Bratislav Lukić

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• PhD
• Research fellow at European Synchrotron Radiation Facility

Proton exchange membrane fuel cells (PEMFCs) are important clean energy technology, yet the material and structural complexity of their membrane electrode assemblies (MEAs) can hamper the development of next‐generation structures, as even a subtle change to one component can have a significant impact on others. Mathematical modelling of PEMFC MEAs...

In the present study, microconcrete (MC) samples were exposed to dynamic quasi-oedometric compression (QOC) tests and visualised in-situ by the means of MHz synchrotron X-ray phase-contrast imaging in the ESRF synchrotron in order to analyse the damage mechanisms governing the mechanical behaviour of concrete under high-strain-rate confined compres...

Perfluorohexane is a biocompatible material that serves as a liquid core for acoustically-responsive agents in biomedical applications. Despite its relatively widespread usage, there is a lack of experimental data determining its thermodynamic properties. This challenges numerical simulations to predict the acoustic response of agents developed usi...

Oil serves as both the high-temperature heating medium during deep-frying unit operations and a contributor to the organoleptic properties of deep-fried foods. Its absorption is linked to structural deformations during deep-frying that create pathways for oil to enter the food microstructure. This study proposes a 4D imaging system (three spatial d...

We present measurements of the wavelength of electrothermal instabilities (ETI) formed during underwater electrical explosions of aluminum (Al), silver (Ag), and molybdenum (Mo) wires. Wires were exploded using a ∼450 ns rise time and ∼120 kA amplitude current pulse delivered by a pulse generator. Images of the exploding wires were captured by mult...

The first damage mechanism in composites in tension is transverse cracking, which is here studied in 3D at a kHz rate, using time-resolved X-ray multi-projection imaging. Radiographs taken at three angles with synchrotron radiation enabled the detection of crack propagation and other damage mechanisms related to the final failure of composites. Dee...

This study highlights the importance of investigating the behaviour of the inner layers of carbon fibre-reinforced polymer (CFRP) laminates under dynamic compression, using Synchrotron-based techniques to understand damage initiation and failure propagation at high strain rates. Open and filled hole specimens with three different CFRP architectures...

The dynamic fracture properties of porous ceramics were studied using single bunch synchrotron X-ray phase contrast imaging. The modified brazilian geometry was used to initiate and propagate a pure mode I crack. The specimen was compressed using the Split Hopkinson bars at strain rates of the order of \(10^2\) s\(^{-1}\). Main cracks were isolated...

Gas-encapsulated drops, much like antibubbles, are drops enclosed in a bubble within a liquid. They show potential as payload carriers in fluid transport and mixing techniques where sound waves can be leveraged to induce the collapse of the gas core and the subsequent release of the drop. Here, the interaction of millimetre-sized gas-encapsulated d...

Metal anodes hold considerable promise for high-energy-density batteries but are fundamentally limited by electrochemical irreversibility caused by uneven metal deposition and dendrite formation, which compromise battery lifespan and safety. The chaotic ion flow (or ion flux vortex) near the electrode surface, driving these instabilities, has remai...

Solid‐state batteries are compelling candidates for next‐generation energy storage devices, promising both high energy density and improved safety, by utilizing metallic Li as the negative electrode. However, they suffer from poor cyclability and rate capability, which limits their wide application. Degradation in these devices occurs through compl...

This study investigates water vapor condensation processes in a fractured porous medium (sandstone), focusing on the effects of fracture conductivity, matrix porosity, and imposed flow rate of the vapor. Cylindrical samples of Fontainebleau sandstone were pre-fractured using the Brazilian splitting test and subjected to a constant vapor and air mix...

Understanding bubble behaviour under ultrasound excitation is key for applications like industrial cleaning and biomedical treatments. Our previous work demonstrated that ultrasound-induced shape instabilities in microbubbles generate periodic jets capable of puncturing cells and enabling targeted drug delivery (Cattaneo et al., 2024). This study i...

Ultra‐high‐speed synchrotron‐based hard X‐ray (i.e. above 10 keV) imaging is gaining a growing interest in a number of scientific domains for tracking non‐repeatable dynamic phenomena at spatio‐temporal microscales. This work describes an optimized indirect X‐ray imaging microscope designed to achieve high performance at micrometre pixel size and m...

