Search results for: thermal loading

Authors: Sakti Mandal

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Varying distribution of land surface temperature in an urbanized environment is a globally addressed phenomenon. Usually has been noticed that criticality of surface temperature increases from the periphery to the urban centre. As the centre experiences maximum severity of heat throughout the year, it also represents most critical zone in terms of thermal condition. In this present study, an attempt has been taken to propose a quantitative approach of thermal critical zonation (TCZ) on the basis of seasonal temperature variation. Here the zonation is done by calculating thermal critical value (TCV). From the Landsat 8 thermal digital data of summer and winter seasons for the year 2014, the land surface temperature maps and thermally critical zonation has been prepared, and corresponding dataset has been computed to conduct the overall study of that particular study area. It is shown that TCZ can be clearly identified and analyzed by the help of inter-seasonal temperature range. The results of this study can be utilized effectively in future urban development and planning projects as well as a framework for implementing rules and regulations by the authorities for a sustainable urban development through an environmentally affable approach.

Keywords: thermal critical values (TCV), thermally critical zonation (TCZ), land surface temperature (LST), Landsat 8, Kolkata Municipal Corporation (KMC)

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Authors: Gregory Kelly, Gary Chai, Sittampalam Manoharan, Deborah Delaney

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A Structural Number (SN) can be calculated for a road pavement from the properties and thicknesses of the surface, base course, sub-base, and subgrade. Historically, the cost of collecting structural data has been very high. Data were initially collected using Benkelman Beams and now by Falling Weight Deflectometer (FWD). The structural strength of pavements weakens over time due to environmental and traffic loading factors, but due to a lack of data, no structural deterioration curve for pavements has been implemented in a Pavement Management System (PMS). International Roughness Index (IRI) is a measure of the road longitudinal profile and has been used as a proxy for a pavement’s structural integrity. This paper offers two conceptual methods to develop Pavement Structural Deterioration Curves (PSDC). Firstly, structural data are grouped in sets by design Equivalent Standard Axles (ESA). An ‘Initial’ SN (ISN), Intermediate SN’s (SNI) and a Terminal SN (TSN), are used to develop the curves. Using FWD data, the ISN is the SN after the pavement is rehabilitated (Financial Accounting ‘Modern Equivalent’). Intermediate SNIs, are SNs other than the ISN and TSN. The TSN was defined as the SN of the pavement when it was approved for pavement rehabilitation. The second method is to use Traffic Speed Deflectometer data (TSD). The road network already divided into road blocks, is grouped by traffic loading. For each traffic loading group, road blocks that have had a recent pavement rehabilitation, are used to calculate the ISN and those planned for pavement rehabilitation to calculate the TSN. The remaining SNs are used to complete the age-based or if available, historical traffic loading-based SNI’s.

Keywords: conceptual, pavement structural number, pavement structural deterioration curve, pavement management system

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Authors: Bharath Kenchappa, Kunigal Shivakumar

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Lightweight, low thermal conductivity and high temperature resistant materials or the system with moderate mechanical properties and capable of taking high heating rates are needed in both commercial and military applications. A single material with these attributes is very difficult to find and one needs to come with innovative ideas to make such material system using what is available. To bring down the cost of the system, one has to be conscious about the cost of basic materials. Such a material system can be called as the thermal barrier system. This paper focuses on developing, testing and characterization of material system for thermal barrier applications. The material developed is porous, low density, low thermal conductivity of 0.1062 W/m C and glass transition temperature about 310 C. Also, the thermal properties of the developed material was measured in both longitudinal and thickness direction to highlight the fact that the material shows isotropic behavior. The material is called modified Eco-Core which uses only less than 9% weight of high-char resin in the composite. The filler (reinforcing material) is a component of fly ash called Cenosphere, they are hollow micro-bubbles made of ceramic materials. Special mixing-technique is used to surface coat the fillers with a thin layer of resin to develop a point-to-point contact of particles. One could use commercial ceramic micro-bubbles instead of Cenospheres, but it is expensive. The bulk density of Cenospheres is about 0.35 g/cc and we could accomplish the composite density of about 0.4 g/cc. One percent filler weight of 3mm length standard drywall grade fibers was used to bring the added toughness. Both thermal and mechanical characterization was performed and properties are documented. For higher temperature applications (up to 1,000 C), a hybrid system was developed using an aerogel mat. Properties of combined material was characterized and documented. Thermal tests were conducted on both the bare modified Eco-Core and hybrid materials to assess the suitability of the material to a thermal barrier application. The hybrid material system was found to meet the requirement of the application.

Keywords: aerogel, fly ash, porous material, thermal barrier

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Authors: Veronique Jubera, Guillaume Salek, Manuel Gaudon, Alain Garcia, Alain Demourgues

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Luminescence of transition metal and rare earth elements cover ultraviolet to far infrared wavelengths. Applications of phosphors are numerous. One can cite lighting, sensing, laser, energy, medical or military applications. But regarding each domain, specific criteria are required and they can be achieved with a strong control of the chemical composition. Emission of doped materials can be tailored with modifications of the local environment of the cations. For instance, the increase of the crystal field effect shifts the divalent manganese radiative transitions from the green to the red color. External factor as heat-treatment can induce changes of the doping element location or modify the unit cell crystalline symmetry. By controlling carefully the synthesis route, it is possible to initiate emission shift and to establish the thermal history of a compound. We propose to demonstrate through the luminescence of divalent manganese and trivalent rare earth doped oxide, that it is possible to follow the thermal history of a material. After optimization of the synthesis route, structural and optical properties are discussed. Finally, thermal calibration graphs are successfully established on these doped compounds. This makes these materials promising probe for thermal sensing.

