Effect Of Shell Thickness Research Articles

Hierarchical nanoarchitectonics of hollow hexanitrostilbene (HNS) microspheres to improve safety and combustion performance

Hollow structures have great potential in the field of energetic materials due to their excellent properties. In this study, nitrocellulose (NC) was used as a binder, and hollow-structured HNS/NC microspheres were prepared in the form of a suspension using the microjet droplet technology. The effects of spray velocity, suspension concentration, and receiving liquid temperature on the morphology, particle size, cavity structure, and pore size of the microspheres were systematically investigated. Subsequently, the effects of shell thickness and pore size on the dispersibility, specific surface area, crystal structure, thermal performance, mechanical sensitivity, and combustion performance of the microspheres were further studied. The results show that compared with the raw HNS, the hollow HNS/NC microspheres have good dispersibility, while retaining the crystal structure and chemical structure of the raw HNS, and have a lower activation energy, which is expected to achieve a rapid energy release reaction. In addition, compared with the solid HNS/NC microspheres, the hollow HNS/NC microspheres have a higher specific surface area (19.658 m2·g−1 vs 31.335 m2·g−1) and better safety performance (6 J vs 50 J). The ignition experiment results show that the hollow structure significantly enhances the combustion performance of HNS (305 ms vs 92 ms), improving the energy release efficiency. This preparation method is simple, efficient, and easy to scale up, providing a more universal and environmentally-friendly technical approach for the multi-structural design of energetic microspheres.

Investigation on dynamic response of thin spherical shells impacted by flat-nose projectile based on a novel damage model

Thin-shell structures are widely used in various engineering applications. It is essential to investigate the impact resistance of thin-shell structures, to provide theoretical support for engineering applications. Numerous impact tests have been conducted on thin spherical shells using ballistic guns. The effects of the impact velocity and shell thickness on the deformation and fracture of thin spherical shells are summarized. Moreover, a novel damage model based on statistic damage mechanics is proposed to better predict dynamic responses of thin shells impacted by projectiles. Considering that fracture surfaces are formed by void evolution and are affected by the stress states, the damage level is defined as the ratio of the statistical cross-sectional area of the voids to the cross-sectional area of the representative elements. Utilizing statistical methods, the incorporation of continuous void nucleation, ellipsoidal void growth, and the acceleration of dynamic void evolution are introduced into the novel damage model. Subsequently, numerical investigations of the dynamic response of spherical shells under impact are conducted based on the proposed damage model. The numerical results are consistent with the experimental results in terms of the depression deformations and strain signals. The effects of shell thickness and double-layer structures on the dynamic response of spherical shells are investigated via numerical simulations considering the novel damage model in detail. The results demonstrate that the proposed model can accurately predict the dynamic response of spherical shells impacted by flat-nose projectiles, thus serving as a valuable reference for engineering design.

Enhancing mechanical properties and density of WC-Co with pressureless sintering via shell structure binder jetting additive manufacturing

The binder jetting (BJT) additive manufacturing (AM) process is suitable for producing complex WC-Co cemented carbide parts. To achieve near-full-density in the final parts, the hot isostatic pressing (HIP) sintering process is typically employed to enhance densification. However, HIP sintering requires high equipment specifications and is relatively more costly compared to conventional pressureless sintering. To improve the density of WC-Co parts printed by BJT AM under the pressureless sintering environment, the shell structure printing method was used in this study. The shell structure printing only jets binder to the model's outer profile, creating a shell that encapsulates the central powder, mitigates binder pyrolysis and residual effects on particle densification, and enhances post-sintering density. In this work, the effect of shell thickness, binder type, and printing layer thickness on the density and mechanical properties of the WC-12Co parts under pressureless sintering conditions were investigated. The results show that the density and mechanical properties of the WC-12Co parts significantly improved with the decreasing shell thickness. Specifically, the WC-12Co printed using shell structure achieves a relative density of over 98% and a transverse rupture strength (TRS) of 1954 MPa after pressureless sintering, a result comparable to BJT printed samples treated with HIP sintering. Moreover, the results indicate using a binder with lower residual carbon content and smaller printing layer thickness has a more positive effect on improving density and mechanical strength when employing the shell structure printing method. Microstructure morphology and phase analysis results indicate that the shell structure printing method does not affect the growth of WC grains in the shell and center regions, nor does it influence its phase composition. The shell structure printing method offers a new approach to the manufacturing of near-full-dense WC-Co materials using the BJT process.

