Analysis on the Loading Stress, Thermal Stress and Coupling Stress in PCC-AC Composite Pavement

2011 ◽  
Vol 383-390 ◽  
pp. 2700-2704
Author(s):  
Bin Yang ◽  
Tai Qin Yang ◽  
Gao Dian Peng
Keyword(s):  
Thermal Stress ◽  
Temperature Gradient ◽  
Crack Initiation ◽  
Maximum Temperature ◽  
Dowel Bar ◽  
Maximum Temperature Gradient ◽  
Reflection Crack

PCC-AC composite pavement has the advantages of high carrying capability and excellent comfort. The maximum temperature gradient formula of PCC-AC composite pavement in Guangxi region is fitted. The loading stress, thermal stress and coupling stress in AC layer of with dowel bar can significantly reduced. All kinds of stresses are also decreased with the narrow dowel bar space. Therefore, the Shrinking joints of composite pavement with dowel bars can greatly reduce the probability of reflection crack initiation. As the thickness of AC layer, there is greater influence on thermal stress and coupling stress than on loading stress, The loading stress, thermal stress and coupling stress in PCC layer decreases with the thickness increasing of AC layer, their relationship is linear. The loading stress and coupling stress of PCC layer reduce significantly with increasing the PCC thickness. AC layer also plays a role in reducing the loading stress and coupling stress of PCC layer.

scholarly journals Minimum maximum temperature gradient coil design

2012 ◽  
Vol 70 (2) ◽  
pp. 584-594 ◽  
Author(s):  
Peter T. While ◽  
Michael S. Poole ◽  
Larry K. Forbes ◽  
Stuart Crozier
Keyword(s):  
Temperature Gradient ◽  
Gradient Coil ◽  
Maximum Temperature ◽  
Coil Design ◽  
Gradient Coil Design ◽  
Maximum Temperature Gradient

Diurnal temperature gradients in shallow water produced by populations of artificial aquatic macrophytes

1978 ◽  
Vol 56 (9) ◽  
pp. 1099-1106 ◽  
Author(s):  
H. M. Dale ◽  
T. J. Gillespie
Keyword(s):  
Temperature Gradient ◽  
Leaf Area ◽  
Aquatic Macrophytes ◽  
Time Of Day ◽  
Maximum Temperature ◽  
Water Evaporation ◽  
Vertical Temperature ◽  
Area Index ◽  
Leaf Arrangement ◽  
Maximum Temperature Gradient

Three artificial populations, with leaf area indices (L) of 4.4, 1.5, and 0.54 were submerged in identical tubs of 1-m3 capacity. Experiments showed that the maximum vertical temperature gradient of the water varied and was dependent on the ratio of solar radiation to wind speed, the leaf area index, and the arrangement of the leaves in the population. The time of day of the maximum temperature gradient was also dependent on L and leaf arrangement. The interception of the light energy by the leaf surface heated the water locally, while the shadow beneath caused the temperature to remain low. With fewer plants, water evaporation was slightly greater. Evaporation resulted in a marl deposit which was confined to the upper surface of the leaves.

Effects of Averaging the Heat Transfer Coefficient on Predicted Material Temperature and Its Gradient

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Chien-Shing Lee ◽  
Tom I-P. Shih ◽  
Kenneth Mark Bryden
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Temperature Gradient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Biot Number ◽  
Maximum Temperature ◽  
Gradual Transition ◽  
The Heat Transfer Coefficient ◽  
Maximum Temperature Gradient

The heat transfer coefficient (HTC) is often averaged spatially when designing heat exchangers. Since the HTC could vary appreciably about a heat transfer enhancement feature such as a pin fin or a rib, it is of interest to understand the effects of averaging the HTC on design. This computational study examines those effects via a unit problem—a flat plate of thickness H and length L, where L represents the distance between pin-fins or ribs. This flat plate is heated on one side, and cooled on the other. Variable HTC is imposed on the cooled side—a higher HTC (hH) over LH and a lower HTC (hL) over LL = L − LH. For this unit problem, the following parameters were studied: abrupt versus gradual transition between hH and hL, hH/hL, LH/L, and H/L. Results obtained show that if the averaged HTC is used, then the maximum temperature in the plate and the maximum temperature gradient in the plate can be severely underpredicted. The maximum temperature and the maximum temperature gradient can be underpredicted by as much as 36.3% and 542%, respectively, if the Biot number is less than 0.1 and as much as 13.0% and 570% if the Biot number is between 0.25 and 0.4. A reduced-order model was developed to estimate the underpredicted maximum temperature.

