Coupled Effects Of Temperature Research Articles

Damage characterization of high- and low-temperature performance of porous asphalt mixtures under multi-field coupling

Porous asphalt (PA) have attracted considerable interest due to their functional advantages such as significant water permeability and noise attenuation properties. Nevertheless, its vulnerability to damage significantly hinders its widespread application. Therefore, this paper aims to investigate the damage characteristics of PA's high- and low-temperature performance under the coupled effects of moisture and temperature. Firstly, Hamburg Wheel-Tracking Test (HWTT) and three-point bending tests were conducted on PA under different coupling conditions. Subsequently, its damage characteristics were analyzed using the three-stage permanent deformation model, logistic model, and two-way analysis of variance (ANOVA) method. The findings indicate that under dry conditions, PA-13 exhibits a linear decrease in rutting resistance within the temperature range of 40–60 °C, followed by a significant decrease at 70 °C. During immersion in water, PA-13 undergoes a second and third-stage rutting evolution process, with an accelerated creep rate observed at 70°C. High temperatures exacerbate the viscoelastic damage of PA-13, while multi-field coupling promotes the simultaneous occurrence of viscoelastic damage and stripping damage. Furthemore, the results of the two-way ANOVA indicate that moisture has a more significant impact on high-temperature performance damage. In addition, in a dry environment, the low-temperature crack resistance of PA-13 deteriorates with decreasing temperature, but there is little difference at −20 °C and −30 °C. This is attributed to PA-13 exhibiting flexible cracking at 0 °C and −10 °C, while undergoing brittle cracking at −20 °C and −30 °C. Additionally, the coupled effect of temperature and moisture reduces the damage tolerance of PA-13 and accelerates its cracking process. The results of the two-way ANOVA indicate that both low temperature and treatment methods have a statistically significant impact on low-temperature performance, with treatment methods having a higher degree of influence. The findings of this paper contribute to an in-depth understanding of the damage mechanism of PA-13.

Coupled effects of temperature and suction on the anisotropic elastic shear moduli of unsaturated soil

Elastic shear moduli of soil at various temperatures and suctions are important for analysing the serviceability limit state of energy piles and many other structures. Up to now, however, the coupled effects of temperature and suction on elastic shear modulus and the stiffness anisotropy, have not been well understood. This experimental study investigated the anisotropic elastic shear modulus of a compacted lateritic clay. A temperature and suction-controlled triaxial apparatus equipped with bender element probes and local strain measurements was used. Soil suctions from 0 to 300 kPa, and a temperature range of 5–40 °C were applied. The results at saturated and unsaturated conditions consistently reveal that the shear modulus is smaller after heating at a given stress and suction. Several mechanisms may contribute to this thermal-induced reduction in shear modulus, such as the heating-induced reduction of interparticle force and air–water surface tension. Moreover, the reduction in shear modulus upon heating depends on the shear plane and the degree of anisotropy changes.

Experimental and Numerical Study on Chloride Transport in Unsaturated Concrete: Highlighting Temperature, Humidity, and Mineral Admixtures.

Chloride transport within concrete is critical for the durability of reinforced concrete structures; however, its diffusion under the coupling action of temperature and humidity has not been fully comprehended. Therefore, in this work, the coupling effects of temperature, relative humidity, and mineral admixtures on chloride transport in concrete were investigated through experimental and numerical simulation work. The results show that the chloride diffusion coefficient decreases with the decreased temperature and growth of relative humidity; however, the chloride concentration on the concrete surface is increased with the growth of temperature and relative humidity. Moreover, compounding about 15% fly ash (FA) and 30% granulated ground blast furnace slag (GGBS) to replace the cement is the most beneficial for improving the antichloride capacity of concrete, considering also the strength. In addition, the numerical simulation considering the coupled effect of temperature and relative humidity of chloride transport in concrete has good agreement with that of experimental results.

