Manufacturing large, monolithic composite parts, such as a car body or an aircraft fuselage, requires a large and complex mold. As a result, the process can be quite costly. Alternatively, such complex parts can be manufactured less expensively by assembling a series of smaller parts using various joining techniques.
Manufacturers have several options for joining such parts. Fasteners are the most common method. Fasteners do not require surface preparation and are easy to inspect. In addition, the parts can be disassembled if necessary. However, fasteners have several drawbacks. One is stress concentration due to the holes in the substrates. They also add significant weight to the structure. And, they’re expensive. Fasteners account for 19 to 42 percent of the total cost of a composite aircraft structure.