Methodology for the Optimization of Bolting Sequences for Wind Generator Flanges

Abstract

In bolted joints, bolts are tightened to a uniform preload in order to improve their operational behavior. This preload is not easy to achieve due to several phenomena that occur during the tightening sequence; in the case of wind generator bolted joints, which present a gap between the contact surfaces of the flanges, the elastic interaction is by far the most prejudicial of them. As a consequence, the tightening sequence is very costly, typically consisting on a large number of passes. Based on a metamodel created in previous work, this work presents methodology for the optimization of the tightening sequence, which consists on calculating the load to be applied to each bolt so as to achieve the target uniform preload at the end of the sequence in only one pass or two at the most. This methodology is based on optimization methods used for pressure vessel bolted joints has provided satisfactory results (validated via FE analyses) with a very low computational cost.