Key Points for Eccentric Bolt Connection Calculation

In fastener connection design, eccentric loads and eccentric clamping are common. When the load line deviates from the bolt group center or clamping force line, an additional moment is generated, causing uneven bolt loading and uneven joint face pressure.

Minimum preload calculation is fundamental. In eccentric scenarios, the additional moment must be considered. If preload is insufficient, some bolts may fail due to overload, and local separation may occur on the joint face.

Separation load calculation is the core difficulty. This refers to the critical load at which gaps begin to appear on the joint face. Traditional concentric analysis underestimates separation risk because it does not account for the additional moment.

Flange face deflection analysis is essential. Flanges have relatively low stiffness and are prone to bending deformation under eccentric loads, further unevenly distributing joint face pressure. Beam theory or thin plate theory can be used to calculate flange deflection.

For complex eccentric bolt connection systems, finite element analysis is advantageous. It can accurately simulate geometry, material properties, and contact relationships, providing detailed data on bolt load distribution, joint face pressure distribution, and deflection deformation.

In summary, bolt connection calculation under eccentric loads and eccentric clamping must go beyond traditional concentric analysis, focusing on the additional moment to accurately calculate minimum preload and separation load, while correcting for connection deflection. For complex scenarios such as flange connections, finite element analysis is recommended.