Titel Deelnemers "Korte inhoud" "How nouns turn into adjectives. The emergence of new adjectives in French, English and Dutch through debonding processes" "Kristel Van Goethem, Hendrik De Smet" "© John Benjamins Publishing Company. This study focuses on French, English and Dutch adjectives that arise through debonding from N+N (and N+A) compounds or compound-like sequences (e.g. the adjectival uses of English 'key' and French clé ""key""). Debonding is a type of degrammaticalization defined by Norde as ""a composite change whereby a bound morpheme in a specific linguistic context becomes a free morpheme"" (Norde, 2009: 186). We investigate for each of the three languages how the debonding process is impacted by three different factors: (1) the semantics of the noun subject to debonding, (2) the degree of prosodic and morphological cohesion of the sequence, (3) the presence of adjective inflection in the language. It is furthermore argued that in the case of Dutch, an additional process should be taken into account, that is the possibility of clipping of N+A compounds (e.g. stapel ""lit. pile; madly in love"" < stapelverliefd ""lit. pile-in love; madly in love"")." "Numerical study of transitional brittle-to-ductile debonding of a capsule embedded in a matrix" "Francisco Antonio Gilabert Villegas, David Garoz Gómez, Wim Van Paepegem" "This work presents a numerical study that addresses the role of the interfacial fracture energy on the debonding process of a capsule embedded in an elastic matrix, which undergoes a uniaxial far-field stress. The motivation of this work is to analyze and to understand the effects of this energy in the framework of the so-called encapsulation-based self-healing cementitious materials, where glass capsules filled with a fluid healing agent are embedded in a cement-based matrix. A two-dimensional plane strain model based on a combination of the classical finite element method and cohesive surface techniques implemented in the commercial code Abaqus r has been used. It has been found that there exist three types of debonding regimes, ranging from a perfect brittle response up to a ductile-limited response, and whose range of validity is governed by a straightforward dimensionless number able to predict the type of debonding as a function of flexural properties of the capsule and the interface strength." "Hybrid modeling of an adhesive bonding process, case study : polyphenylene sulfide" "Saeideh Khatiry Goharoodi, Jeroen Jordens, Bart Van Doninck, Guillaume Crevecoeur" "Adhesive bonding is a joining process used in several industries such as aerospace, automotive, civil construction and manufacturing. Traditionally, the optimization of the parameters for this process is performed by adhesive experts via trial and error which is expensive and time-consuming. Therefore having a process model for optimization purposes is of great interest. In this study, we develop such process model which includes cost, visual quality and joint strength properties for Polyphenylene sulfide bonding use-case. We adopt analytical modeling approaches for those process properties that do not require extensive system knowledge and are not effected by large number of process parameters, namely cost and visual quality. Additionally, we use data-driven genetic programming approach to model the more nonlinear process property, meaning joint strength of the bond. Consequently, we employ a hybrid approach by combining available knowledge and experimental data. The process model can then be implemented for process optimization or to create a digital twin which predicts if the product quality is in scope." "ESD process assessment of 2.5D and 3D bonding technologies" "Eric Beyne, Marko Simicic, Geert Van der Plas, Serena Iacovo, Shih-Hung Chen" "Heterogeneous bonding technologies are an attractive way to assemble high performance computing systems today. However, ESD risks of 2.5D/3D bonding are not fully understood. To help ESD control engineers and tool manufacturers, this paper describes the 2.5D/3D bonding processes and gives practical insights into the relevant ESD process assessment steps." "Debonding at the fiber/matrix interface in carbon nanotube reinforced composites: Modelling investigation" "Stepan Lomov, Larissa Gorbatikh" "© 2018 Elsevier B.V. Debonding at the fiber/matrix interface is an important failure mechanism in composite materials. It controls, among others, the intralaminar cracking process. A large amount of experimental data exists indicating that the addition of carbon nanotubes (CNTs) in a composite can hinder onset and development of these cracks. Here we report results of a modelling study aiming to better understand the effect of carbon nanotubes on the fiber/matrix debonding. The study is performed on an example of a carbon fiber/epoxy unidirectional composite with two practically realizable CNT configurations: agglomerated CNTs in the matrix and CNTs grown on fibers. The composites are subjected to transverse tension. The stress distribution prior to debonding is predicted using a two-scale finite element model based on the embedded element technique. The onset and propagation of the debond are then analyzed using a surface-based cohesive zone model with a linear traction-separation law. Our results show that CNTs have a strong effect on the stress distribution in the matrix and the debonding process, although their effect on the latter is less pronounced. CNT agglomerates are found to act as stiff microscopic inclusions leading to magnification of stress concentrations and earlier initiation of the debonding process. The composites with CNTs grown on fibers, on the other hand, show suppression of stress concentrations at the interface and slight delay in the debonding onset compared to the composite without CNTs." "Fibre-Matrix Interface Longitudinal Debonding and Translaminar Fracture of Fibre-Reinforced Composites: Model Development and Experimental Validation" "Fibre-reinforced composites (FRCs) have brought about a significant transformation in the realm of materials