Title Promoter Affiliations Abstract "Improvement of the processing of natural fibres for composites and development of natural fibre composite applications." "Ignace Verpoest" "Structural Composites and Alloys, Integrity and Nondestructive Testing" "Focus in the project will be on novel ways to prepare fibrous preforms or prepregs for composites manufacturing. The Vietnamese partners will focus on processes to make mat-like preforms. Also, further work will be done on the extraction of bamboo and coconut technical fibres. Applications will be developed with the automotive sector in Vietnam and with composite moulding companies (helmet application). K.U. Leuven will also work on fibre handling, preforming and prepregging processes. The target is to develop processes to make uni-directional (UD) fibre arrangements. KU Leuven will further be responsible for characterisation and treatment of fibres, composite processing and characterisation of composite properties. The surface science approach for interface optimisation will be further developed. Hybrid composites of bamboo and coconut will be explored." "Integration of hybrid composites in the industrialised composite automotive process chain" "Yentl Swolfs, Stepan Lomov" "Structural Composites and Alloys, Integrity and Nondestructive Testing (SCALINT)" "This PhD research is run as part of HyFiSyn project with BMW. The aim of the project is to introduce hybrid fiber composites into the industrial process chain. The first step of this project will be to perform screening experiments to analyse the percentage of hybrid effect obtained with different fiber combinations (Glass/Carbon, Glass/Steel, Carbon/Steel) in various loading conditions like tension, impact and flexural. Based on the results of screening experiments the fiber combinations will be matched with the potential applications and then the prototype will be prepared. • Investigate mechanisms of action of hybrid materials (elongation, pretension, corrosion, shrinkage during process, mechanical behavior under static and crash loadings); • Validate the design approach on a real part: prototyping, passing the paint shop and testing" "COMPOST - mechanically recycling thermoplastic composite overmoulded part production scraps into new parts" "Lincy Pyl" "Université catholique de Louvain, SOLVAY, Brussels Hoofdstedelijk Gewest - INNOVIRIS, Mechanics of Materials and Constructions" "Self Sensing Composites using selectively distributed conductive networks in CPCs (Conductive Polymer Composites)" "Ludwig Cardon" "Department of Materials, Textiles and Chemical Engineering, Department of Materials Science and Engineering" "The research aims to develop an innovative sensor network with resistivity-strain behaviour through construction of oriented and selectively distributed conductive networks in CPCs. The network consists of thermoplastic nanofilled sensors which afterwards can be woven into a conductive layer and then be embedded as a sensor layer inside a composite structure to monitor behaviour and integrity of these materials." "Dynamic Modeling of Macro-Fiber Composite Transducers Integrated into Composite Structures" "Michael Sebek, Wim Desmet" "Production Engineering, Machine Design and Automation (PMA) Section" "Composite structures have been already widely applied in engineering. Laminated composites using isotropic or anisotropic layers provide numerous options for designing lightweight structural components, that have high static stiffness and excellent impact resistance for automotive and aerospace products. However, lightweight structures can be susceptible to external disturbances due to mass reduction and light damping in many cases. As a result, unwanted vibrations and noise can easily occur on these structures. Smart structures that use multifunctional materials as actuators/sensors spurred considerable amount of research, aiming at reducing these noise and vibrations. Macro-fiber composite (MFC) piezoelectric transducers are attractive choices in engineering because of their flexibility, reliability, and high-performance compared to other types of transducers. Comprehensive design of composite structures with integrated MFC transducers is essential for appropriate deploying control systems in noise and vibrations suppression. Finite Element Modeling (FEM) methods are commonly used for modeling piezoelectric systems, however, such kind of large-scale model always needs to be reduced for dynamic applications. For example, MFC transducers can be used in vibro-acoustic systems for noise and vibrations control, while, reducing the piezoelectric vibro-acoustic system model could be challenging because the controller design and real-time simulations require stable low-order models. Conventional model order reduction techniques, such as the Krylov subspace projection and the balanced truncation, project the system model into an equivalent vector space so that many important physical parameters are not preserved by the reduced-order model. Consequently, it is also challenging to determine the optimal placement and piezoelectric fibrous orientation of MFC transducers on a host structure with the consideration of their mechanical influences. There is no effective approach yet for addressing these deficiencies in the literature. Therefore, laminated composite plates with spatially distributed rectangular MFC transducers are studied in this dissertation. Equivalent Substructure Modeling (ESM) approach is developed to generate stable structure-preserving low-order system models of piezoelectric composite structures. First, we developed equivalent forces as a new solution to characterize the inverse piezoelectric effect of the integrated transducer, meanwhile, the corresponding direct piezoelectric effect is also derived. Then, the analytical