A Noval Concept of Combined Cold Expansion and Surface Processing of Fastener Holes Using Rotating Tool

Bolts, rivets and location pins are commonly used in various engineering applications for assembly of components and structures. The holes produced for the assembly is susceptible to cracks due to fatigue caused by tensile loads applied. These cracks can be prevented or its propagation can be prolonged by inducing compressive residual stress in the material around the hole. Cold expansion hole is one of the techniques used to induce compressive stress zone, by inserting a tapered mandrel/pin or ball into an undersized hole. A novel application of the cold expansion and surface modification of walls of the cylindrical hole is presented. Predrilled holes of different diameters in commercially available aluminum and Al- 2014-T6 aluminum alloy plates are cold expanded using a specially fabricated tapered tool that rotates and simultaneously traverses through the hole. The tapered tool expands the hole to the desired diameter and also stirs the internal wall of the hole. In order to understand the role of frictional heating and stirring in the cold expansion of holes three mediums, namely, dry (without cooling and lubricating), metal working fluid (cooling and lubricating) and Al2O3 nanoparticles (lubricating and frictional heating) are used. The residual stress, surface roughness and hardness of the wall of the holes are measured and SEM images are captured. Significant residual stresses are induced in the material around the hole region. Significant hardness improvement with reasonable surface finish is obtained. Moreover the cold expanded holes showed considerable improvement in the fatigue life of the holes. The fatigue life is found to be directly proportional to residual stresses induced around the hole and inversely proportional to surface roughness. Hardness has a negative impact on fatigue life. The rotating tool cold expansion process is compared with conventional cold expansion process and good efficiency of cold expansion is achieved in case of Al-2014-T6 aluminum alloy material using nanoparticles, in terms of fatigue life achieved. It is observed that frictional heating and the plastic deformation have combined effect on the performance of the cold expansion of cylindrical holes

Intelligent Destination Recommender and Community Builder

Recommendation engines make use of machine learning techniques and generally deal with ranking and rating of products/users. With the help of this system we aim to suggest different destinations to users based on their interest and previous visits. Along with recommendations we also aspire to enable users to build travel communities for people sharing similar interests .This shall help travelers with planning ,meeting like-minded people,safety and enthralling experience. As per the analysis done on pre-existing systems we discerned that enabling users to build a community of travelers visiting the same destination is an eccentric attribute proposed. This distinctive attribute of building communities shall be implemented using the basics of clustering algorithms in Machine learning

Development of CCME WQI model for the groundwater appraisal for drinking in Basaltic terrain of Kadava River basin, Nashik, India

1933-1940In this study, Canadian Council of Ministers of the Environment, Water Quality Index (CCMEWQI) model has been used to ascertain the groundwater suitability for drinking in Kadava River basin located in Nashik district, Maharashtra. Therefore, forty (40) representative groundwater samples were collected from different dug/bore well during Pre (PRM) and Post (POM) monsoon seasons of 2011 and analyzed by standard procedures of APHA. The parameters like pH, EC, TDS, TH, Ca, Mg, Na, K, Cl, F, SO4 and NO3 were considered to compute the CCME WQI model. The results of CCME WQI values inferred that 7.5 % in PRM and 17.5 % samples in POM seasons fall in poor category. Moreover, 77.5 % and 60 % samples fall in marginal category in PRM and POM seasons. While, 15 % and 22.5 % samples came under fair category in PRM and POM seasons. Spatial distribution maps illustrated that North, Central and South regions are identified as vulnerable for drinking; hence, unfit for drinking. In a nutshell, groundwater quality is significantly deteriorated because of agricultural practices and anthropogenic activities, therefore appropriate monitoring along with proper remedial measures is essential to sustain the groundwater quality in the river basin

