Applied Mechanics and Materials Vols. 766-767

Abstract: Dimple is a slight indentation in a surface. Dimples create turbulence by creating vortices which delays the boundary layer separation resulting in decrease of drag, increasing aerodynamic efficiency, manoeuvrability and also the angle of stall. The present work focused on the understanding of the effect of dimples on boundary layer separation, lift, drag, critical angle of attack, aerodynamic efficiency of wings. The airfoils without any dimples and with circular dimples as inward and outward on are studied. Types of dimples considered in 3D studies are circular and octagon dimple then computational analysis is done using ANSYS FLUENT CFD software, applying subsonic flow, in three dimensional co-ordinate system. The results are compared with a straight wing without dimples. Then suggestions and conclusions are made.

Abstract: The main factors that cause the failure of gears are the bending stress and contact stress of the gear tooth. Out of these, failure of gears due to contact stress is high compared to bending stress. Stress analysis has been a key area of research to minimize failure and optimize design. This paper gives a finite element model for introspection of the stresses in the tooth during the meshing of gears. Specifically, helix angle is important for helical gears. Using modeling software, 3-D models for different helix angles in helical gears were generated, and the simulation was performed using ANSYS 12.0 to estimate the contact stress. The Hertz equation and AGMA standard was used to calculate the contact stress. The results of the theoretical contact stress values, using Hertz and AGMA are compared with the stress values from the FEA for different helix angles and the results are tabulated and discussed.

Abstract: In this study, to predict the surface roughness of stainless steel-304 in Magneto rheological Abrasive flow finishing (MRAFF) process, an artificial neural network (ANN) and regression models have been developed. In this models, the parameters such as hydraulic pressure, current to the electromagnet and number of cycles were taken as variables of the model.Taguchi’s technique has been used for designing the experiments in order to observe the different values of surface roughness . A neural network with feed forward with the help of back propagation was made up of 27 input neurons, 7 hidden neurons and one output neuron. The 6 sets of experiments were randomly selected from orthogonal array for training and residuals were used to analyze the performance. To check the validity of regression model and to determine the significant parameter affecting the surface roughness, Analysis of variance (ANOVA) and F-test were made. The numerical analysis depict that the current to the electromagnet was an paramount parameter on surface roughness.Key words: MRAFF, ANN, Regression analysis

Abstract: There has been a recent increase in emphasis on comfort in most vehicular transports these days. Air springs were used and then removed from commercial usage. This paper conducts an analysis to showcase the improvement it terms of material application by using rubber which is reinforced with aluminium to increase its performance and strength. FEA is carried out to simulate various load conditions with respect to both rubber and rubber reinforced with aluminium. The structural changes are noted and described.

Abstract: There has been a recent increase in emphasis on small satellite because of their low cost, short development time’s relative simplicity, and cost efficiency. However, these satellites do have drawback. Their small size results in small surface areas which often translate into thermal and power constraint. A satellite basically any object that revolves around a planet in a circular or elliptical orbit path. nanosatellites are satellites that weigh less than 10Kg. These types of satellites are designed and developed to carry payloads that are much smaller and has a life span not more than 1 year generally. The below analysis is done on a Low Earth Orbiting Satellite.

Abstract: Specific improvement of a quality of the product and its productivity improvement mainly depend on the designing and fixing of the tolerance of that product. This is done prior to the design stage of the product. Design of tolerance is based on its functional conditions only then its specification for each component in a mechanical system is developed. The finalized tolerance is printed as a drawing (blue print tolerance), inclusive of individual part details, fit and function parameter, critical parameter and design criteria.This paper reveals a new comprehensive and analytical method for fixing an optimal tolerance by worse case limit. This is done to reduce the manufacturing cost and to improve the quality loss of the product by using the expoentional cost function. An example illustrates the proposed model attached with solution method.

Abstract: There is always a need for hand tools and hand operated products that are well designed. Designing a good handle is critical at work, especially when the product is operated for an extended period of time. This paper deals with the iron box used in the garment industry. Prolonged use of this product that is un ergonomically designed would create muscular pain in the wrist and shoulders. Here the handle of this conventional iron box is redesigned with a tilting angle that would minimize stress in the human wrist. Finally this is analysed using RULA (Rapid Upper Limb Assessment) tool in CATIA V5.

Abstract: Incremental forming is a recent sheet metal forming process that has high flexibility and repeatability. Unlike conventional forming methods this process is applicable mainly in the production of prototypes or small batches of automobile body panels, headlight reflectors, etc. In this investigation IS 513 CR3 Deep Drawing quality steel sheets of thickness 0.6 mm were incrementally formed into pyramids to study their formability characteristics. Experiments were conducted under three different spindle speeds (1000, 1500 and 2000 rpm), three tool feeds (1200, 1400 and 1600 mm.min-1) and three step depths (0.4, 0.5, and 0.6 mm). Forming time, thickness distribution and formability of the final components were studied. FEA models were created using Abaqus software and validated with experimental results.

Abstract: The present work is mainly carried out to study the distribution of temperature in friction stir welded plate of Aluminium alloy. A 3-D finite element simulation model was developed to predict temperature distribution and residual stress in Friction Stir Welding (FSW) of Al 7075 alloy. The effect of angular velocity of tool, axial load and welding speed on the heat generated between the tool and plate to be welded was investigated. The simulations obtained were based on three factor five level central composite rotatable design. Second order polynomial equations for predicting the temperature was developed. Residual stresses for friction stir welded plates due to thermal cycles were predicted. The maximum temperature developed in friction stir welded plated increases with the increase of rotational speed of tool and axial load where as it decreases with increase in welding speed.

Abstract: The fuselage is one of the main component in aircraft to carry payload and passenger. The fuselage enclosed with high weight structure. The fuselage is hollow tube which holds all parts of the airplane together. The shape of the fuselage based on the mission of the aircraft. A supersonic fighter plane will be having streamlined fuselage to reduce the drag force enclosed with high speed flight and similarly the shape vary depend on the velocity. The design of fuselage is very complicated for designers because it takes about 60% of total weight of the aircraft and the contribution of fuselage towards performance and the stability is very decent. This paper investigates the fatigue behavior of the fuselage under dynamic equilibrium state made of both aluminum alloy and Kevlar composite. Those results can be applied to optimize the fuselage structure thereby the better structure can be made.