Experimental Investigation on Effect of Shell Thickness and Infill Density on Mechanical Properties of Polymer 3D Printing Process (MEX)

Abstract: A cutting-edge advancement in advanced manufacturing is the use of a revolutionary technique called threedimensional printing. The primary objective of three-dimensional printing, in comparison to traditional manufacturing methods, is to efficiently create intricate geometries in a shorter timeframe while maintaining the desired characteristics of the object. This task cannot be achieved by conventional production methods. In order to produce any component, it is vital for us to get the necessary material and then secure the power supply. In the process of three-dimensional printing, a diverse range of materials, such as polymers, metal powders, ceramic powder, and others, are used. Several variables contribute to the situation, including the amount of material used. In this specific instance, we are striving to maximize the use of material while maintaining the product's quality prior to printing. The criteria that have the most significant influence on the quantity of material required and the printing time are mostly determined by several key features. This category encompasses several factors, like layer height, infill density, print speed, shell thickness, and more. Furthermore, the line width or layer width is an additional criterion that significantly affects the amount of material used. Expanding the line width will lead to a higher expenditure of material, while reducing the layer width will result in a reduction in material consumption. The breadth of a layer is directly proportional to the amount of material used. The width of this line directly affects the duration of the printing process, the strength of the bond, and the quality of the completed product's surface. Significant changes in the line width could potentially lead to a print failure. Our objective is to enhance the efficiency of material use and printing time by adjusting the line width while maintaining the same layer height and applying various infill densities. This will allow us to maintain a consistent layer height. This research unequivocally proves that a model with 100% infill has no impact on the amount of material required. However, it does result in an increased printing time as the shell thickness decreases, printing time increases. The discoveries made in this study clearly demonstrate this. However, the layer width exhibits varying behavior depending on the kind of infill utilized. Decreasing the degree of infill not only reduces the amount of material used, but also increases the printing time.

Collapse of concrete target subjected to embedded explosion of shelled explosive

This paper broadens previous research concerning spalling damage in concrete structures under buried explosions, by additionally examining the effects of shell thickness and shell head length of the warhead experimentally and numerically. In the experiment, concrete targets were subjected to the embedded explosion of cylindrical shelled explosives with different charge masses, shell thicknesses, and shell head lengths. The results reveal that thicker charge shells and longer shell heads decrease the surface area and the depth of spalling damage on the rear surface of concrete structures. In addition, to investigate the damage mechanism and predict the critical collapse thickness (CCT), two- and three-dimensional finite-element models were developed and correlated well with the experimental results. Parametric analyses are also applied to examine how the embedded depth, length-to-diameter ratio, shell thickness, and shell head length affect the CCT for a buried explosion. Finally, an empirical formula is proposed to estimate the CCT based on these factors.

Magnetic interaction effects in Fe3O4@CoFe2O4 core/shell nanoparticles

The magnetic properties of core/shell nanoparticles (NPs) depend on the various parameters, including the magnetic interactions, but these effects have not been well studied. Here, we systematically investigated the structure and magnetic properties of Fe3O4@CoFe2O4 core/shell NPs. X-ray diffraction (XRD), scanning electron microscopy (SEM), and scanning transmission electron microscopy (STEM) confirmed the formation of Fe3O4@CoFe2O4 core/shell NPs. Magnetic measurements of the core/shell NPs were performed on both dried-pressed and well-dispersed in wax states. For the dried-pressed NPs, we found that the temperature-dependent magnetization curves of core/shell NPs vary significantly compared to that of core NPs due to spin interactions at the core/shell interface. Besides, the hysteresis loops of the core/shell NPs at 10 K are constricted, probably due to the interparticle interaction. For the core/shell NPs dispersed in wax, the hysteresis loops were smooth at all temperatures between 10 and 300 K due to the attenuated interparticle interaction. The high HC of 9.14 kOe (at 10 K) of the dispersed NPs is twice larger than that of the dried-pressed powders (4.23 kOe). Our study provides new insights into the effects of shell thickness and interparticle interaction on the magnetic properties of Fe3O4@CoFe2O4 core/shell NPs.

