Applied Mechanics and Materials Vol. 787

Abstract: This paper deals with the transient thermal analysis of brake disc of Variable Braking Force (VBF) system using computer software ANSYS. Generally, brake system is designed to apply frictional resistance to stop the vehicle. In VBF system the frictional resistance applied to the brake disc can be varied by changing the effective disc radius based on the pillion load. The rotor disc is commonly manufactured using cast iron (CI) or stainless steel (SS). In this work, these materials are taken for analysing the temperature distribution of VBF system. In addition to, an effort has been made here to suggest the best suited material for brake disc. By the way, it is evident that the rise in disc surface temperature is higher for VBF system compared with conventional system (constant effective disc radius (r) = 110mm).

Abstract: An automobile braking system has a crucial role for safety of the passenger and riding quality of the vehicle. The brakingforce mainly depends on the normal reaction on the wheel and the coefficientof adhesion between the tire and the road surface. Sometimes the motorcycle may be over braked (Braking force exceeds the traction capacity between tire and ground) that increases vehicle stopping distance due to wheel sliding. So a variable braking force (VBF) system is developed in whichthe effective brake disc radius is variedbased on the pillion load on the motorcycle, for varying the rear wheel braking force that develops between tire and road surface. Whenever amotorcycleis loaded, the normal reaction on the rear wheel is increased.Thus the amount of braking force required to halt the motorcycle withminimum stopping distance and stability of the motorcycle, is based on the pillion load on the motorcycle. Hencethe amount of braking forcedeveloped between the road surface and the tire is varied in the variable braking force system. In this work, a mathematical modeling is developed and analyzed using MATLAB when the rear brake is applied for a motorcycleduring cornering for conventional disc brake system and the variable braking force system. It is found that variable braking force system develops more amount of yaw rate and lateral displacement when it is compared with conventional disc brake.

Abstract: Desiccant evaporative cooling system is a potential environment-friendly alternative to conventional vapour compression chillers. A desiccant wheel is the heart of this heat driven cooling system and it uses a solid desiccant for dehumidification with silica gel being most widely used. The desiccant material is coated, impregnated or formed in a place on the supporting rotor structure. The matrix consists of multiple channels in the direction of axis of rotation of the wheel. Proper design of the wheel is very important for the successful operation of the system and theoretical models are very useful tool in predicting the performance and design optimization. One of the major difficulties in numerical modelling of the desiccant wheel is the lack of knowledge of adsorption equilibrium of porous medium.In this paper, adsorption equilibria of the silica gel is studied and the different theories existing to characterize the adsorption process and different equations for prediction of adsorption equilibria are compared and used in a theoretical model predicting the wheel performance. The results of the different models are compared with experimental data and conclusions are drawn.

Abstract: Annular diffusers are primarily used to convert the kinetic energy of the exhaust flow into pressure energy. The performance of the diffusers are often measured using pressure recovery maps, that generally do not consider the distortion of flow at the inlet due to other upstream machine components. A high swirl velocity at the inlet could often account for large energy losses and hence it is necessary to curb the swirl component by appropriate design considerations. In this present work,it is desired to establish the swirl number range at the inlet of an annular diffuser for its effective and efficient performance and increased pressure recovery of the diffuser. “Swirl effect” on the fluid flow parameters with and without struts is compared, to give the idea of the numerical variation in the parameters.Computational fluid dynamics (CFD) analysis was performed to determine the maximum pressure recovery based on variations in the inlet swirl number. Thus, the flow was studied under varied conditions and a relation between the input parameters and the general pattern of flow for the specified input conditions was critically examined.