Keywords: emission, thermal sensing, transition metal, rare eath element

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Authors: I. Kadek Candra Parmana Wiguna, Wiwik Budiawan, Heru Prastawa

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Semarang has become not only a metropolitan city but also a centre of government that has experienced significant changes in urban land use. Temperature increases in urban areas result from the expansion of development. The average temperature in Semarang reached 27.10°C to 29.60°C in 2022. The state of thermal sensation is very dependent on the mode of operation; Industrial Engineering building is mostly equipped with an air conditioner (AC). This study aims to analyze the thermal comfort level and energy consumption of air conditioners in classroom of industrial engineering. Participants in this study amounted to 31 students with data collection for 4 weeks. Results of the physical environment are Ta in: 25.52°C, Ta out: 32.71 °C, Rh in: 61.14%, Rh out: 59.43%, and Av in: 0.037 m/s. The results of clothing insulation are 41% of the respondents belonged to the categories 0.31 - 0.5 clo (summer domming) and 0.51 - 0.70 clo (spring clothing). Regarding the predicted mean vote (PMV), the average value is 0.63, and only 14.85% result of the predicted percentage dissatisfied (PPD). The neutral temperature with measurement Griffith’s constant 0.5/°C was 27.16°C, but the statistical test results show that the comfort temperature to use TSV ≤ 0 which is 28.55°C. The highest average power (watt) measurement results during week 3, which is 1613.65 watts. It is concluded in this study that the thermal comfort conditions in the classroom are adequate and acceptable to more than 90% of respondents.

Keywords: thermal comfort, PMV/PPD, air conditioner, TSV

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Authors: Mehmet Halkaci, Ekrem Öztürk, Mevlüt Türköz, H. Selçuk Halkacı

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Hydromechanical deep drawing (HMD) process is an advanced manufacturing process used to form deep parts with only one forming step. In this process, sheet metal blank can be drawn deeper by means of fluid pressure acting on sheet surface in the opposite direction of punch movement. High limiting drawing ratio, good surface quality, less springback characteristic and high dimensional accuracy are some of the advantages of this process. The performance of the HMD process is affected by various process parameters such as fluid pressure, blank holder force, punch-die radius, pre-bulging pressure and height, punch diameter, friction between sheet-die and sheet-punch. The fluid pressure and bank older force are the main loading parameters and affect the formability of HMD process significantly. The punch diameter also influences the limiting drawing ratio (the ratio of initial sheet diameter to punch diameter) of the sheet metal blank. In this research, optimal loading (fluid pressure and blank holder force) profiles were determined for AA 5754-O sheet material through fuzzy control algorithm developed in previous study using LS-DYNA finite element analysis (FEA) software. In the preceding study, the fuzzy control algorithm was developed utilizing geometrical criteria such as thinning and wrinkling. In order to obtain the final desired part with the developed algorithm in terms of the punch diameter requested, the effect of punch diameter, which is the one of the process parameters, on loading profiles was investigated separately using blank thickness of 1 mm. Thus, the practicality of the previously developed fuzzy control algorithm with different punch diameters was clarified. Also, thickness distributions of the sheet metal blank along a curvilinear distance were compared for the FEA in which different punch diameters were used. Consequently, it was found that the use of different punch diameters did not affect the optimal loading profiles too much.

Keywords: Finite Element Analysis (FEA), fuzzy control, hydromechanical deep drawing, optimal loading profiles, punch diameter

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Authors: Sakkarin Chingulpitak, Somchai Wongwises

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Over the past several decades, the development of electronic devices has led to higher performance. Therefore, an electronic cooling system is important for the electronic device. A heat sink which is a part of the electronic cooling system is continuously studied in the research field to enhance the heat transfer. To author’s best knowledge, there have been only a few articles which reported the thermal performance of plate-fin heat sink with perforation. This research aims to study on the flow and heat transfer characteristics of the solid-fin heat sink (SFHS) and laterally perforated plate-fin heat sink (LAP-PFHS). The SFHS and LAP-PFHSs are investigated on the same fin dimensions. The LAP-PFHSs are performed with a 27 perforation number and two different diameters of circular perforation (3 mm and 5 mm). The experimental study is conducted under various Reynolds numbers from 900 to 2,000 and the heat input of 50W. The experimental results show that the LAP-PFHS with perforation diameter of 5 mm gives the minimum thermal resistance about 25% lower than SFHS. The thermal performance factor which takes into account the ratio of the Nusselt number and ratio of friction factor is used to find the suitable design parameters. The experimental results show that the LAP-PFHS with the perforation diameter of 3 mm provides the thermal performance of 15% greater than SFHS. In addition, the simulation study is presented to investigate the effect of the air flow behavior inside the perforation on the thermal performance of LAP-PFHS.

