Martine Wevers

• Professor
• Co-ordinator of Research Group "Materials Performance and Nondestructive Testing at KU Leuven

Hybrid organic-inorganic functional nanocomposites are crucial in advancing electronics, biomedicine, and environmental science. These multifunctional and multiphase systems combine flexibility and stretchability with a broad spectrum of functional properties. This review delves into the fundamental (di)electric, thermal, and mechanical properties...

All‐solid‐state polymer dielectrics benefit from a superior voltage window and conveniently circumvent fire hazards associated with liquid electrolytes. Nevertheless, their future competitiveness with alternative energy storage technologies requires a significant enhancement in their energy density. The addition of conductive 2D MXene particles is...

It is a frequently overlooked phenomenon that matter can produce sound emissions when undergoing a phase transition. The exact cause of this sound is until now not modeled and understood in depth, but it appears certain that sudden volume changes, cracks, friction, and other sources that occur during e.g. crystal decay/growth in melting/freezing pr...

Nanoparticles are gaining importance as a reinforcing or functional phase in fibrous composites. However, an optimised deagglomeration and uniform distribution of these particles in the matrix is pivotal to exploit their nanoscale properties fully. Classical dispersion methods like shear mixing have proven insufficient, and high-energy (ultra)sonic...

In this work, an ultrasonic approach for early detection of fatigue-induced material changes in an aluminium alloy plate under dynamic loading is developed and validated. Material degradation followed by the emergence and growth of a crack was created by a fatigue machine while monitoring the modulation of sinusoidal ultrasonic wave packets sent al...

The kidney’s microstructure, which comprises a highly convoluted tubular and vascular network, can only be partially revealed using classical 2D histology. Considering that the kidney’s microstructure is closely related to its function and is often affected by pathologies, there is a need for powerful and high-resolution 3D imaging techniques to vi...

Cementitious brittle construction materials are susceptible to fracturing due to their heterogeneous material composition and relatively weak bond between the aggregates and paste. Hence, enhanced methods of fracture analysis in these materials are an important subject of research. The acoustic emission technique (AET) is frequently used in the stu...

Water ingress in composite structures is a potentially costly problem, and its detection before related damage begins to appear is of utmost importance. Carbon black fillers (CB) and epoxy matrices can be used to produce water-sensitive nanocomposites that can be integrated into composites during production. Nevertheless, the effects of water uptak...

Laser Doppler scanning vibrometry is used for imaging spectral vibration components in a carbon fiber-reinforced composite plate that contains a sub-surface delamination defect caused by hammer impact. The images reveal sideband generation at the location of the defect, reflecting mechanical nonlinearity-induced mixing between a high amplitude, low...

It is a mostly overlooked phenomenon in physical chemistry that matter produces characteristic sound emissions when passing through a phase transition. The origin of this sound is not yet fully understood, but it is certain that sudden changes in volume, cracks, friction between crystallites and other sources must be considered, but a generally acc...

Water ingress in composite structures is an extremely costly problem, and its detection before related damage begins to appear is of utmost importance. Nanocomposites, based on epoxy matrices and Carbon Black fillers (CB), are promising humidity sensors that can be integrated in composite structures during production. Nevertheless, the effects of w...

3D nanoparticles are important as reinforcing or functional phase in polymer composite materials; however, an optimised deagglomeration and uniform distribution of these particles is required to fully exploit their nanoscale properties. Classical dispersion methods like shear mixing have proven insufficient, and high-energy ultrasonication, as the...

Hypothesis: Characterizing the microstructure of an ice/surface interface and its effect on the icephobic behavior of surfaces remains a significant challenge. Introducing X-ray Computed Tomography (XCT) can provide unprecedented insights into the internal (porosity) and interfacial structures, i.e. wetting regime, between (super)hydrophobic surfa...

Sensing systems, especially when used for interrogating the structural integrity of aircraft in traditional inspections or for structural health monitoring, are frequently working in a quasi-linear mode. However, this approach leads to difficulties in some cases like weak signal contrast with respect to interfering baseline fluctuations, especially...

