Experimental Research On Prestress Loss And Corrosion Rule Of Base Anchor Bolt Of Wind Turbine

In the background of global energy shortage,renewable new energy has become a hot spot in research and development.Wind energy has attracted people's attention due to low cost and large reserves.In recent years,wind power technology has been greatly developed,promoting install capacity and efficiency increase of wind turbines(WT).However,due to the poor working environment of the WT,many collapse accidents occurred in the WT structure.One of the main reasons was the corrosion of foundation anchor bolts.Prestressed anchor bolt,as an important connecting part between WT foundation and tower barrel,played a key role in structure safety.Therefore,it was very important to detect the corrosion of the anchor bolt of the WT.In this paper,the rule of prestressing force change under corrosion condition of WT bolt is studied by experiment and numerical calculation.The main research contents of this paper were as follows.An experimental system for accelerated corrosion detection of anchor bolts by electrification was designed.Test with the same foot size and material bolt as the WT,study on the influence of corrosion on prestressing force and its changing law.Firstly,on the basis of defining the principle of corrosion,the experimental system of corrosion was designed.The experimental equipment and loading process were determined.Complete six groups of test conditions of 7%,10%,12%,15%,17% and 20% loss of prestressing force.Establishment of field equipment for experimental model and electrochemical accelerated corrosion test.Monitoring the variation of prestressing force and cross-section corrosion during the process.The change rule and influence of corrosion on anchor bolt prestressing force were studied.The change of section after corrosion of anchor bolt was analyzed,and the change rule of section under different conditions of prestress loss was obtained..The bolt was divided into several sections and the area of each section was measured.Summarize the difference of corrosion degree in different positions,and get the distribution law of cross-section area of bolt.With the changes of different working conditions of prestress loss,getting the different size of bolt in the same corrosion condition.Combined with the change of mass parameters before and after corrosion of the anchor,obtaining the relationship between prestress loss and section loss.A corrosion model of prestressing anchor bolt is established.Based on the experiment,the model was simplified and the theoretical formula of the corrosion model was deduced.The bolt stiffness value was obtained by ABAQUS modeling,and the relationship between corrosion rate and cross-section change was determined.Based on the experiment data,the corrosion model was modified,the relationship between the prestress loss and the section loss was obtained.Based on this,a safety assessment method was established.By Faraday's law getting mass loss in theory and actually,combined with the equivalent accelerated relationship getting time scale transformation between test with actually.Computer vision technology was used,through adjust the camera's positions,distances and angles,the 3D model reconstruction of the anchor is completed,and obtaine the shape of the rod after reconstruction.Establish corrosion pit defects with bolt ANSYS three-dimensional finite element model to analyze the stress distribution rule.Complete the parametric analysis of the size change with the corrosion pit and study the influence on the maximum stress and displacement of the bolt.