Standard Methods for Aerospace Stress Analysis

10Joints and Fasteners

10.1 Introduction to Joints and Fasteners

At locations where a structure has to transition to another type of structure, normally joints and fasteners are used. The joints and fasteners in the connection transfer loads and need to be designed sufficiently to withstand the associated stress levels. There are general concepts that need to be discussed for designing such connection joints (mechanical or adhesive), and in this chapter, those major concepts are explored.

10.2 Fastener‐Connection Failure

10.2.1 Mechanical Joints (Lugs) Analysis

For a mechanical joint or lug where load is transferred from the lugs on one side to another set via a fastener or pin, the loading is defined as shown by Figure 10.1.

The joint failure is by tension in the net cross‐section, shear tearing out bearing, shear of the pin or fastener, or bending of the pin. The lug schematics are defined as shown in Figure 10.2.

The bearing area and the net tension area are defined as

(10.1)

(10.2)

The ultimate allowable lug for tension failure is defined by

(10.3)

where F_atu is the ultimate tensile strength of the lug material and axial load tension factor, Kt is determined from Figure ...