Статті в журналах: "Thermal solicitations"

1

Zhang, Jiamin, Daniel Dias, Qiujing Pan, Chunjing Ma, and Cristina de Hollanda Cavalcanti Tsuha. "Long-Term Thermo-Hydraulic Numerical Assessment of Thermo-Active Piles—A Case of Tropical Soils." Applied Sciences 12, no. 15 (July 29, 2022): 7653. http://dx.doi.org/10.3390/app12157653.

Повний текст джерела

Анотація:

Thermo-active piles are an upcoming technology for the utilization of subsurface geothermal energy in urban areas. This environmentally friendly technology has already been widespread for the heating and cooling of buildings in temperate regions, whereas in tropical regions it is still limited due to their unbalanced energy demands. This paper presents 3D thermo-hydraulic coupled numerical simulations to assess the long-term performance of thermo-active pile systems in tropical environments for different energy demands. The simulations are based on real data (in situ tests and field investigations) considering three typical thermal solicitations, thereby maintaining their practical relevance. Moreover, the energy exchange within soil control volumes is quantified based on an approach that allows calculating conductive and advective divergence. Parametric analyses regarding thermal solicitation, pile diameter, and groundwater flow are also performed. The results indicate that groundwater flow plays the most important role in improving the thermal balance of thermo-active piles.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Crăciun, Radu Cristian, Sergiu Stanciu, Ramona Cimpoeşu, Florin Săndulache, Adela Ioana Ursanu Dragos, and Mihai Axinte. "Smart Alloys for Automotive Bumpers." Applied Mechanics and Materials 809-810 (November 2015): 578–83. http://dx.doi.org/10.4028/www.scientific.net/amm.809-810.578.

Повний текст джерела

Анотація:

Bumper beam absorbs the accidental kinetic energy by deflection in low-speed impact and by deformation in high-speed impact. Based on the last years necessity of lighter materials and safer usage of vehicles we try to come with a new class of materials for bumper systems. Analyze of metallic materials is cheaper when the analyze take place on a computer avoiding the metallic loss or energy consume. We present few results obtained in Catia software about the behavior of some metallic materials under external solicitations in function of the mechanical properties of metallic elements, geometry of the element, restrains and solicitation points. Shape memory alloy are smart materials that can use the external mechanical energy damping to thermal energy in bumper applications. In martensite to austenite domain we observe an increase of damping mechanical capacity with possible applications in bumper systems.

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Mustapha, Feriel, Damien Guilbert, and Mohammed El-Ganaoui. "Investigation of Electrical and Thermal Performance of a Commercial PEM Electrolyzer under Dynamic Solicitations." Clean Technologies 4, no. 4 (September 26, 2022): 931–41. http://dx.doi.org/10.3390/cleantechnol4040057.

Повний текст джерела

Анотація:

Hydrogen generation through electrolyzers has gained a growing interest from researchers and industries to decarbonize transportation and electricity production. The performance of electrolyzers is strongly dependent on their operating conditions, such as the supply current, temperature, and pressure. To meet near-zero emissions, the electrolyzer must be supplied by low-carbon energy sources. Therefore, renewable energy sources must be considered. However, these sources are strongly linked with the weather conditions, so they have a high dynamic behavior. Therefore, this article is focused on the investigation of the effects of these dynamic solicitations on the electrical and thermal performance of electrolyzers. In this study, a proton exchange membrane (PEM) has been chosen to carry out this investigation. Experimental tests have been performed, emphasizing the relationship between the electrical and thermal performance of the PEM electrolyzer. The purpose of this work is to provide an optimal scenario of the operation of the electrolyzer under dynamic solicitations and consequently, to decrease the degradation of the electrolyzer.

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Rammal, D., H. Mroueh, and S. Burlon. "Impact of thermal solicitations on the design of energy piles." Renewable and Sustainable Energy Reviews 92 (September 2018): 111–20. http://dx.doi.org/10.1016/j.rser.2018.04.049.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Antonaci, Paola, and Davide Masera. "Mechanical Behavior of Structural Concrete Made with Recycled Aggregates from Tunnel Excavation." Key Engineering Materials 452-453 (November 2010): 121–24. http://dx.doi.org/10.4028/www.scientific.net/kem.452-453.121.

Повний текст джерела

Анотація:

The results of an experimental study concerning the behavior of concretes made with recycled aggregates under repeated mechanical and thermal actions are presented. A comparison with the performances achieved by similar concretes made with traditional aggregates in the same working conditions eventually made it possible to estimate the actual quality and durability of the recycled concretes examined and identify possible limitations in their use. The laboratory protocol here adopted is suggested as a practical experimental procedure to test hardened concretes and pre-qualify their performances with respect to compressive actions and thermal solicitations.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Maghsoodi, S., and O. Cuisinier. "Energy pile skin friction at interface in clays under temperature cycles." Géotechnique Letters 12, no. 3 (September 1, 2022): 1–24. http://dx.doi.org/10.1680/jgele.21.00153.

Повний текст джерела

Анотація:

In energy geostructures the long-term shaft resistance is affected by cyclic thermo-mechanical loads associated to structural loads and cyclic thermal solicitations. This study aims to investigate the effect of monotonic and cyclic thermal loads on normally consolidated and overconsolidated kaolin clay-rough steel interface. The peak shear stress of interface increased with temperature while the critical state shear strength remained unchanged. For cyclic temperature tests, with applying 10 temperature cycles (5-60°C) to normally consolidated kaolin clay interface, significant thermal contraction was observed but the shear strength increased as much as one single heating test. Normally consolidated interface contracted upon heating while overconsolidated samples dilated. These results highlighted the impact of thermal cycles on clayey interface which was stress history dependent.

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Le Touz, Nicolas, Jean Dumoulin, Gianluca Gennarelli, and Francesco Soldovieri. "A joint thermal and electromagnetic diagnostics approach for the inspection of thick walls." Geoscientific Instrumentation, Methods and Data Systems 6, no. 1 (February 8, 2017): 81–92. http://dx.doi.org/10.5194/gi-6-81-2017.

Повний текст джерела

Анотація:

Abstract. In this study, we present an inversion approach to detect and localize inclusions in thick walls under natural solicitations. The approach is based on a preliminary analysis of surface temperature field evolution with time (for instance acquired by infrared thermography); subsequently, this analysis is improved by taking advantage of a priori information provided by ground-penetrating radar reconstruction of the structure under investigation. In this way, it is possible to improve the accuracy of the images achievable with the stand-alone thermal reconstruction method in the case of quasi-periodic natural excitation.