science, redefining the possibilities of engineering and design. The exceptional mechanical properties of FRCs, including their high stiffness- and strength-to-weight ratio, have enabled their widespread adoption in industries ranging from aerospace and automotive to renewable energy applications. As we look to the future, FRCs offer a tantalising prospect of a sustainable and eco-friendly alternative to traditional materials. Furthermore, the ongoing development of novel manufacturing techniques, computational tools, characterisation methods, and material chemistries is expected to unlock the full potential of FRCs. In this regard, carbon FRCs (and their hybrids) serve as a beacon of ingenuity and possibility, heralding a significant contender among the vast array of materials to choose from. The failure of FRCs is a complex phenomenon that involves various intricate stress distribution and damage propagation mechanisms. The multifaceted nature of this process is rooted in the interplay of numerous factors, such as the nature of the reinforcing fibres and matrix, their interface, the microstructural design of the FRC, and the loading conditions. Furthermore, the failure mechanisms can operate at multiple length scales, from the microscale, where the individual fibres and their interactions with the matrix come into play, to the macroscale, where the overall structural behaviour of the FRC manifests itself. Unravelling this complex failure behaviour requires a multifaceted approach integrating advanced experimental techniques, theoretical models, and numerical simulations. The overarching goal of this thesis is to advance the field of fibre-matrix interface and mesoscale translaminar fracture modelling through approaches that incorporate a comprehensive spectrum of overlooked intricacies as well as the observed phenomena derived from cutting-edge experiments. At first glance, the title of this dissertation may imply that it pertains to two different topics. However, the first component of the title - fibre-matrix interface longitudinal debonding - concerns a major energy-dissipating mechanism during translaminar fracture of FRCs, which governs their damage tolerance and notch sensitivity, and is the focus of the second component. Accurate prediction of fibre break accumulation and FRC ply failure necessitates a thorough understanding of the stress redistribution in the presence of a broken fibre and the accompanying interfacial failure. Following a comprehensive review of various methods for characterising the fibre-matrix interface, the research begins with finite element simulations at the fibre level. These simulations explore the debonding of a single broken fibre from the elastoplastic matrix and the consequent axial stress redistribution. Upon model validation via laser Raman spectroscopy stress/strain data from the literature, subsequent models are analysed, where a broken fibre is encompassed by intact fibres arranged in either hexagonal or random configurations. The use of multifibre models has enabled the accurate prediction of reallocated stress state and the shape of stress concentration factor (SCF) profiles in response to the applied strain. This approach effectively addresses the modelling challenges and overestimation of SCFs observed in earlier, fully-bonded finite element models. The parametric investigations conducted for each of the three cases indicate that higher values of interfacial friction coefficients, shear strength and fracture toughness, and a greater post-cure cooling gradient reduce the extent of debonding. Such shortened debond lengths correspond to amplified stress concentration factors on adjacent fibres. Moreover, within the representative volume element, lower fibre volume fractions coincide with shorter debond lengths and, consequently, shorter ineffective fibre lengths. These refined stress redistributions, in conjunction with the probabilistic attributes of fibre strength, can be leveraged by longitudinal strength models to yield robust strength predictions. Using the novel double-edge notch specimen for a single-fibre fragmentation test, the intricate interfacial failure behaviour of single-fibre composites, doped with ceramic (barium titanate) particles, is thoroughly investigated. The integration of digital volume correlation (DVC) into synchrotron computed tomography enables quantitative strain mapping in the proximity of the fibre break(s) and offers perspective onto the real-time development of microscale damage and failure phenomena. According to the global DVC approach results, fibre break(s) causes a peak in the axial strain profile due to the opening of the break, and two peaks in the shear strain profile owing to elevated shear stresses at either side. These datasets are valuable assets for validating numerical models of single-fibre composites. By comparing the predicted and experimentally obtained axial strain/stress recovery lengths and the extent of the shear-dominant zones, a more precise estimation of interfacial properties can be made. Fibre hybridisation in FRCs enables the customisation of materials to fulfil particular specifications regarding strength, stiffness, weight, ultimate failure strain or other characteristics. The analysed fibre-hybrid composites combine two distinct types of carbon fibres, one with a high strain-to-failure and low modulus, and the other with a high modulus and low-strain-to-failure. To examine the failure mechanisms underlying translaminar fracture in interlayer/intrayarn hybrids and non-hybrid laminates, in-situ experiments utilising synchrotron radiation computed tomography were conducted on novel downsized compact tension specimens with 0° and 90° thin plies. The major results highlight the in-situ discrepancy in the progression of cracks across different plies and delineate fibre (or bundle) pull-outs, as a significant energy dissipation mechanism during translaminar fracture. With the aid of literature data and reasonable assumptions, it was feasible to develop a mesoscale finite element model that incorporates