Enthesis lesions are one of the prevalent causes of injuries in the tendon tissue. The gradient of mineralization, extracellular matrix organization and auxetic mechanical properties, make enthesis regeneration challenging. Innovative electrospun fascicle-inspired nanofibrous poly(L-lactic)acid/collagen type I blend scaffolds were developed. Specif...

Polyamide 6 and its composites are widely used in engineering applications that are exposed to high strain rate deformation. This paper investigates the thermomechanical properties of two polyamide 6 composites, both reinforced with 30 wt% short glass fibres, and one of which additionally contains an impact modifier, to provide an understanding of...

The intersection of dynamic compression, high-rate material response and X-ray science has seen rapid growth in the last decade, leading to the establishment of specialized end-stations at international facilities such as Linac Coherent Light Source LCLS (Matter at Extreme Conditions-MEC) and Advanced Photon Source APS (Dynamic Compression Sector-D...

Oil acts as a high-temperature heating medium while also contributing to the organoleptic properties in energy dense deep-fried foods. The amount of oil absorbed is associated with the rapid structural deformation of food during deep-frying, creating pathways for oil to enter the internal microstructure. Here, we describe a 4D imaging system (three...

Laser-driven dynamic compression experiments of plastic materials have found surprisingly fast formation of nanodiamonds (ND) via X-ray probing. This mechanism is relevant for planetary models, but could also open efficient synthesis routes for tailored NDs. We investigate the release mechanics of compressed NDs by molecular dynamics simulation of...

Porosity, with its structure-dependent flow properties (permeability and tortuosity) and transport properties (thermal conductivity and thermal diffusivity), is closely related to the accretion, thermal metamorphism, and associated hydrothermal alteration of ordinary chondrite (OC) parent bodies. Using synchrotron radiation microtomography (SRμCT),...

A promising solution to reduce energy usage and mitigate the wear of drilling and comminution tools during mining operations involves inducing vibrations within the piezoelectric phases dispersed in the structure of rocks using alternating current (AC). This paper presents experimental evidence of AC-induced weakening of Kuru granite, manifested as...

Dynamic tensile fracturing of two quasi-brittle geomaterials during high strain rate spalling as observed in situ utilizing ultra-high speed single bunch X-ray phase-contrast radiography is presented (image acquisition rate of 1.4 MHz with 32 µm pixel size). A spalling experimental set-up, based on a single Hopkinson bar, has been developed to appl...

Neutron imaging has gained increasing attention in recent years. A notable domain is the in-situ study of flow and concentration of hydrogen-rich materials. This demands precise quantification of the evolving concentrations. Several implementations deviate from the ideal conditions that allow the direct applicability of the Beer–Lambert law to asse...

The present study demonstrates experimental evidence of subsurface mesoscale damage initiation and evolution in angle-ply CFRP laminates under high strain-rate loading at low temperatures using synchrotron-based X-ray MHz radiography. A bespoke set of loading, temperature control and in-situ X-ray imaging systems were applied to simultaneously corr...

Kink band formation is the primary failure mode of unidirectional carbon fibre reinforced polymer composites (CFRP) loaded under compression, and the kinking stress is highly dependent on defects and fibre misorientation. However, the micromechanics of how defects and fibre misorientation impact kink initiation and propagation is not well understoo...

Ghost imaging (GI) redefines how we capture images of objects. Unlike conventional imaging systems where light directly interacts with the object being imaged, ghost imaging uses the combination of information from two types of detectors: a conventional, multi-pixel detector that does not directly view the object, and a single-pixel detector, which...

Porosity in directed energy deposition (DED) deteriorates mechanical performances of components, limiting safety-critical applications. However, how pores arise and evolve in DED remains unclear. Here, we reveal pore evolution mechanisms during DED using in situ X-ray imaging and multi-physics modelling. We quantify five mechanisms contributing to...

Dynamic loadings, such as earthquakes, blasts, and impacts, are commonly encountered in mining and underground infrastructures, and therefore predicting the failure of geomaterials, including cement, concrete and rock at high strain rates holds significant importance. The exploration of fracturing and deformation properties in materials under dynam...

