Jixie qiangdu (Jan 2019)
FATIGUE STRENGTH ANALYSIS OF HIGH-STRENGTH JOINT BOLTS UNDER MULTIAXIAL NONPROPORTIONAL LOADING SPECTRUM
Abstract
A method about fatigue strength analysis of high-strength joint bolts was proposed on the background of gearbox housing joint design of the wind turbine. The method was based on the theory of multi-axial fatigue. And the calculation process of the method described as following: first,the multi-axial non-proportional loads,which loading on the hub blade because of natural wind,were transformed into corresponding stress spectrum after the process of the stress calculation of housing FE model and the stress treated according to the rain-flow counting rules. Second,the Mises stress was synthesized at the calculation nodal location of the bolt cross section from the multi-axial stress spectrum. And third,the fatigue damage of the nodal location was calculated according to the VDI2230 standard under the consideration of the bolt material S-N curve. Finally,the fatigue safety factor of the joint bolts was obtained according to the theory of Palmgren-Miner. Application software was programmed according to the method. With the software,a case of high-strength joint bolt fatigue strength was analyzed,and the fatigue safety factor is1. 819 within the design life of 20 years. The paper proposes a new way to evaluate the fatigue strength of high-strength joint bolts under complex loading condition.