Keywords: heat sink, parallel flow, circular perforation, non-bypass flow

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Authors: Anastasia Stamatiou, Markus Odermatt, Dominic Leemann, Ludger J. Fischer, Joerg Worlitschek

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The successful integration of thermal energy storage in industrial processes is expected to play an important role in the energy turnaround. Latent heat storage technologies can offer more compact thermal storage at a constant temperature level, in comparison to conventional, sensible thermal storage technologies. The focus of this study is the development of latent heat storage solutions based on the Phase Change Slurry (PCS) concept. Such systems promise higher energy densities both as refrigerants and as storage media while presenting better heat transfer characteristics than conventional latent heat storage technologies. This technology is expected to deliver high thermal power and high-temperature stability which makes it ideal for storage of process heat. An evaluation of important batch processes in industrial applications set the focus on materials with a melting point in the range of 55 - 90 °C. Aluminium ammonium sulfate dodecahydrate (NH₄Al(SO₄)₂·12H₂O) was chosen as the first interesting PCM for the next steps of this study. The ability of this material to produce slurries at the relevant temperatures was demonstrated in a continuous mode in a laboratory test-rig. Critical operational and design parameters were identified.

Keywords: esters, latent heat storage, phase change materials, thermal properties

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Authors: M. Sadique, S. Ainane, Y. F. Yap, P. Rostron, E. Al Hajri

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The presence of sand in production lines in the oil and gas industries causes material degradation due to erosion-corrosion. The material degradation caused by erosion-corrosion in pipelines can result in a high cost of monitoring and maintenance and in major accidents. The process of erosion-corrosion consists of erosion, corrosion, and their interactions. Investigating and understanding how the erosion-corrosion process affects the degradation process in certain materials will allow for a reduction in economic loss and help prevent accidents. In this study, material loss due to erosion-corrosion of mild steel under impingement of sand-laden water at 90˚ impingement angle is investigated using a submerged impingement jet (SIJ) test. In particular, effects of jet velocity and sand loading on TWL due to erosion-corrosion, weight loss due to pure erosion and erosion-corrosion interactions, at a temperature of 29-33 °C in sea water environment (3.5% NaCl), are analyzed. The results show that the velocity and sand loading have a great influence on the removal of materials, and erosion is more dominant under all conditions studied. Changes in the surface characteristics of the specimen after impingement test are also discussed.

Keywords: erosion-corrosion, flow velocity, jet impingement, sand loading

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Authors: Ravindra Raju, Vidhu Kampurath

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For smooth transition of the power from the engine to the transmission system, a clutch is used. In agricultural tractors, friction clutches are widely used in power transmission applications. To transmit the maximum torque in friction clutches, selection of materials is one of the important tasks. The present used material for friction disc is Asbestos, Ceramic etc. In this study, analysis is performed using composites materials. The composite materials are considered due to their high strength to weight ratio. Composite materials like kevlar49, kevlar 29U were used in the study. The paper presents a systematic approach to optimize the structural and thermal characteristics of the clutch friction pad. A single plate clutch is modeled using Creo 2.0 software and analyzed using ANSYS. Thermal analysis considers the reduction of heat generated between the friction surfaces and reducing the temperature rise during the steady state period. Structural analysis is done to minimize the stresses developed as a result of the loading contact between friction surfaces. Also, modal analysis is done to optimize the natural frequency of the friction plate to avoid being in resonance with the engine frequency range. The analysis carried out on ANSYS workbench to get the foremost appropriate friction material for clutch. From the analyzed results stress, strain / total deformation values and natural frequency of the materials were compared for all the composite materials and the best one was taken out. For the study purpose, specifications of the clutch are obtained from the MF1035 (47KW) Tractor model.

Keywords: ANSYS, clutch, composite materials, creo

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Authors: Carmen Viñas Arrebola, Antonio Rodriguez Sanchez, Sheila Varela Lujan, Mariano Gonzalez Cortina, Cesar Porras Amores

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The research group TEMA from the School of Building (UPM) is working in the line of energy efficiency and comfort in building. The need to reduce energy consumption in the building construction implies designing new constructive systems. These systems help to reduce both consumption and energy losses in order to achieve adequate thermal comfort for people in any type of building. In existing buildings the best option is the rehabilitation focused on thermal insulation. The aim of this paper is to design, monitor and analyze the first results of thermal behavior of the ETICS system in façades. This retrofitting solution consists of adding thermal insulation on the outside of the building, helping to create a continuous envelope on the façades. The analysis is done by comparing a rehabilitated part of the building with ETICS system and another part which has not been rehabilitated, and it is taken as reference. Both of them have the same characteristics. Temperature measurements were taken with type K thermocouples according to the previous design of the monitoring and in the same period of time. The pilot building of the study is situated in Benimamet Street, in San Cristobal de Los Ángeles, in the south of Madrid. It was built in the late 50s. The 51st entrance hall, which is restored, and the 47th entrance hall, in original conditions, have been studied.