Coupled effects of temperature and relative humidity on desiccation curling of a clayey soil

Soil curling caused by drying is a common phenomenon in nature, and it can vary depending on different atmospheric effects. To investigate the coupled effects of temperature and relative humidity on soil curling, a sequence of desiccation experiments were performed by using elongated strip soil samples in the laboratory. The soil curling process is divided into five stages: vertical settlement stage, lateral contraction stage, concave-up curling stage, curling recovery stage and convex-up curling stage. In this study, the soil evaporation characteristic and curvature curves are obtained under different temperature and relative humidity conditions. The findings revealed that a lower relative humidity results in a higher evaporation rate and a smaller maximum concave-up curling curvature for soil samples. Additionally, as the temperature increased, the water content associated with concave curling decreased. The maximum concave-up curling curvature was determined by the transition from the appearance of concave-up curling to the maximum curvature of concave-up curling. Under the coupled effect of temperature and relative humidity, all the water content associated with the occurrence of concave-up curling, maximum concave-up and convex-up curling appearance are reduced with increasing temperature and decreasing relative humidity. As the temperature ranged from 20 °C to 40 °C, the maximum concave-up curling curvature initially decreased and then increased. Conversely, the maximum concave-up curling curvature increased within the relative humidity range of 30% to 45%.

Study on accelerated aging rate of asphalt binder under multi-factors coupling conditions

The aging behavior of asphalt binder in service is complex. The accelerated aging methods commonly used in the laboratory are difficult to reproduce the aging behavior of asphalt binder in service. The purpose of this study is to develop a method for predicting the properties of asphalt binder in service. First, a multi-factor accelerating (MFA) aging method was developed to accelerate the aging of asphalt binder. Multi-scale characterization and correlation analysis were conducted on the MFA-aged asphalt binder. Then, the evaluation index of MFA aging was defined, which was used to establish the prediction equation for asphalt binder aging. Finally, the time correlation between field aging, pressure aging vessel (PAV) aging and MFA aging was constructed separately. The results show that accelerated aging of asphalt binder at atmospheric pressure and service temperature can be achieved by the coupled effect of temperature, ultraviolet light and rain. After 5-day MFA aging, the Glover-Rowe (G-R) parameter, an index for evaluating the cracking resistance of asphalt binder, was increased by 308%. The carbonyl index, an index for evaluating the content of chemical functional groups of asphalt binder, was increased by 67%. The correlation between the G-R parameter and the carbonyl index was linear, and the goodness-of-fit was greater than 0.9. The carbonyl index as a key chemical index may reflect the macroscopic properties of asphalt binder. The prediction equation for aging was established based on the carbonyl index of field-aged asphalt binder in Beijing, with reliability greater than 0.98. PAV aging for 20 h was equivalent to 1.35 years of asphalt binder service in Beijing. MFA aging method can better predict the aging time in the field. The prediction accuracy was 97.2%, which was 4.9% higher compared to that of PAV aging. MFA aging for 5 days was equivalent to about 2 years of asphalt binder service in Beijing.

Experimental investigation on coal desorption characteristics and spontaneous combustion properties evolution under the coupled effect of temperature and pressure

Gas desorption patterns and microscopic pore structure morphology in coal are influenced by the coupled effects of temperature and pressure, and their effects on the spontaneous combustion (SC) characteristics of coal cannot be ignored. In this paper, two types of coal samples, lean coal and fat coal from high gas-prone SC mines, are used as test objects. A self-designed experimental platform for coupling gas adsorption and desorption with coal spontaneous combustion (CSC) and heating and oxidation was used. Firstly, orthogonal tests on the desorption of methane from coal under the coupling effect of different temperatures and pressures were carried out to obtain a gradual decrease of methane desorption from coal with increasing temperature under the same pressure conditions. The results show that the pore volume and specific surface area of coal show a monotonic decreasing pattern with increasing temperature and pressure, while the percentage of micropores and mesopores, which promote the oxygen reaction of coal, show an increasing trend. In addition, a comparative analysis of the characteristic temperature points of the first stage showed that the characteristic temperature points of the desorbed coal were higher than those of the original coal, reflecting the higher SC activity of the desorbed coal; and the crossover temperature points of the lean coal and the fat coal were 79 °C and 88 °C, respectively, after desorption during the heating and oxidation process, which also confirmed the high SC activity of the desorbed coal. Based on the above findings, the methane concentration calculation model of the mining area was applied to redraw the oxidation zone using the mining area of the 41,201 working face of Hongyang No. 2 Mine as an example, and the area was reduced by 39.5%. The research results of the paper can provide guidance for the prevention and control of fire hazards in mines with high gas-prone SC.