Degradation of existing structures poses a serious threat to our built environment. The aim of this paper is to investigate the use of acoustic emission monitoring in degradation assessment of existing structures, focusing specifically on corrosion damage detection in reinforced concrete structures. Reinforcement corrosion is seen as one of the mos...

Biological tissues comprise a spatially complex structure, composition and organization at the microscale, named the microstructure. Given the close structure-function relationships in tissues, structural characterization is essential to fully understand the functioning of healthy and pathological tissues, as well as the impact of possible treatmen...

Degradation of existing structures poses a serious threat to our built environment. The aim of this paper is to investigate the use of acoustic emission monitoring in degradation assessment of existing structures, focusing specifically on corrosion damage detection in reinforced concrete structures. Reinforcement corrosion is seen as one of the mos...

Corrosion is a major issue in construction and infrastructure management, giving rise to high repair costs, safety concerns and structural failures. Especially reinforcement corrosion in concrete structures is a complex issue. As degradation starts internally, visual inspection lacks efficiency in early stages of the corrosion process. Acoustic Emi...

To facilitate the development of new brain metastasis (BM) treatment, an easy-to-use and clinically relevant animal model with imaging platform is needed. Rhabdomyosarcoma BM was induced in WAG/Rij rats. Post-implantation surveillance and characterizations were systematically performed with multiparametric MRI including 3D T1 and T2 weighted imagin...

In-situ testing capabilities of lab-scale industrial computed tomography are rapidly improving. In the present study, the compressive deformation behaviour of a flax fibre-reinforced epoxy composite is studied in an in-situ compression test with stepwise loading, during 3D imaging with X-ray Computed Tomography (XCT). The 3D volumes are processed w...

This work presents an iterative method in dynamic computed tomography (dynamic CT) which enables accurate reconstruction and scaling correction simultaneously. Recent achievements in dynamic CT have shown the feasibility of reconstructing an image of an object while simultaneously estimating its temporal deformation model parameters. Those approach...

In-situ testing capabilities of lab-scale industrial computed tomography are rapidly improving. In the present study, the compressive deformation behaviour of a flax fibre-reinforced epoxy composite is studied in an in-situ compression test with stepwise loading, during 3D imaging with X-ray Computed Tomography (XCT). The 3D volumes are processed w...

The present paper derives best practices to accurately simulate the installation process of a Blind Rivet Nut (BRN) using FEA. A BRN is a mechanical fastener used to equip plate material with a threaded part. The installation of a BRN inherently induces a high contact force which can have detrimental consequences when applied to non-metals such as...

Recently, in-situ X-ray Computed Tomography (CT) has shown its potential for 3D damage analysis in composite materials. However, the characterization of damage in X-ray tomograms is not always straightforward, and it requires post-processing of the 3D images. In this study, we explore the potential of Digital Volume Correlation (DVC) for the detect...

Worldwide, asset managers are struggling with the management of ageing infrastructure in reinforced concrete. Early detection of reinforcement corrosion, which is generally considered as the major problem, can help to perform dedicated maintenance and repair. The acoustic emission technique is promising to reach this goal. However, research on the...

Featured Application This work presents In-plane Heatwave Thermography as a new in-service qualification method of fasteners in aircraft fuselage panels. By performing feasibility tests on a serviceable part of an aircraft, the results of this work aim towards the application in an industrial environment like the aircraft hangar. A benchmark and co...

We apply Digital Image Correlation (DIC) to X-ray Computed Tomography (CT) slices for characterization of individual fibers misalignment in continuous fiber composites. This is an atypical application of DIC since the input is slices of a CT tomogram acquired at one time step, whereas the input of the typical deformation analysis application is 2D...

We have performed synchrotron computed tomography on two different fiber-reinforced composites while they were being continuously in-situ loaded in 0° tension. One material is a glass/epoxy laminate and the other is a carbon/epoxy laminate. The voxel size is 1.1 µm, which allows clear recognition of the glass fibers, but not distinct individual car...

It has been shown in acoustic emission literature that the distance between a possible cracking event and a receiver is affecting the signal parameters providing a wrong image of the real fracture characteristics. In this study, lab-scale experimental tests on masonry components are performed in order to determine the disturbance of the acoustic em...