Effect of encased concrete on section temperature gradient of corrugated steel web box girder

2021 ◽  
pp. 136943322199249
Author(s):  
Feng Zhang ◽  
Jia Shen ◽  
Jinyi Liu
Keyword(s):  
Temperature Gradient ◽  
Solar Radiation ◽  
Maximum Temperature ◽  
Daily Maximum ◽  
Box Girder ◽  
Structural Temperature ◽  
Corrugated Steel Web ◽  
Maximum Temperature Gradient ◽  
Lateral Temperature ◽  
Concrete Section

Thirty-two temperature sensors, a solar radiation sensor, wind speed, and direction sensor were installed on the bridge for the field monitoring of structural temperature, solar radiation, and wind. The frequency was set at 60 min for 211 days. Empirical equations were used to predict the maximum vertical and lateral temperature gradients, and the daily maximum and minimum mean temperatures of the corrugated steel web box girder. The results showed that the temperature gradient of the corrugated steel web box girder was closely related to the temperature gradient of air. The vertical maximum temperature gradient occurred at 4 pm. The height of the box girder had a significant effect on the accuracy of the predicted vertical maximum temperature gradient. Compared with the section without encased concrete, the maximum temperature gradient of the encased concrete section was reduced by 10.48%. Encased concrete showed minimal effect on both the vertical and lateral temperature gradient of the top plate part, however, the effect on the vertical temperature gradient of the haunch reduced by 17.19%. The maximum temperature gradient of corrugated steel with a composite encased concrete section was 4.12°C, which was less than that of the section without encased concrete at 5.06°C. The encased concrete had a significant effect on the maximum temperature gradient of corrugated steel web with a 26.99% deviation.

scholarly journals Further Results on Studies of Temperature-Gradient Metamorphism

1982 ◽  
Vol 28 (98) ◽  
pp. 205-210 ◽  
Author(s):  
E. E. Adams ◽  
R.L. Brown
Keyword(s):  
Temperature Gradient ◽  
Maximum Temperature ◽  
Material Strength ◽  
Snow Pack ◽  
Laboratory Studies ◽  
Thermodynamic Process ◽  
Temperature Variations ◽  
Field Investigations ◽  
Maximum Temperature Gradient

AbstractA correlation between temperature gradient in snow–pack and material strength is found to exist in laboratory studies on temperature gradient metamorphism of snow. These results are in agreement with earlier field investigations and eliminate diurnal solar and temperature variations as reasons for the existence of the maximum temperature gradient in the zone of minimum strength. Also the laboratory studies have indicated that locally dense layers such as ice crusts tend to enhance weakness directly below the crust due to local alteration of the thermal regimen. Further studies are continuing to describe the thermodynamic process of temperature gradient metamorphism more exactly.

Study on Conjugate Thermal Performance of a Steam-Cooled Ribbed Channel with Thick Metallic Walls

2021 ◽  
Author(s):  
Lei Xi ◽  
Liang Xu ◽  
Jianmin Gao ◽  
Zhen Zhao
Keyword(s):  
Heat Transfer ◽  
Temperature Gradient ◽  
Thermal Performance ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Performance ◽  
Thick Wall ◽  
Maximum Temperature ◽  
Transfer Performance ◽  
Ribbed Channel ◽  
Maximum Temperature Gradient

Abstract In this work, a conjugate heat transfer model was established to numerically investigate the conjugate thermal performance of a steam-cooled ribbed channel with thick metallic walls. By employing the software of ANSYS CFX, the flow field in the channel and the temperature field in the solid channel were calculated. The flow behavior, heat transfer performance and temperature gradient distributions of ribbed channels with wall thickness (δ) of 1–5 mm, rib height-to-hydraulic diameter (e/D) of 0.047–0.188, rib pitch-to-height ratio (P/e) of 5–15 and rib angle-of-attack (α) of 30°–90° were compared and analyzed. The optimum structure parameters of thick-wall ribbed channel with higher heat transfer performance and lower maximum temperature gradient were obtained. The results show that the SST k-ω turbulence model is more suitable for the conjugate heat transfer problem of steam in the thick-wall ribbed channels. The friction factor reduces gradually with the increase of Re, increases greatly with the increase of e/D and α, and first increases then decreases with the increase of P/e. The average Nusselt number increases up to 8.81 times, while the maximum temperature gradient decreases about 45.35% when Reynolds number varies from 10,000 to 70,000. The rib angle of about 45°–60°, e/D of 0.188, and P/e of 10 are suitable to obtain the optimum thermal performance of steam flow in the ribbed channel. The influence of δ on the flow and heat transfer characteristics is non-significant.