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Chacón, L., J. Viña, A. Argüelles, R. Zenasni, and I. Viña. "Evaluación del comportamiento mecánico de compuestos PEI â fibra de vidrio ante solicitaciones térmicas." Boletín de la Sociedad Española de Cerámica y Vidrio 43, no. 2 (April 30, 2004): 420–22. http://dx.doi.org/10.3989/cyv.2004.v43.i2.557.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Baldinelli, Giorgio, Francesco Bianchi, Agnieszka A. Lechowska, and Jacek A. Schnotale. "Dynamic thermal properties of building components: Hot box experimental assessment under different solicitations." Energy and Buildings 168 (June 2018): 1–8. http://dx.doi.org/10.1016/j.enbuild.2018.03.001.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Seng, Billy, Camille Magniont, Sandra Gallego, and Sylvie Lorente. "Behavior of a hemp-based concrete wall under dynamic thermal and hygric solicitations." Energy and Buildings 232 (February 2021): 110669. http://dx.doi.org/10.1016/j.enbuild.2020.110669.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Alvear, D., J. A. Capote Abreu, M. Lázaro, J. Crespo, I. Fletcher, S. Welch, and J. Torero. "Modelado de las solicitaciones de los elementos estructurales de hormigón en edificios de gran altura en incendios reales." Informes de la Construcción 63, no. 522 (June 1, 2011): 83–91. http://dx.doi.org/10.3989/ic.09.005.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Ziouche, A., M. Zergoug, N. Boucherrou, H. Boudjellal, M. Mokhtari, and S. Abaidia. "Pulsed eddy current signal analysis of ferrous and non-ferrous metals under thermal and corrosion solicitations." Russian Journal of Nondestructive Testing 53, no. 9 (September 2017): 652–59. http://dx.doi.org/10.1134/s1061830917090108.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Avram, Petru, Marius Stelian Imbrea, Bogdan Istrate, Sorin Iacob Strugaru, Iulian Cucos, Catalina Axinte, and Corneliu Munteanu. "Wear Resistance and XRD Analyses of CMoCuNiCrSiBO Coatings Obtained by Thermal Deposition on OLC45 Substrate." Applied Mechanics and Materials 659 (October 2014): 10–15. http://dx.doi.org/10.4028/www.scientific.net/amm.659.10.

Повний текст джерела

Анотація:

Idlers are machine elements which are subjected to friction solicitations. The geometry, dimensions and weight can’t be modified that is why we decided to modify the contact surface by coating. We have chosen the steel type OLC 45 and we coated it with CMoCuNiCrSiBO by thermal deposition. The selection of these materials was made after a detailed study of the literature. After we obtained the samples, we subjected them to qualitative analyses SEM and XRD and to Quantitative analysis – wearing – destructive test where we obtained the friction coefficient between two coated surfaces [1]. We made the samples which we have analyzed by X-Ray Diffraction and we obtained the quality of the coating [2]. The results showed that the new material has a better structure than the basic material, and we can estimate a high durability of the machine elements coated. On friction test we have determined friction coefficient value.

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Avram, Petru, Marius Stelian Imbrea, Bogdan Istrate, Sorin Iacob Strugaru, Iulian Cucos, Catalina Axinte, and Corneliu Munteanu. "Wear Resistance and XRD Analyses of CNiCrSiBO Coatings Obtained by Thermal Deposition on OLC45 Substrate." Applied Mechanics and Materials 659 (October 2014): 16–21. http://dx.doi.org/10.4028/www.scientific.net/amm.659.16.

Повний текст джерела

Анотація:

In army industry are some of machine elements that are subjected to wear solicitations and must have a high wear resistance. The impact of their damage and also their maintenance costs are very high, that is why we proposed to improve their performances. Researches in surface engineering allow the obtaining of new systems of materials by coating the base material surface with other material having superior properties. In order to improve the machine elements durability, we proposed to obtain a new system of materials by thermal deposition. We have chosen the steel type OLC45 as base material and we coated it with CNiCrSiBO. We made the samples which we have analyzed by X-Ray Diffraction and we obtained the quality of the coating. The results showed that the new material has a better structure than the base material, and we can estimate a high durability of the machine elements coated.

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Mann, Ruddy, Vincent Magnier, Itziar Serrano-Munoz, Jean-Francois Brunel, Florent Brunel, Philippe Dufrenoy, and Michele Henrion. "Non-linear mechanical behavior of a sintered material for braking application using digital image correlation." Mechanics & Industry 18, no. 6 (2017): 601. http://dx.doi.org/10.1051/meca/2017031.

Повний текст джерела

Анотація:

Friction materials for braking applications are complex composites made of many components to ensure the various performances required (friction coefficient level, low wear, mechanical strength, thermal resistance, etc.). The material is developed empirically by a trial and error approach. With the solicitation, the material evolves and probably also its properties. In the literature, the mechanical behavior of such materials is generally considered as linear elastic and independent of the loading history. This paper describes a methodology to characterize the mechanical behavior of such a heterogeneous material in order to investigate its non-linear mechanical behavior. Results from mechanical tests are implemented into material laws for numerical simulations. Thanks to the instrumentation, some links with the microstructure can also be proposed. The material is made of a metallic matrix embedding graphite and ceramic particles and is manufactured by sintering. It is used for dry friction applications such as high-energy brake for trains, cars and motorcycles. Compression tests are done with digital image correlation to measure full-filled displacement. It allows to calculate strain fields with enough resolution to identify the material heterogeneity and the role of some of the components of the formulation. A behavior model of the material with plasticity and damage is proposed to simulate the non-linear mechanical behavior and is implemented in an FEM code. Results of mechanical test simulations are compared with two types of experiments showing good agreement. This method thus makes it possible to determine mechanical properties at a virgin state but is extensible for characterizing a material having been submitted to braking solicitations.

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Cazajus, V., B. Lorrain, H. Welemane, Y. Paranthoen, and M. Karama. "Thermo-mechanical behaviour of ceramic metal brazed assemblies." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 222, no. 4 (October 1, 2008): 291–97. http://dx.doi.org/10.1243/14644207jmda195.

Повний текст джерела

Анотація:

This study investigates the effects of residual stresses developed during brazing on the performance of brazed ceramic metal joints. The thermal expansion gradient between ceramic and metallic materials leads to the development of such stresses during the cooling phase of the brazing process, which consequently reduce the strength of these composite structures. Here, the objective is to compare the failure behaviour of various assemblies observed during experimental tests and obtained through numerical simulations. In order to get a representation consistent with the physical mechanisms involved, these simulations must account for the brazing phase giving rise to residual stresses before applying in use solicitations to brazed joints. This paper focuses on the tensile strength of ceramic metal joints, for which two brittle failure modes (within the ceramic or at the interface) are observed during the experimental tests.