Effect of shell thickness on mechanical behavior of Al/Ti core-shell nanowires during three-point bending and unloading

The molecular dynamics models of Al and Al/Ti core-shell nanowires (NWs) are established using the large-scale atomic/molecular massively parallel simulator (LAMMPS) to simulate the loading and unloading of the three-point bending of NWs and to investigate the effect of Ti shell thickness on the mechanical behavior of core-shell NWs during loading and unloading. The results show that the Ti shell thickness considerably affects the mechanical properties of the NWs during the bending process. As the shell thickness of the NWs increases from 0 Å to 10 and 20 Å, their Young's moduli and yield strength first decreases and then increases; this is attributed to the unique evolution of the core-shell structure during the bending process. When the shell thickness is 0 Å, the yielding mechanism of the Al NWs involves the slip of the face-centered cubic (FCC) lattice plane to generate the hexagonal close-packed (HCP) stacking fault. During the subsequent plastic deformation, the FCC lattice plane continues to slip, resulting in the generation and annihilation of Shockley dislocations and HCP stacking faults. Finally, the Al NWs become completely amorphous at the cross section at the midpoint. The yielding mechanism of core-shell NWs involves the plastic deformation of the Ti shell at the bottom of the NW, followed by the continuous outward expansion of the plastic deformation region with increasing loading; this leads to the formation of a fan-shaped region at the bottom of the NW. Finally, the NWs are divided into different components according to their structure and atomic energy, and the driving force for each component during NW unloading is determined. Moreover, the strengthening effect of the shell thickness on the recovery performance of the NWs is investigated. The results show that Body Al provides the main driving force for the shape recovery of Al NW during the unloading process, and Surface Ti and Body Ti provide the main driving force for the shape recovery of the core-shell NWs. Larger the shell thickness, stronger the NW recovery performance during unloading. This study may facilitate the understanding of the unique mechanical behavior of the core-shell NWs.

Microencapsulation of a salt hydrate phase change material by resorcinol formaldehyde through electrohydrodynamic disintegration of coaxially layered filament

Uniform microcapsules of size on the order of 100 nm with CaCl2.6H2O at the core and resorcinol formaldehyde as the shell was made by electro hydrodynamically disintegrating the coaxially layered filament. The shell thickness was varied by changing the flow ratio. The effect of shell thickness on the phase change temperature and the heat flow at its peak value during the DSC scan were reviewed to ascertain the extent of thermal equilibration, and the fraction of PCM melting at the peak value of heat flow. The integrity of the shell was evaluated by sustained dipping in deionized water for a month. The DSC scan was repeated after several heating-cooling cycles to understand the cycle life of the microcapsules.

Influence of Core Type and Shell Thickness on Avian-Inspired Structural Colors Produced from Melanin Nanoparticle Assemblies.

Hollow melanosomes found in iridescent bird feathers, including violet-backed starlings and wild turkeys, enable the generation of diverse structural colors. It has been postulated that the high refractive index (RI) contrast between melanin (1.74) and air (1.0) results in brighter and more saturated colors. This has led to several studies that have synthesized hollow synthetic melanin nanoparticles and fabricated colloidal nanostructures to produce synthetic structural colors. However, these studies use hollow nanoparticles with thin shells (<20 nm), even though shell thicknesses as high as 100 nm have been observed in natural melanosomes. Here, we combine experimental and computational approaches to examine the influence of the varying polydopamine (PDA, synthetic melanin) shell thickness (0-100 nm) and core material on structural colors. Experimentally, a concomitant change in overall particle size and RI contrast makes it difficult to interpret the effect of a hollow or solid core on color. Thus, we utilize finite-difference time-domain (FDTD) simulations to uncover the effect of shell thickness and core on structural colors. Our FDTD results highlight that hollow particles with thin shells have substantially higher saturation than same-sized solid and core-shell particles. These results would benefit a wide range of applications including paints, coatings, and cosmetics.

Efficient Photoelectrochemical Hydrogen Generation Using Eco-Friendly "Giant" InP/ZnSe Core/Shell Quantum Dots.

InP quantum dots (QDs) are promising building blocks for use in solar technologies because of their low intrinsic toxicity, narrow bandgap, large absorption coefficient, and low-cost solution synthesis. However, the high surface trap density of InP QDs reduces their energy conversion efficiency and degrades their long-term stability. Encapsulating InP QDs into a wider bandgap shell is desirable to eliminate surface traps and improve optoelectronic properties. Here, we report the synthesis of "giant" InP/ZnSe core/shell QDs with tunable ZnSe shell thickness to investigate the effect of the shell thickness on the optoelectronic properties and the photoelectrochemical (PEC) performance for hydrogen generation. The optical results demonstrate that ZnSe shell growth (0.9-2.8 nm) facilitates the delocalization of electrons and holes into the shell region. The ZnSe shell simultaneously acts as a passivation layer to protect the surface of InP QDs and as a spatial tunneling barrier to extract photoexcited electrons and holes. Thus, engineering the ZnSe shell thickness is crucial for the photoexcited electrons and hole transfer dynamics to tune the optoelectronic properties of "giant" InP/ZnSe core/shell QDs. We obtained an outstanding photocurrent density of 6.2 mA cm-1 for an optimal ZnSe shell thickness of 1.6 nm, which is 288% higher than the values achieved from bare InP QD-based PEC cells. Understanding the effect of shell thickness on surface passivation and carrier dynamics offers fundamental insights into the suitable design and realization of eco-friendly InP-based "giant" core/shell QDs toward improving device performance.

