Skip to main content

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


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.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6


  1. A.R. Ghasemi, M. Mohandes, Composite blades of wind turbine: design, stress analysis, aeroelasticity, and fatigue, in Wind TurbinesDesign, Control and Applications (2016)

  2. D. Liu, X. Shang, Failure investigation of the wind turbine blade root bolt. J. Fail. Anal. Prev. 13(3), 333–339 (2013)

    Article  Google Scholar 

  3. J. Zhang, A. Li, C. Zhang et al., Failure and fracture analysis of bolt assembled on the fan used in the internal combustion engine. J. Fail. Anal. Prev. 16(2), 302–309 (2016)

    Article  Google Scholar 

  4. J. Zhang, B.F. Wen, J.T. Zhao, W. Shi, Failure analysis on fracture of high-strength bolts for fastening wind turbine. Phys. Test. Chem. Anal. Part A: Phys. Test. 50(12), 933–935 (2014)

  5. F.R. Hutchings, P.M. Unterweiser, Failure analysis: the British Engine Technical Reports. IEEE Trans. Reliab. 35(4), 374 (1986)

    Article  Google Scholar 

  6. Q. Zhao, F. Liu, L. Wang et al., Effects of Thread Rolling on 1240 MPa Titanium Hi-Bolt (Aeronautical Manufacturing Technology, Beijing, 2016)

    Google Scholar 

  7. J.A. Escobar, A.F. Romero, J. Lobo-Guerrero, Failure analysis of submersible pump system collapse caused by assembly bolt crack propagation by stress corrosion cracking. Eng. Fail. Anal. 60, 1–8 (2016)

    Article  Google Scholar 

Download references


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

Author information

Authors and Affiliations


Corresponding author

Correspondence to Xiaochen Wang.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Zheng, Z., Wang, X., Guo, W. et al. Failure Analysis of a MW-Class Wind Turbine Blade Root Bolt. J Fail. Anal. and Preven. 19, 986–991 (2019).

Download citation

  • Received:

  • Revised:

  • Published:

  • Issue Date:

  • DOI:


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