Fabien Leonard

The University of Manchester · UoMaH

Selective Electron Beam Melting (SEBM) is a promising powder bed Additive Manufacturing technique for near-net-shape manufacture of high-value titanium components. However without post manufacture HIPing the fatigue life of SEBM parts is currently dominated by the presence of porosity. In this study, the size, volume fraction, and spatial distribut...

The mixture of ammonium nitrate (AN) prills and fuel oil (FO), usually referred to as ANFO, is extensively used in the mining industry as a bulk explosive. One of the major performance predictors of ANFO mixtures is the fuel oil retention, which is itself governed by the complex pore structure of the AN prills. In this study, we present how X-ray c...

Zusammenfassung Durch den großflächigen Einsatz der Computertomographie (CT) in unterschiedlichen Industriebereichen steigen auch die Anforderungen an die quantitative Bildanalyse. Subjektive Bildwahrnehmung muss durch objektive Algorithmen ersetzt werden. In diesem Artikel stellt die Bundesanstalt für Materialforschung und -prüfung (BAM), die seit...

Two biopolyol-based foams derived from banana leaves (BL) or stems (BS) were produced, and their compression mechanical behavior and 3D microstructure were characterized. Traditional compression and in situ tests were performed during 3D image acquisition using X-ray microtomography. A methodology of image acquisition, processing, and analysis was...

Metal foams are a class of materials with immense potential. The complex topology in these lightweight systems is responsible for their outstanding mechanical and thermal properties. Furthermore, this is the same reason why thermal assessment of metal foams is challenging. While conventional analytical techniques provide useful data, modern-age tec...

Fused filament fabrication (FFF), also known under the brand name fused deposition modelling, has recently emerged as a more straightforward and economic alternative to established 3D printing or additive manufacturing technologies such as powder bed fusion for metal part manufacturing. In this work, we report on possible approaches to the measurem...

This is a supplementary material for the 'Digital twin' paper, where the following is included: - Pore quantification (sphere fitting vs skeletonization) - Cross-verification and validation tests for effective medium models in PULsE - Specific heat of the metal foams - Geodesic distance calculation tips

In this work, we report on several possible approaches to the measurements of fused deposition modelling (FDM) sintering shrinkage rates (SSR) from X-ray computed tomography (XCT) data. Metallic parts were produced using FDM technology which relies on an isotropic scaling factor applied to the STL model of the part to be produced to compensate for...

While global Digital Volume Correlation (DVC) yields more accurate results compared to local DVC, its main drawback remains the computational power needed to store and update the entire reference and deformed volumes during the optimisation process. This effectively prevents the use of global DVC for large volumes, with the exact size limit dependi...

Fused filament fabrication (FFF), also known under the brand name fused deposition modelling, has recently emerged as a more straightforward and economic alternative to established 3D printing or additive manufacturing technologies such as powder bed fusion for metal part manufacturing. In this work, we report on possible approaches to the measurem...

While global Digital Volume Correlation (DVC) yields more accurate results compared to local DVC, its main drawback remains the computational power needed to store and update the entire reference and deformed volumes during the optimisation process. This effectively prevents the use of global DVC for large volumes, with the exact size limit dependi...

Metal foams are a class of materials with immense potential. The complex topology in these lightweight systems is responsible for their outstanding mechanical and thermal properties. Furthermore, this is the same reason why thermal assessment of metal foams is challenging. While conventional analytical techniques provide useful data, modern-age tec...

The determination of the anisotropy of materials’ microstructure and morphology (pore space) in Diesel Particulate Filter (DPF) materials is an important problem to solve, since such anisotropy determines the mechanical, thermal, and filtration properties of such materials. Through the use of a dedicated (and simple) segmentation algorithm, we show...

Layer-by-layer Additive Manufacturing by means of Laser-Powder Bed Fusion offers many prospects regarding the design of lattice structures used for example in gas turbines. However, defects such as bulk porosity, surface roughness, and re-entrant features are exacerbated in non-vertical structures such as tilted struts. The characterization and qua...

The paper introduces 3D least squares matching as a technique to analyze multi-temporal micro-tomography data in civil engineering material testing. Time series of tomography voxel data sets are recorded during an in-situ tension test of a strain-hardening cement-based composite probe at consecutive load steps. 3D least squares matching is a techni...

We show how the combination of the spatial autocorrelation function and permeability calculations, applied to 3D X-ray computed tomography data, can yield quantitative information on the anisotropy of both meso-structure and fluid flow in Diesel Particulate Filter (DPF) materials, such as Cordierite and SiC. It was found that both the degree of ani...

The paper presents the results of a series of combined mechanical and in-situ morphological investigations on highstrength strain-hardening cement-based composites (SHCC). Tension and compression experiments were performed in a CT scanner employing a dedicated mechanical testing rig. The in-situ microtomographic scans enabled correlating the measur...