Keywords: comfort in building, energy efficiency in building, ETICS, thermal properties

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Authors: Arber Sejdiji, Jan Schmitz-Huebsch, Christian Mittelstedt

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Due to its use in a broad range of temperatures, the prediction of elastic properties of fiber composite materials under thermal load is significant. Especially the transversal stiffness dominates the potential of use for fiber-reinforced composites (FRC). A numerical study on the influence of thermal stress on transversal stiffness of fiber-reinforced composites is presented. In the numerical study, a representative volume element (RVE) is used to estimate the elastic properties of a unidirectional ply with finite element method (FEM). For the investigation, periodic boundary conditions are applied to the RVE. Firstly, the elastic properties under pure mechanical load are derived numerically and compared to results, which are obtained by analytical methods. Thereupon thermo-mechanical load is implemented into the model to investigate the influence of temperature change with low temperature as a key aspect. Regarding low temperatures, the transversal stiffness increases intensely, especially when thermal stress is dominant over mechanical stress. This paper outlines the employed numerical methods as well as the derived results.

Keywords: elastic properties, micromechanics, thermal stress, representative volume element

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Authors: Ankur Mundhra, Shubhadeep Chakraborty, Y. R. Singh, Vishal Das

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Seismic data scaling affects the dynamic range of a data and with present day lower costs of storage and higher reliability of Hard Disk data, scaling is not suggested. However, in dealing with data of different vintages, which perhaps were processed in 16 bits or even 8 bits and are need to be processed with 32 bit available data, scaling is performed. Also, scaling amplifies low amplitude events in deeper region which disappear due to high amplitude shallow events that saturate amplitude scale. We have focused on significance of scaling data to aid interpretation. This study elucidates a proper seismic loading procedure in workstations without using default preset parameters as available in most software suites. Differences and distribution of amplitude values at different depth for seismic data are probed in this exercise. Proper loading parameters are identified and associated steps are explained that needs to be taken care of while loading data. Finally, the exercise interprets the un-certainties which might arise when correlating scaled and unscaled versions of seismic data with synthetics. As, seismic well tie correlates the seismic reflection events with well markers, for our study it is used to identify regions which are enhanced and/or affected by scaling parameter(s).

Keywords: clipping, compression, resolution, seismic scaling

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Authors: Sibani Bisoyi, Ute Zschieschang, Alexander Hoyer, Hagen Klauk

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Abstract— Organic thin-film transistors (TFTs) have great potential to be used for various applications such as flexible displays or sensors. For some of these applications, the TFTs must be able to withstand temperatures in excess of 100 °C, for example to permit the integration with devices or components that require high process temperatures, or to make it possible that the devices can be subjected to the standard sterilization protocols required for biomedical applications. In this work, we have investigated how the thermal stability of low-voltage small-molecule semiconductor dinaphtho[2,3-b:2’,3’-f]thieno[3,2-b]thiophene (DNTT) TFTs is affected by the encapsulation of the TFTs and by the ambient in which the thermal stress is performed. We also studied to which extent the thermal stability of the TFTs depends on the channel length. Some of the TFTs were encapsulated with a layer of vacuum-deposited Teflon, while others were left without encapsulation, and the thermal stress was performed either in nitrogen or in air. We found that the encapsulation with Teflon has virtually no effect on the thermal stability of our TFTs. In contrast, the ambient in which the thermal stress is conducted was found to have a measurable effect, but in a surprising way: When the thermal stress is carried out in nitrogen, the mobility drops to 70% of its initial value at a temperature of 160 °C and to close to zero at 170 °C, whereas when the stress is performed in air, the mobility remains at 75% of its initial value up to a temperature of 160 °C and at 60% up to 180 °C. To understand this behavior, we studied the effect of the thermal stress on the semiconductor thin-film morphology by scanning electron microscopy. While the DNTT films remain continuous and conducting when the heating is carried out in air, the semiconductor morphology undergoes a dramatic change, including the formation of large, thick crystals of DNTT and a complete loss of percolation, when the heating is conducted in nitrogen. We also found that when the TFTs are heated to a temperature of 200 °C in air, all TFTs with a channel length greater than 50 µm are destroyed, while TFTs with a channel length of less than 50 µm survive, whereas when the TFTs are heated to the same temperature (200 °C) in nitrogen, only the TFTs with a channel smaller than 8 µm survive. This result is also linked to the thermally induced changes in the semiconductor morphology.

Keywords: organic thin-film transistors, encapsulation, thermal stability, thin-film morphology

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Authors: Xi Luo, Xu Ji, Yunfeng Wang, Guoliang Li, Chongqiang Yan, Ming Li

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Two different kinds of cross V-shape solar air collectors are designed and constructed. In the transverse cross V-shape collector, the V-shape bottom plate is along the air flow direction and the absorbing plate is perpendicular to the air flow direction. In the lengthway cross V-shape collector, the V-shape absorbing plate is along the air flow direction and the bottom plate is perpendicular to the air flow direction. Based on heat balance, the mathematical model is built to evaluate their performances. These thermal performances of the two cross V-shape solar air collectors and an extra traditional flat-plate solar air collector are characterized under various operating conditions by experiments. The experimental results agree well with the calculation values. The experimental results prove that the thermal efficiency of transverse cross V-shape collector precedes that of others. The air temperature at any point along the flow direction of the transverse cross V-shape collector is higher than that of the lengthway cross V-shape collector. For the transverse cross V-shape collector, the most effective length of flow channel is 0.9m. For the lengthway cross V-shape collector, a longer flow channel is necessary to achieve a good thermal performance.