Surface modification and nanocomposite layering of fastener-hole through friction-stir processing

status: publishe

Surface modification and nanocomposite layering of fastener-hole through friction-stir processing

his investigation studied the surface modification and nanocomposite layering of the cylindrical surface of a fastener-hole using friction-stir processing. A tapered tool rotates and transverses a predrilled hole that gradually expands and simultaneously stirs the surface. The stirring modifies the hole's cylindrical surface to help improve the hardness and resist against fatigue loading. Introduction of nanoparticles between the tool and the hole during the friction stirring results in formation of a nanocomposite layer that further improves the fatigue performance. The process development and resulting changes in surface finish, hardness, compressive residual stress near the hole, and fatigue life are presented; the strengthening mechanisms and their relationship with the process parameters are discusse

Combined Cold Expansion and Friction Stir Processing of Fastener Holes in Aluminum Alloy Al-2014-T6

Cold expansion is used to induce compressive stress zone, by inserting a tapered mandrel/pin or ball into an undersized fastener hole in order to improve fatigue life. In this paper, combined cold expansion and friction stir processing of fastener holes in aluminium alloy Al-2014-T6 is presented wherein the cold expansion tool rotates and thus friction stirs the cylindrical surface of a fastener hole while expanding it. The residual stress, surface roughness and hardness of wall of fastener holes are measured and SEM images are captured. The combined cold expansion method is evaluated for three conditions at tool and fastener hole interface, namely wet (i.e., in presence of metal working fluid), solid lubricant (i.e., in presence of Al2O3 nanoparticles), and dry (i.e., without any external medium). The conventional cold expansion process is compared with combined cold expansion and friction stir processing. The results indicate efficacy of using nanoparticles as a medium in combined cold expansion and surface processing of Al-2014-T6 aluminium alloy to improve surface integrity and fatigue life

A fundamental investigation on rotating tool cold expansion: Numerical and experimental perspectives

In this study, we present the development of a novel technique for cold expansion using a rotating tapered mandrel that friction processes the cylindrical wall of the fastener hole and simultaneously cold expands it. The developed technique, named as rotating tool cold expansion (RTCE), is experimentally and numerically investigated. A 3D thermomechanical finite element model for predicting the compressive residual stress, responsible for delaying crack propagation from the edges of the holes, is introduced. The efficacy is that RTCE is assessed for varying degrees of cold expansion under different lubricating conditions at the tool-workpiece interface, such as dry, metal working fluid, and nanopowder. The plastic deformation combined with friction stirring at the tool-workpiece interface helps the RTCE in controlling the surface damage at entry and exit of the hole that is most often observed with the conventional cold expansion technique. Enhanced friction due to the nanopowder at the tool-workpiece interface helps in sustaining efficacy of the RTCE even at a higher degree of cold expansion which otherwise leads to surface damage with other medium

Geochemistry, Petrogenesis and Tectonic Setting of Metavolcanics and their Implications for Gold Mineralisation in Gadag Gold Field, Southern India

Gold bearing metavolcanics of Gadag Gold Field (GGF) are represented by mafic (metabasalt, metabasaltic andesite), intermediate (metaandesite) and felsic (metadacite, metarhyolite) rocks. Mafic metavolcanic rocks are low-K Fe-rich tholeiites and were derived by partial melting of the upper mantle sources with high Fe/Mg ratios and low M values. Intermediate and felsic metavolcanics were formed by remelting of these tholeiites mainly in crustal regimes. Although a complete sequence of metavolcanic rocks from mafic to intermediate to felsic fractions occurs, these products were not the result of differentiation from a single magma, crustal contamination was involved in the formation of intermediate and felsic rocks. A clear gap in the chemical composition as well as index of differentiation among the mafic, intermediate and felsic fractions indicate that these metavolcanics constitute a typical bimodal character. It is suggested that these metavolcanics were emplaced in an active continental margin or a continental island arc setting. The petrogenetic processes of formation of Fe-rich tholeiites that evolved in an active continental margin or a continental island arc setting could have provided a favourable geochemical environment for gold mineralisation under the conditions of deformation and metamorphism