ECN publicatie:
Titel:
Strength and fatigue testing of large size wind turbine rotors: vol. 1:rationale and directions
 
Auteur(s):
Grol, H.J. van
 
Gepubliceerd door: Publicatie datum:
ECN 1996
 
ECN publicatienummer: Publicatie type:
ECN-C--95-052 ECN rapport
 
Aantal pagina's: Volledige tekst:
207  Niet beschikbaar.

Samenvatting:
Some 20 industries were approached through a questionnaire. The workconcerned full size Natural Vibration Tests (NVT), Static Strength Tests (SST) and Fatigue Strength Tests (FST). Principal objectives were to determine points of departure to arrive at well defined mechanical test results in relation to design and manufacturing, to give recommendations on procedures and methodologies how to perform these tests, and to address the costs and benefits. Mechanical tests were to be executed also. The work is documented in three different volumes: this one, vol. 2: Full-size NVT and SST. A reference case, and vol. 3: Full-size FST. A reference case. The tests concern modelling, calculations, production methods or materials. With regard to the NVTs the principal objectives have been formulated, implying a specification which key quantities should be verified (mass, location of center of gravity, stiffness and resonance frequencies). The SST has been elaborated in terms of the performance of the Limit Load Test(s) (LLT), the Ultimate Load Test(s) (ULT) and a Failure Load Test (FLT), particularly in relation to the test objectives. A guideline on the practical performance of the SSTs was drafted, containing directions on different items. The FST has been elaborated in terms of the performance of an Ultimate Fatigue Strength Test(s) (UFT) and subsequently the Residual (Ultimate) Strength Test(s) (RST) and a Residual Failure Strength Test (RFST), all in relation to the test objectives. Also a guideline on the practical performance of the FSTs was drafted, containing directions on different items. Present regulations (standards) of CIWI, DS, GL and IEC can certainly be improved. The recommended safety factors being it on loads, or on materials or even on the product of them show too large differences. More attention should be paid to a consistent design approach of static versus fatigue strength and to the possibility that safety factors can be verified through proper laboratory tests. The very first blade the manufacturer will rely on, shall be used as the first test specimen for the performance of the NVTs and the SSTs. 22 figs., 15 tabs., 20 refs.


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