In the present paper, finite element simulations are used to gain a better understanding of the setting process of a blind rivet nut. A blind rivet nut is a mechanical fastener capable of clinching materials whilst providing a threaded solution without the need for thread forming. The technique relies on plastic deformation introduced by axial comp...

Featured Application This work contributes to the development of a monitoring system for the remote detection, localization and quantification of melting ice. Acoustic emission measurements enable the remote monitoring in an environment where the region of interest is neither optically nor physically accessible. The kerosene tank of civil aircraft...

Laser-based ultrasonic inspection is an emerging versatile non-contact technique for defect detection in a variety of critical components. This article reports on the adaptation of this method for the inspection of rotating cylindrical components undergoing varying stress, by detecting the dynamically changing mechanical response of cracks, which g...

In this paper, an experimental study conducted on Red Clay brick masonry “triplets” built with Cement and Lime-based mortars is presented. Monitoring of fracture is executed by Acoustic Emission (AE) and Digital Image Correlation (DIC). First, for a profound understanding of individual properties, small scale experiments were conducted for characte...

Corrosion of the reinforcement is one of the major deterioration mechanisms in existing reinforced concrete (RC) structures causing considerable costs for maintenance and repair. The development of reliable tools to localise and characterise such damage is essential to assess the structural capacity. This paper investigates the use of the acoustic...

The influence of moisture on the mechanical properties of bamboo fibre reinforced composites was assessed both for static and hygroscopic cyclic conditioning. Static conditioning revealed that bamboo fibre reinforced composites show a smaller decrease in Young's modulus with moisture content than other natural fibre reinforced composites such as fo...

Corrosion of the reinforcement is one of the major deterioration problems in existing reinforced concrete (RC) structures. One of the important damage modes is the deterioration of the bond between steel and concrete. In this paper, the acoustic emission (AE) technique is evaluated for damage detection, characterisation and localisation during the...

X-ray Computed Tomography (X-ray CT) has become a vital tool for product quality inspection. The X-ray CT analysis of 3D printed composites, with a layer-by-layer structure of carbon fibre/polyamide and polyamide plies, demonstrates how the void content increases with an increasing number of consecutive carbon fibre layers. Not only the void conten...

Despite the fact that external cervical resorption (ECR) is a well-known and rather frequently met condition, the driving force of this phenomenon still remains unclear. Recently, hypoxia has been linked to ECR. Thus, the aim of this work was to investigate the existence of hypoxia in ECR and hypothesize on its role at the time of extraction. This...

It is a well-known fact that inappropriate levels of moisture can harm different kinds of structures, especially also in cultural heritage. This does not only regard hygroscopic materials but all assemblies where small quantities of water can change the physical properties of materials and structures. Damage modes range from crack formation due to...

Carbon fiber reinforced polymer is a material widely used nowadays in different application areas. All sectors, especially the aeronautics industry, demand components of high mechanical performance, but also with high durability and reliability, hence the need for advanced health assessing methods and to monitor the integrity of the components thro...

Many existing reinforced concrete (RC) structures are suffering from corrosion damage. The development of reliable tools to characterise and localise such damage is essential to assess the structural capacity. The acoustic emission (AE) technique has proven to be promising for this purpose. However, this technique poses challenges to reliably inter...

Determining the mechanical behaviour of masonry under compression remains challenging, as masonry is anisotropic and heterogeneous in nature. This paper focuses on an Acoustic Emission (AE)-based method to quantify the progressive damage in masonry under cyclic compressive loads. In this study, eight masonry walls were built in combination with fou...

Localization of the AE source in heterogeneous materials such as masonry is a complex task. Except for the anisotropy of bricks, mortar joints affect the localization accuracy due to the brick-mortar interfaces and the different proportion of them in two perpendicular directions for the same length. In addition, experimental studies have shown that...

A signal-based clustering algorithm was developed to distinguish different acoustic emission (AE) signals during accelerated corrosion of small-scale reinforced mortar samples. The algorithm was validated with visual data obtained from microfocus X-ray computed tomography (micro-CT). Results show that localised AE events accord to the damage seen o...

The main objective of this experimental study is to evaluate AE source location and to characterize the fracture modes in masonry under direct shear tests. In this study, triplets were built with a higher and a lower compressive strength brick in combination with cement mortar. Using average frequency and RA value analysis, fracture modes were char...

