Effect Of Temperature Cycling Research Articles

Temperature cycling effect on structural, optical and electrical properties of nanostructured sodium titanates

Sodium titanates represent a promising alternative for the construction of anodes for sodium-ion batteries. To study the electrical response of nanostructured sodium titanate samples under plausible temperature conditions, we evaluate the electrical impedance in the range of temperatures from −30 ∘C to 50 ∘C, and the effect of consecutive temperature cycling. Strong changes in electrical properties are observed during the first temperature cycle, followed by a stabilization in the consecutive cycles. This behavior is reversible when the sample is exposed to external conditions and room temperature for less than an hour. Probably a structural and surface water removal and a surface water reabsorption occur, affecting the charge carriers and with it the impedance. Structurally, no differences are detected before and after the cycles, nor when evaluating only the vacuum process. However, when the optical properties are evaluated we find non-reversible changes after the temperature cycles. The optical behavior after the temperature cycling becomes uniform, the same type of electronic defects become predominant and similar direct and indirect band gap values are obtained, regardless of the starting synthesis condition. These results have significant implications for potential technological applications of these materials.

Durability of MICP-reinforced calcareous sand in marine environments: Laboratory and field experimental study

As eco-friendly methods, microbial induced carbonate precipitation (MICP) method was used to reinforce the calcareous sand in the South China Sea in this paper. The durability characteristics and deterioration mechanism of MICP-reinforced calcareous sand under various environment factors were investigated synthetically based on the unconfined compressive strength, mass loss rate and microscopic morphology in laboratory and field experimental study. Results show that, the unconfined compressive strength value of the sample is only 35.19 % of the initial strength, while the mass loss rate is about 6.69 % after 30-days of field marine environment erosion. MICP-reinforced calcareous sand shows the strongest resistance to temperature cycles, followed by dry-wet cycles, coupling effect of temperature and dry-wet cycle and salt spraying with drying cycles. MICP-reinforced calcareous sand exhibits the worst resistance to the field marine conditions, but the integrity of the sample could still be maintained after 30-days of field tests. The deterioration mechanism of MICP-reinforced calcareous sand is consistent under the various environmental cycles. First, the weakly cemented calcium carbonate crystals on the sample surface fall off, and then the hard-shell layer on the sample surface became weaker under various erosion. Finally, the internal cemented structure of the sample was gradually destroyed. The results indicated the utilization value of the MICP method in ocean engineering, but it is necessary to enhance the performance of the MICP-reinforced calcareous sand to ensure its protective effect after a certain environmental impact cycle.

Effects of load level, dimensional effects and temperature conditions on the pressure sensitivity of short carbon fiber cementitious composites

Carbon fiber reinforced cementitious composites (CFRCC) are a kind of sensing materials in structural self-monitoring system. However, their performances still need to be enhanced. In this study, the effects of load level, dimensional effect, temperature and temperature cycles on the pressure sensitivity of CFRCC with hydroxyethyl cellulose (HEC) dispersant were systematically investigated. Simultaneously, the change rate of resistance was adopted to quantify the pressure and temperature sensitivity of CFRCC. It is found that the pressure sensitivity of CFRCC is stable as load level is below 50 per of the ultimate load. With the increasing size of the specimens, the compressive strength of CFRCC gradually declines whereas its change rate of resistance hikes quickly, both of which show obvious size effect. Furthermore, in the range of 5 °C to 80 °C, the resistivity of CFRCC demonstrates the effect of negative temperature coefficient (NTC), and the sensitivity coefficients of CFRCC tend to decrease with the increasing temperature. Compared with the sensitivity coefficient at 70 °C, the sensitivity coefficient of each specimen at 15 °C have increased by four times. In addition, the pressure sensitivity of CFRCC has significantly decreased after temperature cycles, and especially after 20 temperature cycles, CFRCC’s maximum change rate of resistance decreases by about 30% compared to the initial one. Therefore, CFRCC can be directly used in concrete structures to undertake the task of structural health self-monitoring.

