Tow-Based Discontinuous Composites (TBDCs) are a new class of composite materials that combine high strength and stiffness with in-plane isotropy making them of interest in high-end structural applications. Despite their potential, efficient connection methods are currently lacking and the adhesive bonding behaviour of TBDC structures remains unexplored. This work, therefore, seeks to address this gap by analysing the quasi-static performance of TBDC adhesive joints under mode I loading condition. Double Cantilever Beam (DCB) tests were performed using two adhesives with contrasting toughness levels: a moderate (∼600 J/m 2) and a high toughness adhesive (> 2400 J/m2). When a moderate-toughness adhesive was used, a combination of cohesive failure and composite damage was observed, with only a small scatter in the experimental results. In contrast, the use of the high-toughness adhesive led to a shift in damage mechanisms towards the composite micro-architecture, resulting in fracture toughness values in the region of 800 J/m2, with a larger experimental scatter. Acoustic Emission analysis identified matrix cracking and fibre/matrix debonding as the dominant damage mechanisms. These findings were validated by the post-mortem fractography analysis via Scanning Electron Microscopy. This work therefore provides the first detailed analysis of the damage mechanism in adhesively bonded TBDCs, which have potential in aerospace and automotive applications.

In the immediate future, wind power will provide more electricity than any other technology based on renewable and low-emission energy sources. As a result, the size of offshore wind turbines has increased to harvest more wind energy in order to achieve the 2050 EU carbon neutral targets. The use of composites opens great prospects in the design and manufacture of the wind turbine blades due to their optimization versatility but composites perform poorly under impact and are sensitive to environmental factors. To combat this, blade manufacturers employ polymer-based surface coatings, caps or tapes to protect the composite structure. However, it is the repeated impact of rain droplets combined with the high blade tip speed, which are mostly contributing to the erosion of wind turbine blades [1]. The hindering of leading-edge erosion could be obtained through its multilayer material optimization i.e. Leading Edge Protection LEP [2]. Both the surface erosion and the intra-layer adhesion are affected by the shock wave propagation through the thickness of the LEP system produced from the collapsing water droplet after impact [3]. It is necessary to increase the interfacial fracture toughness resistance of the multy-layered system from the surface to the interface boundaries to damp the surface damage and avoid subsurface delamination [4]. Therefore, validated models considering the developed multicomplex stress states and the material degradation due to environmental loads are required for design purposes toward anti-erosion protection performance. This investigation summarizes the review of the current literature conducted in the framework of the IEA Wind TCP (International Energy Agency Wind Technology Collaboration Programme) - Task 46 Erosion of wind turbine blades [5]. It focuses on two main issues: firstly, the LEP material configuration used in industry considering the blade integration technology and, secondly, the modelling techniques and numerical procedures currently used to predict both wear surface damage and interface delamination failure. This work will allow for the identification of gaps within the research that can be explored during IEA Wind Task 46.