Reinforcement corrosion is believed to be the most common and most expensive deterioration mechanism in existing reinforced concrete (RC) structures. One of the important damage modes due to corrosion is the deterioration of bond between steel and concrete. In this paper, the Acoustic Emission (AE) technique is evaluated for damage detection, chara...

This paper deals with an improved representation of the progression of damage in lime-based masonry under cyclic loads using the Acoustic Emission (AE) technique. Stress-strain relations are a familiar concept in engineering which detail the elastic-plastic behaviour of the material. During AE monitoring, AE activates with the increase of stress an...

Historical masonry structures during the decades, were composed with a variety of brick and mortar types according to materials availability of each region and the desirable mechanical properties in each specific case. Different composition of mortars leads to another masonry behavior, and each one is suited for different structural purposes. A cru...

The paper presents an overview of cases in which the analysis of the internal structure and mechanical properties of fibre reinforced composites is performed based on the micro-computed X-ray tomography (micro-CT) reconstruction of the composite reinforcement geometry. In all the cases, the analysis relies on structure tensor-based algorithms for q...

Acoustic emission (AE) is a powerful technique for detection and analysis of the elastic waves produced by the failure mechanisms in construction materials such as masonry. In this study, the different fracture mechanisms are studied in relation to the properties of bricks and mortars. The fracture process is being evaluated using the combination o...

Several important technological and economic trends are shaping the research on non-destructive testing techniques. X-ray computed tomography is also a NDT product of these ongoing developments and has become a very important tool for doctors, material scientists, geologists, biologists, civil engineers, bio-engineers, dentists, quality engineers,...

VoxTex software (KU Leuven) employs 3D image processing, which use the local directionality information, retrieved using analysis of local structure tensor. The processing results in a voxel 3D array, with each voxel carrying information on (1) material type (matrix; yarn/ply, with identification of the yarn/ply in the reinforcement architecture; v...

In this paper an experimental study conducted on Red Clay brick masonry triplets built with Cement- and Hydraulic Lime-based mortars is presented. Monitoring of fracture is conducted by Acoustic Emission (AE) and Digital Image Correlation (DIC). Representative masonry triplet elements are tested in shear for investigation of the fracture mechanisms...

Background: The aim of this study was to assess the resistance to compression (stiffness) of frequently used stents for right ventricular outflow tract prestenting. In addition, to assess the corrosion potential when different types of stent alloys come into contact with each other. Method: Different stents were tested in vitro in various combin...

Corrosion of the reinforcement is one of the most common and most expensive deterioration mechanism in reinforced concrete (RC) structures. While a lot of research has been performed on the design of new RC structures, estimating the remaining capacity of existing structures with corroded reinforcement still requires dedicated attention. One of the...

A procedure to identify the fibre modulus from the results of tensile tests with a quasi-UD material is presented. In quasi-UD materials fibres may be misaligned, which makes the inverted rule of mixtures not applicable for the calculation of the fibre modulus. In this paper the modulus of flax fibre is identified based on finite element modelling...

Additive manufacturing techniques such as Selective Laser Melting (SLM) allow carefully controlled production of complex porous structures such as scaffolds. These advanced structures can offer many interesting advantages over conventionally produced products in terms of biological response and patient specific design. The surface finish of AM part...

Purpose: The aim of this work is to model the dose dependence of the darkening of GafChromic(?) EBT3 films by combining the optical properties of the polydiacetylene polymer phases, and a modified version of the single-hit model, which will take the stick-like shape of the monomer microcrystals into account. Second, a comparison is made between th...

In the very high cycle fatigue regime, internal crack initiation can occur in Ti-6Al-4V because of the formation of facets, which are α grains that have fractured in a transcrystalline and planar manner. Because this crack initiation phase occupies most of the fatigue life, it is essential to understand which mechanisms lead to facet formation. Fat...

Corrosion of the reinforcement is the most common degradation mechanism in reinforced concrete (RC) structures, causing large maintenance and repair costs. A lot of research has been done on the performance-based design of new RC structures, but there is still a lack of well-developed methods to assess the condition of existing RC structures. In or...

