Stiffening offshore composite wind-blades bonding joints by carbon nanotubes reinforced resin - a new concept

Offshore wind-blades with excessive lengths (>100 m) are critical parts because of monolithic bonding that is holding the two halves, which may lead to sudden separation of edges while wind-turbine is in service. Offshore wind generation maintenance teams are targeting zero-maintenance. As a matter of fact, in the event of initiating mechanical damage, top and bottom skins of a wind blade should hold together as long as possible to allow enough time for maintenance to take place. We suggest an innovative concept that is a two-step strategy which consists first in strengthening the bond joints with carbon-nanotubes (CNTs), that be followed by a stitching of the two bonded joints with a composite cord. It is worthwhile to note that CNT can either reinforce the two halves of wind-blades and/or be added in between the pre-pregs composite plies before curing, to enhance bonding stiffness. A Finite Element model is proposed where simulation takes into account parameters such as CNT-weight fraction, chirality and CNTs inclination versus mechanical loading. Higher stiffness of joints and higher delamination strength for composites, are expected out of the concept. This article is intended to be a preliminary numerical study that must be viewed as a proof of concept.