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SPARS FOR WIND TURBINE ROTOR BLADES


AWARD WINNING


SPARS

Lower material cost and weight Less production time and space Constant quality through continuous production


A DOUBLE PLUS

Acrosoma速 3D-stitched panel

Unstitched sandwich panel

There is absolutely no skin delamination on Acrosoma 速 panels because Acrosoma stitches the two skins through the foam core, which results in a high buckling resistance. Buckling is merely initiated by impurities in the skins. Due to the fact that the Acrosoma 速 Panel is produced in a continuous, computer controlled process, the quality has more than doubled compared to hand lay-up or VaRTM, which significantly reduces the safety factor for buckling.


FOR BUCKLING RESISTANCE

Panels that cannot delaminate

The size of wind turbines will further increase with the development and installation of off-shore wind turbines. Longer blades result in the requirement for new materials and new production methods. The use of currently available materials and present production methods have almost reached the limits of their technical capabilities and straight forward up-scaling is no longer the solution for the future development of wind turbines. The advantages of standard sandwich panels are their very high bending stiffness, high strength and low weight. However, they are made in hand lay-up or VaRTM and have imperfections, and this causes delamination under buckling forces. Safe structural design of standard sandwich panels as sparring, leads to a higher weight and consequently a higher cost. Designing the spars with Acrosoma速 panels, will lead to the use of less material compared to VaRTM, due to a combination of a higher delamination resistance, a high quality and an absence of impurities.


SPARS IN


CONTINUOUS LENGTHS

Advantages of the Continuous Production Process: - The Acrosoma 速 Panel can be made in every length desired. - The infeed allows various combinations of resin (vinyl ester and epoxy) and fibers (carbon, aramid and glass) during the production process. - The strict monitoring of the Panel during the entire production process allows the panels to have a constant quality over its entire length. - This process allows production of large quantities.

Spars can be cut out with only a 12% loss.


KEEPING WEIGHT DISTRIBUTION

Bending deformation in function of length Conventional composition Acrosoma composition

The composition of spars can be very complex with variation in foam thickness and fibre lay-ups. Feasibility studies have shown, however, that replacing the complex spars by Acrosoma速 panels, which have one composition and thickness over the entire length, results in the same weight distribution and bending stiffness. With hand lay-up or VaRTM as a production method, this composition may be relatively easy to handle, but will result in loss of quality, a longer production time and a larger production space when used in mass production.


AND BENDING STIFFNESS EQUAL

Weight distribution in function of length

Conventional composition Acrosoma composition

The Acrosoma® Production Process is a continuous process which results in several advantages: - Lengths of 60 meters and more are within reach. - The tapered form of the spar can be cut out resulting in spars that can be made in one piece. - A constant quality is assured because the production process is kept simple and easily controllable. The Acrosoma® production machine has a capacity of 150m² per hour (= 250.000 m² per year).


WEIGHT AND COST REPLACING CONVENTIONAL SPAR Weight and prices per m² panel based on standard comparable panel composition materials Conventional spar

Acrosoma® 3D 3D-stitched spar

weight

cost

weight

cost

foam core

12%

17%

12%

17%

fibres

32%

18%

32%

18%

resin

56%

37%

56%

37%

labour

7%

2%

additional production material

20%

0%

depreciation equipment

1%

20%

total buckling resistance

100%

100% 100%

100%

94% 133%

Replacing a conventional spar by an Acrosoma ® Spar, respecting the weight distribution, leads to no weight reduction, but more importantly to a direct manufacturing cost saving of 6%. This replacement will therefore not only result in extra indirect assembling cost cutting, but also the need for a significantly smaller production area.


IMPROVEMENT REDESIGNING CONVENTIONAL SPAR Weight and prices per m² panel based on standard comparable panel composition materials Conventional spar

AcrosomaÂŽ 3D 3D-stitched spar

weight

cost

weight

cost

foam core

12%

17%

12%

17%

fibres

32%

18%

22%

14%

resin

56%

37%

27%

13%

labour

7%

2%

additional production material

20%

0%

depreciation equipment

1%

20%

total buckling resistance

100%

100% 100%

61%

66% 100%

When Acrosoma is involved in the design of the blade from the very beginning, the composition of the spar can be optimized. This will result in a very significant weight and cost reduction. This new spar design will also result in extra indirect assembly cost cutting, and the need for a significantly smaller production area.


CONNECTIONS TO THE BLADE

SKIN

Different connections from spar to skin with glued-on pultruded profiles are possible.


OPTIONAL LENGTH SPLIT-UP

Spar in several pieces of each 13.5m is possible through a “click connection”.

“Click” connection system

Two pultruded profiles are bonded to the spar parts and connect the spar pieces to one long part.


OTHER PANEL APPLICATIONS

The application of Acrosoma速 panels is also possible in the construction of nacelles, especially since Acrosoma is also involved in the construction of towers.


Weight [kg/m²]

Bending stiffness per mm panel [GPa mmÂł]

Edgewise compressive strength [MPa]

Lengthwise

Widthwise

Lengthwise

HD60

9

9.400

8.500

55

CV2

9

37.200

17.000

35

AAM

18

56.500

56.500

180

Different panel compositions are possible. HD60, CV2 and AAM are given as examples. Please consult the Acrosoma Engineering Department for more information on any kind of application.


FEA,

FEA results using ABAQUS

Acrosoma has developed an in-house methodology to calculate the behaviour of the Acrosoma structures in various load cases. • 3D CAD-modeling using CATIA V5 • FEA using ESAComp and ABAQUS combined with Acrosoma methodology With this methodology, Acrosoma engineers are able to integrate different densities of fibers in ABAQUS and make various simulations. Even combinations with customized blade mesh models are possible. A first consultation is free.


TESTING,

QUALITY CONTROL

An Instron machine is used to accurately check the properties. These results are continuously reported back to the FEA.

With fiber optic sensors and own test bench, large structures are tested with a force of up to 450kN at 3Hz.

Dimensional control of Acrosoma structures using a Nikon Metris laser radar.


TOOLING STRUCTURES

Support for INVAR egg box moulds

Transport frame for shells.

Acrosoma can offer the suited transport frames, the tooling structures for transport and assembling frames for large composite structures, thanks to the Airbus A350XWB program where Acrosoma provided the transport frame for the shells.


TEMPORARY ROAD MATTING

The experience in an airfield matting-program, resulted in the development of panels for temporary roads. These panels are reusable, interlocked, light weighted and very strong. Weight: 18kg/m² Resists 120 bar on a CBR/6 soil. Panel dimensions: 1,2 meters x 2,4 meters



Acrosoma Spars