Polycarbonate composites are widely used in products exposed to high strain rate deformation. This paper investigates the thermomechanical properties of polycarbonate and 20 wt% glass fibre reinforced polycarbonate to provide characterisation data and improved mechanistic understanding of the response to load, supported by Dynamic Mechanical Analys...

Solid-state batteries are compelling candidates for next generation energy storage devices, promising both high energy density and improved safety, by utilizing metallic Li as the negative electrode. However, they suffer from poor cyclability and rate capability, which limits their wide application. Degradation in these devices occurs through compl...

Pulsed-power-driven underwater electrical explosion of cylindrical or conical wire arrays produces supersonic water jets that emerge from a bath, propagating through the air above it. Interaction of these jets with solid targets may represent a new platform for attaining materials at high pressure (>10¹⁰ Pa) conditions in a university-scale laborat...

X-ray multi-projection imaging (XMPI) has the potential to provide rotation-free 3D movies of optically opaque samples. The absence of rotation enables superior imaging speed and preserves fragile sample dynamics by avoiding the centrifugal forces introduced by conventional rotary tomography. Here, we present our XMPI observations at the ID19 beaml...

Hard X-ray imaging with ultra-high speed acquisition rates using synchrotron-based sources or free-electron lasers has recently gained significant attention: commercially available CMOS-based cameras as basis for indirect detection allow for the use of radioscopy with MHz acquisition rates in a routine manner. Hence, an increasing number of experim...

We successfully demonstrate X-ray fluorescence Ghost Imaging on synchrotron sources. We present a new robust protocol against drifts and positioning errors that opens the way to study previously inaccessible samples such as liquids.

Each year approximately 99% by mass of energetic material use takes place in the quarrying, mining, construction and petrochemical industries. The coupling of explosively driven shock waves to heterogeneous geological materials is of scientific and industrial relevance. Here we report the first experiments conducted with energetic materials at the...

Slow multiphase flow in porous media is intriguing because its underlying dynamics is almost deterministic, yet depends on a hierarchy of spatiotemporal processes. There has been great progress in the experimental study of such multiphase flows, but three-dimensional (3D) microscopy methods probing the pore-scale fluid dynamics with millisecond res...

This work investigates the fundamental role of cavitation bubble clouds in stone comminution by focused ultrasound. The fragmentation of stones by ultrasound has applications in medical lithotripsy for the comminution of kidney stones or gall stones, where their fragmentation is believed to result from the high acoustic wave energy as well as the f...

X ray fluorescence ghost imaging (XRF-GI) was recently demonstrated for x ray lab sources. It has the potential to reduce the acquisition time and deposited dose by choosing their trade-off with a spatial resolution while alleviating the focusing constraints of the probing beam. Here, we demonstrate the realization of synchrotron-based XRF-GI: we p...

Magnetic Pulse Welding (MPW) facilitates the permanent joining of dissimilar metallic materials through the sudden impact generated by a magnetic pulsed field. The process can introduce distinct morphological features at the interface of bi-material joints, which subsequently affect the joint’s quality and durability. This article delves into the i...

Despite their diverse applications, experimental studies on multi-phase flow with phase change in fractured porous media are rare in the literature. In this study, water condensation of vapor in a fractured sandstone is investigated by means of 3D rapid in situ neutron tomography (30 s per tomogram). A water vapor and air mixture is injected at a c...

Ultrafast radiographic imaging and tracking (U-RadIT) use state-of-the-art ionizing particle and light sources to experimentally study sub-nanosecond dynamic processes in physics, chemistry, biology, geology, materials science and other fields. These processes, fundamental to nuclear fusion energy, advanced manufacturing, green transportation and o...

X-ray Fluorescence Ghost Imaging (XRF-GI) was recently demonstrated for x-ray lab sources. It has the potential to reduce acquisition time and deposited dose by choosing their trade-off with spatial resolution, while alleviating the focusing constraints of the probing beam. Here, we demonstrate the realization of synchrotron-based XRF-GI: We presen...