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Hernández, M. F., P. V. López, A. Violini, G. Suárez, M. S. Conconi, and N. M. Rendtorff. "Dense alumina-mullite composite ceramics from alumina and spodumene-albite feldspar binary mixtures: Processing and properties." Science of Sintering 51, no. 4 (2019): 445–58. http://dx.doi.org/10.2298/sos1904445h.

Повний текст джерела

Анотація:

A processing strategy for obtaining alumina-spodumene ceramics from fine commercial powders is presented. In this work, a spodumene addition to calcined alumina powder was performed and their proportion was explored between 15 and 45 wt%. The industrial spodumene presented secondary phases, mainly albite and quartz. Mechanical properties were evaluated. Although they were lower than those of sintered alumina, based on the achieved values an adequate behavior in structural applications can be assumed, especially taking into account that the better mechanical behavior was coupled with the lower thermal expansion. Relatively low thermal expansion( ? 5 x 10-1?C-1) behaviors were observed in one of the developed materials. Noncrystalline phases containing lithium were detected. We assume that all the lithium oxide incorporated through the spodumene is in the glassy phase after the sintering of the materials. This difference in lithium concentration in the composition of the resulting glass affected the thermal expansion of the developed materials. Particularly with low lithium content (30 wt% of additive) the material performance was enhanced. This, together with the mechanical behavior, encourages structural applications with high thermomechanical solicitations. With the information gathered, a wide range of materials with specific properties can be obtained by modulating the spodumene-alumina proportion only.

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Mammeri, Abdelhamid, and Mostefa Lallam. "Elaboration of an Analytical Formula for the Calculation of the Surface Temperature." Civil Engineering Journal 5, no. 10 (October 21, 2019): 2260–69. http://dx.doi.org/10.28991/cej-2019-03091409.

Повний текст джерела

Анотація:

Pavement structures are sometimes subject to repeated dimensional variations of thermal origin generating mechanical stresses that may be detrimental to their durability. Among the most frequently observed degradations, by these stress, are the transverse cracks whose frequency, depth, and variable openings reduce the ride comfort. In this context, where such solicitations are preponderant and the strong variation is noticed on the surface, an analytical approach for calculating the surface temperature of a flexible pavement has been proposed. This approach is able to deal with the transient thermal problem including the phenomenon of ambient temperature and the influx of solar flux specifically for arid regions where the sky is often clear. This approach is adopted because it proposes a simplified calculation of the surface temperature. The model was built on a database measured on the experimental pavement of the laboratory of Egletons GEMH (France), using the calculation code Eureqa formulate. Although neglected in the domain's literature, the meteorological parameters (air temperature and solar flux) are taken into consideration in the analytic function because they give good prediction. The model has practical meanings to predicting the maximum, minimum, and amplitude of the pavement surface temperature. Hence, a good surface temperature assessment provides a key factor for further thermal cracking modeling.

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Dahanni, Hiam, Aya Rima, Kamilia Abahri, Chady El Hachem, and Hassan Assoum. "Impact of the 3D morphology on the hygro-thermal transfer of hygroscopic materials: application to spruce wood." Journal of Physics: Conference Series 2069, no. 1 (November 1, 2021): 012008. http://dx.doi.org/10.1088/1742-6596/2069/1/012008.

Повний текст джерела

Анотація:

Abstract Spruce wood is a bio-based material that is well known in the building construction field because of its good thermal and acoustic properties. It has a heterogeneous anatomical structure and also hygroscopic nature which offers the possibility to swell or shrink–in accordance to–relative humidity solicitations. In this context, the aim of this paper is to investigate the influence of the microstructure of spruce wood on the mechanisms of heat and mass transfers. The novelty of this article is that a real 3D spruce wood structure is taken into account to model hygrothermal transfer within the material. A 3D X-ray micro-tomography was investigated for the reconstruction of the material at a resolution of 3.35 μm/pixel. Hygrothermal model was developed in order to predict the influence of the anatomical structure of wood on the material behaviour. The resulting 3D temperature and relative humidity profiles show a significant dependence on the morphological structure of the material and the mechanisms that are at the microscopic scale have an influence on the macroscopic scale.

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Eid, Salam, Chawki Lahoud, Marwan Brouche, Mohamed Hmadi, and Christy Lahoud. "Modeling and Validation of the Enthalpy-Temperature Curve for Phase Change Materials." Materials Science Forum 1050 (January 18, 2022): 149–59. http://dx.doi.org/10.4028/www.scientific.net/msf.1050.149.

Повний текст джерела

Анотація:

Thermo-dynamical studies have proven that introducing phase change materials (PCM) to the building’s envelope could decrease the heat transfer exchange rate and maintain the inside thermal comfort for long periods. Among all types of PCM applications in the building’s envelope, the cement-plaster is the most cost-effective. The composite PCM-plaster material was formed by mixing predefined mass percentages of PCM microcapsules with local cement, sand, and water. This paper aims to establish a direct solution for the enthalpy-temperature variations for the PCM composite material. This solution will enable to study the effect of the composite material on buildings' energy loads. The obtained model has been also validated against experimentally tested samples and results were in complete agreement. This model will enable researchers to obtain the correct heat response when the envelope of the building is subjected to different external weather solicitations.

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Roşu, Radu, Viorel-Aurel Şerban, Alexandra Bucur, Mihaela Popescu, and Dragoş Uţu. "Caracterisation of Titanium Nitride Layers Deposited by Reactive Plasma Spraying." Journal for Technology of Plasticity 36, no. 1 (January 1, 2011): 17–24. http://dx.doi.org/10.2478/v10211-011-0003-2.

Повний текст джерела

Анотація:

Caracterisation of Titanium Nitride Layers Deposited by Reactive Plasma SprayingForming and cutting tools are subjected to the intense wear solicitations. Usually, they are either subject to superficial heat treatments or are covered with various materials with high mechanical properties. In recent years, thermal spraying is used increasingly in engineering area because of the large range of materials that can be used for the coatings. Titanium nitride is a ceramic material with high hardness which is used to cover the cutting tools increasing their lifetime. The paper presents the results obtained after deposition of titanium nitride layers by reactive plasma spraying (RPS). As deposition material was used titanium powder and as substratum was used titanium alloy (Ti6Al4V). Macroscopic and microscopic (scanning electron microscopy) images of the deposited layers and the X ray diffraction of the coatings are presented. Demonstration program with layers deposited with thickness between 68,5 and 81,4 μm has been achieved and presented.

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Bensayah, Amina, Hamida Bencheikh, and Amina Abdessemed. "Mzabite Heritage in Southern Algeria: What Bioclimatic Lessons can Be Learned to Optimize Thermal Comfort?" MATEC Web of Conferences 278 (2019): 04005. http://dx.doi.org/10.1051/matecconf/201927804005.