piezoelectric couplings are introduced into an equivalent substructuring process for modeling piezoelectric systems, and experiments verified the validation of the ESM approach. After then, two types of study cases are given to demonstrate the advantages of the ESM approach for evaluating the placement and piezoelectric fibrous orientation of a MFC transducer on a non-homogeneous composite plate. At last, the vibro-acoustic study of composite plates with integrated MFC transducers is carried out. The ESM approach is used to generate a stable low-order model, and validated by experimental data. The piezoelectric reciprocal relations in a vibro-acoustic field are defined. The work enables MFC transducers to expand their application in vibro-acoustics." "Sustainable use of natural fibres of local origin as reinforcement for composite materials for low cost and thermal insulated housing in the Peruvian Andean region: implementing a research group on composite materials at National University of Central Per" "Aart Willem Van Vuure" "Structural Composites and Alloys, Integrity and Nondestructive Testing (SCALINT)" "This project aims to improve the material living conditions of the inhabitants of the central Peru region, in particular the construction of inexpensive housing in rural Andean areas via the development of low cost building materials made of composites reinforced with ichu fibres, which are locally available. These local fibres serve not only as the reinforcing phase of the composite material, but also add thermal insulation properties, reducing the effect of the extreme weather conditions of the region.This objective will be achieved by strengthening the infrastructure and human capacity of local researchers at National University of Central Peru (UNCP). A permanent research group dedicated to novel bio composites reinforced by local natural fibres will be established. Researchers will be trained in state-of-the-art technologies for composite development and manufacturing. Moreover, the direct beneficiaries (inhabitants of Andean communities) will also receive special training in order to take up the new sustainable building technology" "Investigation of the structural, chemical and magnetic state of the metal/oxide interface in composite multiferroics" "André Vantomme" "Nuclear and Radiation Physics, Quantum Solid State Physics (QSP)" "Metal/oxide interface is a fundamental component in many devices such as magnetic sensors, piezoelectric transducers, and capacitors. The electrical properties of metal/oxide heterostructures are determined by the type of contact formed at the interface, i.e. Schottky or Ohmic contact. As devices are becoming smaller in size, interfaces are becoming even more important due to an increase in the surface to volume ratio. The metal/oxide interface is also a key component in composite multiferroics consisting of ferromagnetic metals and ferroelectric oxides. Recently, in search for multifunctional materials, the composite multiferroics are acquiring a lot of attention. These materials not only have two or more ferroic properties simultaneously (such as ferroelectricity, ferromagnetism) but there may also be a coupling between these ferroic orders, known as magnetoelectric (ME) coupling. Such a coupling allows control of magnetic properties via an electric field and control of electric properties via a magnetic field. Since the coupling originates at the interface between the two components, the composite properties are significantly influenced by interface characteristics. Therefore, in order to realize composite multiferroics with significant ME coupling as well as structurally stable interfaces for electronic device applications, it is important to understand metal/oxide interfaces and to identify the effect of an electric field on the interface structure and properties.The aim of this thesis work is to study the chemistry and magnetic spin structure of FM-metal/FE-oxide (multiferroic composite) interfaces and investigate the effect of an applied electric field on their structural, chemical and magnetic state. For this purpose, we use the unique possibilities offered by isotope sensitive techniques to selectively probe the interface chemistry and magnetism in different types of metal/oxide heterostructures before, during and after the application of an electric field. This is done by enriching the interface with 57Fe which is a Mössbauer active isotope. Two complementary characterization techniques (Mössbauer spectroscopy and nuclear resonant scattering of synchrotron radiation) are employed to investigate different types of metal/oxide interfaces such as Fe/BaTiO3, Fe/LiNbO3, Fe/SrTiO3, Fe/BiFeO3 and Fe/MgO. Based on the results, we propose a model for the electric field–induced modifications of the metal/oxide interface. A correlation between the oxide properties (such as the electrical permittivity, work function, and ferroelectric polarization) and the electric field-induced ion transport across the metal/oxide interface is established. The work function difference between the metal and the oxide determines the initial charge build-up at the interface. The electric permittivity and polarization of the FE-oxide are responsible for the electric field-induced ion transport across the interface. Application of an electric field above a threshold field value results in the formation of a thick intermixed interfacial layer and leads to an irreversible decrease of the magneto-electric coupling properties. Therefore, multiferroic studies on FM/FE heterostructures should be performed at electric fields below the threshold field value. The interface between the metal and a very high dielectric constant oxide can be oxidized or reduced depending on the polarity and magnitude of the applied electric field. The final state of