Fatigue of shaft flange bolted joints under preload force and dynamic response

Abstract

The bolted joints are used for flange connections which are subjected to preload forces and dynamic loads. This combination of static and dynamic loads in threaded joints result with complex interaction of high mean stresses, high notch effect, thread flanks contact forces and moments, and contact surfaces slippage which leads to fatigue damage. The Multi-body system dynamic model of shaft was used for assessment of dynamic behavior. Finite element model of shaft flange connection, with detailed thread joints made of heat treatable steel 30CrNiMo8 under preload condition and nonlinear thread flanks contact, was created. The Rainflow cycle counting was used as a cycle count method for describing the load cycle with local stress-strain hysteresis loop. Influences of mean stresses, bolt diameter, and stress gradients were taken into account according to FKM guidelines. The most critical fatigue locations were obtained at thread roots.

Keywords

• thread fatigue
• joint integrity
• flange bolted joint
• thread flanks contact
• thread forces and moments
• fkm guidelines
• multiaxial fatigue