Keywords: cross v-shape, performance, solar air collector, thermal efficiency

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Authors: Raquib Ahsan, Md. Mahir Asif, Md. Zahidul Alam

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A huge portion of old masonry buildings in Bangladesh are vulnerable to earthquake. In most of the cases these buildings contain unreinforced masonry wall which are most likely to be subjected to earthquake damages. Due to deterioration of mortar joint and aging, shear resistance of these unreinforced masonry walls dwindle. So, retrofitting of these old buildings has become an important issue. Among many researched and experimented techniques, ferrocement retrofitting can be a low cost technique in context of the economic condition of Bangladesh. This study aims at investigating the behavior of ferrocement retrofitted unconfined URM walls under different types of cyclic loading. Four 725 mm × 725 mm masonry wall units were prepared with bricks jointed by stretcher bond with 12.5 mm mortar between two adjacent layers of bricks. To compare the effectiveness of ferrocement retrofitting a particular type wire mesh was used in this experiment which is 20 gauge woven wire mesh with 12.5 mm × 12.5 mm square opening. After retrofitting with ferrocement these wall units were tested by applying cyclic deformation along the diagonals of the specimens. Then a comparative study was performed between the retrofitted specimens and control specimens for both partially reversed cyclic load condition and cyclic compression load condition. The experiment results show that ultimate load carrying capacities of ferrocement retrofitted specimens are 35% and 27% greater than the control specimen under partially reversed cyclic loading and cyclic compression respectively. And before failure the deformations of ferrocement retrofitted specimens are 43% and 33% greater than the control specimen under reversed cyclic loading and cyclic compression respectively. Therefore, the test results show that the ultimate load carrying capacity and ductility of ferrocement retrofitted specimens have improved.

Keywords: cyclic compression, cyclic loading, ferrocement, masonry wall, partially reversed cyclic load, retrofitting

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Authors: Bijit Kalita, K. V. N. Surendra

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Rotating disk is one of the most indispensable parts of a rotating machine. Rotating disk has found many applications in the diverging field of science and technology. In this paper, we have taken into consideration the problem of a heavy spinning disk mounted on a rotor system acted upon by boundary traction. Finite element modelling is used at various loading condition to determine the mixed mode stress intensity factors. The effect of combined shear and normal traction on the boundary is incorporated in the analysis under the action of gravity. The variation near the crack tip is characterized in terms of the stress intensity factor (SIF) with an aim to find the SIF for a wide range of parameters. The results of the finite element analyses carried out on the compressed disk of a belt pulley arrangement using fracture mechanics concepts are shown. A total of hundred cases of the problem are solved for each of the variations in loading arc parameter and crack orientation using finite element models of the disc under compression. All models were prepared and analyzed for the uncracked disk, disk with a single crack at different orientation emanating from shaft hole as well as for a disc with pair of cracks emerging from the same center hole. Curves are plotted for various loading conditions. Finally, crack propagation paths are determined using kink angle concepts.

Keywords: crack-tip deformations, static loading, stress concentration, stress intensity factor

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Authors: Levent Basayigit, Mert Dedeoglu, Fadime Ozogul

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In this study, an application was carried out to determine the Volcanic Soils by using remote sensing.  The study area was located on the Golcuk formation in Isparta-Turkey. The thermal bands of Landsat 7 image were used for processing. The implementation of the climate model that was based on the water index was used in ERDAS Imagine software together with pixel based image classification. Soil Moisture Index (SMI) was modeled by using the surface temperature (Ts) which was obtained from thermal bands and vegetation index (NDVI) derived from Landsat 7. Surface moisture values were grouped and classified by using scoring system. Thematic layers were compared together with the field studies. Consequently, different moisture levels for volcanic soils were indicator for determination and separation. Those thermal wavelengths are preferable bands for separation of volcanic soils using moisture and temperature models.

Keywords: Landsat 7, soil moisture index, temperature models, volcanic soils

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Authors: H. Rahman, T. Donchev, D. Petkova

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Earthquakes claim thousands of lives around the world annually due to inadequate design of lateral load resisting systems particularly shear walls. Additionally, corrosion of the steel reinforcement in concrete structures is one of the main challenges in construction industry. Fibre Reinforced Polymer (FRP) reinforcement can be used as an alternative to traditional steel reinforcement. FRP has several excellent mechanical properties than steel such as high resistance to corrosion, high tensile strength and light self-weight; additionally, it has electromagnetic neutrality advantageous to the structures where it is important such as hospitals, some laboratories and telecommunications. This paper is about results of experimental research and it is incorporating experimental testing of two medium-scale concrete shear wall samples; one reinforced with Basalt FRP (BFRP) bar and one reinforced with steel bars as a control sample. The samples are tested under quasi-static-cyclic loading following modified ATC-24 protocol standard seismic loading. The results of both samples are compared to allow a judgement about performance of BFRP reinforced against steel reinforced concrete shear walls. The results of the conducted researches show a promising momentum toward utilisation of the BFRP as an alternative to traditional steel reinforcement with the aim of improving durability with suitable energy dissipation in the reinforced concrete shear walls.  