the interface is determined by the polarization history of the heterostructure. These results provide a better understanding of electric field driven ion transport at metal/oxide interfaces and have important implications for the further development of composite multiferroic and complex oxide heterostructures in general." "Extraction optimisation for and hygroscopic behaviour of flax fibres in composite applications" "Jan Ivens" "Chemical Engineering, Kulak Kortrijk Campus, Materials Technology, De Nayer (Sint-Katelijne-Waver) Campus, Materials Technology, Group T Leuven Campus" "Flax fibres (Linum Usitatissimum) combine excellent mechanical properties with a very low density. In terms of specific stiffness they can compete with E-glass fibres. This is why they are currently used in lightweight applications such as composites. However, there are two main factors inhibiting their breakthrough in this market:1. The cost of flax fibres compared to glass fibres remains high due to the energy and labour-intensive production process of the fibres and limited fibre yield.2. Flax fibres are sensitive to moisture absorption. This makes composite producers are wary to use these fibres in their applications as they are worried about the implication of this absorption on the short- and long-term composite properties. This raises the question on the durability of these materials, especially in conditions where cyclic variations of relative humidity are expected.This dissertation therefore aims to identify the critical parameters and fibre characteristic needed to obtain fibres which can be used in composites and reveal the effects of moisture during static and dynamic hygroscopic loading.It was found that fibre fineness has a large influence on the transverse composite properties. In the current production process, this parameter is controlled in part by the degree of retting of the stems but largely by scutching and hackling. For coarse fibres, even a mild combing operation is sufficient to drastically increase transverse performance of the composites. The degree of retting impacts the longitudinal tensile response of the composites. A higher degree of retting lowers the modulus of the fibres, except in the initial elastic response region. The fibre variety nor the purity have a direct effect on the mechanical performance of the fibres.In the second part of this thesis kinetic and equilibrium parameters of the moisture absorption and desorption process were collected and connected to the microstructure of the fibre and composites. It was established that the diffusion behaviour of flax fibres both in- and ex-composite was Fickian in absorption. During desorption, deviations from this behaviour were found when equilibrating to extremely low relative humidity. The diffusion coefficients were found to be dependent on the moisture concentration of the fibres. Furthermore, the longitudinal and transverse mechanical properties of flax fibre composites decrease as their moisture content increases. An exception is the longitudinal tensile strength which increases, due to the plasticizing effect of water. To link these observations to the microstructure, the fibres were chemically modified aiming at altering their moisture behaviour. From this a theory is proposed which describes the diffusion process in technical flax fibres.Finally, the effect of hygroscopic fatigue of the composites was examined. After very few cycles, flax fibres composites show extensive debonding and technical fibre splitting. These damage modes severely impact transverse performance of the composites." "Non-isothermal consolidation of hybrid composite materials" "Jan Ivens" "Structural Composites and Alloys, Integrity and Nondestructive Testing (SCALINT)" "Het onderzoek richt zich op de consolidatie en de ontwikkeling van hechtingssterkte in hybride composieten, bestaande uit continue vezelversterkte thermoplastische onderdelen en korte vezelversterkte thermoplasten. Het onderzoek combineert experimenteel en modelleringswerk om de ontwikkeling van intiem contact en hechting onder niet-isotherme procescondities te beschrijven en van daar uit de hechtingssterkte en dimensionale stabiliteit van de composietstukken te voorspellen." "Automated NDT of Industrial Composite Parts by Enhanced Optical Infrared Thermography" "Mathias Kersemans" "Department of Materials, Textiles and Chemical Engineering" "Progress in materials science has led to novel high-performant materials, like fiber reinforced plastics (or composites), which are nowadays more and more used in aerospace and automotive industry. However, the composed nature of these materials makes them also sensitive to certain damage features. To assess the structural health, engineers have devised various non-destructive test approaches. One emerging technique concerns optical infrared thermography, in which the material is optically stimulated, and the thermal response is captured with an infrared camera. There are several thermographic implementations described in literature, but unfortunately there is no consensus on the optimal approach. In this project, we will investigate optical infrared thermography and identify both its opportunities and limitations for NDT of composite materials. This involves a critical evaluation of different excitation approaches as well as various post-processing techniques to enhance the detectability of (deep) defects. The experimental study is supported by numerical modelling. Further, human interpretation of the thermographic data may yield inaccurate (or even wrong) results. Therefore, an algorithm will be implemented to efficiently extract and size defects in an objective way. This study is not limited to coupon samples, but will explicitly lay the bridge towards real composite parts with industrial complexity."