Effect of Cyclic Temperature and Fatigue Load on the Performance of Bond Strength at High-Strength Concrete–UHPC Interface

One of the most important components of box beam bridges is the shear key that connects the box beams together. The shear keys in box beam bridges often fail at the interface. In recent years, ultrahigh-performance concrete (UHPC) has been successfully used to cast these shear keys. The current study investigates the effect of temperature cycles on bond performance between a high-strength concrete (HSC) box beam and UHPC shear key. The interfacial bond performance was evaluated by subjecting specimens to 60, 120, and 180 freeze-thaw (FT) cycles representing 1, 2, and 3 years of environmental exposure. Some direct tension specimens that were subjected to 180 FT cycles were additionally subjected to 1-Hz frequency fatigue cycles with stress reversals. Using the direct tension, pull-off, slant shear, and bishear assessment methods, the test results have demonstrated that the number of FT cycles did not affect bond performance in terms of strength and failure modes. The test results also showed that standard specifications underestimate the cohesion and friction coefficients evaluated using Mohr-Coulomb’s and Carol’s approaches for concrete placed against intentionally roughened surfaces. Furthermore, it was found that fatigue loading with stress reversals did not diminish the direct tensile bond strength of the specimens.

Effect of temperature and thermal cycles on the mechanical behavior of sandwich structure with entangled metallic wire mesh

As a novel rigid–flexible heterogeneous material, the sandwich structure with the entangled metallic wire mesh (EMWM) core has obvious advantages on thermo-mechanical performances due to its all-metallic material and structure. Of particular and complexity is the crosslinked microstructure of EMWM core, leading to ambiguous mechanical behaviors of the sandwich structure under gradient temperature and thermal cycles. In the work, the compressive and shear properties of the sandwich structure in different structure directions of the EMWM core were investigated, as well as the thermal cycling failure. The experimental result reveals that the sandwich structure has an excellent compression performance when the temperature below 750 °C. With the temperature increasing, the shear performance of the sandwich structure exhibits a trend from rise to decline. Furthermore, the shear property of the sandwich structure in the transversal direction is better than that in the longitudinal direction. And, the effect of thermal cycle on the failure behaviors (including, the deformation of face-sheet and the delamination of EMWM core) of the sandwich structure was observed. In the number of thermal cycles ranged of 50–200, there are few declinations of the compression and shear performance of the sandwich structure.

Effect of temperature cycling on the leakage mechanism of TSV liner

The temperature cycling tests of 0, 100 and 300 cycles were carried out on the double blind TSV samples, and the TSV liner microstructure, I-V and CV of the temperature cycled samples were tested. The failure mechanism of TSV liner during temperature cycling was clarified. Combined with microstructure observation, the process of TSV liner SiO2 degradation caused by temperature cycling was studied. The result shows that, with the increasing cycles from 0 to 100 and 300, the morphology of TSV liner gradually getting defective with exhibition of microcracks and microvoids initiation along sidewall interface compared to the 0-cycled TSV samples. With further increasing of cycles to 300, the interfacial penetrating cracks occurred within sidewall interface. This microstructure evolution are directly relative to transition of its failure mechanism. The failure mechanism is dominated by the Schottky emission leakage for the 0-cycled and 100-cycled TSV samples, which will translate to the mechanical cracking with the generation of penetration cracking along the TSV liner for the 300-cycled TSV samples. Moreover, the defect density in the positively charged SiO2 layer at the TSV liner increased by 120 % before and after 100 temperature cycles. These defects are caused by the severe degradation of SiO2 layer introduced by 100 temperature cycles.

The effects of atypical diurnal temperature cycles on regression-based downscaling of daily temperature extrema in the Central United States

The effects of atypical diurnal temperature cycles on regression-based downscaling of daily temperature extrema in the Central United States

Effects of Temperature and Thermal Cycles on Frictional Behavior of Kaolin–Concrete Interface

Effects of Temperature and Thermal Cycles on Frictional Behavior of Kaolin–Concrete Interface

