Journal of Failure Analysis and Prevention

, Volume 19, Issue 4, pp 986–991 | Cite as

Failure Analysis of a MW-Class Wind Turbine Blade Root Bolt

  • Zhunbei Zheng
  • Xiaochen WangEmail author
  • Wenbin Guo
  • Zhanjun Yang
  • Xingxin Sun
  • Xiuguang Li
Technical Article---Peer-Reviewed


Failure analysis of a fractured high strength bolt used in a MW Class wind turbine blade connection system was conducted to clarify the failure cause and to determine the prevention method. Applying detailed mechanical characteristics and metallurgical investigations, the bolts failure cause can be attributed to bending fatigue. Evidenced by the nut polished markings, insufficient tightening was considered as the important reason for the bolt failure. The thread microstructure indicated that the fractured bolt thread was rolled rather than machined. However, rolling induced cracks locating on the thread crest and non-uniformly distributed decarburized layer on the bolt thread root existed. Thus, it can be concluded that the bolt failure was caused by the insufficient tightening and improper manufacturing procedure.


Wind turbine blade High strength bolt Insufficient tightening Decarburized layer Cyclic bending fatigue 



This study was supported by the Datang Power Company Fundamental Research Funds under Grant No. JT2016-01.


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Copyright information

© ASM International 2019

Authors and Affiliations

  • Zhunbei Zheng
    • 1
  • Xiaochen Wang
    • 1
    • 2
    Email author
  • Wenbin Guo
    • 1
  • Zhanjun Yang
    • 1
  • Xingxin Sun
    • 1
  • Xiuguang Li
    • 1
  1. 1.China Datang Northwest Electric Power Test and Research InstituteXi’anChina
  2. 2.School of AutomationXi’an University of Post and TelecommunicationXi’anChina

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