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Top1. Introduction
Joining of materials to achieve high strength and optimum functionality of design has been utilized for a long time. In an almost completely metallic manufacturing environment, mechanical joining processes using nails, screws, nuts and bolts, along with heat-based joining techniques such as welding, brazing, soldering etc. were employed. Modern engineering systems are increasingly using components that combine two or more materials for performance enhancement. Adhesive bonding is a modern assembly technique where two similar or non-similar materials (metals, plastics, composites, etc.) are joined using an adhesive. It is an alternative method by which materials can be joined to generate assemblies or structures without the use of mechanical fasteners. In adhesive bonded product, the load is passed from one adherend to another adherend via the adhesive layer in the overlap region. Thus the adhesive serves as a medium for load transmission.
Different methods have been explored to increase and optimize the strength of adhesive joints. Among these, one way that various researchers have tried is adding some supplementary material (in the form of additives) to the adhesive to augment the adhesive bond strength (Smith et al., 1991; Richards et al., 1993; Kim & Robertson, 1998). In this regard, a paper by the authors of this work may be referred (Acharyya, et al., 2008). From the applications point of view of adhesive joints, it is obvious that adhesive joints will be primarily used in load bearing structures. A major hurdle in this regard is the difficulty of strength evaluation of adhesive joints. For ensuring safety of the designed joint, stress analysis is of primary importance. Over a long period of time (5-6 decades), different researchers have proposed different models for specific adhesive joint systems.