Dwell sensitivity in titanium alloys is generally attributed to the phenomenon of load shedding, which is a time dependent redistribution of stress from weak grains, with their c-axis perpendicular to the loading direction, to strong grains, with their c-axis approximately parallel to the loading direction. This leads to the formation of internal q...

Aim: To understand the pattern of external cervical resorption (ECR) in endodontically treated teeth. To compare characteristics and mechanisms of ECR in root filled teeth with those established in teeth with vital pulps. Methodology: Seven cases of endodontically treated permanent teeth displaying ECR were investigated. ECR diagnosis was based...

Objectives: (1) To evaluate the effect of cavity depth and composite type on the interfacial debonding in bulk-filled cavities. (2) To correlate the theoretical shrinkage stress and the level of interfacial debonding determined by acoustic emission (AE). Methods: 80 sound molars were divided in two groups to receive a Class-I cavity (3.5×3.5mm)...

In the very high cycle fatigue regime, the location of crack initiation in titanium alloys is known to shift from the surface towards the bulk of the material. This internal fatigue crack initiation results in faceted features on the fracture surface. These facets are in fact alpha grains that have been broken in a planar manner. Typically, a clust...

Acoustic Emission (AE) is a powerful technique for detection and analysis of the elastic waves produced by the failure mechanisms. In this study the different fracture mechanisms are studied in relation to the properties of the bricks, mortar and their interface. The fracture process is being evaluated using the AE technique. The isolation of the A...

Introduction: The aim of this study was to investigate the 3-dimensional (3D) structure and the cellular and tissue characteristics of external cervical resorption (ECR) in vital teeth and to understand the phenomenon of ECR by combining histomorphological and radiographic findings. Methods: Twenty-seven cases of vital permanent teeth displaying...

Damage development in masonry is particularly complex. Acoustic Emission (AE) is a powerful technique for detection and analysis of the elastic waves produced by the failure mechanisms. However, in-situ characterization of such structures is complicated due to the uncertainties caused by heterogeneity which hinders the accurate localization of dama...

With the aim to correlate the global properties of refractory mortars with the micro-mechanical processes, a series of uni-axial compression and shear tests was conducted. The test program was developed with the view that the shear grain slip and cracks are frequent failure mechanism under compressive loads. The micro-structural changes during comp...

On the request of Brussels Airlines corrosion of the floor structure of the A320 family aircrafts was examined in order to formulate approaches for corrosion protection. Corrosion maps were constructed of the FWD and AFT wet areas by investigating C-check reports of the period between January 2015 and June 2016. An overview of the possible corros...

Acoustic emission (AE) was used as a tool for detecting, evaluating and for better understanding of the damage mechanism and failure behavior in composites during mechanical loading. Methodology was developed for tensile test of natural fibres (bamboo single fibre). A series of experiments were performed and load drops (one or two) were observed in...

Introduction Different metals in close physical contact lead to electrolysis and corrosion; this may downsize the strength and durability of the stents. Lack of data did not to allow pre-stenting in several trials by FDA. Methods : Stents used in the analysis: Cheatham-Platinum (Pl-Ir-Au), Andrastent (Co-Cr), Optimus (Co-Cr), Sapien (SS316L) Sapien...

Purpose: This work provides an interpretation of the chromatic properties of GafChromic™EBT3 films based on the chemical nature of the polydiacetylene (PDA) molecules formed upon interaction with ionizing radiation. The EBT3 films become optically less transparent with increasing radiation dose as a result of the radiation-induced polymerization of...

Fatigue cracks in titanium alloys are often found to initiate at faceted alpha grains. In the very high cycle fatigue regime, crack initiation tends to shift from the surface towards the interior of the material, and more initiation facets can be found on the fracture surface. In this study, fatigue tests were performed on drawn and heat-treated Ti...

Liquid metal embrittlement (LME) induced quasi-brittle fracture characteristics of a 9Cr–1Mo ferritic–martensitic steel (T91) after fatigue cracking in lead–bismuth eutectic (LBE) have been investigated at various length scales. The results show that the LME fracture morphology is primarily characterized by quasi-brittle translath flat regions part...