Aggregate Gradation Variation on the Properties of Asphalt Mixtures

National highway projects present a crucial role in economic growth, as they have a great influence on the national income. Therefore, the decision makers plan to construct these projects at a rapid rate. To achieve the just aforesaid, the utilization of asphalt of adequate quality and gradation is essential. The key problem which lies in recent decades is that many types of asphalt mixtures are rejected and reconstructed in the site due to the gradation variation of aggregates in the asphalt mixture which waste raw materials, cost and time. Thus, this research seeks to assess the possibility of accepting asphalt mixes with aggregates gradation variation (within the range from +4% above the upper specification limit to −2% below the lower specification limit). A wearing surface mix with gradation 3B was prepared according to the Egyptian code. The gradation variation was presented as the aggregate gradation is out of the specification limits during Hot Mix Asphalt (HMA) production. The aggregate gradations lie above and below the upper and lower specification limits, respectively, by ±2%, ±4% and ±6%. The design gradation of the control mix was included as a reference case. The different mix properties were measured using the Marshall Mix design method. Then, the performance of HMA mixes was evaluated under the effects of high temperature and water cycles through applying wheel loading tracking and Indirect Tensile Strength (ITS) tests. The results show that the 3B mixes with a gradation within a range of +4% to −2% of the upper and lower specification limits recorded the lowest rutting depth and the highest water damage resistance in hot regions compared to ordinary asphalt mixes. In summary, the new aggregate gradation limits will provide a reference for the design of asphalt mixture in hot climate regions.

Microstructure evolution and mechanical behavior of copper through‑silicon via structure under thermal cyclic loading

The through‑silicon via (TSV) technique is widely applied in the latest highly integrated circuits packaging. However, one of the prevalent failure modes is caused by thermal cyclic loading from power fluctuations of the chip. Different thermal expansion coefficients of Cu and Si could cause a mismatch of thermal stresses under temperature cycling, which will lead to thermal fatigue failure of structure. In the current study, thermal cycling experiments are performed on Cu-TSV samples to investigate the effect of temperature cycling on microstructure evolution and mechanical behavior. The electron backscatter diffraction analysis is conducted to investigate the grain size, local texture and microstructure evolution of Cu. Based on the crystal plasticity theory, a constitutive model considering temperature and grain size effect is developed, and the parameters are calibrated. Combining crystal plasticity theory and finite element analysis, the effects of grain orientation and different grain sizes on the stress distribution and plastic work evolution of TSV structure under thermal cyclic loading are investigated.

Effects of Temperature and Thermal Cycles on the Elastic Shear Modulus of Saturated Clay

Effects of Temperature and Thermal Cycles on the Elastic Shear Modulus of Saturated Clay

Lipid Biomarkers From Microbial Mats on the McMurdo Ice Shelf, Antarctica: Signatures for Life in the Cryosphere.

Persistent cold temperatures, a paucity of nutrients, freeze-thaw cycles, and the strongly seasonal light regime make Antarctica one of Earth’s least hospitable surface environments for complex life. Cyanobacteria, however, are well-adapted to such conditions and are often the dominant primary producers in Antarctic inland water environments. In particular, the network of meltwater ponds on the ‘dirty ice’ of the McMurdo Ice Shelf is an ecosystem with extensive cyanobacteria-dominated microbial mat accumulations. This study investigated intact polar lipids (IPLs), heterocyte glycolipids (HGs), and bacteriohopanepolyols (BHPs) in combination with 16S and 18S rRNA gene diversity in microbial mats of twelve ponds in this unique polar ecosystem. To constrain the effects of nutrient availability, temperature and freeze-thaw cycles on the lipid membrane composition, lipids were compared to stromatolite-forming cyanobacterial mats from ice-covered lakes in the McMurdo Dry Valleys as well as from (sub)tropical regions and hot springs. The 16S rRNA gene compositions of the McMurdo Ice Shelf mats confirm the dominance of Cyanobacteria and Proteobacteria while the 18S rRNA gene composition indicates the presence of Ochrophyta, Chlorophyta, Ciliophora, and other microfauna. IPL analyses revealed a predominantly bacterial community in the meltwater ponds, with archaeal lipids being barely detectable. IPLs are dominated by glycolipids and phospholipids, followed by aminolipids. The high abundance of sugar-bound lipids accords with a predominance of cyanobacterial primary producers. The phosphate-limited samples from the (sub)tropical, hot spring, and Lake Vanda sites revealed a higher abundance of aminolipids compared to those of the nitrogen-limited meltwater ponds, affirming the direct affects that N and P availability have on IPL compositions. The high abundance of polyunsaturated IPLs in the Antarctic microbial mats suggests that these lipids provide an important mechanism to maintain membrane fluidity in cold environments. High abundances of HG keto-ols and HG keto-diols, produced by heterocytous cyanobacteria, further support these findings and reveal a unique distribution compared to those from warmer climates.