Повний текст джерела

Анотація:

It is urgent to act currently on the problems of overconsumption of energy as well as the environment and the economy. Energy is a direct mechanical source of many devices of an artificial thermal environment of the modern habitat. To cope with the consequences of the exceed consumption of domestic use, architecture takes part by focusing on the old constructive and functional solutions. The researchers are interested even fascinated by ancient and vernacular architecture; its buildings are a masterpiece of urban planning in matters of environment. Our study has clearly chosen as an example The Mzab valley; a qualitative and retrospective analysis which aims to describe and classify all the solutions and traditional climate strategies developed by the Mzabites to produce a real thermal comfort and a residential heritage to fight against climatic solicitations. We have checked and observed in parallel if these strategies are convergent or divergent with the recommendations and the needs of the specific comfort in our case study and predetermined in this paper by the method of Givoni. This analysis has shown that Mzabite architecture symbolizes an ancient bioclimatic knowledge, Its strategies generate a perfect harmony between climate, habitat and occupant, they formed an inspiring reference and exemplary lessons available of the designers; by re-adapting these ancient solutions and techniques of our ancestors with a suitable manner to contemporary architecture, and contributing to the improvement of comfortable climate.

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Braga, D., Amilcar Ramalho, Pedro Nuno Silva, and Albano Cavaleiro. "Study of Abrasion Resistance of Steels by Micro-Scale Tests." Materials Science Forum 514-516 (May 2006): 544–48. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.544.

Повний текст джерела

Анотація:

Steels continue to have a preponderant role in mechanical components under all type of wear solicitations namely, abrasion. The ability of micro-scale abrasion test for evaluating the properties of bulk materials has been widely demonstrated. However, only recently this technique was especially developed to characterize thin-coated materials. This study presents results obtained in micro-scale abrasion tests performed on different low and high alloy steels. These steel samples underwent thermal and chemical (nitriding) treatments with the aim of enhancing their surface hardness. Nitriding parameters were varied so as to obtain different structures (with and without formation of a “white layer” of iron nitrides (ε-Fe2-3N or γ’-Fe4N compound layer). Test conditions such as normal load and concentration of the abrasive medium (SiC particles in distilled water) were changed in order to obtain a 2 or 3 body wear contact type. Results obtained allowed to compare the specific wear rate ks for the different steels and treatments tested as well as to relate the influence of surface hardness and test parameters on the wear mechanisms.

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Paglia, L., V. Genova, M. P. Bracciale, C. Bartuli, F. Marra, M. Natali, and G. Pulci. "Thermochemical characterization of polybenzimidazole with and without nano-ZrO2 for ablative materials application." Journal of Thermal Analysis and Calorimetry 142, no. 5 (October 28, 2020): 2149–61. http://dx.doi.org/10.1007/s10973-020-10343-4.

Повний текст джерела

Анотація:

AbstractDuring the ballistic atmospheric re-entry, a space vehicle has to withstand huge thermo-mechanical solicitations because of its high velocity and the friction with the atmosphere. According to the kind of the re-entry mission, the heat fluxes can be very high (in the order of some MW m−2) ;thus, an adequate thermal protection system is mandatory in order to preserve the structure of the vehicle, the payload and, for manned mission, the crew. Carbon phenolic ablators have been chosen for several missions because they are able to dissipate the incident heat flux very efficiently. Phenolic resin presents satisfying performance but also environmental drawbacks. Thus, a more environmental-friendly solution was conceived: a high-performance thermoplastic material, polybenzimidazole (PBI), was employed instead of phenolic resin. In this work PBI-ablative material samples were manufactured with and without the addition of nano-ZrO2 and tested with an oxyacetylene flame. For comparison, some carbon-phenolic ablators with the same density were manufactured and tested too. Thermogravimetric analysis on PBI samples was carried out at different heating rates, and the obtained TG data were elaborated to evaluate the activation energy of PBI and nano-filled PBI. The thermokinetics results for PBI show an improvement in thermal stability due to the addition of nano-ZrO2, while the oxyacetylene flame test enlightens how PBI ablators are able to overcome the carbon phenolic ablators performance, in particular when modified by the addition of nano-ZrO2.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Sitzia, Fabio. "The San Saturnino Basilica (Cagliari, Italy): An Up-Close Investigation about the Archaeological Stratigraphy of Mortars from the Roman to the Middle Ages." Heritage 4, no. 3 (August 16, 2021): 1836–53. http://dx.doi.org/10.3390/heritage4030103.

Повний текст джерела

Анотація:

The manufacturing technology of historical mortars from the Roman to Medieval period apparently has not undergone evolutions. As reported in the literature, a quality decrease in the raw material occurred after the fall of the Roman Empire. During the Roman Age, the mortars presented the requirements of long durability due to hydraulic characteristics, and in later times, the production has only partially maintained the ancient requirements. To focus on the different production technologies between Roman and Medieval mortar, this research presents the case study of San Saturnino Basilica (Italy), where an archaeological mortar stratigraphy from Roman to Middle Ages is well preserved. An archaeometric characterization was performed to compare the mortars of the Roman period with the mortars of the Medieval period collected from the case-study monument. This comparison was carried out by measuring some physical-mechanical, mineralogical, petrographic and thermal features that give more information about the durability and resistance to mechanical solicitations and weathering. After the characterizations, contrary to what is reported in the bibliography, a better quality of Medieval materials than Roman ones is pointed out. This has been highlighted by higher hydraulicity, mechanical performance, and a more appropriated particle-size distribution of aggregates.

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Sellami, Amira, Mohamed Kchaou, Riadh Elleuch, and Yannick Desplanques. "Thermal analysis of pad-on-disc contact under tribological solicitations: a coupled numerical–experimental approach to identify surface temperatures and flow partition coefficient." Heat and Mass Transfer 52, no. 9 (November 17, 2015): 1923–34. http://dx.doi.org/10.1007/s00231-015-1708-y.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Pras, Maxime, Jean-François Gérard, Luana Golanski, Guilhem Quintard, and Jannick Duchet-Rumeau. "Key Role of the Dispersion of Carbon Nanotubes (CNTs) within Epoxy Networks on their Ability to Release." Polymers 12, no. 11 (October 29, 2020): 2530. http://dx.doi.org/10.3390/polym12112530.

