The SHM system is completed with an optimized sensors setup to monitor the most relevant deformation modes. Additionally, it enables precise fine-tuning of the DT model using machine learning, resulting in an accurate Hybrid Analysis Model.

Our modular and flexible DT-based SHM solution can be customized for any offshore wind platform concept, covering substructure, towers, mooring, and umbilicals. The solution is demonstrated through sea trials on Enerocean’s W2Power prototype.

'''Key words''': Rubber composites; carbon black; RVE; finite element

FOREST will develop novel lightweight multifunctional biocomposites as a competitive alternative to conventional composites. New chemistries will be developed based on bio-based materials (reactive and nonreactive polymeric systems and fire-retardant additives) in combination with fully recycled carbon fibre and EMI particles.

These biocomposite candidates will be obtained using one-shot manufacturing techniques, involving out-of-autoclave (OOA) processes to build and test prototypes (TRL5) with improved multifunctional properties (mechanical resistance, fire-retardant, EMI-shielding) for transport applications.

By conducting initial static tests on the joints, we identified crucial values for the rate at which energy is released under mode II conditions. These values served as a benchmark to establish the approach for dynamic fatigue testing. Our objective was to generate characteristic curves that illustrate how these adhesive joints behave when fatigue delamination begins, while also assessing the impact of varying exposure periods on their performance. To enhance result interpretation, we employed a probabilistic model rooted in the Weibull distribution to analyse the experimental data.

The results show that adhesive joints experience a decrease in their delamination resistance when exposed to a saline environment.

In this context, Structural Health Monitoring (SHM) technologies consists of a built-in sensors network providing real-time condition and the damage state of a structure. SHM brings several benefits. First of all, SHM ensures safety in-flight through continuously assessing damages and alerting if strength reduction approaches acceptable limits. The data obtained are useful for future structure retrofitting and new developments. Moreover, SHM has the potential to support and speed up the certification of thermoplastic composite joint. SHM data give added value to each individual fatigue test contributing to a greater understanding of damage progression and making fatigue campaign shorter and more efficient.

In the present work, both quasi-static as well as fatigue tests were conducted to evaluate performances of thermoplastic induction welded joints. Strain gauges and purpose-designed electromagnetic-based SHM sensor were integrated into the specimens in order to collect useful data during tests in three main cases: lap-joint specimens manufactured (i), (ii) with two different set of process parameters and (iii) with an artificially generated lack of weld at the joint interface. The approach proposed and data collected by the sensors has provided valuable information for understanding damage propagation in this kind of joint.

A drone has been manufactured using a Composites 3D printer. The design of the unmanned aerial vehicle (UAV) has been carried out and the manufacture of the different elements using long and short carbon fiber, looking for the configuration that provides the best combination of mechanical properties with a lower weight of the drone.

Extensiometric gauges are designed and printed on a flexible substrate using a combination of conductive and dielectric inks and the gauges are embedded in the composite during the manufacture of the pieces. These embedded gauges allow monitoring the flexion produced in flight of the drone frame, monitor bumps and defects during the useful life of the drone and increase the functionalities of the UAV without increasing the weight of the same and the number of elements.

Likewise, the conventional wiring has been replaced by printed wiring making the connections between the motors and the speed controllers.

For this reason, the flame retardancy of thermoplastic prepregs and thermosetting prepregs, applicable to the transport sector, has been studied by incorporating superficial flame-retardant layers based on expandable graphite. In the case of thermoplastic composites, work has been done with polypropylene laminates reinforced with fiberglass fabrics, addressing flame retardancy by incorporating a functional layer of expandable graphite.

In the case of thermosetting composites, furanic basalt fibre and recycled carbon fibre prepregs have been studied. The flame retardancy of basalt prepregs has been addressed incorporating halogen-free flame retardants in thermosetting matrix, and the flame retardancy of recycled carbon fibre prepregs has been addressed by a combined strategy incorporating halogen-free flame retardants in thermosetting matrix and superficial fire-retardant layers on the composite, based on expandable graphite.

Limited to mechanical recycling, recycling alternatives for CFRP with thermosetting resins have focused on thermochemical treatments, usually pyrolysis to recover the fibres, degrading the matrix. In addition to thermal routes, solvent treatments under supercritical conditions have also been studied. However, these processes exclude resin recovery and involve a partial loss of mechanical properties of the fibres due to the heat treatment (450-550 °C).

As an alternative, a solvolysis using mild conditions is proposed to treat CFRPs with amine-hardened epoxy resins, so that the fibres are recovered with all their properties and the organic matrix is materially valorised. This process is applied to reference materials of known composition and validated with real residues with good results in terms of degree of resin decomposition. The recovered fibres show almost resin-free surface and seem to have mechanical properties comparable to those of virgin fibres.

In this context, in this work a metal part has been replaced by a version of it in SMC and topological optimization tools have been used in the conceptual design stage. The possible variants have been analyzed when entering the mechanical data of the material, due to its anisotropic nature, as well as the influence of temperature on them, due to the fact that in the working environment the piece is subjected to 130 ºC. To do this, samples of material have been molded and a mechanical characterization has been carried out to understand the behavior of the material with respect to fiber orientation and temperature. Then, using the PTC Creo design tool, a topological optimization and subsequent adaptation were carried out to improve the processability of the component. The most promising versions have been virtually validated using finite elements with Abaqus software.

In conclusion, this work has demonstrated the viability of using topology optimization techniques in the conceptual design of components with SMC materials. Furthermore, in combination with simulation techniques using finite elements, they have proven to be tools that reduce and perfect product development in composite materials.

In this research, the mechanical strength of induction welded thermoplastic composites have been evaluated at sample level. Characterization specimens have been obtained by welding: (i) short carbon fiber reinforced polyether ether ketone (SCFR/PEEK), with 10 % carbon content, processed by additive manufacturing – fused deposition modeling; and (ii) multidirectional carbon fiber reinforced polyether ether ketone (CFR/PEEK) laminates processed by oven consolidation. The mechanical characterization of the strength has been carried out by means of the block shear test method. In addition, light optical microscopy has been performed to analyse the SCFR/PEEK - CFR/PEEK interface. Infrared thermography (IRT) has been considered for the non-destructive characterization of the welded joints to evaluate the feasibility of being applied as an inspection method for induction welded structures. IRT results have been validated by X-ray computed tomography.

Following this green line, this article presents the Life Cycle Assessment (LCA) study of new generation trains, mainly based on lightweighted primary structures made of composite material (about 30-50% weight loss compared to conventional ones).

The composite materials are novelty in the railway sector. Their introduction brings a clear advantage from the point of view of train capacity or energy/infrastructure canon savings. However, it needs to be justified from the LCA point of view.

Two different stages are developed in this article. An LCA of the new prototypes (production, assembly, transport and use phase). It is completed with an LCA of conventional structures. The second phase presents a comparison between the environmental impact produce using CFRP materials or metallic materials at the end of a useful life (EoL) of a carbody.

The results indicates that, at EoL, the composite material would be more economically and environmentally attractive than the current materials.