20 December 2010
20 December 2010
Hexcel recently initiated a design study with Aerodyn Energiesysteme GmbH to evaluate the weight-saving implications of producing wind blade spar caps from prepreg rather than the resin infusion process.
The spar cap is the major load-carrying structure within a wind blade.
For the Hexcel study the aerodyn 50.3m 2.5MW Windclass III blade design was selected. This blade is currently manufactured using resin-infused glass fibre and is commercially available and in operation. Hexcels HexPly M9.6F/32%/1600+50/G+F prepreg was selected for the comparative trials. This 1600 g/m FAW glass UD material uses 2400 tex E-glass filament rovings and contains a 50g/m glass fleece to support the evacuation of air during the cure of the lay-up structure. The mechanical performance of the material was tested by IMA Dresden.
According to Hexcel, after carrying out a number of tests and validating the results, the aerodyn study concluded that replacing a glass fibre infused spar cap with a prepreg design will result in a weight reduction of approximately 400kg in spar structures - 3-4% of the total blade weight - mainly due to the superior strength and stiffness that glass UD prepregs provide in both tensile and compression mode. Hexcel say that the use of prepreg rather than infusion could therefore result in a total cost saving of approximately 1,300 Euros per blade, based on potential savings in material costs and man-hours in production.
Commenting on the results of the study, Andrea Domenichini, Hexcel Senior Vice President and General Manager for Wind Energy said: The aerodyn study confirms and reinforces that the use of prepreg brings significant performance advantages as well as weight-savings when compared with infusion technology. Combined with the cost-saving advantages, prepreg technology will be even more compelling for the wind blade designs of the future.
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