Coupled Effects of Temperature and Humidity on Fracture Toughness of Al-Mg-Si-Mn Alloy.

The combined effect of temperature and humidity on the fracture toughness of aluminium alloys has not been extensively studied, and little attention has been paid due to its complexity, understanding of its behaviour, and difficulty in predicting the effect of the combined factors. Therefore, the present study aims to address this knowledge gap and improve the understanding of the interdependencies between the coupled effects of temperature and humidity on the fracture toughness of Al-Mg-Si-Mn alloy, which can have practical implications for the selection and design of materials in coastal environments. Fracture toughness experiments were carried out by simulating the coastal environments, such as localised corrosion, temperature, and humidity, using compact tension specimens. The fracture toughness increased with varying temperatures from 20 to 80 °C and decreased with variable humidity levels between 40% and 90%, revealing Al-Mg-Si-Mn alloy is susceptible to corrosive environments. Using a curve-fitting approach that mapped the micrographs to temperature and humidity conditions, an empirical model was developed, which revealed that the interaction between temperature and humidity was complex and followed a nonlinear interaction supported by microstructure images of SEM and collected empirical data.

Microstructure and tensile properties of IN718 superalloy aged with temperature/stress coupled field

The microstructures and tensile properties of the IN718 superalloy aged with and without stress were investigated. The results showed that in the temperature/stress coupled field, the coarsening of the γ″ phase and precipitation of the δ phase in the alloy were significantly accelerated. The alloys aged with stress showed lower strength and plasticity compared to those without stress, indicating that the degradation of the tensile properties was accelerated by the applied stress when aging, and such degradation was explained as follows. The accelerated coarsening and quantity reduction of the γ″ phase was caused by the coupled effect of temperature and stress. This weakens the strengthening effect of the γ″ phase on the alloy and the ability to capture and accumulate dislocations. When many needle-like δ phases precipitated near the grain boundaries, many micro-cracks formed, propagated rapidly, and connected along the zones without γ″ phases. Such microcrack propagation was unstable, resulting in plastic deformation localization.

Laboratory investigation of coal sample permeability under the coupled effect of temperature and stress

Laboratory investigation of coal sample permeability under the coupled effect of temperature and stress

High-temperature failure mechanism and defect sensitivity of TC17 titanium alloy in high cycle fatigue

• Internal crack initiation with nanograins is found in TC17 alloy at 400 °C. • Oxygen-rich layer formed at high temperature affects surface crack initiation. • Fatigue strength of notched specimens is insensitive to high temperature. • A fatigue strength model is proposed including effect of temperature and defect. Crack initiation is an essential stage of fatigue process due to its direct effect on fatigue failure. However, for titanium alloys in high-temperature high cycle fatigue (HCF), the crack initiation mechanisms remain unclear and the understanding for the defect sensitivity is also lacking. In this study, a series of fatigue tests and multi-scale microstructure characterizations were conducted to explore the high-temperature failure mechanism, and the coupled effect of temperature and defect on TC17 titanium alloy in HCF. It was found that an oxygen-rich layer (ORL) was produced at specimen surface at elevated temperatures, and brittle fracture of ORL at surface played a critical role for surface crack initiation in HCF. Besides, internal crack initiation with nanograins at high temperatures was a novel finding for the titanium alloy. Based on energy dispersive spectroscopy, electron backscatter diffraction and transmission electron microscope characterizations, the competition between surface and internal crack initiations at high temperatures was related to ORL at surface and dislocation resistance in inner microstructure. The fatigue strengths of smooth specimens decreased at elevated temperatures due to the lower dislocation resistance. While the fatigue strengths of the specimens with defect were not very sensitive to the temperatures. Finally, a fatigue strength model considering the coupled effect of temperature and defect was proposed for TC17 titanium alloy.

