Applied Mechanics and Materials Vols. 766-767

Abstract: Formability of a material is defined as its ability to deform into desired shape without being fracture. There will always be a need for formability tests, a larger number of tests have been used in an effort to measure the formability of sheet materials. Aluminium Alloy 6061 is a magnesium and silicon alloy of aluminium. It is also called as marine material as it has high corrosion resistance to seawater. In this paper Formability test of AA6061 sheet is done by Forming Limit Diagram (FLD) Analysis. FLD or Forming Limit Curve (FLC) for the forming processes of AA6061 sheets is obtained by Experimental method and FEM. Experimental method involves Deep drawing test of the sheet and ANSYS software is used for FEM.

Abstract: The squeeze casting of aluminium alloys is a rapidly developing technical process that offers the potential for widespread utilization and growth. Squeeze casting process is the result of search of new production processes which are capable of producing components with high integrity. Squeeze casting also called as liquid metal forging combines the advantages of both casting and forging in one operation. Squeeze casting process is suited for all melting ranges of metals. But nowadays, light weight materials like aluminium and magnesium are mostly used in the aerospace and automotive industries. In this attempt, Squeeze casting of AA6061 was done by varying the process parameters such as squeeze pressure at three levels(40 MPa, 80 MPa and 120 MPa) , die preheat temperature at 200 °C and pressure applied duration at 15 seconds respectively and the components were produced. The specimens were made from these components and they were tested for tensile strength and fatigue life. It was observed that the tensile strength and fatigue life exhibited by the components were enhanced with the increase in squeeze pressure.

Abstract: Shape memory alloy (SMA) is an intermetallic compound able to recover, in a predetermined shape during a thermal cycle while generating mechanical work. The primary objective of this research is to develop a shape memory alloy based micro-positioning stage. This paper reports about the training, actuation method of NiTi shape Memory alloy thin sheets and its displacement measurement through Michelson Interferometer. The SMA based Tripod was fabricated the actuation was done using an electrical biasing with 5 A(1.2 Volt) where a displacement of around 6.10 mm was achieved. The actuation studies were also performed using a laser with a optimum fluence of 100 mJ/cm² that is of upto7.25 mm achieved.

Abstract: Performance of Non Asbestos brake pad requires the optimization of numerous criteria. Alumina fibre is a metallic material which is light weight, excellent wear resistance, thermal stability and structural reinforcement properties. Hence the present work deals with the development of three friction composites in the form of standard disc brake pads using same ingredients in same proportion except alumina fiber containing 7%wt, 11%wt & 14% wt which is compensated by synthetic barites (filler) containing 16%wt, 12%wt & 9% wt and designated as NA01, NA02 and NA03 respectively. Various physical, thermal and mechanical characterizations are carried out as per IS2742 Part 3 standards in which the loss of ignition decreased while the specific gravity, compressive strength and hardness increased with the fiber increase. Then the tribological properties (Fade and Recovery) are tested using Chase Test following IS2742 Part 4 standards. The fade μ and recovery μ % were significantly influenced by the amount of fibre combinations. It was proved that, increase in amount of alumina fibre % had significant effect on fade μ %.Thermo Gravimetric Analysis (TGA) proves that higher fiber content has more thermal stability leading to good fade resistance. Over all NA03 formulation is proved as superlative performer.

Abstract: In this work Al-Si-Cu Functionally Graded Material (FGM) is developed using centrifuge technique. The method used in this work to produce FGM is totally different compared to other centrifugal process which helped in producing solid cylindrical parts. The FGM is characterized through Microstructure and Hardness and it is found that the Cu segregated at the bottom of the casting and Si at the top due to the density difference. Similarly the hardness and the ultimate tensile strength at the bottom of the casting and at the top of the casting region is more when compared to region in-between the top and bottom of the casting.

