from the normal-mode solution.

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Thermally Induced Convective Circulation and Precipitation over an Isolated Volcano

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-14-0327.1 ◽

2016 ◽

Vol 73 (4) ◽

pp. 1667-1686 ◽

Cited By ~ 6

Author(s):

Alexandros P. Poulidis ◽

Ian A. Renfrew ◽

Adrian J. Matthews

Keyword(s):

Surface Temperature ◽

Wrf Model ◽

Volcanic Hazards ◽

Pyroclastic Flows ◽

Weather Research And Forecasting ◽

Atmospheric Conditions ◽

Thermally Induced ◽

Average Value ◽

Wind Speeds ◽

Precipitation Increase

Abstract Intense rainfall over active volcanoes is known to trigger dangerous volcanic hazards, from remobilizing loose volcanic surface material into lahars or mudflows to initiating explosive activity including pyroclastic flows at certain dome-forming volcanoes. However, the effect of the heated volcanic surface on the atmospheric circulation, including any feedback with precipitation, is unknown. This is investigated here, using the Weather Research and Forecasting (WRF) Model. The recent activity at the Soufrière Hills Volcano (SHV), Montserrat, is a well-documented case of such rainfall–volcano interaction and is used as a template for these experiments. The volcano is represented in the model by an idealized Gaussian mountain, with an imposed realistic surface temperature anomaly on the volcano summit. A robust increase in precipitation over the volcano is simulated for surface temperature anomalies above approximately 40°C, an area-average value that is exceeded at the SHV. For wind speeds less than 4 m s−1 and a range of realistic atmospheric conditions, the precipitation increase is well above the threshold required to trigger volcanic hazards (5–10 mm h−1). Hence, the thermal atmospheric forcing due to an active, but nonerupting, volcano appears to be an important factor in rainfall–volcano interactions and should be taken account of in future hazard studies.

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Incorporating Phase Change Materials to Mitigate Extreme Temperatures in Asphalt Concrete Pavements

Volume 8: Heat Transfer and Thermal Engineering ◽

10.1115/imece2016-67765 ◽

2016 ◽

Author(s):

Bhagya Athukorallage ◽

Darryl James

Keyword(s):

Thermal Conductivity ◽

Surface Temperature ◽

Asphalt Concrete ◽

Phase Change Materials ◽

Volume Fraction ◽

Lower Surface ◽

Extreme Temperatures ◽

Thermally Induced ◽

Lower Surface Temperature ◽

Maximum Surface Temperature

The use of Phase Change Materials (PCMs) in asphalt pavement mixtures potentially offers a solution for regulating extreme temperatures that can cause thermally-induced rutting in pavement systems. The primary objective of this study is to fundamentally understand the effect on the heat transfer and maximum surface temperature in flexible pavement systems that includes PCMs. In particular, we consider a pavement structure in which PCM is embedded in the asphalt-concrete layer with varying volume fractions. Our simulation results show that the pavement system embedded with PCMs yield lower surface temperature values than systems without PCM (maximum temperature decrease is 1.5°C for the distributed PCM with a volume fraction of 30%). Further, we observe a higher temperature drop through the PCM-embedded asphalt layer compared to a pavement without PCM, and regions possessing temperature values less than 45°C that may help to reduce the thermally induced rutting problems. The simulation yields another interesting result: increasing PCM volume fraction beyond 60% results in higher surface temperature values. This increase in the maximum surface temperature may be explained by the fact that the PCM used in the simulation has a lower thermal conductivity than that of the asphalt-concrete that ultimately results in a lower effective thermal conductivity value for the system. Finally, we observe that an increase in the effective thermal conductivity yields lower surface temperature for the PCM embedded pavement system.

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Morphologies of Nonadherent Al2O3 and Matching Substrate Surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010009587x ◽

1972 ◽

Vol 30 ◽

pp. 524-525

Author(s):

C. S. Giggins ◽

J. K. Tien ◽

B. H. Kear ◽

F. S. Pettit

Keyword(s):

Electron Microscopy ◽

Oxide Scale ◽

Oxidation Resistance ◽

Substrate Surface ◽

Morphological Features ◽

Thermally Induced ◽

Oxide Spallation ◽

Oxidation Resistant ◽

Induced Stresses ◽

Substrate Surfaces

The performance of most oxidation resistant alloys and coatings is markedly improved if the oxide scale strongly adheres to the substrate surface. Consequently, in order to develop alloys and coatings with improved oxidation resistance, it has become necessary to determine the conditions that lead to spallation of oxides from the surfaces of alloys. In what follows, the morphological features of nonadherent Al2O3, and the substrate surfaces from which the Al2O3 has spalled, are presented and related to oxide spallation.The Al2O3, scales were developed by oxidizing Fe-25Cr-4Al (w/o) and Ni-rich Ni3 (Al,Ta) alloys in air at 1200°C. These scales spalled from their substrates upon cooling as a result of thermally induced stresses. The scales and the alloy substrate surfaces were then examined by scanning and replication electron microscopy.The Al2O3, scales from the Fe-Cr-Al contained filamentary protrusions at the oxide-gas interface, Fig. 1(a). In addition, nodules of oxide have been developed such that cavities were formed between the oxide and the substrate, Fig. 1(a).

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