Stress Distribution in Bolted Joints

In the side view of a bolted connection under load, the stress peaks around the bolt appear very clearly (Fig. 32.2). The unstressed zones of the component appear yellow, e.g., in the upper right-hand corner. Moving from this unstressed area toward the bolt, a series of colored lines are crossed until the zone of greatest stress is reached around the shaft of the bolt. A plan view of the connection reveals a similar picture a high concentration of stresses around the bolt (Fig. 32.3). At these points the component is vulnerable to damage. A similar pattern of stress distribution is observed in components that are fastened together with rivets or spot welds. 

Due to the force applied, the fastener is shifted under shear between the two sheets, and the eccentricity of the force introduces a considerable momentum locally into the joint. The sheets undergo local bending. When the load is increased, the rivet holes are additionally deformed into an oval shape, especially in the thin aluminum face layer of a sandwich panel. The deflection of the joint even leads to small separations between the sheets in the overlapping region. 

32 Advanced Mass Transport Applications with Elastic Bonding of Sandwich Components 

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