Mechanical Engineering

The ability to mitigate the vibrations by a magnetorheological elastomer (MRE) isolator varies with the amplitude of the excitation and the magnetic field. To implement semi-active vibration control, a mathematical model representing the dynamic response over a wide frequency range is crucial. In the present study, an attempt was made to develop a mathematical model for the designed MRE isolator over a wide frequency range under different operating conditions. A model-based fuzzy controller was developed to implement semi-active control attributes over a broadband frequency. The methodology entails that the MRE isolator operating in shear mode was designed. The performance of the isolator was evaluated over a frequency range of 15–80 Hz with varying input currents and excitation amplitudes. The transmissibility response of MRE isolator was mathematically represented using viscoelastic constitutive relations. The isolator system was represented in state-space form, and its parameters...

This paper presents thermal performance of various single glazing window glasses covered with and without window overhang shading. Buildings are designed with laterite stone walls with different dimensions of overhang shading devices on single glazing windows in four different climatic zones of India: Ahmedabad (Hot & dry), Bangalore (moderate), Calcutta (warm & humid) and Hyderabad (composite). In this study, five glass materials such as clear, bronze, green, grey and blue-green were selected. Total three hundred and twenty building models with and without window overhangs were designed in four climatic zones of India using Design builder 4.3.0.039. Thermal simulation was carried out in Energy plus 8.1 simulation tool. From the results, it is observed that laterite buildings with grey glass window with 1.5m overhang shading device were found to be energy efficient from the least heat gain point of view in south direction among three hundred and twenty building models studied in four climatic zones of India. The results of the study help in selecting the best window glass material and also help in selecting appropriate dimensions for overhang shading device for reducing cooling loads in buildings.

Buildings account for about 40% of total electricity use in the world for artificial cooling and artificial day lighting and they are also responsible for 40% CO 2 emissions. This work reports a comprehensive investigation of thermal performance characteristics which include thermal transmittance, thermal admittance, decrement factor and the time lag for both homogeneous and composite building walls. A computer program with the cyclic admittance method was developed to study unsteady thermal performance characteristics. The Five building materials such as, cellular concrete, mud brick, concrete block, burnt brick and fly ash bricks were selected for the study. The heat transfer characteristics of five homogeneous building walls and their five composite walls were studied in detail. From the results, it is observed that fly ash brick homogeneous walls and their composite walls are energy efficient from the lowest decrement factor and the highest time lag perspective among five homogeneous and five composite walls studied. The decrement factor and time lag values of homogeneous fly ash bricks were observed to be 0.401 and 8.159 h, respectively, whereas the values of composite fly ash brick walls were observed to be 0.342 and 9.199 h, respectively.

The energy consumption associated with the cooling of the buildings is huge. In India buildings consume about 33% of country's power production for cooling and day lighting. The building enclosures such as walls, roofs and glasses play very vital role in reducing cooling loads in the buildings. The proper combination of window glass materials and wall materials can cut down the cooling costs extensively. In the present work, five different glass materials such as clear, bronze, grey, green and blue-green glass materials were selected and four different building materials such as burnt brick, cinder concrete, dense concrete and fly ash brick either side plastered with cement plaster were selected. Total twenty building models with various combinations of window glass and wall materials were designed in licensed Design builder 4.3.0.039 version and thermal analysis was carried out in Energy plus 8.1 software package. Thermal performance of various building models in four different climatic zones such as hot and dry, temperate, warm and humid and composite were investigated. From the results of the study, it is observed that fly ash brick wall building model with grey window glass is found to be energy efficient in all Indian climatic zones from the reduced cooling load point of view among all studied combinations in East, West, North and South orientations. From the results it is observed that the fly ash brick buildings with grey glass window is observed to be the most energy efficient combination for reducing cooling loads as they gain the least heat gain in south orientation (21.51 kWh) for Ahmedabad region. The results of the study help in designing energy efficient passive buildings.

Analytical solution quest for viscoelastic shear thinning fluid flow through circular conduit is a matter of great prominence as it directly evolvesmost efficient criteria to investigate various responses of independent parameters. Envisaging this facet present endeavour attempts to develop a computational model for designing runner conduit lateral dimension in a plastic injection mould through which thermoplastic melt gets injected. At outset injection phenomenon is represented by governing equations on the basis of mass, momentum and energy conservation principles [1]. Embracing Hagen Poiseuille flow problem analogous to runner conduit injection the manuscript uniquely imposes runner conduit inlet and outlet boundary conditions along with relative to appropriate assumptions; governing equations evolve a computation model as criteria for designing. To overwhelm Non-Newtonian's abstruse Weissenberg-Rabinowitsch correction factor has been adopted byaccommodating thermoplastic melt behaviour towards the final stage of derivation. The resulting final computational model is believed to express runner conduit dimensions as a function of available type of injection moulding machine specifications, characteristics of thermoplastic melt and required features of component being moulded. Later the equation so obtained has been verified by using dimensional analysis method.

This manuscript deliberates traditional runner design criteria issue in injection moulding; thereon proposes a novel criterion. Traditional runner design concepts are heuristic, iterative, probabilistic, manipulative etc. obviously with scant confidence; perhaps absence of idealistic criteria could be attributed. Hence this endeavour envisions to trait such flaw immunity intrinsically within runner conduit a design criterion itself. The proposed criterion might concurrently inoculate injection moulding machine specifications, thermoplastic material characteristics and component features to exemplify mould performance and moulding quality.

Conservation principles are used to represent all physical transformations occurring in the universe, accordingly are also adopted to design runner conduit for thermoplastic melt injection. Conservation principles for thermoplastic melt injection through runner conduit are implemented by considering cylindrical co-ordinates system relevant to its geometrical configuration for deriving governing equations. While the continuity equation ensures volumetric conservation of thermoplastic melt, the momentum equation represents equilibrium of forces on thermoplastic melt injection through runner conduit. During an injection moulding cycle heat and work done energy transformations are balanced by implementing first and second law of thermodynamics. Thermoplastic melt state change through the runner conduit for a particular cycle is appreciated by heat conduction equation. Traditionally inertia and entropy contribution is neglected to skip rigorousness, nevertheless they continue to prevail. Especially in very frequently used non-circular runner cross section conduits, their influence is highly significant. Hence the current endeavour attempts to computationally model, continuousness, equilibrium, energy balance and phase transformative runner design criteria by implementing conservation principles.