Повний текст джерела

Анотація:

Carbon nanotube (CNT)-reinforced nanocomposites represent a unique opportunity in terms of designing advanced materials with mechanical reinforcement and improvements in the electrical and thermal conductivities. However, the toxic effects of these composites on human health have been studied, and very soon, some regulations on CNTs and on composites based on CNTs will be enacted. That is why the release of CNTs during the nanocomposite lifecycle must be controlled. As the releasing depends on the interfacial strength that is stronger between CNTs and polymers compared to CNTs in a CNT agglomerate, two dispersion states—one poorly dispersed versus another well dispersed—are generated and finely described. So, the main aim of this study is to check if the CNT dispersion state has an influence on the CNT releasing potential in the nanocomposite. To well tailor and characterize the CNT dispersion state in the polymer matrix, electronic microscopies (SEM and TEM) and also rheological analysis are carried out to identify whether CNTs are isolated, in bundles, or in agglomerates. When the dispersion state is known and controlled, its influence on the polymerization kinetic and on mechanical properties is discussed. It appears clearly that in the case of a good dispersion state, strong interfaces are generated, linking the isolated nanotubes with the polymer, whereas the CNT cohesion in an agglomerate seems much more weak, and it does not provide any improvement to the polymer matrix. Raman spectroscopy is relevant to analyze the interfacial properties and allows the relationship with the releasing ability of nanocomposites; i.e., CNTs poorly dispersed in the matrix are more readily released when compared to well-dispersed nanocomposites. The tribological tests confirm from released particles granulometry and observations that a CNT dispersion state sufficiently achieved in the nanocomposite avoids single CNT releasing under those solicitations.

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Privas, Edwin, and Laurent Chabert. "Reflector features and physics consideration issued from the Jules Horowitz Reactor design analyses." EPJ Nuclear Sciences & Technologies 4 (2018): 18. http://dx.doi.org/10.1051/epjn/2018040.

Повний текст джерела

Анотація:

Mechanic solicitations induced by neutron and photon interactions have to be featured for components lifespan determination. TechnicAtome is in charge of both the design and building on behalf of CEA of the 100 MW Jules Horowitz Reactor (JHR). This modular Material Testing Reactor is under construction in southern France, with radioisotope production and material testing capabilities. Inner core components have been designed based on mechanical and thermohydraulic considerations. Both studies require neutronic physical quantities like the neutron flux and deposited energies. The JHR reflector is outside the primary loop and is composed of beryllium. Gamma shields are partially positioned between the reflector and the core to reduce photon heating on aluminum structures. The design is completed and this paper deals with the neutronic and photonic impacts on the reflector. A Monte Carlo methodology based on the MCNP code was developed to model the reactor and enhance fluxes and energy deposited maps. MCNPs mesh options are used over the detailed geometry model. The convolution with mechanical meshes enables to determine neutronic parameters on local structures, material by material. Time required for such modeling is very long if one requires results on every mesh with a maximum uncertainty of 2% (1σ). To reduce time calculation by a factor 3.5 on refined meshes, MCNP biasing methods have been used. Spatial distribution of the gamma heating shows the importance of the interface with the surrounding area. For example, photon and neutron interactions close to the gamma shield create numerous photons with lower energy adding heating at the shield interfaces. In order to keep high flux in the experimental part of the reflector, gamma shields are not continuously set around the reactor vessel. Consequently, some photon leakage arises in the reflector area, with limited impact on aluminum structures. The overall thermal flux map shows local effects and gradients that have to be taken into account by the physics studies. Material swellings are deduced from the fluxes on all reflector structures.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Florea, Costel, Costică Bejinariu, Viorel Paleu, Daniela Chicet, Ioan Carcea, Adrian Alexandru, and Nicanor Cimpoesu. "Chromium Addition Effect on Wear Properties of Cast-Iron Material." Applied Mechanics and Materials 809-810 (November 2015): 572–77. http://dx.doi.org/10.4028/www.scientific.net/amm.809-810.572.

Повний текст джерела

Анотація:

A new cast iron material with a higher Cr content than usual is analyzed by chemical, micro-structural and friction coefficient point of view. The material was obtained by classical melting and the results compared with the experimental results obtained from a standard cast-iron used for applicative disk brake. Four different mechanical solicitation rates were used on the same material surface and the same load. The solicitation regime can be considered as semi-liquid and similar to a raining day experimental conditions. In this paper no thermal considerations were present or discussed. The results present a bigger friction coefficient of the new material and further considerations are necessary for example in a different friction regime.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Mausam, Kuwar, Sumit Kumar, Subrata Kumar Ghosh, Arun Kumar Tiwari, and Mudit Sehgal. "Solicitation of nanoparticles/fluids in solar thermal energy harvesting: A review." Materials Today: Proceedings 26 (2020): 2289–95. http://dx.doi.org/10.1016/j.matpr.2020.02.495.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Bugden, Shawn C., and Roger M. Evans. "Vocal solicitation of heat as an integral component of the developing thermoregulatory system in young domestic chickens." Canadian Journal of Zoology 75, no. 12 (December 1, 1997): 1949–54. http://dx.doi.org/10.1139/z97-826.

Повний текст джерела

Анотація:

Young domestic chickens (Gallus gallus) were able to regulate their body temperature in a laboratory setting, where vocalizations triggered a period of rewarming (35 °C) in an otherwise cold environment. Vocal solicitation of a rewarming period functioned in an analogous manner to the parental brooding response to a vocalizing chick. The number of vocally generated rewarming bouts increased if the cold-challenge temperature was decreased from 20 to 5 °C. The body temperature and ambient temperature maintained during vocal regulation were not significantly affected by the cold-challenge temperature. Thermoregulatory reliance on vocally induced rewarming bouts decreased with age as endothermic capability and the ability to retain heat improved. This decreased reliance on vocally induced heat inputs matches the pattern of decline of parental brooding seen in chicks reared in a natural setting. Body temperature at both cold-challenge temperatures increased with age, while the preferred ambient temperature decreased with age. This pattern is also found in the young of many birds species tested in spatial thermal gradients. Vocal solicitation of heat thus appears to form an integral and finely tuned part of the overall thermoregulatory system of these young precocial birds.

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Espira, Anton, and Roger M. Evans. "Energy savings from vocal regulation of ambient temperature by 3-day-old domestic chicks." Canadian Journal of Zoology 74, no. 4 (April 1, 1996): 599–605. http://dx.doi.org/10.1139/z96-069.

Повний текст джерела

Анотація:

Precocial domestic chicks (Gallus domesticus) become endothermic at or soon after hatching, but when chilled still vocalize to solicit heat from a parent or surrogate. In this study, we examined the potential energy savings resulting from vocal solicitation of heat by comparing the oxygen consumption of 3-day-old chicks facing a cold challenge of 20 °C with and without the option of regulating ambient temperature by vocally soliciting 2-min periods of rewarming at 35 °C from a surrogate parent in the laboratory. Body temperature was unaffected by vocal regulation, but the thermal gradient between body and ambient temperature was reduced by 5.0 ± 0.4 °C (mean ± SE). Mass-specific oxygen consumption [Formula: see text] increased by 62.5% to a near steady state mean of 3.64 mL∙g−1∙h−1 during constant chilling at 20 °C, but increased by only 48.1%, to 3.08 mL∙g−1∙h−1, during vocal regulation. Relative to chilled controls, vocally regulating chicks had a mean net energy saving of 15.4% during the final, stable 15 min of testing. Vocal solicitation of heat from a brooding parent seems likely to be an important means of saving energy expended in thermoregulation in some precocial species when young chicks are exposed to low ambient temperatures under natural conditions.