Abstract: The Demand and increase in the cost of fossil fuels have made the entire world to turn towards the renewable energy resources. There are various renewable energy out of which solar energy is the efficient energy and available in abundant. The main disadvantage of solar energy is that it is not continuous and it is available only in the day time and so the storage of solar thermal energy is considered as an important one. In this study, thermal energy is transmitted through the therminol-55 oil which is the Heat Transfer Fluid (HTF). D-Mannitol-a white, crystalline solid with the chemical formula C₆H₈(OH)₆ is taken as the Phase Change Material (PCM) and stored inside the copper cylindrical encapsulations. The D-mannitol PCM was stored in the copper cylinder encapsulations with and without fins. These encapsulations were immersed in a cylindrical mild steel tank containing HTF. The therminol-55 oil was allowed to flow through the solar parabolic trough collector to transfer heat. Along with this, an additional heater was provided for heating HTF up to the temperature 300oC. This hot oil was allowed to flow in to the PCM tank where the PCM copper cylinders were immersed. The experiments were conducted in two stages one with finned encapsulations and another without finned encapsulations. Here the experiments were done in two modes one is charging mode and another one is discharging mode. In charging mode the temperature of the HTF was raised to 300oC and was allowed to cool during its discharging mode to 120 oC. The time taken for the charging and discharging of heat was measured to analyse the heat transfer study of thermal storage system.

Abstract: An Experimental study on phase change heat energy storage system (PCHES) using Erythritol as a phase change material (PCM) has been carried out. Simple and popularly used domestic solar thermal applications make use of direct radiation energy of the sun for cooking, liquid heating, drying and many others as it is the remarkable potential renewable energy source. Effective utilization of such energy can be made with the development of economically operating phase change heat energy storage (PCHES) which is elemental in spanning the gap between supply and demand of energy. PCHES that stores the latent heat of fusion of phase change materials is provocative because of its huge storage density. An integrated Solar wax melting unit with phase change thermal energy storage using ethylene glycol as heat transfer fluid(HTF) to transfer the heat from parabolic dish collector to the wax melting unit is investigated. In this experimental setup, the paraffin wax container is kept in an insulated heat retrieval unit. Heat stored during the daytime by the PCHES is utilized in the off sunshine hours.

Abstract: An experimental study is conducted to investigate heat transfer enhancement in Thermal Energy Storage system (TES) with paraffin wax as a Phase Change Material (PCM). Therminol 66 is used as a heat transfer fluid (HTF) to carry the heat throughout circuit. The PCM is encapsulated in spherical shells which is stored in the storage tank. The work includes study of heat transfer rates between HTF and PCM with different encapsulation materials namely Copper, Aluminium and Brass. A series of experiments were conducted to investigate the time required and heat transfer rates of HTF during the processes of charging and discharging of the PCM. Experimentally, Copper was found to have the maximum heat transfer rate and Brass was found to have the least cost/kW of energy stored. In discharging process, the cumulative heat gained by HTF from the brass encapsulated PCM is higher (1419.8 kJ) than aluminium (1199.96 kJ) and copper (815.24 kJ). Thus it can be concluded the brass is the most economical encapsulating material for enhancing the heat transfer in a thermal storage system than copper. The heat transfer from the HTF to PCM occurs in copper are 4.9% faster when compared to Brass and 2.3% faster than Aluminum encapsulation. On the other hand, The cost per kW energy transfer from the different encapsulated materials proves that the brass is cost effective during both charging and discharging process.

Abstract: The main objective of our project is to conserve the available solar energy and improve its utilization with the help of phase change material; here we have absorbed solar energy to prepare food especially for cooking rice, boiling potatoes and eggs. The use of PCM in the solar cooker has improved its efficiency over conventional solar cooker and cooking food hot in off sunshine hours. It is being eco-friendly and other than that it save fuel, gas, coal which are exhaustible source of energy. In the present article some of different phase change materials are studied for solar cooking and among them Coconut Oil (commercial grade) is found to be a good latent heat storage which is experimentally tested in a simple box type solar cooker and the comparison is made with and without PCM.Key word: solar cooker, coconut oil, concentrating lens, phase change materials.

Abstract: A model has been established based on numerical calculation to analyze a vertical tube in tube stainless steel generator with forced convective boiling. Refrigerant vapour is generated from the weak refrigerant-absorbent solution takes place in the middle tube of the generator, when hot water through the outer side is used as boiling medium and the pipe arrays inserted is the phase change material containment. This paper shows the results of the TRNSYS modeling and simulation of a solar absorption cooling system under the weather conditions of Chennai in order to partially satisfy the thermal demand of a building room. The maximum hourly thermal load reaches 165 kW. The suggested model operates with concentrating parabolic collectors, a NH₃-H₂O single effect absorption air-conditioning system, hot water storage with PCM and an external auxiliary boiler. As a result of the method simplifying for the varying climate and different orientation of the components are analyzed. These outcomes show that the prime system could succeed a yearly solar fraction of 0.58.