scholarly journals Further Results on Studies of Temperature-Gradient Metamorphism

1982 ◽  
Vol 28 (98) ◽  
pp. 205-210 ◽  
Author(s):  
E. E. Adams ◽  
R.L. Brown
Keyword(s):  
Temperature Gradient ◽  
Maximum Temperature ◽  
Material Strength ◽  
Snow Pack ◽  
Laboratory Studies ◽  
Thermodynamic Process ◽  
Temperature Variations ◽  
Field Investigations ◽  
Maximum Temperature Gradient

AbstractA correlation between temperature gradient in snow–pack and material strength is found to exist in laboratory studies on temperature gradient metamorphism of snow. These results are in agreement with earlier field investigations and eliminate diurnal solar and temperature variations as reasons for the existence of the maximum temperature gradient in the zone of minimum strength. Also the laboratory studies have indicated that locally dense layers such as ice crusts tend to enhance weakness directly below the crust due to local alteration of the thermal regimen. Further studies are continuing to describe the thermodynamic process of temperature gradient metamorphism more exactly.

scholarly journals Thermal–Fluid–Solid Coupling Analysis on the Temperature and Thermal Stress Field of a Nickel-Base Superalloy Turbine Blade

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3315
Author(s):  
Liuxi Cai ◽  
Yao He ◽  
Shunsen Wang ◽  
Yun Li ◽  
Fang Li
Keyword(s):  
Thermal Stress ◽  
Temperature Gradient ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Nickel Base Superalloy ◽  
Barrier Coating ◽  
Thermal Stress Field ◽  
Nickel Base ◽  
Stress Damage ◽  
Superalloy Turbine Blade

Based on the establishment of the original and improved models of the turbine blade, a thermal–fluid–solid coupling method and a finite element method were employed to analyze the internal and external flow, temperature, and thermal stress of the turbine blade. The uneven temperature field, the thermal stress distribution characteristics of the composite cooling turbine blade under the service conditions, and the effect of the thickness of the thermal barrier coating (TBC) on the temperature and thermal stress distributions were obtained. The results show that the method proposed in this paper can better predict the ablation and thermal stress damage of turbine blades. The thermal stress of the blade is closely related to the temperature gradient and local geometric structure of the blade. The inlet area of the pressure side-platform of the blade, the large curvature region of the pressure tip of the blade, and the rounding between the blade body and the platform on the back of the blade are easily damaged by thermal stress. Cooling structure optimization and thicker TBC thickness can effectively reduce the high temperature and temperature gradient on the surface and inside of the turbine blade, thereby reducing the local high thermal stress.

Estimating the Stress-Strain State of Roll by Temperature Gradient in the Course of its Heat Treatment

2021 ◽  
Vol 316 ◽  
pp. 967-972
Author(s):  
Alexander S. Savinov ◽  
Sergey M. Andreev ◽  
Nikolay A. Feoktistov
Keyword(s):  
Heat Treatment ◽  
Temperature Gradient ◽  
Strain State ◽  
Thermal State ◽  
Maximum Temperature ◽  
Cast Billet ◽  
Treatment Schedule ◽  
Stress Strain ◽  
Metallurgical Enterprise ◽  
Stress Strain State

The paper considers the issue of mathematical simulating the stress-strain state of a roll in the course of its heat treatment. It is shown that a sound heat treatment schedule affects significantly the economic efficiency of a metallurgical enterprise. The mathematical apparatus is provided to estimate the thermal interaction in the casting-furnace system, based on which a program for calculating the thermal state of a roll during heat treatment has been developed. Using this program allows evaluating the thermal stresses occurring in a roll during the heat treatment cycle and reducing the risk of discontinuity in the roll cast billet. Also, using the program developed, allows significant reducing the engineer-technologist man-hours for the design of the process cycle of the casting heat treatment. An example of calculating the thermal state of a roll with a diameter of 930 mm in casting is given. The change in the dynamics of the maximum temperature gradient along the product radius is shown, while correlating it with the furnace setting.

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