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Jebahi, Radhia, Helmi Aloui, and Nadia Chaker. "3D FE Study of a Hybrid Linear Actuator for Electronic Valve Control Under Thermal Solicitation." International Review on Modelling and Simulations (IREMOS) 7, no. 5 (October 31, 2014): 791. http://dx.doi.org/10.15866/iremos.v7i5.3653.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Zhao, Guang Wei, Xi Cong Ye, Zeng Min Shi, and Wen Jun Liu. "Effect of Cooling Rate on the Microstructure of Al-5.17Cu-2.63Si Cast Alloy." Advanced Materials Research 813 (September 2013): 157–60. http://dx.doi.org/10.4028/www.scientific.net/amr.813.157.

Повний текст джерела

Анотація:

The effect of cooling rate on the solicitation microstructure of a ternary cast Al-5.17Cu-2.63Si alloy is investigated. To create widely different cooling rates for the investigated alloy, the melts were cast into four molds made of different materials: aluminum, graphite, sand, and alumina-silicate-fiber felt (a thermal insulated material), respectively. The cooling curves for each mold specimen were simultaneously measured using calibrated K-type thermocouples, which are linked to a PC computer. The microstructures are characterized in terms of eutectic volume fraction and second dendrite arm spacing. The experiment result shows that increasing the cooling rate increases the amount of eutectic phase and decreases significantly the second dendrite arm spacing.

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Saadati, Yousef, Gilbert Lebrun, Jean-Francois Chatelain, and Yves Beauchamp. "Experimental investigation of failure mechanisms and evaluation of physical/mechanical properties of unidirectional flax–epoxy composites." Journal of Composite Materials 54, no. 20 (January 27, 2020): 2781–801. http://dx.doi.org/10.1177/0021998320902243.

Повний текст джерела

Анотація:

Using natural fibers as reinforcement in polymer matrix composites necessitates evaluating the latter under different modes of solicitation. This allows extracting its material properties for engineering design and research purposes. The main objective of the study is preparing a consistent set of material properties for unidirectional flax fiber-reinforced epoxy composite with defined composition and basic configuration. These data are prerequisites for growing researches on flax fiber-reinforced epoxy composites, especially for numerical analysis purposes using the finite element method. In this work, partially green unidirectional-flax fiber-reinforced epoxy composites are tested for physical and mechanical properties and studied for their failure modes. Tension, compression, flexion, and shear properties, as well as physical properties like density, specific heat capacity and thermal diffusivity, are evaluated according to ASTM standard test methods. Flax fibers, which are composites by themselves, come in bundles in the composites and demonstrate a complex behavior. Therefore, a fractographic analysis has been conducted to understand the macro and microscale failure mechanisms to correlate them with the material properties. The results are in good agreement with those of the literature, when available, but they mainly show the specific behavior of unidirectional-flax composites subject to different solicitation modes, especially compression and direct shear modes evaluated this way for the first time for unidirectional-flax fiber-reinforced epoxy composite. They cover most of the data required for engineering design and numerical analysis by methods like finite element method, particularly for simulating the machining process of flax fiber-reinforced epoxy composite in the ongoing works.

Стилі APA, Harvard, Vancouver, ISO та ін.

36

ABRAHAM, CHRISTINE L., and ROGER M. EVANS. "Metabolic costs of heat solicitation calls in relation to thermal need in embryos of American white pelicans." Animal Behaviour 57, no. 4 (April 1999): 967–75. http://dx.doi.org/10.1006/anbe.1998.1060.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Shahzadi, Iqra, and S. Nadeem. "A comparative study of Cu nanoparticles under slip effects through oblique eccentric tubes, a biomedical solicitation examination." Canadian Journal of Physics 97, no. 1 (January 2019): 63–81. http://dx.doi.org/10.1139/cjp-2018-0009.

Повний текст джерела

Анотація:

The particular mechanical, chemical, and thermodynamic properties of nanofluids build up a subject of immense interest for researchers of all areas. Such types of fluids have special significance in biomedical research due to their novel and immeasurable applications the in latest biomedical solicitation examination, such as drug delivery. Therefore, the focus of this study is to investigate the comparative study of copper nanoparticles under slip effects through oblique eccentric cylinders. For peristaltic pumping, an appropriate model is presented and its application is urged because of the way that the thread infusion inside the human body empowers creation of a methodology for restorative inserting with the slightest possible surgical injury. The outer lying tube has a wave of sinosiodual nature whereas the inner thread is of velocity V. Lubrication approach is used to calculate the dimensionless expressions for temperature and velocity profile. The inner tube satisfied no-slip condition while the outer tube has partial slip condition. The innovation with different sundry parameters is also presented via graphs. The attributes of this study are presented in the last section and a good agreement is found with existing literature. Significant increase in the heat transfer rate is observed in the presence of thermal slip parameter with the inclusion of copper nanoparticles. It is also found that the pressure rise enhances in the retrograde pumping region with the increase in inclination angle. It is important to note that slip causes decreases in the trapped bolus. This analysis finds valuable theoretical information for nanoparticle use as a drug agent in the field of bio-inspired applications.

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Alvarez-Perez, Marco A., Valentina Cirillo, Maria Giovanna Pastore Carbone, Marianna Pannico, Pellegrino Musto, and Vincenzo Guarino. "In Vitro Cell Interactions on PVDF Films: Effects of Surface Morphology and Polar Phase Transition." Materials 14, no. 18 (September 11, 2021): 5232. http://dx.doi.org/10.3390/ma14185232.

Повний текст джерела

Анотація:

In recent years, several studies have validated the use of piezoelectric materials for in situ biological stimulation, opening new interesting insights for bio-electric therapies. In this work, we investigate the morphological properties of polyvinylidene fluoride (PVDF) in the form of microstructured films after temperature-driven phase transition. The work aims to investigate the correlations between morphology at micrometric (i.e., spherulite size) and sub-micrometric (i.e., phase crystallinity) scale and in vitro cell response to validate their use as bio-functional interfaces for cellular studies. Morphological analyses (SEM, AFM) enabled evidence of the peculiar spherulite-like structure and the dependence of surface properties (i.e., intra-/interdomain roughness) upon process conditions (i.e., temperature). Meanwhile, chemical (i.e., FTIR) and thermal (i.e., DSC) analyses highlighted an influence of casting temperature and polymer solution on apolar to polar phases transition, thus affecting in vitro cell response. Accordingly, in vitro tests confirmed the relationship between micro/sub-microstructural properties and hMSC response in terms of adhesion and viability, thus suggesting a promising use of PVDF films to model, in perspective, in vitro functionalities of cells under electrical stimuli upon mechanical solicitation.