Migration and deposition behavior of silica powder in saturated sand: coupled effects of temperature and flow rate

Migration and deposition behavior of silica powder in saturated sand: coupled effects of temperature and flow rate

Coupled effects of temperature and compressive strain on aging of silicone rubber foam

The coupled effects of temperature and compressive strain on aging behaviors and mechanisms of silicone rubber foam were investigated by conducting the accelerated aging tests. The silicone rubber foams subjected to various levels of temperature and compressive strain were characterized by Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, micro hardness, volume fraction, compression set, continuous stress relaxation, mechanical properties, and thermogravimetric analysis (TGA) etc. The ATR-FTIR results indicate that the complex oxidation reactions (crosslinking, chain scission, and oxidation of side chains) occurred simultaneously with the formation of oxidation products. The high temperature facilitated the increase in crosslinking density and enhanced the thermal stability of the foams, implying that the oxidation crosslinking predominated over chain scission leading to the formation of a denser network structure. The physical and mechanical properties of the foams underwent significant changes due to the oxidation reactions and the irreversible collapse of the porous microstructure. The elevated temperature and the compressive stress both have a direct effect on the degradation of the foam. The elevated temperature played a more important role in changes of the physical-mechanical properties and microstructure.

Coupled effect of temperature and stress on the microstructure and stress rupture behavior of 9% Cr-CrMoV dissimilar welded joints

Based on the practical application requirements, the weld rotor was chosen as a preferable candidate to adapt to the higher steam temperature. In this study, the rupture behavior and fracture mode for the 9% Cr-CrMoV dissimilar welded joints are investigated. The specimens both rupture in the heat affected zone of CrMoV steel with a ductile rupture mode. The rupture time of the specimen under lower stress at higher temperature is shorter than that under higher stress at lower temperature. Additionally, the microstructure observation shows that the increased temperature can accelerate the precipitation and growth of the second phase particles. The micro-voids caused by these particles can reduce the ductility of the welded joint and resultantly lead to the premature fracture.

Stability analysis of an unsaturated clay slope based on the coupled effect of temperature and saturation

In view of clay slope instability caused by environmental temperature and rainfall infiltration in summer and autumn, the mechanism of the effect of temperature and saturation on unsaturated clay slope stability is discussed. To achieve this objective, this study uses theoretical and numerical methods. Based on the theory of unsaturated clay and the law of heat conduction, the relationship between cohesion and matrix suction of unsaturated clay was derived considering the influence of temperature and saturation. Taking into consideration the effects of temperature and saturation, the coupling equation for the shear strength of unsaturated clay was constructed under conditions of rainfall infiltration. The coupling equation for temperature and saturation was used using the strength reduction method, and the slope stability was analysed using FLAC software. The results show that: (i) cohesion in the unsaturated clay slope increases with increasing depth; (ii) the safety factor is smaller when taking into consideration the coupled effect of temperature and saturation than when the temperature effect is not taken into consideration; and (iii) the clay slope is unstable when the coupled effect of temperature and saturation is taken into consideration, but is stable when the coupled effect of temperature and saturation is not considered and soil saturation reaches 80%. Thematic collection: This article is part of the Role of water in destabilizing slopes collection available at: https://www.lyellcollection.org/cc/Role-of-water-in-destabilizing-slopes

Coupled Effects of Temperature, Pressure, and pH on Water Oxidation Thermodynamics and Kinetics

Coupled Effects of Temperature, Pressure, and pH on Water Oxidation Thermodynamics and Kinetics

Comparative study of formability characteristics in deep drawing of DP 590 steel using analytical models

ABSTRACT The aim of the present work is to perfectly utilise the resources with minimal wastage of material by the implementation of theoretical models for prediction of different responses of deep drawing viz., limiting drawing ratio (LDR), and maximum drawing load (MDL). Initially, some trial and error experimental and finite element (FE) simulations are performed to find the coefficient of friction (COF) values under lubricated (L) and non-lubricated (NL) conditions which is difficult to find from experiments. The various processing conditions like temperature, blank holding pressure (BHP), blank diameter and lubrication are used as input. The coupled effect of temperature and lubrication helped in increasing the formability of the material and also reduced the maximum load required to draw the cup. The experimental limiting drawing ratio (LDR) was observed to be 1.933 under 400°C lubricated condition which is 3.53% more than other processing conditions. Further, several models namely: Leu, Whiteley, Hosford, Atkinson, Siebel, Siebel-Beissiwagner, Lange and Groover have been applied for the prediction of LDR and MDL among which Leu’s and Siebel’s analytical relation has displayed the least error of 2.452% and 7.977% respectively.

