Simple Lap Joint Geometry
The chapter outlines the basic mechanics of adhesively bonded simple lap joints, focusing on the analytical solutions that have been developed. This can be viewed as foundational material for the chapters in this book that deal with numerical modelling of
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Impact Chiaki Sato
Abstract This chapter treats mechanical aspects of adhesively bonded joints subjected to impact loads. Fundamentals of impact mechanics of solids are introduced in Sect. 10.2, where stress wave phenomena are explained. A simple formulation of lap joints subjected to an impact stress, which is based on the Volkersen model, is given and calculated numerically with the discrete element finite difference method in Sect. 10.3. Fundamentals of the finite element method for dynamic problems are introduced in Sect. 10.4, where two types of methods: implicit and explicit schemes are explained. In Sect. 10.5, a calculation result of a single lap joint with the finite element method is shown as an example. Experimental methods for evaluating the impact strength are discussed in Sect. 10.6. Stress distributions and their variation as a function of time for joints subjected to impact loads are given by calculations based on analytical models and the finite element method.
10.1 Introduction Adhesively bonded joints in actual products may be sometimes subjected to impact loading. For example, passenger cars can be subjected to impact loading in case of crash. Recent car structures of steel have many adhesively bonded parts such as door panels, engine bonnets, and in addition, main structures in some cases. Almost all the inner panel and the outer panel of a door are joined together with the combination of adhesion and metal plastic working, which is called hemming technique. The engine bonnet has an outer skin and an inner stiffener that are joined with an adhesive and spot welding. The technique is called weld bonding, and it can also be applied to the main structures of recent expensive cars instead of using spot welding only. Even for the joints with plastic parts including bumper, adhesion is employed Chiaki Sato Precision and Intelligence Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan, e-mail: [email protected]
ยจ L.F.M. da Silva, A. Ochsner (eds.), Modeling of Adhesively Bonded Joints, c Springer-Verlag Berlin Heidelberg 2008
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quite often. In order to prove the crashworthiness of the structures, the evaluation and estimation of the impact strength of such joints are indispensable for appropriate design. Particularly, when the joints are used in critical parts, passenger safety depends strongly on their design. Therefore, adhesively bonded joints have become very important recently, and automobile engineers have aimed at establishing design rules. Mobile electronic devices such as mobile phones or pocket PCs are the other typical case, and they have many joints bonded with adhesives or pressure sensitive adhesives. They are also subjected to impact loading in case of drop, and the situation is not rare as almost all users have experienced such a case. It is, therefore, necessary to ensure the impact durability of the joints in the design process. Despite the facts, much research on impact phenomena of adhesively bonded joints has n
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