Local fatigue behavior in tapered areas of large offshore wind turbine blades

37th Risø International Symposium on Materials Science

Hosseiny, Seyed Aydin Raeis^1 ; Jakobsen, Johnny^1

Department of Mechanical and Manufacturing Engineering, Aalborg University, Aalborg, Denmark^1

关键词: Catastrophic failures;    Different damages;    High stress concentration;    Load-carrying elements;    Material utilization;    Multi-axial fatigue;    Sub-modeling approach;    Wind turbine blades;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/139/1/012022/pdf
DOI  :  10.1088/1757-899X/139/1/012022

来源: IOP

【 摘 要 】

Thickness transitions in load carrying elements lead to improved geometries and efficient material utilization. However, these transitions may introduce localized areas with high stress concentrations and may act as crack initiators that could potentially cause delamination and further catastrophic failure of an entire blade structure. The local strength degradation under an ultimate static loading, subsequent to several years of fatigue, is predicted for an offshore wind turbine blade. Fatigue failure indexes of different damage modes are calculated using a sub-modeling approach. Multi axial stresses are accounted for using a developed failure criterion with residual strengths instead of the virgin strengths. Damage initiation is predicted by including available Wohler curve data of E-Glass fabrics and epoxy matrix into multi-axial fatigue failure criteria. As a result of this study, proper knock-down factors for ply-drop effects in wind turbine blades under multi-axial static and fatigue loadings can be obtained.