The Effect of Temperature Cycling on the Magnetic Degradation and Microstructure of a Zn-Coated NdFeB Magnet

Temperature cycling tests in various temperature ranges were carried out to investigate the magnetic degradation of the Zn-coated NdFeB magnet. The losses of the surface magnetic field and magnetic flux were well fitted by using an index model. Compared with the lower limit temperature, the upper limit temperature had more obvious effect on the magnetic degradation. Once the upper limit temperature exceeded ≥160 °C, the magnetic degradation mainly occurred during the first cycle, which was different from the gradual decline with an increase in cycle number at a temperature of ≤140 °C. Moreover, the temperature cycling with a maximum upper limit temperature of 180 °C led to a loss of the remanence intensity, while the coercivity remained stable. Microstructure and element distribution analysis revealed that the oxidation of the Zn coating layer during the temperature cycling causes its cracking and an insertion of the oxygen element into the NdFeB substrate. The Nd-, Pr-rich phase at grain boundaries provided diffusion channels for oxygen elements, leading to a surface oxidation of NdFeB grains.

Interactive effects of ocean acidification, ocean warming, and diurnal temperature cycling on antioxidant responses and energy budgets in two sea urchins Strongylocentrotus intermedius and Tripneustes gratilla from different latitudes

To accurately predict the fitness of marine ectotherms under the climate change scenarios, interactive effects from multiple environmental stressors should be considered, such as ocean acidification (OA), ocean warming (OW) and diurnal temperature cycling (DTC). In this work, we evaluated and compared the antioxidant capacity and metabolism homeostasis of two sea urchins, viz. the temperate species Strongylocentrotus intermedius and the tropical species Tripneustes gratilla, in response to oceanic conditions under a climate change scenario. The two species were treated separately/jointly by acidic (pH 7.6), thermal (ambient temperature + 3 °C), and temperature fluctuating (5 °C fluctuations daily) seawater for 28 days. The activities of antioxidant enzymes (catalase and superoxide dismutase) and the cellular energy allocation in the urchins' gonads were assessed subsequently. Results showed that exposure to OA, OW, and DTC all induced antioxidant responses associated with metabolism imbalance in both S. intermedius and T. gratilla. The physiological adjustments and energy strategies towards exposure of OA, OW, and DTC are species specific, perhaps owing to the different thermal acclimation of species from two latitudes. Moreover, decrease of cellular energy allocation were detected in both species under combined OA, OW, and DTC conditions, indicating unsustainable bioenergetic states. The decrease of cellular energy allocation is weaker in T. gratilla than in S. intermedius, implying higher acclimation capacity to maintain the energy homeostasis in tropical urchins. These results suggest that climate change might affect the population replenishment of the two sea urchins species, especially for the temperate species.

Thermal hysteresis in microtubule assembly/disassembly dynamics: The aging-induced degradation of tubulin dimers

The assembly/disassembly of biological macromolecules plays an important role in their biological functionalities. Although the dynamics of tubulin polymers and their super-assembly into microtubule structures is critical for many cellular processes, details of their cyclical polymerization/depolymerization are not fully understood. Here, we use a specially designed light scattering technique to continuously examine the effects of temperature cycling on the process of microtubule assembly/disassembly. We observe a thermal hysteresis loop during tubulin assembly/disassembly, consistently with earlier reports on the coexistence of tubulin and microtubules as a phase transition. In a cyclical process, the structural hysteresis has a kinetic component that depends on the rate of temperature change but also an intrinsic thermodynamic component that depends on the protein topology, possibly related to irreversible processes. Analyzing the evolution of such thermal hysteresis loops over successive cycles, we found that the assembly/disassembly ceases after some time, which is indicative of protein aging leading to its inability to self-assemble after a finite number of temperature cycles. The emergence of assembly-incompetent tubulin could have major consequences for human pathologies related to microtubules, including aging, neurodegenerative diseases and cancer.