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Xu, Xitong, Shengbo Chen, Yan Yu, and Sen Zhang. "Atmospheric Anomaly Analysis Related to Ms > 6.0 Earthquakes in China during 2020–2021." Remote Sensing 13, no. 20 (October 11, 2021): 4052. http://dx.doi.org/10.3390/rs13204052.

Повний текст джерела

Анотація:

The attention towards links of atmospheric parameter variation and earthquakes has increased exponentially by utilizing new methods and more accurate observations. Persistent research makes it possible to gain insight into the precursor mechanism of earthquakes. In this paper, we studied the universality of detecting atmospheric anomalies associated with earthquakes based on tidal force fluctuation in China for earthquakes of Ms > 6.0, and explored the influence of tidal force on tectonic stress. The data of air temperature, geopotential height, ozone mixing ratio, and relative humidity from the National Center for Environmental Prediction (NCEP) were analyzed to reveal the spatiotemporal variation of atmospheric anomalies at multiple isobaric surfaces. Furthermore, the coupling of atmospheric parameters was investigated. The results showed that continuous solicitation exerted by tidal forces could change the strength of tectonic stress that causes earthquakes. The evolution pattern of air temperature, geopotential height, and relative humidity could be supported by atmospheric thermal vertical diffusion, while the anomalies of ozone mixing ratio was not evident. This verified the feasibility of detecting multi-parameter atmospheric anomalies associated with earthquakes based on tidal force fluctuation. Our results provide more evidence for understanding the atmospheric precursor characteristics of earthquakes.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Alpe´rine, S., and L. Lelait. "Microstructural Investigations of Plasma-Sprayed Yttria Partially Stabilized Zirconia TBC (In Relation to Thermomechanical Resistance and High-Temperature Oxidation Mechanisms)." Journal of Engineering for Gas Turbines and Power 116, no. 1 (January 1, 1994): 258–65. http://dx.doi.org/10.1115/1.2906802.

Повний текст джерела

Анотація:

This study deals with microstructural investigations of plasma-sprayed yttria partially stabilized zirconia thermal barrier coatings, performed by classical and analytical transmission electron microscopy. The aim of the study was to determine eventual relationships between coating microstructure and toughness. The ceramic/metal interface, which plays an important role during TBC thermomechanical solicitation, has also been studied. In the 6–8 wt. percent Y2O3 range, the metastable tetragonal t′ phase is observed, showing special faulted microstructural features, such as grain twinning and antiphase boundary planes. Moreover, after high-temperature annealing in air, a very fine and stable precipitation of the equilibrium cubic phase appears. It is believed that these microstructural elements could act as crack deviation sites and enhance the coatings’ intrinsic toughness. Microstructural investigations of the alumina scales grown during high-temperature annealing reveal yttrium segregation at oxide grain boundaries as well as significant quantities of zirconium inside the alumina grains. The oxide growth seems to be dominated by a classical grain boundary oxygen diffusion mechanism. The presence of zirconium inside the alumina grains suggests that Al2O3 also partially forms by chemical reduction of ZrO2 by Al.

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Dezecache, Guillaume, Claudia Wilke, Nathalie Richi, Christof Neumann, and Klaus Zuberbühler. "Skin temperature and reproductive condition in wild female chimpanzees." PeerJ 5 (December 5, 2017): e4116. http://dx.doi.org/10.7717/peerj.4116.

Повний текст джерела

Анотація:

Infrared thermal imaging has emerged as a valuable tool in veterinary medicine, in particular for evaluating reproductive processes. Here, we explored differences in skin temperature of twenty female chimpanzees in Budongo Forest, Uganda, four of which were pregnant during data collection. Based on previous literature in other mammals, we predicted increased skin temperature of maximally swollen reproductive organs of non-pregnant females when approaching peak fertility. For pregnant females, we made the same prediction because it has been argued that female chimpanzees have evolved mechanisms to conceal pregnancy, including swellings of the reproductive organs, conspicuous copulation calling, and solicitation of male mating behaviour, to decrease the infanticidal tendencies of resident males by confusing paternity. For non-pregnant females, we found slight temperature increases towards the end of the swelling cycles but no significant change between the fertile and non-fertile phases. Despite their different reproductive state, pregnant females had very similar skin temperature patterns compared to non-pregnant females, suggesting little potential for males to use skin temperature to recognise pregnancies, especially during maximal swelling, when ovulation is most likely to occur in non-pregnant females. We discuss this pattern in light of the concealment hypothesis, i.e., that female chimpanzees have evolved physiological means to conceal their reproductive state during pregnancy.

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Pricop, Bogdan, Marian Grigoraș, Firuța Borza, Burak Özkal, and Leandru-Gheorghe Bujoreanu. "On the Possible Cause of Sudden Storage Modulus Increase during the Heating of PM FeMnSiCrNi SMAs." Nanomaterials 12, no. 14 (July 8, 2022): 2342. http://dx.doi.org/10.3390/nano12142342.

Повний текст джерела

Анотація:

A sudden increase in storage modulus (ΔE′) was repeatedly recorded during the heating of powder metallurgy (PM) 66Fe-14Mn-6Si-9Cr-5Ni (mass. %) shape memory alloy specimens subjected to dynamic mechanical analysis (DMA), under constant applied strain amplitude and frequency. This instability, exceeding 12 GPa, was associated with the reverse martensitic transformation of α′-body centered cubic (bcc) martensite to γ-face centered cubic (fcc) austenite, overlapped on a magnetic transition. This transition, observed by thermomagnetic measurements (T-MAG), was associated with the temporary spontaneous alignment of magnetic spins, which lasted until thermal movement became prevalent, during heating. ΔE′ was located around 250 °C on DMA thermograms and this temperature had the tendency to increase with the solution treatment temperature. On T-MAG diagrams, magnetization saturation temperature decreased from 405 °C to 52 °C with the increase in applied magnetic field from 20 Oe to 1 kOe and the increase in mechanically alloyed powder volume from 20% to 40%. On scanning electron micrographs, the presence of thermally induced α’-bcc martensite was emphasized together with the sub-bands that impede its stress-induced formation during DMA solicitation. On X-ray diffraction patterns of the solution-treated specimens, the presence of 22–82% α′-bcc martensite was identified, together with 8–55% retained austenite. It was assumed that the pre-existence of austenite together with α’-bcc martensite, in the microstructure of the solution-treated specimens, favored the magnetic transition, which destabilized the material and caused the storage modulus increase. The specimen comprising the largest amounts of austenite experienced the largest ΔE′.