Apparatus for Coupled Effects of Suction, Temperature, and Stress on Thermal Conductivity of Unsaturated Sand

Abstract A suction-controlled thermo-mechanical apparatus was developed to measure thermal conductivity of unsaturated sand at different temperatures (5°C to 75°C) and isotropic net normal stresses (35 to 400 kPa). Coupled effects of temperature and stress level on thermal conductivity of unsaturated sand are investigated. Increases in confining stress cause an increase in thermal conductivity of the sand and are hysteretic with loading direction. Thermal conductivity increases appreciably as stress and temperature increase at intermediate degrees of saturation (S ∼ 0.3 to 0.75). Maximum thermal conductivity occurs at 75.5°C and 400 kPa when S = 0.54 where the value of thermal conductivity is about twice that at 5°C and 35 kPa. The results indicate that the apparatus has the capability to effectively measure thermal response of near-surface sand under ranges of naturally occurring changes in temperature, stress, and moisture content.

Study on Safety Performance of Building Finish Layer under Thermomechanical Coupling Condition

The building finish layer is a comprehensive structural system including the building exterior insulation system and building exterior finish. Combining with buildings has the advantage of reducing wall heat loss and building deformation caused by large temperature differences. Since the building finish layer is prone to cracking, hollowing, and peeling, during the application process, its safety needs to be studied and certified. This study prepares 20 groups of specimens, 15 anchor bolts in each group. The anchor bolt pull‐out strength test is carried out. Anchoring damage evolution law and failure mode of anchor bolts are investigated. And the influence of anchoring methods on the pull‐out bearing capacity is analyzed. In addition, ABAQUS finite element data simulation is carried out. The stress state of finish in thermomechanical coupling condition and without the effect of temperature are compared and analyzed. The influence factors of anchor bolt pull‐out strength and the influence of temperature load on the long‐term performance of building finish layer are obtained. The durability of the building finish layer is analyzed. The results show that the anchoring strength of the anchor bolt is positively correlated with the anchoring depth. The anchoring strength is influenced significantly by anchoring construction sequence and temperature. The stress under the coupled effect of temperature and load is greater than that of the single effect of load, and the stress distribution changes significantly. Due to thermal expansion and contraction, the anchor bolt would loosen, which is more prone to damage the building finish layer in a low temperature environment. The weight relationship of each influencing factor of the building finish layer is proposed. A systematic evaluation index system is established. The results of this study provide a basis for subsequent related research work and engineering applications.

Coupled Effect of Temperature and Strain Rate on Mechanical Properties of Steel Fiber-Reinforced Concrete

The dynamic mechanical properties of steel fiber-reinforced concrete (SFRC) under high temperature and high strain rate were studied using a split Hopkinson pressure bar (SHPB) of 74 mm in diameter. As it is difficult to achieve constant strain rate loading in SHPB experiments with high temperature and high strain rate, this paper first presents a method for determining the strain rate under non-constant strain rate loading conditions. This method is proposed to deal with experimental data under non-constant strain rate loading conditions. Then, the influences of temperature on the ultimate compressive strength, peak strain, and failure modes of SFRC under different strain rates were analyzed and the results show that SFRC has a strain rate hardening effect. This paper also points out that there is a strain rate threshold for SFRC. If the strain rate is less than the strain rate threshold, there is a temperature softening effect. Conversely, if the strain rate is greater than the strain rate threshold, there is a temperature hardening effect. Finally, the relationship between the ultimate compressive strength and fiber volume fraction, strain rate, and temperature is presented and the prediction results are consistent with the experimental data.

Coupled Effect of temperature and additions on the rheological behavior of concrete equivalent mortars (CEM)

The aim of this work is to study the influence of mineral additions on the rheological behavior of low impact environmental concrete with its concrete equivalent mortar (CEM) at different temperatures.The experimental study is carried out on cement-based CEM substituted by two additions namely, natural pozzolana (PZ) and marble powder (PM), with a substitution rate of 5 to 20%, a ratio of water on binder E / L = 0.5 and a percentage of superplasticizer based on polycarboxylates SP = 0.30%. The rheological parameters, the workability and the flow time of the mixtures were tested by a coaxial rheometer, a mini cone and the LCPC maniabilitimetre respectively at 10 ° C, 20 ° C and 30 ° C. The results show that the substitution of cement by natural pozzolana and marble powder in binary system generally improved viscosity and yield stress at 20°C and 30°C, while at 10°C natural pozzolana negatively affected the rheological parameters and workability.