Ammonium nitrate (AN) prills are commonly used as an ingredient in industrial explosives and in fertilisers. Conventional techniques (such as BET or mercury intrusion porosimetry) can measure the open porosity and specific surface area of AN prill, but the closed porosity is not obtainable. This work was focused on evaluating X-ray computed tomogra...

An ultrasonic vibration post-treatment procedure was suggested for additively manufactured lattices. The aim of the present research was to investigate mechanical properties and the differences in mechanical behavior and fracture modes of Ti6Al4V scaffolds treated with traditional powder recovery system (PRS) and ultrasound vibration (USV). Scannin...

In order to characterise the material and damage behaviour of additively manufactured polyamide 12 (PA12) under quasi-static load and to implement it in a numerical model, experiments under quasi-static load as well as microstructural investigations were carried out. Selective laser sintering (SLS) was used as the manufacturing process. For the cla...

As humanity contemplates manned missions to Mars, strategies need to be developed for the design and operation of hospitable environments to safely work in space for years. The supply of spare parts for repair and replacement of lost equipment will be one key need, but in‐space manufacturing remains the only option for a timely supply. With high fl...

Nominal-actual comparisons are routinely performed to compare a manufactured specimen to a reference specimen. X-ray Computed Tomography (CT) has brought a profound change in the way that tolerance verifications are performed in industry, by allowing the inner and outer geometries of an object to be measured, without the need for external access or...

While in the past few years a frantic activity around additive manufacturing (AM) is underway in industry, in order to optimize production and reduce costs, BAM (Bundesanstalt für Materialforschung und -prüfung) has by its mission focused on the control of component and materials safety. The freeform (design freedom of new and conventional componen...

In this paper we report on the characterization by X-ray computed tomography of calcium phosphate (CaP) and polycaprolactone (PCL) coatings on Ti-6Al-4V alloy scaffolds used as a material for medical implants. The cylindrical scaffold has greater porosity of the inner part than the external part, thus, mimicking trabecular and cortical bone, respec...

Corrosion rates of strained grade UNS S32202 (2202) and UNS S32205 (2205) duplex stainless steel wires have been measured, in situ, using time-lapse X-ray computed tomography. Exposures to chloride-containing (MgCl 2) atmospheric environments at 50 °C (12-15 M Cl − and pH ~5) with different mechanical elastic and elastic/plastic loads were carried...

The layer-by-layer Additive Manufacturing (AM) by means of Selective Laser Melting (SLM) offers many prospects regarding the design of a part used in aeroplane components and gas turbines. However, structural deviations from the nominal morphology are unavoidable. The cooling of the finished part leads to shrinkage and a high surface roughness is i...

Up to now, there exists a lack of methods for the additive manufacturing of voluminous ceramic parts with properties comparable to those of conventionally manufactured ones. A high density after sintering is needed to reach the superior properties of ceramic materials. We have developed a new additive manufacturing method, Laser-Induced Slip castin...

Several cylindrical specimens and dental implants, presenting diagonal lattice structures with different cell sizes (600, 900 and 1200 μm) were additively manufactured by selective laser melting process. Then they were implanted for two months in a sheep. After removal, they were studied by Archimedes’ method as well as X-ray computed tomography in...

One of the great strengths of X-ray computed tomography over conventional inspection methods (ultrasound, thermography, radiography) is that it can image damage in 3D. However for curved or deformed composite panels it can be difficult to automatically ascribe the damage to specific plies or inter-ply interfaces. An X-ray computed tomography (CT) d...

Metallic lattice structures intentionally contain open porosity; however, they can also contain unwanted closed porosity within the structural members. The entrained porosity and defects within three different geometries of Ti-6Al-4V lattices, fabricated by Selective Electron Beam Melting (SEBM), is assessed from X-ray computed tomography (CT) scan...

The use of novel multi-scale correlative methods, which involve the coordinated characterisation of matter across a range of length scales, are becoming of increasing value to materials scientists. Here, we describe for the first time how a multi-scale correlative approach can be used to investigate the nature of ductile fracture in metals. Specime...

Shock tube systems are non-electric explosive fuses employed in blasting and demolition applications to trigger the detonation of explosive charges. Their working principle is based on the explosive reaction of a fine explosive powder on the tubing´s inner surface, generating a shock wave travelling at a velocity of 2,100 m/s along the length of th...

The reinforcement of concrete with polymer fibers provides resistance to crack formation. The orientation distribution of these fibers has a significant influence on the mechanical behavior of the material. To optimize material performance, micromechanical models that are capable of making accurate predictions of the mechanical behavior of composit...

Electron Beam Melting (EBM) as a means of Additive Manufacturing (AM), is of interest for the fabrication of intricate geometries for cellular materials in areas where complex architectures are needed, e.g. biomedical implants. Most studies have focused on specific geometries and so the effect of the structure on mechanical performance is not well...

