Thin-layer element method for multi-stage rotor bolt loosening identification.

In order to solve the problem of difficult simulation of the bolted joint structure of rotors, this study proposes an improved sub-regional thin-layer element method (ISRTL) and applies it to the equivalent simulation of the joint interface in the presence of bolt deviations. The theory introduces the fractal theory and Hertz contact theory to calculate the thin-layer parameter for the region with weak influence of bolt preload. The trend of dynamic response under different loosening deviation conditions is investigated. The experimental study of bolt deviation under axial tension and transverse vibration was carried out using a drum-disk rotor. The frequency and stiffness with bolt loosening position conform to M-type trend. The error of the eigenfrequencies calculated by the proposed method is within 3 % from the experimental results. The results demonstrate that ISRTL method has high accuracy and efficiency in the simulation study for the assembly deviation of rotor bolt connections. [ABSTRACT FROM AUTHOR]