Keywords: shear walls, internal fibre reinforced polymer reinforcement, cyclic loading, energy dissipation, seismic behaviour

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Authors: Innocent C. Ezenwa, Takashi Yoshino

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Knowledge of the transport properties of Fe and its alloys at extreme high pressure (P), temperature (T) conditions are essential for understanding the generation and sustainability of the magnetic field of the rocky planets with a metallic core. Since Pt, an unfilled d-band late transition metal with an electronic structure of Xe4f¹⁴5d⁹6s¹, is paramagnetic and remains close-packed structure at ambient conditions and high P-T, it is expected that its transport properties at these conditions would be similar to those of ε-Fe. We investigated the T-dependent electrical resistivity of solid and liquid Pt up to 8 GPa and found it constant along its melting curve both on the liquid and solid sides in agreement with theoretical prediction and experimental results estimated from thermal conductivity measurements. Our results suggest that the T-dependent resistivity of ε-Fe is linear and would not saturate at high P, T conditions. This, in turn, suggests that the thermal conductivity of liquid Fe at Earth’s core conditions may not be as high as previously suggested by models employing saturation resistivity. Hence, thermal convection could have powered the geodynamo before the birth of the inner core. The electrical resistivity and thermal conductivity on the liquid and solid sides of the inner core boundary of the Earth would be significantly different in values.

Keywords: electrical resistivity, thermal conductivity, transport properties, geodynamo and geomagnetic field

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Authors: Bhavana V. Mohite, Satish V. Patil

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Bacterial cellulose (BC) is an alternative for plant cellulose (PC) that prevents global warming leads to preservation of nature. Although PC and BC have the same chemical structure, BC is superior with its properties like its size, purity, porosity, degree of polymerization, crystallinity and water holding capacity, thermal stability etc. On this background the present study focus production and applications of BC as antimicrobial wound dressing material. BC was produced by Gluconoacetobacter hansenii (strain NCIM 2529) under shaking condition and statistically enhanced upto 7.2 g/l from 3.0 g/l. BC was analyzed for its physico mechanical, structural and thermal characteristics. BC produced at shaking condition exhibits more suitable properties in support to its high performance applications. The potential of nano silver impregnated BC was determined for sustained release modern antimicrobial wound dressing material by swelling ratio, mechanical properties and antimicrobial activity against Staphylococcus aureus. BC in nanocomposite form with other synthetic polymer like PVA shows improvement in its properties such as swelling ratio (757% to 979%) and sustainable release of antibacterial agent. The high drug loading and release potential of BC was evidenced in support to its nature as antimicrobial wound dressing material. The nontoxic biocompatible nature of BC was confirmed by MTT assay on human epidermal cells with 90% cell viability that allows its application as a regenerative biomaterial. Thus, BC as a promising new generation antimicrobial wound dressing material was projected.

Keywords: agitated culture, biopolymer, gluconoacetobacter hansenii, nanocomposite

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Authors: Michael Tupý, Jaroslav Císař, Pavel Mokrejš, Dagmar Měřínská, Alice Tesaříková-Svobodová

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The worldwide problem is that the recycled PVB is wildly stored in landfills. However, PVB have very similar chemical properties such as PVC. Moreover, both of them are used in plasticized form. Thus, the thermal properties of plasticized PVC obtained from primary production and the PVB was obtained by recycling of windshields are compared. It is carried out in order to find degradable conditions and decide if blend of PVB/PVC can be processable together. Tested PVC contained 38 % of plasticizer diisononyl phthalate (DINP) and PVB was plasticized with 28 % of triethylene glycol, bis(2-ethylhexanoate) (3GO). Thermal and thermo-oxidative decomposition of both vinyl polymers are compared such as DSC and OOT analysis. The tensile strength analysis is added.

Keywords: polyvinyl chloride, polyvinyl butyral, recycling, reprocessing, thermal analysis, decomposition

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Authors: Ya Lv

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This article presents the application of the semi-analytic method (SAM) in the thermal management solution (TMS) of the energy storage system (ESS). The TMS studied in this work is fluid cooling. In fluid cooling, both effective heat conduction and heat convection are indispensable due to the heat transfer from solid to fluid. Correspondingly, an efficient TMS requires a design investigation of the following parameters: fluid inlet temperature, ESS initial temperature, fluid flow rate, working c rate, continuous working time, and materials properties. Their variation induces a change of thermal performance in the battery module, which is usually evaluated by numerical simulation. Compared to complicated computation resources and long computation time in simulation, the SAM is developed in this article to predict the thermal influence within a few seconds. In SAM, a fast prediction model is reckoned by combining numerical simulation with theoretical/empirical equations. The SAM can explore the thermal effect of boundary parameters in both steady-state and transient heat transfer scenarios within a short time. Therefore, the SAM developed in this work can simplify the design cycle of TMS and inspire more possibilities in TMS design.

