Structural Testing of 500 kW Wind Turbine Blade Root Connection

Veera Sesha Kumar, C and Jayaraman, M (2014) Structural Testing of 500 kW Wind Turbine Blade Root Connection. Project Report. National Aerospace Laboratories.

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This report describes details of structural static test carried out on a specimen joint simulating the blade root connection of a 500 kW wind turbine blade that was developed by NAL under NMITLI program. The objectives of the test are to demonstrate the structural integrity of the joint and to measure percentage load acting on the bolt when the joint is subjected to external load corresponding to the critical load case. The T-bolt connection is chosen for blade root joint for its simplicity compared to other joints and its effectiveness to improve fatigue life of the bolt. A design preload of 120 kN and an external load of 88 kN corresponding to class III gust wind load case, as defined by Germanischer Lloyd (GL), were considered to test the joint. A small segment of the blade root at highly loaded region is considered for testing. The Glass-Epoxy composite laminate of 60 mm thickness representing blade root shell thickness is fabricated using glass fiber and epoxy resin through wet lay-up process. After each of the T-bolts is preloaded to 120 kN, a total load of 264 kN (for 3 bolts) is applied on the simulated blade root-hub joint using a Universal Testing Machine. The maximum strain recorded in the T-bolt and composite laminate after preload were 2370 and 1721 µs respectively. The maximum strain in T-bolt and composite laminate after application of external load were 2780 and 4465 µs respectively. The joint successfully withstood the design ultimate load without any failure and only 24% of external load acted on the T-bolt as predicted meeting all the design objectives.

Item Type: Monograph (Project Report)
Subjects: RENEWABLE ENERGY > Wind Energy
Depositing User: C Veera Sesha Kumar
Date Deposited: 20 Jun 2014 08:36
Last Modified: 20 Jun 2014 08:36

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