# The Concept of Segmented Wind Turbine Blades: A Review
## 8 Conclusions  
The feasibility of a segmented blade largely depends on the risk of the chosen concept. In this respect, concepts that require only limited changes from existing approaches pose less risk and are more likely to succeed. For example, concepts that do not require division of the blade's main structural components, such as the use of separate leading or trailing edge segments, are only small modifications since these require only limited loads to be transmitted across the connections. For this reason, active trailing edge flaps are more likely to succeed than telescopic blades. Similarly, aerodynamically-shaped root extenders pose only a small modification from existing root extenders, which are well known in the industry. Furthermore, concepts incorporating a spar-bridge are close to joints used in sail-planes and tip brakes and have been shown to be feasible. Joints using longitudinal bolts have also been successful and are well known from the blade root design. The fact that large modern blades typically prefer the use of inserts to form a lightweight joint indicates that such joints are better suited for segmentation than flanged, hub-type and T-bol joints. On the other  
Figure 11: Transverse joining concepts. (**a**) Segments joined with lugs [146]. (**b**) segments joined by intermediate pieces [56]. (**c**) segments joined with rivets [145].  
Figure 10: Unique blade connections relying on cables to connect the different segments. (**a**) Blade using pre-tensioned steel cables to hold together the different segments as an alternative to a spar structure [142]. (**b**) Joint using pre-tensioned straps around eccentric bolts [140]. (**c**) U-shaped loops [144]. (**d**) Segmented blade joint relying on pre-tensioned cables to pull the outer segment towards the hub [141].  
hand, breaking up the blade's main structural components poses significant challenges regarding production, maintenance costs and reliability. The failure of the T-bolt prototype blade in Vionis [52] and the unfavorable cost calculation for the T-bolt prototype blade in Dutton [45] indicate the difficulty of making this approach successful. Adhesive joints are also well known in the industry and are sometimes preferred because of their structural and economic efficiency [47]. However, the step from controlled conditions to in-field production of such connections is large. Yet, it may be possible to assemble the blade segments using local, perhaps temporary facilities. Furthermore, to avoid air entrapment, such adhesive joints would most likely be produced using vacuum infusion. The issues related to the manufacturing of larger blades are already being countered by manufacturing separate blade components. These are mostly assembled in the factory using either adhesive or mechanical joints. While blade segmentation poses serious challenges, the wide variety of possibilities and the potential benefits are bound to lead to further developments in this field. Furthermore, segmentation appears most likely to be cost effective for very large, offshore turbines or on-shore turbines with promising conditions, but accessibility issues.  
The work leading to this publication has been supported by VLAIO(Flemish government agency for Innovation and Entrepreneurship) under the SBO\"OptiWind: Serviceability optimisation of the next generation offshore wind turbines\" (Project No. 120029).  
The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses or interpretation of data; in the writing of the manuscript; nor in the decision to publish the results.