Keywords: semi-analytic method, fast prediction model, thermal influence of boundary parameters, energy storage system

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Authors: Obinna Emmanuel Ezenkwa, Sani Amril Samsudin, Azman Hassan, Ede Anthony

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A major challenge of polypropylene (PP) in high-heat application areas is its poor thermal stability. Under high temperature, PP burns readily with high degradation temperature and can self-ignite. In this study, PP is reinforced with hybrid filler of graphene (xGNP) and rice husk (RH) with RH at 15 wt%, and xGNP varied at 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 parts per hundred (phr) of the composite. Compatibilizer MAPP was also added in each sample at 4phr of the composite. Sample formulations were melt-blended using twin screw extruder and injection moulding machine. At xGNP optimum content of 1.5 phr, hybrid PP/RH/G1.5/MAPP nanocomposite increased in thermal stability by 24 °C and 30 °C compared to pure PP and unhybridized PP/RH composite respectively; char residue increased by 513% compared to pure PP and degree of crystallization (Xc) increased from 35.4% to 36.4%. The observed thermal properties enhancement in the hybrid nanocomposites can be related to the high surface area, gap-filling effect and exfoliation characteristics of the graphene nanofiller which worked in synergy with rice husk fillers in reinforcing PP. This study therefore, shows that graphene nanofiller inclusion in polymer composites fabrication can enhance the thermal stability of polyolefins for high heat applications.

Keywords: polymer nanocomposites, thermal stability, exfoliation, hybrid fillers, polymer reinforcement

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Authors: Bineet Kumar

Abstract:

Many civil engineering infrastructures frequently encounter repetitive loading during their service life. Due to the inherent complexity observed in concrete, like quasi-brittle materials, understanding the fatigue behavior in concrete still posesa challenge. Moreover, the fracture process zone characteristics ahead of the crack tip have been observed to be different in fatigue loading than in the monotonic cases. Therefore, it is crucial to comprehend the energy dissipation associated with the fracture process zone (FPZ) due to repetitive loading. It is well known that stiffness degradation due to cyclic loadingprovides a better understanding of the fracture behavior of concrete. Under repetitive load cycles, concrete members exhibit a two-stage stiffness degradation process. Experimentally it has been observed that the stiffness decreases initially with an increase in crack length and subsequently increases. In this work, an attempt has been made to propose an analytical expression to predict energy dissipation and later the stiffness degradation as a function of crack length. Three-point bend specimens have been considered in the present work to derive the formulations. In this approach, the expression for the resultant stress distribution below the neutral axis has been derived by correlating the bending stress with the cohesive stresses developed ahead of the crack tip due to the existence of the fracture process zone. This resultant stress expression is utilized to estimate the dissipated energydue to crack propagation as a function of crack length. Further, the formulation for the stiffness degradation has been developed by relating the dissipated energy with the work done. It can be used to predict the critical crack length and fatigue life. An attempt has been made to understand the influence of stress amplitude on the damage pattern by using the information on the rate of stiffness degradation. It has been demonstrated that with the increase in the stress amplitude, the damage/FPZ proceeds more in the direction of crack propagation compared to the damage in the direction parallel to the span of the beam, which causes a lesser rate of stiffness degradation for the incremental crack length. Further, the effect of loading frequency has been investigated in terms of stiffness degradation. Under low-frequency loading cases, the damage/FPZ has been found to spread more in the direction parallel to the span, in turn reducing the critical crack length and fatigue life. In such a case, a higher rate of stiffness degradation has been observed in comparison to the high-frequency loading case.

Keywords: fatigue life, fatigue, fracture, concrete

Procedia PDF Downloads 95

Authors: Nuo Duan, Yi Pik Cheng

Abstract:

This paper presents the data of a series of two-dimensional Discrete Element Method (DEM) simulations of a large-diameter rigid monopile subjected to cyclic loading under a high gravitational force. At present, monopile foundations are widely used to support the tall and heavy wind turbines, which are also subjected to significant from wind and wave actions. A safe design must address issues such as rotations and changes in soil stiffness subject to these loadings conditions. Design guidance on the issue is limited, so are the availability of laboratory and field test data. The interpretation of these results in sand, such as the relation between loading and displacement, relies mainly on empirical correlations to pile properties. Regarding numerical models, most data from Finite Element Method (FEM) can be found. They are not comprehensive, and most of the FEM results are sensitive to input parameters. The micro scale behaviour could change the mechanism of the soil-structure interaction. A DEM model was used in this paper to study the cyclic lateral loads behaviour. A non-dimensional framework is presented and applied to interpret the simulation results. The DEM data compares well with various set of published experimental centrifuge model test data in terms of lateral deflection. The accumulated permanent pile lateral displacements induced by the cyclic lateral loads were found to be dependent on the characteristics of the applied cyclic load, such as the extent of the loading magnitudes and directions.

Keywords: cyclic loading, DEM, numerical modelling, sands

Procedia PDF Downloads 321

Authors: S. M. Mahbobur Rahman

Abstract:

Whole building energy simulation models are widely used for predicting future energy consumption, performance diagnosis and optimum control.  Black box building energy modeling approach has been heavily studied in the past decade. The thermal response of a building can also be modeled using a network of interconnected resistors (R) and capacitors (C) at each node called R-C network. In this study, a model building, Case 600, as described in the “Standard Method of Test for the Evaluation of Building Energy Analysis Computer Program”, ASHRAE standard 140, is studied along with a 3R2C thermal network model and the ASHRAE clear sky solar radiation model. Although building an energy model involves two important parts of building component i.e., the envelope and internal mass, the effect of building internal mass is not considered in this study. All the characteristic parameters of the building envelope are evaluated as on Case 600. Finally, monthly building energy consumption from the thermal network model is compared with a simple-box energy model within reasonable accuracy. From the results, 0.6-9.4% variation of monthly energy consumption is observed because of the south-facing windows.