Abstract: A Fuzzy Inference System (FIS) is considered as an effective tool for solution of many complex engineering systems when ambiguity and uncertainty is associated with the systems. The water quality is an important issue of relevance in the context of present times. The proposed model is designed to predict Water Quality Index (WQI) for Chunnambar, Ariyankuppam, Puducherry Region, Southern India. A systematic investigation of the pollution level at Chunnambar from March 2013 to February 2014 was carried out. The untreated domestic wastes from various parts of the Ariyankuppam town are directly discharged into the river which leads to increased level of pollution. The present studies emphasis on the magnitude of pollution by monitoring key water quality parameters such as Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), pH and Temperature. FIS simplifies and speed up the computation of WQI as compared to the currently existing standards. In this paper, the proposed model is compared with Indian Water Quality Index (IWQI) and it is found that the designed model predicts accurately.

Abstract: A Theoretical model was developed to study the potential use of surface texturing for reducing the friction between a piston ring and cylinder liner. The model can predict the load-carrying capacity and friction force of the piston compression ring from Reynolds equation. The investigation is carried out using different dimple depths as well as different dimple diameters. Micro-dimples on the piston ring were able to generate significant hydrodynamic support. Numerical results show that surface texturing can decrease the friction force and extend the load-carrying capacity. The optimum surface texturing parameters such as dimples depth and dimples diameter were found.

Abstract: This article examines the fracture toughness of end notched flexure (ENF) composite specimens of three different lay-ups. Experiments were conducted on these glass/epoxy specimens and the critical fracture energy,, was evaluated based on compliance based beam method (CBBM). Classical methods require crack length measurements, which are not easy to obtain as propagation occurs rapidly without a clear opening. The CBBM is based on crack equivalent concept, which does not require crack length monitoring during propagation and hence the crack growth resistance curve (R-curve) can be generated in a much easier way. Moreover, the CBBM accounts the non-negligible energy dissipation in the fracture process zone (FPZ) in addition to stress concentrations near crack tip, contact between specimen arms at the pre-crack region and root rotation effects. Hence, the complete R-curves of ENF specimens of different lay-ups were obtained using the CBBM with higher degree of accuracy. It was observed that the unidirectional specimen did show higher propagation toughness value than the angle-ply and cross-ply specimens.

Abstract: Nut embedded disc grinding wheels, also known as disc grinding or F-Type wheels, are required for many production jobs. Nut pull-out is a common problem encountered in disc grinding wheels. The present work proposes a simple fixture, using which the integrity of the nut in the grinding wheel can be assessed. This method can be adopted by any grinding wheel manufacturer for a realistic estimate of nut pull out strength in double disc grinding wheels.

Abstract: Long cylindrical tubes exhibit poor energy absorption due to Euler’s buckling mode when they are used to absorb impact energy. Circumferential grooves are introduced in the tube to force the plastic deformation which helps to control the buckling mode. Quasi-static and impact tests are performed and the load-displacement curves are studied. The results are also compared with the ones for the geometrically identical tubes. Non-linear finite element analyses are also carried out to simulate quasi-static and impact test conditions. The numerical predicted crushing force and fold formation are found to be in good agreement with the experimental results. The results revealed that grooves can stabilize the deformation behaviour and thus the proposed method could be a good candidate as a controllable energy absorption element.

Abstract: Dissimilar friction stir welding was carried out between AA6061-T6 and AA7075-T6 aluminum alloys. The effect of tool rotational speed and welding speed, on microstructure and mechanical properties were analysed in detail and presented. The tool rotational speed, welding speed, axial load and shoulder diameter to pin diameter (D/d ratio) were the parameters taken into consideration for the study. It was concluded that the tensile strength and hardness value gradually increased with the increase in tool rotational speed and decreased with the further increase in tool rotational speed. The microstructural analysis was carried out for the high strength specimen at various zones. Fine grain size and proper material mixing were observed in the stir zone. Fractographic image of the fractured surface for the high strength joint was presented and discussed. The joint fabricated with tool rotational speed 1000 RPM, welding speed 25 mm/min, axial load 6 kN and D/d ratio 3 exhibited superior mechanical properties when compared to all other joints.