Fastener shear load distribution

P(l) The conditions of equUlbrium shall always be fulfilled when determining fastener load distribution, the shear stress distribution in the vicinity of fastener holes and the flexural stresses in the end-plate. 

Figure 5.19(c) of the EUROCOMP Design Code shows the shear stress distribution, sn. along the so-called shear-out plane. The actual stress field depends on a number of parameters such as elastic properties of the laminate and the fastener, clearance, friction and load magnitude, and loading direction (tensile or compressive). 

The influence of member stiffness (elasticity and geometry) on the bolt load distribution is illustrated by a simple example. Figures 5.7 and 5.8 show schematically a single-lap joint with uniform lap thickness loaded in tension. The upper and lower parts represent the joined members and the layer between represents a row of fasteners. When the load is applied, the members deform concentrically and the fasteners in shear. If the members were rigid, the fasteners would transfer equal amounts of the load, and the shear deformation would be equal in all fasteners (Figure 5.7). 

A typical shear stress or strain distribution in an adhesively bonded lap joint is shown in Figure 5.38. If fasteners are placed in conventional positions (i.e. metal bolted connections), they are located in the area of minor shear stresses. Therefore, when the joint is undamaged the fasteners will be only moderately loaded. 

---