Riveted Joints

Riveted joints are permanent mechanical connections used for sheet structures, dissimilar materials, and assemblies where welding is undesirable. The load passes through rivet shear and bearing pressure at the holes.

Basic checks

For \(z\) equally loaded rivets in \(m\) shear planes,

$$\tau=\frac{F}{zmA_r}\le[\tau],\qquad A_r=\frac{\pi d^2}{4}.$$

Bearing pressure in a plate of thickness \(t\) is

$$p_b=\frac{F}{zdt}\le[p_b].$$

The plate must also be checked across its net section:

$$\sigma_{net}=\frac{F}{(b-z_hd)t}\le[\sigma],$$

where \(z_h\) is the number of holes cut by the section.

Eccentric groups

An eccentric force creates direct shear plus a moment. In a linear elastic group model the moment-induced force on rivet \(i\) is proportional to its distance from the group centroid:

$$F_{Mi}=\frac{Mr_i}{\sum r_j^2}.$$

Vector addition identifies the most highly loaded rivet.

Design rules

Pitch and edge distance must prevent tear-out and permit installation. Hole quality, fit, corrosion protection, inspection, and fatigue detail category often govern service performance more strongly than the nominal static calculation.

Joint layouts and efficiency

Lap joints introduce eccentricity because the connected plate centrelines do not coincide. Butt joints with cover plates can reduce eccentricity and provide one or two shear planes. Joint efficiency compares the strength of the riveted pitch length with that of the unperforated plate; the weakest of rivet shear, bearing, net-section rupture, and edge tear-out governs.

Load distribution

Equal load sharing is a first approximation for compact, symmetric groups. Elastic deformation of plates and rivets makes the end rivets of long joints more highly loaded. Eccentric forces additionally produce group rotation and secondary forces. Fatigue design therefore limits joint length or uses a more refined distribution model.

Hole and rivet formation

Drilled or punched holes must meet the specified quality. Punching can damage the hole edge and may require reaming for fatigue-sensitive work. During setting, the rivet expands to fill the hole and forms the closing head. Setting temperature and sequence influence residual clamping and distortion.

Fatigue and durability

Fatigue cracks frequently initiate at hole edges, especially in the first transverse row. Smooth load introduction, adequate pitch, good hole finish, clamping, and corrosion protection improve life. Inspect for loose rivets, fretting products, cracked paint, deformation, and leakage in sealed constructions.

Calculation sequence

1. Select lap or butt arrangement and number of rows.
2. Determine force per rivet, including eccentric moment.
3. Check rivet shear and plate bearing.
4. Check net-section rupture, edge tear-out, and block failure.
5. Evaluate fatigue, joint efficiency, stiffness, and sealing.
6. Specify hole making, riveting sequence, inspection, and corrosion protection.