separate cohesive failure definitions for the 0° and 90° plies. The quantitative data from the downsized specimens can then be utilised in constructing and validating mesoscale finite element models for translaminar fracture. In summary, the development of models for microscale longitudinal fibre-matrix debonding and mesoscale translaminar fracture, as presented in this thesis, represents a notable stride forward in the characterisation, prediction, and enhancement of failure behaviour in FRCs. The utilisation of advanced in-situ imaging technologies, in combination with the development of novel specimens, has opened new perspectives in understanding the failure behaviour of the model and unidirectional carbon FRCs." "Acoustic Emission Monitoring of Debonding of External Reinforcing Patches from Concrete" "Svetlana Verbruggen" "The present study concerns the characterization of the fracture process inconcrete beams which are externally reinforced by means of composite materials. The reinforcement comes in the form of CFRP (Carbon Fiber Reinforced Polymer) strip and TRC (Textile Reinforced Cement) layer. In order to monitor the accumulation of fracture beneath the non-transparent layer, AE (Acoustic Emission) sensors are used. The results show that the different mechanisms starting from concrete cracking due to tensile stresses at the bottom up to the shear debonding of the patches exhibit quite distinct acoustic signatures and can be identified. Waveform parameters such as duration and frequency content provide strong characterization capacity concerning the different processes. Valuable feedback is supplied by DIC (Digital Image Correlation) which verifies the moments of debonding by the significant strain release on the surface of the patch. Discussion is done on the in-situ application of this methodology and the limitations that may apply due to scattering and damping on the propagating waves." "Epoxy adhesives with reversible hardeners : controllable thermal debonding in bulk and at interfaces" "Filip Van Lysebetten, Tim Maiheu, Johan Winne, Filip Du Prez" "On-demand adhesive dismantling has the potential to improve multimaterial product recycling, but its implementation has been hampered by a critical trade-off between strong bonding and easy debonding. As a result, the temperature range in which these temporary adhesives can be used is relatively limited. Here, a new class of dynamic epoxy resins is reported that significantly extends this upper temperature limit and still achieves fast debonding. Specifically, two types of dynamic polyamidoamine curing agents for epoxy hardening are developed, being polysuccinamides (PSA) and polyglutaramides (PGA). As the dynamic debonding/rebonding process of PSA and especially PGA linkages is more thermally demanding and at the same time more thermally robust than previously reported dynamic covalent systems, the resulting materials can be triggered at high temperatures, and at the same time remain bonded over a wide temperature range. The versatility of the PSA and PGA dynamic adhesive curing system is demonstrated in classical bulk adhesive formulations, as well as in dynamic covalent linking to a PSA- or PGA-functionalized surface. As a result, an attractive drop-in strategy is achieved for producing debondable and rebondable epoxy adhesives, with high complementarity to existing adhesive resin technologies and applicable in an industrially relevant temperature window." "Numerical modelling and experimental validation of debonding and heat transfer of carbon fiber reinforced composite under reciprocating sliding" "Houcine Dhieb, Jean-Pierre Celis" "© 2016 Elsevier Ltd Compressive and shear stresses as well as the generation of heat are critical issues in the failure mechanism of carbon fiber reinforced epoxy composites under reciprocating sliding. In this work, the mechanical stress distribution and maximum surface temperature generated on the wear track by reciprocating sliding against stainless steel counter body are modelled numerically. The computational results are used to directly compare them to experimental data to discuss the contact status and failure mechanism during the sliding process applying different sliding frequency and external environment. The debonding between the carbon fibers and the epoxy is modelled considering a cohesive interface modelling. We demonstrate numerically that the sliding frequency has a significant effect on heat generation. Experimentally, at higher frequencies, a more pronounced debonding and crack formation take place in the sub-surface region which is not the case at lower sliding frequencies. Water acts as a cooling agent and decreases the debonding because it functions as a plasticizer agent for the epoxy matrix." "Numerical analysis of debonding between CFRP strips and concrete in shear tests under static and blast loads" "Azer Maazoun, Stijn Matthys, Bachir Belkassem, David Lecompte, John Vantomme" "The present paper deals with the finite element (FE) analysis of the bond slip between concrete and carbon fiber reinforced polymer (CFRP) strips in a single bond shear test under static loads and in a double bond shear test under blast loading. A plastic damage material model and an elastic material model are used to model the concrete prism and the unidirectional CFRP strip, respectively. The bond interface between concrete and CFRP strip is simulated using a cohesive bond model. For the static loads, the numerical model is validated with experimental tests available in the literature. The debonding failure mode, the delamination loads and the strain distribution along the CFRP strip are predicted. The numerical results show a good agreement with the experimental data using the cohesive bond model. For the blast loads, the validated cohesive bond model is used. A parametric study with respect to the width and the length of the CFRP is conducted. Moreover, the reflected pressure and impulse are varied to highlight the effect of the propagation of the blast wave in the debonding process under blast loads."