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Le Tran, Hoang-Long, Cristol Anne-Lise, Hosdez Jérôme, and Magnier Vincent. "Relationship Between Mechanical Behavior and Microstructure Evolution of Sintered Metallic Brake Pad Under the Impact of Thermomechanical Stress." Journal of Tribology 144, no. 6 (August 30, 2021). http://dx.doi.org/10.1115/1.4052065.

Повний текст джерела

Анотація:

Abstract It is well known that on the brake pad material, the triptych microstructure-properties-solicitations is the key to better understand the phenomena caused by braking stress. The challenging issues are the evolution of this triptych, i.e., the impact of thermal stress and mechanical stress on the microstructure which undoubtedly induces changes in properties. In order to solve the issues without tackling them in all their complexity, this study proposes an experimental approach where physics is decoupled but inspired by the braking sequence in terms of applied temperature gradient and braking loads. Two experimental tests were carried out. The first one is the thermal solicitation test where a temperature gradient from 400 °C to 540 °C was applied to the material. The second one is the thermomechanical test where a compressive load at 20 MPa was applied under the same thermal gradient. The experiment time is fixed for 2 min, equivalent to the time of one braking stroke. The referred material is sintered metallic composite, which is widely used as the brake pad material for high energy railway. As a result, it shows that coupled thermomechanical stress has a greater impact on material properties than decoupled one. This impact is related to the microstructure where graphite inclusions play an important role.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Patrice Berthod. "Microstructures and Metallographic Characterization of Superalloys." Journal of Material Science and Technology Research 6 (October 31, 2019). http://dx.doi.org/10.31875/2410-4701.2019.06.6.

Повний текст джерела

Анотація:

Superalloys are metallic alloys with specific microstructures and atoms in solid solution allowing good mechanical and chemical properties at high temperature, typically higher than 1000°C. They present many different types of {matrix – precipitates} combinations which can be characterized at each step of their elaboration, by specifying the chemical compositions and the crystalline network of the phases present. After test on a sample (laboratory scale), or after the deterioration in service of a component leading to its replacement by a new one (industrial scale), the superalloys constituting these pieces are often usefully examined. This aims to specify the changes occurred in their microstructures as well as in their surface or sub-surface, due to the endured thermal, mechanical and chemical solicitations. These characterizations can be simply done using basic low-magnification optical microscopic examinations. Other means such as electronic microscopy and other advanced apparatus may be usefully involved for further investigations. After a brief history about superalloys, an overview of the phenomenological aspects of their mechanical and chemical solicitations during their use at high temperature, the metallographic techniques which are usually employed to characterize them are presented and illustrated in the case of a chosen family of superalloys.

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Dalla Santa, Giorgia, Simonetta Cola, and Antonio Galgaro. "Assessment of frost and heating penetration in compacted clay layers of landfill top covers in temperate climate." Bulletin of Engineering Geology and the Environment 81, no. 12 (November 11, 2022). http://dx.doi.org/10.1007/s10064-022-02999-z.

Повний текст джерела

Анотація:

Abstract Compacted clay (CC) layers are commonly used as hydraulic barriers in landfills, thanks to their impervious capacity. However, mechanical and hydraulic properties of CC can be significantly affected by temperature variations due to the heat produced by waste degradation as well as to external air temperature and weathering. Previous experimental tests show that the most detrimental occurrence is the cyclic freezing–thawing (FT) that can increase the hydraulic conductivity of CC up to one order of magnitude. This paper aims at assessing the temperature distribution in a landfill multilayered top cover in several scenarios of temperature solicitations, in order to evaluate the depth of frost penetration. For this purpose, a 2D hydro-thermal coupled finite element model representing a case study landfill top cover has been developed; each constituting layer has been characterized by physical and thermal properties acquired through direct measurements on sampled materials in unfrozen and frozen conditions. The model provides a reliable time description of the isotherm distribution within the layered top cover in several temperature scenarios typical of a temperate climate, thus estimating the penetration of the frost front as well as of high temperatures.

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Dai, Quanwei, Dongmei Zhang, and Zili Li. "Mechanical assessment of energy wall in the long term." Acta Geotechnica, May 28, 2022. http://dx.doi.org/10.1007/s11440-022-01579-5.

Повний текст джерела

Анотація:

AbstractEmbedded retaining walls equipped with ground heat exchangers is one kind of energy geostructures, harvesting the shallow ground energy for heating and cooling buildings. However, past investigations mainly focus on the thermal assessment of energy walls, but pay limited attention to mechanical wall behavior and associated ground response. At present, there is no standard preliminary code for assessing the long-term mechanical performance of energy walls. In this study, a comprehensive literature review is conducted to summarize the existing studies on the long-term mechanical behavior of both conventional retaining walls and thermo-active ones, respectively. The review identifies three most critical mechanical factors for energy walls (i.e., horizontal wall movement, ground settlement, and basement heave), while their permissible values can be referred to standard preliminary design criteria of conventional retaining walls in the short-term and limited long-term field measurements. For elaborating the application of design criteria, a parametric study is implemented to evaluate the long-term mechanical performance of energy walls in stiff clay under various thermal conditions, including the influence of thermal solicitations, station temperature and asymmetrical operation mode. The vivid assessing results show that the thermal-induced mechanical movements due to geothermal operation may cause unfavorable serviceability issues (e.g., cracks), but are unlikely to bring critical damages to the structural performance. The identified critical mechanical factors and evaluation of thermal influences in this study provide some guidance for the mechanical assessment of long-term energy wall behavior, particularly in the light of limited field measurements and demonstration cases.

Стилі APA, Harvard, Vancouver, ISO та ін.

47

"Magnetohydro Dynamic Steady Flow Between Two Parallel Porous Plates of a Viscous Fluid Under Angular Velocity with Inclined Magnetic Field." International Journal of Recent Technology and Engineering 8, no. 4 (November 30, 2019): 615–19. http://dx.doi.org/10.35940/ijrte.b1863.118419.

Повний текст джерела

Анотація:

The Model is made as the Steady Magnetohydro dynamic streams with an exact speed between parallel penetrable plates are considered. The issue is seen methodically by using comparability change, whose game plan oversees growing fluid stream with a dashing velocity. The Major Applications of Magnetohydro dynamic (MHD) are the controller of generators, the system containing Cooling and thermal structures, improvement of polymer, Fuel industries etc. The objective of this paper is to look at the Steady Magnetohydro dynamic stream of thick fluid with a saucy speed between parallel porous plates when the fluid forced to their back position by the way of the dividers of each partition at a comparative rate. The issue is decreased to a third solicitation direct differential condition which depends upon a Suction Reynolds number R and M1 for which a right course of action is gotten.

Стилі APA, Harvard, Vancouver, ISO та ін.

Статті в журналах з теми "Thermal solicitations"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями