Page 137 - Handbook of Adhesives and Sealants

106 Chapter Three

Figure 3.9 Butt joint designs.

in cleavage stress at the ends of the joint, which seriously impairs its
efficiency. Modifications of lap-joint design include:

1. Redesigning the joint to bring the load on the adherends in-line;
2. Making the adherends more rigid (thicker) near the bond area (see
Fig. 3.8); and
3. Making the edges of the bonded area more flexible for better con-
formance, thus minimizing peel (i.e., tapering the edges of the ad-
herend).
Modifications of lap joints are shown in Fig. 3.10. The joggle-lap
joint design is the easiest method of bringing loads into alignment.
The joggle lap can be made by simply bending the adherends. It also
provides a surface to which it is easy to apply pressure. The double-
lap joint has a balanced construction that is subjected to bending only
if loads on the double side of the lap are not balanced. The beveled
lap joint is also more efficient than the plain lap joint. The beveled
edges, made by tapering the ends of the adherends, allow conformance
during loading. This reduces cleavage stress on the ends of the joint.