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Fatigue properties and design of wing blades for windturbines

Objective

To investigate fatigue properties of wing blade materials and windturbines components and to formulate and validate norms and standards which will be linked to produce a design code.
The fatigue properties of wing blades are being studied in order to develop our knowledge of the response of materials and structures to fluctuating loads. A variety of materials have been studied comprising fibre reinforced plastics as well as laminated wood. The major activity is fatigue testing of blade materials under many conditions of loading and environment. The accumulation of damage is being studied in order to determine suitable failure criteria. Components testing has involved the fatigue testing of blade root connections as well as spars. Monitoring the formation of damage is more difficult, primarily due to the size of the component. Analysis of the results is proceeding together with discussions with test stations and classification societies. This is leading towards the derivation of good working practices, which will assist in the formulation of norms and standards.
The work program covers studies of fatigue properties of a group of fibre reinforced polymers and of laminated wood, and of performance of blade/root connections in fatigue. The results lead to establishment of norms and standards, which form the basis for design guidance.

Three groups of tasks are included in the work program:

1) Fatigue properties of glass/polyester, glass/epoxy, glass/ carbon/polyester and wood/epoxy materials; the studies include fatigue (S-N curves), damage accumulation and failure criteria.

2) Root-joints and spar beams are loaded in fatigue, and performance is monitored.

3) The results are analyzed to establish mechanical models of properties and performance. Norms and standards are evaluated and modified, and a design guide is formulated.

The work program will be carried out in four main phases:

1) characterization;
2) material evaluation;
3) root evaluation.
4) validation

The three first phases will evaluate the following concepts: material selection; fabrication procedures; test methods; test data; on-line monitoring, method of loading, damage accumulation; damage tolerance and failure criteria. Finally, the validation consists of a) the establishment of mechanical (predictive) models by analysis of results; b) the verification of norms and standards where these exist, and recommendations if any changes are required; and c) the formulation of new norms and standards where they are absent, and validation of these. The linking of both sets of norms and standards will include the design code.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

RISOE NATIONAL LABORATORY
Address
Frederiksborgvej 399
Roskilde
Denmark

Participants (9)

DET NORSKE VERITAS AS
Norway
Address
Veritasveien 1
300 Hovik
ENERGY RESEARCH CENTRE OF THE NETHERLANDS
Netherlands
Address
Westerduinweg 3
Petten
FFA - THE AERONAUTICAL RESEARCH INSTITUTE OF SWEDEN
Sweden
Address
12-14,Ranhammarsvaegen 12-14
161 11 Bromma
GENT UNIVERSITY
Belgium
Address
Sint Pietersnieuwstraat 25
9000 Gent
GERMAN AEROSPACE CENTRE
Germany
Address
Linder Höhe
51147 Koeln
STICHTING NATIONAAL LUCHT- EN RUIMTEVAARTLABORATORIUM
Netherlands
Address
Anthony Fokkerweg 2
1006 Amsterdam
Sciotech
United Kingdom
Address
9 Heathwood Yateley
GU17 7TP Camberley
UNIVERSITY OF BATH
United Kingdom
Address
Claverton Down
BA2 7AY Bath
University of Bristol
United Kingdom
Address
Senate House Tyndall Avenue
BS8 1TH Bristol