Despite a century of research, our understanding of cement dissolution and precipitation processes at early ages is very limited. This is due to the lack of methods that can image these processes with enough spatial resolution, contrast and field of view. Here, we adapt near-field ptychographic nanotomography to in situ visualise the hydration of c...

Within the context of the clinical treatment of human body calculi, this paper addresses the role of ultrasonically induced cavitation bubble clouds in the stone comminution. The fragmentation of calculi is widely assumed to be due to the high acoustic wave energy, while the exact contribution of cavitation is currently unknown. Based on in-situ ex...

We present a new technique for the investigation of shock-driven hydrodynamic phenomena in gases, liquids, and solids in arbitrary geome-tries. The technique consists of a pulsed power-driven resistive wire array explosion in combination with multi-MHz synchrotron radiography. Compared to commonly used techniques, it offers multiple advantages: (1)...

Magnetic Pulse Welding (MPW) is a method of growing interest allowing the joining of dissimilar materials such as aluminum and copper. The global mechanical properties of the joint are often evaluated with conventional tests, using the fully welded joint. However, these cannot elucidate the local mechanical properties of the joint or its interface...

Laser-induced cavitation bubble dynamics at different distances from a rigid boundary is investigated using high-speed synchrotron X-ray phase-contrast imaging. This is achieved through the design of a tailored experimental chamber specifically designed to reduce the X-ray absorption along the path length in water while mitigating boundary effects....

Despite a century of research, our understanding of cement dissolution and precipitation processes at early ages is very limited. This is due to the lack of methods that can image these processes with enough spatial resolution, contrast and field of view. Here, we adapt near-field ptychographic nanotomography to in situ visualise the hydration of c...

High-power ultrasonic horns operating at low frequency are known to generate a cone-shaped cavitation bubble cloud beneath them. The exact physical processes resulting in the conical structure are still unclear mainly due to challenges associated with their visualization. Herein, we address the onset of the cavitation cloud by exploiting high-speed...

In the present study, dynamic experiments are developed to investigate the induced damage modes when Lingulid sandstone is subjected to dynamic and impact loading. To do so, a series of spalling tests were carried out in order to investigate the material response at high strain tension rates. This illustrates how structural defects influence the wa...

A constitutive model able to describe both tensile damage and plastic deformation under confinement is a prerequisite to numerically simulate the behaviour of sandstone rock under an impact loading induced in a percussive drilling process. Therefore, model identification under both tensile and high confinement states is needed. In the present work,...

Understanding the migration of high-temperature fluids through the porous medium of cement-based materials has a pivotal role in many engineering applications. The space and time evolution of the free water content and the crack network in these materials creates a complex migration process. In this work, we experimentally investigate water vapour...

Studying the failure behaviour of engineered or natural materials under dynamic loading scenarios is of high importance, for example to investigate the fracture mechanics and to prevent catastrophic failures of constructions. When dynamic loading is coupled to high-speed X-ray imaging, not only surface information but images of the interior of the...

This works reports experimental investigations at different velocities for the auxetic 3D anti-tetra-chiral lattice structure additively manufactured from 316L steel. Velocities range from the quasi-static regime over the Split-Hopkinson regime at 10 m/s to the gas gun regime up to 432 m/s. The dynamic com-paction behaviour is visualized using high...

Ultra High speed X-ray phase contrast imaging (XPCI) synchronised with a custom built Split Hopkinson Tension Bar (SHTB) and a Universal Testing Machine (UTM) was utilised to investigate the defect growth behaviour of Al-Mg-Sc alloy (a.k.a Scalmalloy) in quasi-static to dynamic strain rate regime. These systems provide a unique opportunity for real...

We present the results of the research on underwater electrical explosion of planar copper wire arrays, accompanied by the generation of a planar shock, using the synchrotron-based phase-contrast radiography imaging capabilities of the ID19 beamline at the European Synchrotron Radiation Facility. It is shown that the interaction of a strong shock w...

This paper presents, for the first time, full-field dynamic measurements of vapour injection and condensation within a fractured concrete, observed in-operando by means of rapid neutron radiography (acquisition rate of 30 Hz with 87 mu pixel size). Time-dependant moisture evolution is analysed in terms of equivalent water thickness measurements. We...

