Study On Pre-tightening Force And Deformation Of Bolted Connection With Rabbet Considering Actual Contact

The joint of low pressure shaft in turbofan engine is a typical non-gasketed flange connection structure with rabbet,which requires the uniform preload distribution due to high performance.But in the process of tightening,because of bolt elastic interaction,the final preload distribution could be varied.The face runout of contact surface changed the properties of the elastic interaction,which proposed new requirements of non-gasketed flange research.Thus the two bolts flange FEA model was developed to focus on the effect of bolt space,tightening step and face runout on preload change rate with actual contact.The six bolts flange FEA model was developed to make a comparison between ideal contact and actual contact.The bolt elastic interaction of actual contact was proposed,which provide the final preload distribution of different tightening patterns.And then the effect of tightening start position on final preload distribution was discussed,which could provide theoretical basis for non-gasketed joint assembly.On the other hand,the connection of the rotor in the aeroengine has many bolted joints with rabbet,and the concentricity of the assembly is the core problem that restricts the performance of the engine.Geometric errors and tightening processes can cause deformation of the mounting edge after assembly,resulting in changes in concentricity.In this paper,the coordinated deformation process of the rotor mounting edge and the rabbet is studied,through a simplified rotor FEA model with non-parallel deviation.And the influences of nonparallelism deviation,stop interference,structural size parameters and tightening sequence on assembly concentricity are analyzed in this model.In addition,Comparing the centroid moving trajectory and the final centroid distribution of the shaft end face under different tightening starting positions and different tightening sequences,the influence of the tightening starting position and the tightening sequence on the final eccentricity error is revealed.At the end of the paper,a method of improving the concentricity of rotor assembly by tightening process is proposed under the condition that the parallelism deviation is inevitable.