Selective Electron Beam Melting (SEBM) is a promising powder bed Additive Manufacturing (AM) technique for near net-shape manufacturing of high-value titanium components. However, as with every emerging technique, the manufacturing processes can still be greatly improved and optimised. In particular, the links between AM settings and the resulting...

X-ray refraction is based on optical deflection of X-rays, similar to the well-known small angle X-ray scattering, but hundreds of times more intense, thus enabling shorter measurement time. We show that X-ray refraction techniques are suitable for the detection of pores, cracks, and in general defects. Indeed, the deflected X-ray intensity is dire...

Simple models describing the relationship between basic mechanical properties and the relative density of various types of porous metals (such as foams, sponges and lattice structures) are well established. Carefully evaluating these relationships experimentally is challenging, however, because of the stochastic structure of foams and the fact that...

Fibre reinforced polymer composites (FRPC) are widely used in engineering applications due to their high specific strength and high specific modulus. However, due to the high complexity of the structures and the damage mechanisms, composite materials are increasingly complex. Traditional NDT techniques such as ultrasound C-scan, shearography and th...

Reactor Pressure Vessels (RPV) are manufactured from medium strength low allow ferritic steel specifically selected for its high toughness and weldability. The normal operating temperature of RPV steels is sufficiently high to ensure that the material remains ductile throughout its service life with an extremely low probability of cleavage under no...

This study investigates the development of fatigue damage in 3D woven composites reinforced with a modified layer-to-layer glass fibre preform, exploring the effect of fibre architecture on damage evolution. The results obtained from the mechanical tests were supplemented by the progressive damage observation using X-ray computed tomography (CT). I...

This work investigates the thermal performance of four novel CFC–Cu joining techniques. Two involve direct casting and brazing of Cu onto a chromium modified CFC surface, the other two pre-coat a brazing alloy with chromium using galvanisation and sputtering processes. The chromium carbide layer at the interface has been shown to improve adhesion....

Through its ability to measure otherwise inaccessible internal structures, x-ray computed tomography (CT) has become a useful tool in the field of dimensional metrology. However, the lack of international standards for performance verification and the determination of metrological characteristics has so far prevented it from becoming a standardized...

This study presents the 3D assessment of impact damage in fibre metal laminate (FML) coupons using X-ray computed tomography (CT). CARALL (CArbon Reinforced ALuminum Laminates) FMLs with two different structures were impacted at energies ranging from 10 J up to 30 J. For the first time, CT was employed to successfully assess impact damage in FML in...

This study presents how X-ray computed tomography (CT) can be employed to obtain a more complete 3-dimensional description of damage in carbon fibre reinforced polymer (CFRP) composites. Impact damage was produced with energies ranging from 5 J to 20 J on coupon size (89 mm × 55 mm) composite laminates aimed for primary structures in aerospace appl...

Ductile damage is characterised by the nucleation, growth and coalescence of voids at initiating particles within the volume of high triaxial stresses and plastic strain ahead of a crack-tip or stress concentrator. To establish a more detailed understanding of the mechanism of ductile fracture in the A508 Class 3 ferritic RPV steels and to improve...

X-ray computed tomography (X-ray CT) has been applied to nondestructively characterise changes in the microstructure of a concrete used in the pressure vessel structure of Advanced Gas-cooled Reactors (AGR) in the UK. Concrete specimens were conditioned at temperatures of 105 °C and 250 °C, to simulate the maximum thermal load expected to occur dur...

Reactor pressure vessels (RPV) are manufactured from medium strength low allow ferritic steel specifically selected of its high toughness and weldability. The ability of the RPV to withstand crack propagation is crucial to maintaining the operational safety of the reactor plant. Current generations of RPV steels operate at sufficiently high tempera...

Additive layer manufacturing (ALM) has the potential to allow engineers almost complete freedom of design, with reduced material wastage and tooling costs, as well as shorter lead times on new designs. Unfortunately, most ALM processes invariably lead to porosity in the material deposited. The ALM process investigated here, selective electron beam...

This paper presents an investigation of voids in carbon fibre reinforced epoxy composites manufactured by resin film infusion using X-ray computed tomography (XCT). Two panels were investigated, one formed with a high viscosity resin, the other with a lower viscosity resin. The study focusses on the characterisation of the 3D distribution of voids...

IntroductionExperimental ProceduresResultsDiscussionConclusions Acknowledgements

This study investigates the link between microstructure and stress corrosion cracking susceptibility for three heats of alloy 600 representative of plant components (forged control rod drive mechanism nozzle, rolled divider plate, and rolled divider plate stub). The experimental approach was designed to determine the effect of the manufacturing pro...

This study investigates the effect of the strain path on the stress corrosion cracking (SCC) behaviour of two Ni base alloy materials. Specimens with different strain paths have been produced from two plant components (forged CDRM nozzle and rolled divider plate) and tested in high temperature (360 °C) high pressure primary water environment under...