SparPreg UD Prepreg Spar Solution Brochure (v2)
16Pages

SparPreg™ UD Prepreg Spar Solution www.gurit.com

SparPreg™ UD Prepreg Spar Solution As the design of large multi-megawatt wind turbines progresses, wind turbine blade designers are investigating the benefits of new prepreg materials. Two recently launched Gurit Sparpreg™ products are true game changers and convincing arguments for blade builders to look again at their designs and production processes in a holistic manner. This brochure explores some of the technical and commercial challenges facing WTG designers in the pursuit of longer blades and evaluates the material solutions available to them. Gurit has been supplying materials to...

Gurit Spar Brochure Guide Glass Sparcaps Glass Blade Design Study This study explores the potential for extending the life of a blade design using glass materials by exploring alternative material options to traditionally used E-Glass infusion, including: n E-glass prepreg Page 3 Carbon Sparcaps Carbon Blade Design Study Page 4 A study focussing on the benefits of using carbon fibre, including: n Design limitations of glass n Benefit to blade weight n High modulus glass prepreg Three key design limitations are considered: n Natural Frequency n Tip Deflection Design n Edgewise Fatigue...

Glass Blade Design Study To explore the advantages of higher modulus glass materials such as prepreg and high modulus glass fibres, it is useful to firstly model a traditional glass design and discuss the key design drivers as a function of blade length. A Gurit in-house engineering blade design model was used to calculate the amount of unidirectional glass composite required in a spar cap for a given load case and tip deflection plotted as a function of length. This is shown in the figure below for blades of length 45 to 55m. Thousands Another approach to avoid the blade striking the tower...

Carbon Blade Design Study Even when using thicker blade sections there comes a point when designing with glass becomes increasingly difficult because of high edgewise fatigue loads caused by the rapidly increasing blade weight. The alternative is to use a high modulus fibre like carbon that has inherently more stiffness compared to glass. Although more expensive, carbon provides significant design advantages: n 3 x Modulus Commercial Justification for Carbon n 2 x Strength Carbon spar caps enable the use of more aerodynamic blade n 30% Lower Density profiles (thinner sections), and...

Thermal Expansion The economic advantages of carbon fibre in the spar cap do The focus of the following analysis is split into the two main not generally transfer to other parts of the wind turbine blade, zones of the spar. because they are driven by strength rather than stiffness, and the weight penalty of glass becomes less significant. This means that carbon spar caps need to be interfaced structurally with glass laminate, potentially leading to thermally-induced stresses caused by the difference in coefficient of thermal expansion (CTE) of the two fibre materials. CTE (10-6/°C) 1....

Lightning Protecting Lightning protection of wind turbine blades and generations is a major concern within the industry for a number of reasons: safety of personal during tower maintenance, significant number of insurance claims, costly on-site repairs and costly disruptions to power supply. Furthermore, lightning protection of wind turbine blades becomes more challenging with the increasing size, particularly offshore, where the uppermost blade tip may be 150m above sea level. The main aim of lightning protection is to avoid a lightning arc inside the blade itself, which can overheat the...

Carbon Cost Study The uptake of carbon fibre in the design of wind turbine blades has been restricted due to the high cost of carbon fibre and the difficulties in using it in blade manufacturing processes. The point at which carbon becomes a viable alternative to glass is the subject of much debate due to the many factors that need to be considered. The first benefit is the capability to design with small blade thicknesses increasing the aerodynamic efficiency. This has been illustrated by estimating the effect of blade aerodynamic geometry on energy capture for 3.6 MW turbine with 60m...

9MW, 75m Blade Design Study The next generation of WTG require blades in the region of 75m in length raising new design and processing challenges. Whilst higher modulus materials can greatly help designers, the use of a new material, requiring different processing techniques can in itself prove to be too great a challenge. This section explores the implications of a 75m blade and the options available to maximise the potential of glass fibre. A quantitative comparison of structural designs of three 75m, 9MW blades using e-glass epoxy infused, e-glass epoxy prepreg and r-glass epoxy prepreg...

Flapwise Bending Bill of Materials For the glass spar cap blades, due to the tip deflection For the glass spar cap blades, a strong correlation was seen requirements, it was found that all axial strains due to flapwise between the longitudinal modulus and mass of the unidirectional bending were significantly below allowable values meaning that plies due to the stiffness critical nature of these blades. This the blade flapwise bending strength was not driving the design mass saving, however, only constituted a small percentage of in this case. the total bill of materials for the blades. For...

9MW WTG 75m Blade Cost Study Evaluating the commercial impact of longer, heavier blades on the overall WTG cost is a highly complex calculation dependent on too many factors to be able to generalise. The figure (right) shows just such a conservative estimate using the same approach as for the 50m carbon cost study (page 6) with the weight saving of key WTG components through using carbon spar caps as being up to 35 tonnes for a 75m blade. There are also other important factors to consider such as the fact that carbon spar caps enable lighter, slimmer and therefore more efficient blades...