Effects of temperature and thermal cycles on the mechanical properties of expanded polystyrene foam

Understanding the effects of high temperature and thermal cycles on the mechanical properties of expanded polystyrene (EPS) foam is critical for its use in sandwich panels. This paper presents an experimental investigation of these effects in typical environmental conditions that exist in construction applications. A total of 117 small specimens were cut from metal-faced sandwich panels with EPS core and were exposed to different numbers of thermal cycles and/or sustained high temperatures. The specimens were then loaded under compression, tension, and four-point bending for evaluating the degradation of the mechanical properties of the foam. The thermal cycles reflect typical surface temperature during daily summer conditions, with a period of 24 h each and with a temperature varying between 24°C to 80°C. The results show that the modulus of elasticity of EPS foam in compression reduced by about 38% after exposure to thermal cycles for 45 days, whereas the tensile and shear moduli reduced by about 5.7% and 13.8%, respectively. Exposure to sustained high temperature after thermal cycles led to larger degradation of the elastic and shear moduli in the range of 38%–50%. These degradations can lead to early failures in applications that rely on the EPS foam as a structural component like in insulating sandwich panels.

Ускоренные ресурсные испытания отечественных опытных образцов эластомерных уплотнений для системы подводной добычи нефти и газа

This work was performed with the aim of confirming the competence of Russian industrial enterprises in the development of subsea production system facilities and applies to elastomeric seals of Christmas tree and tubing hanger, and is intended to confirm the service life of elastomeric seals. The essence of the method is to test the cyclic effect of pressure, temperature and several cycles of axial movement on not aged (new) seals and on aged (at the end of the warranty period of storage and operation) seals.

Effect of Temperature Cycling on IMC Growth and Solder Joint Strength of SAC305 Solder Alloy and Low Silver Alloy REL61

This work deals with the comparison of the standard SAC305 (Sn 96.5 %; Ag 3 %; Cu 0.5 %) solder alloy with melting temperature between 217 - 220 °C and an alternative alloy REL61 (SnBiAgCu) with lower silver content and melting temperature in the range of 208 - 215 °C in terms of IMC layer growth during thermal cycling and its effect on the shear strength of the solder joints. The test PCBs were soldered using two different temperature profiles and the temperature cycling was performed under two different conditions. No negative effect of REL61 solder alloy on the growth of the IMC layer under thermal stress and on the subsequent shear strength of the solder joint was found. From this point of view, the REL61 solder alloy can be used as a replacement for the SAC305 solder alloy.

DEM simulation of cyclic thermal consolidation tests considering the effects of relative density and temperature magnitude

The effect of temperature cycles on the granular particles surrounding energy-related structures has received more and more attention. In this paper, thermal consolidation tests with granular materials were simulated by the discrete element method, and different densities and magnitudes of temperature change were considered. The features of densification of the granular materials are effectively reflected in the simulation process. It demonstrates that thermal cycling induces a rising of the stress level and accumulation of volumetric strain within granular materials. The evolution of coordination number and anisotropy was investigated. It demonstrates that temperature cycling induces a significant stress dilation and strain contraction within granular materials, while the corresponding granular anisotropy paraments such as contact number, normal contact force, and tangential contact force has also a small change. Moreover, the relative density and the magnitude of temperature change have a significant effect on the micro-anisotropy of the material.

Paintings crack initiation time caused by microclimate

The current paper aims to use an irreversible cohesive zone model to investigate the effects of temperature and relative humidity cycles on multilayer thin-film paintings. The homogenous one-dimensional paint layers composed of alkyd and acrylic gesso over a canvas foundation (support) with known constant thicknesses are considered as the mechanical model of painting. Experimental data was used for mathematical modeling of canvas as a linear elastic material and paint as a viscoelastic material with the Prony series. Growth of crack through the length of the paint layers under the low amplitude cyclic stresses are modeled by cyclic mechanical loadings. The three-dimensional system is modeled using a finite element method. Fatigue damage parameters such as crack initiation time and maximum loads are calculated by an irreversible cohesive zone model used to control the interface separation. In addition, the effects of initial crack length and layers thickness are studied. With the increase of the painting thickness and/or the initial crack length, the value of the maximum force increases. Moreover, by increasing the Relative Humidity (RH) and the temperature difference at loading by one cycle per day, the values of initiation time of delamination decrease. It is shown that the thickness of painting layers is the most important parameter in crack initiation times and crack growth rate in historical paintings in museums and conservation settings.