In this work the dynamic fracturing of an ultra-high strength cementitious material is probed with in-situ ultra-high speed X-ray phase-contrast diagnostics to investigate the phenomenology of dynamic fracture. Gas gun experiments were conducted on two characteristic samples with two different impact speeds, namely 80 and 190 m/s using the edge-on...

In this work we report full-field dynamic measurements of vapour injection in fractured concrete, observed in-operando by means of rapid neutron radiography (acquisition rate of 30 Hz with 87 µm pixel size). We analyse the time-dependant moisture evolution in terms of the equivalent water thickness inferred straight from recorded radiographies. We...

In this paper, the use of the virtual fields method for the identification of a strongly asymmetric compression–tension response of rock‐like materials under dynamic tensile loading is investigated. The photomechanical spalling set‐up is used, which induces an indirect tensile load in a non‐balanced sample, and the inertial component of the test is...

In this work we validate the use of the virtual fields method for the identification of the asymmetric compression-tension response and post-peak tensile response of rock-like materials under dynamic tensile loading by means of simulated experiments. The photomechanical spalling test is used, that produces an indirect tensile load at high strain r...

Oral presentation concerning the proceeding "Two Processing Techniques to Characterise the Dynamic Crack Velocity in Armour Ceramic Based on Digital Image Correlation" (https://www.researchgate.net/publication/339774420_Comparison_of_Two_Processing_Techniques_to_Characterise_the_Dynamic_Crack_Velocity_in_Armour_Ceramic_Based_on_Digital_Image_Correl...

Fragmentation experiments have been carried out on a sapphire mono-crystalline using the Edge-On impact technique. Direct ultra-high speed photography, with inter-frame time down to 200 ns, was used to record the time resolved evolution of the impact damage during the first thirty microseconds from impact. The influence of the orientation of the pr...

Ceramic materials are being more and more used in bi-layer shielding solutions. When impacted, substantial tensile damage creates within the ceramic tile that manifests as numerous oriented cracks. Understanding the dynamic fracture response under high strain-rates and at the level of a single dynamic crack is of major importance in pushing forward...

Ceramic materials are widely used all around the world in protective solutions as front plate of bilayered configurations, a metallic or composite material being used as backing to absorb the kinetic energy of fragments. However, during the impact, an intense fragmentation process composed of numerous oriented cracks develops in the ceramic plate d...

ESRF team at Beamline ID19.

The experimental testing of concrete and other brittle materials under high-strain rate tensile loading remains a major issue in many research fields and industrial applications. Among the experimental methods, the spalling technique provides a major advantage as it does not rely on a static mechanical balance of the sample. A short compressive pul...

This paper presents the experimental results of the dynamic fracture energy of HPC measured via the photomechanical spalling test. Full field measurements are performed and the stress-fracture opening displacement curves are obtained for each visualized fracture zone from which the specific fracture energy can be calculated. First results obtained...

This paper investigates the application of CMOS-based ultra-high speed camera in characterising materials under dynamic tensile loading. A single Hopkinson bar test is used to induce an axial stress wave in the sample and a grid pattern is filmed during the test to obtain time-resolved full-field kinematic measurements. Then the acceleration fields...

For several decades, ceramic materials have been widely used in bilayered protective configurations. However, the impact loading produces dynamic tensile stresses that spread out the ceramic tile leading to an intense fragmentation made of short oriented cracks. To improve the design of such configurations the fragmentation process needs to be bett...

Poster presented in DYMAT 2018 regarding the identified material response of high performance concrete (HPC) under dynamic tension using the photomechanical spalling test.

Ceramic materials are numerically studied to understand their fracturing behaviour upon dynamic conditions and impact loadings. During a ballistic impact of a projectile against a ceramic armour system, an intense fragmentation composed of numerous oriented cracks, develops in the target. It is the reason why the conditions of crack initiation, pro...

Ceramic materials are numerically studied to understand their fracturing behaviour upon dynamic conditions and impact loadings. During a ballistic impact of a projectile against a ceramic armour system, an intense fragmentation composed of numerous oriented cracks, develops in the target. It is the reason why the conditions of crack initiation, pro...