Keywords: ASHRAE case study, clear sky solar radiation model, energy modeling, thermal network model

Procedia PDF Downloads 146

Authors: M. Benachour, N. Benachour, M. Benguediab

Abstract:

In this investigation, variation of cyclic loading effect on fatigue crack growth is studied. This study is performed on 2024 T351 and 7050-T74 aluminum alloys, used in aeronautical structures. The propagation model used in this study is NASGRO model. In constant amplitude loading (CA), the effect of stress ratio has been investigated. Fatigue life and fatigue crack growth rate were affected by this factor. Results showed an increasing in fatigue crack growth rates (FCGRs) with increasing stress ratio. Variable amplitude loading (VAL) can take many forms i.e with a single overload, overload band etc. The shape of these loads affects strongly the fracture life and FCGRs. The application of a single overload (ORL) decrease the FCGR and increase the delay crack length caused by the formation of a larger plastic zone compared to the plastic zone due without VAL. The fatigue behavior of the both material under single overload has been compared.

Keywords: fatigue crack growth, overload ratio, stress ratio, generalized willenborg model, retardation, al-alloys

Procedia PDF Downloads 364

Authors: Aphinan Phukaoluan, Surachai Dechkunakorn, Niwat Anuwongnukroh, Anak Khantachawana, Pongpan Kaewtathip, Julathep Kajornchaiyakul, Wassana Wichai

Abstract:

Aims: This study aims to address the amount of force delivered by a NiTiCu orthodontic wire with a ternary composition ratio of 46.0 Ni: 49.0 Ti: 5.0 Cu and to compare the results with a commercial NiTiCu 35 °C orthodontic archwire. Materials and Methods: Nickel (purity 99.9%), Titanium (purity 99.9%), and Copper (purity 99.9%) were used in this study with the atomic weight ratio 46.0 Ni: 49.0 Ti: 5.0 Cu. The elements were melted to form an alloy using an electrolytic arc furnace in argon gas atmosphere and homogenized at 800 °C for 1 hr. The alloys were subsequently sliced into thin plates (1.5mm) by EDM wire cutting machine to obtain the specimens and were cold-rolled with 30% followed by heat treatment in a furnace at 400 °C for 1 hour. Then, the three newly fabricated NiTiCu specimens were cut in nearly identical wire sizes of 0.016 inch x0.022 inch. Commercial preformed Ormco NiTiCu35 °C archwire with size 0.016 inch x 0.022 inches were used for comparative purposes. Three-point bending test was performed using a Universal Testing Machine to investigate the force of the load-deflection curve at oral temperature (36 °C+ 1) with deflection points at 0.25, 0.5, 0.75, 1.0. 1.25, and 1.5 mm. Descriptive statistics was used to evaluate each variables and independent t-test was used to analyze the differences between the groups. Results: Both NiTiCu wires presented typical superelastic properties as observed from the load-deflection curve. The average force was 341.70 g for loading, and 264.18 g for unloading for 46.0 Ni: 49.0 Ti: 5.0 Cu wire. Similarly, the values were 299.88 g for loading, and 201.96 g for unloading of Ormco NiTiCu35°C. There were significant differences (p < 0.05) in mean loading and unloading forces between the two NiTiCu wires. The deflection forces in loading and unloading force for Ormco NiTiCu at each point were less than 46.0 Ni: 49.0 Ti: 5.0 Cu wire, except at the deflection point of 0.25mm. Regarding the force difference between each deflection point of loading and unloading force, Ormco NiTiCu35 °C exerted less force than 46.0 Ni: 49.0 Ti: 5.0 Cu wire, except at difference deflection at 1.5-1.25 mm of unloading force. However, there were still within the acceptable limits for orthodontic use. Conclusion: The fabricated ternary alloy of 46.0 Ni: 49.0 Ti: 5.0 Cu (atomic weight) with 30% reduction and heat treatment at 400°C for 1 hr. and Ormco 35 °C NiTiCu presented the characteristics of the shape memory in their wire form. The unloading forces of both NiTiCu wires were in the range of orthodontic use. This should be a good foundation for further studies towards development of new orthodontic NiTiCu archwires.

Keywords: loading force, ternary alloy, NiTiCu, shape memory, orthodontic wire

Procedia PDF Downloads 285

Authors: Alouaoui Redha, Ferhat Samira, Bouaziz Mohamed Najib

Abstract:

In this work, we examine the thermal radiation effect on heat and mass transfer in steady laminar boundary layer flow of an incompressible viscous micropolar fluid over a vertical plate, with the presence of a magnetic field. Rosseland approximation is applied to describe the radiative heat flux in the energy equation. The resulting similarity equations are solved numerically. Many results are obtained and representative set is displayed graphically to illustrate the influence of the various parameters on different profiles. The conclusion is drawn that the flow field, temperature, concentration and microrotation as well as the skin friction coefficient and the both local Nusselt and local Sherwood numbers are significantly influenced by Magnetic parameter, material parameter and thermal radiation parameter.

Keywords: MHD, micropolar fluid, thermal radiation, heat and mass transfer, boundary layer

Procedia PDF Downloads 453