Influence of shell thickness on the thermal stability and melting-like behavior of Al@Fe core–shell nanoparticles from atomistic simulations: a structural and dynamic description

Core–shell nanoparticles (CSNPs) are a class of functional materials that have received important attention nowadays due to their adjustable properties by a controlled tuning of the core or shell. Understanding the thermal response and structural properties of these CSNPs is relevant to carrying out an analysis regarding their synthesis and application at the nanoscale. The present work is aimed to investigate the shell thickness effect on thermal stability and melting behavior of Al@Fe CSNPs by using molecular dynamics simulations. The results are discussed considering the influence of the Fe shell on the Al nanoparticle and analyzing the effect of different shell thicknesses in Al@Fe CSNPs. In general, calorific curves show a smooth energy decline for temperatures greater than room temperature for different shell thicknesses and sizes, corresponding to the inward and outward atomic movement of Al and Fe atoms, respectively, that produce a mixed Al–Fe nanoalloy. Here, the thermal stability of the Al@Fe nanoparticle is gradually lost passing to a liquid-Al@solid-Fe configuration and reaching a mixed Al–Fe state by an exothermic mechanism. Combining quantities of the atomic diffusion and structural identification, a stepped structural transition of the system is subsequently observed, where the melting-like point was estimated. Furthermore, it is observed that the Al@Fe CSNPs with greater stability are obtained with a thick shell and a large size. The ability to control shell thickness and vary the size opens up attractive opportunities to synthesize a broad range of new materials with tunable catalytic properties.

On the theory of multiple encapsulated microbubbles interaction: Effect of lipid shell thickness

Encapsulated microbubbles are empty, micrometer-sized, spherical bubbles, typically micron which are used in many applications as lipid-shells in soft tissues. Here, this paper proposes the theoretical and mathematical modelling of the interaction of lipid-encapsulated microbubbles in soft tissues, as well as an examination of the effect of the thickness of the lipid-encapsulated microbubbles envelope located between the inner and outer radius of the microbubble. The mathematical models are formulated for a single encapsulated microbubble and interacting microbubbles in lipid shells. The first models are placed while considering the effect of shell-thickness on microbubbles in soft tissues. The second one has weak shell-thickness layers on it. In encapsulated single microbubbles and interacting microbubbles, the modified Church equations of shell-thickness microbubbles are formulated and solved analytically. Under the effect of layer thickness, the radii of outer microbubble dynamics are larger than those of inner radii of encapsulated microbubble dynamics, and the radii of bubbles with weak shell thickness in soft tissue are smaller. The clusterization of microbubbles reduces the process of microbubble growth, and interparticle interaction enhances it. In addition, the approximate value of the inner and outer microbubble radius was calculated at the different time intervals when the thickness of the shell, δ=0,15,150,250,350nm. Moreover, the growth process has been studied in different materials such as polymers, albumin, lipids, and liquids, and it turns out the results are consistent with previous works.

Exploring the Enhancement of Exchange Bias in Innovative Core/Shell/Shell Structures: Synthesis and Magnetic Properties of Co-Oxide/Co and Co-Oxide/Co/Co-Oxide Inverted Nanostructures.

In this study, we investigate the enhancement of exchange bias in core/shell/shell structures by synthesizing single inverted core/shell (Co-oxide/Co) and core/shell/shell (Co-oxide/Co/Co-oxide) nanostructures through a two-step reduction and oxidation method. We evaluate the magnetic properties of the structures and study the effect of shell thickness on the exchange bias by synthesizing various shell thicknesses of Co-oxide/Co/Co-oxide nanostructures. The extra exchange coupling formed at the shell-shell interface in the core/shell/shell structure leads to a remarkable increase in the coercivity and the strength of the exchange bias by three and four orders, respectively. The strongest exchange bias is achieved for the sample comprising the thinnest outer Co-oxide shell. Despite the general declining trend of the exchange bias with Co-oxide shell thickness, we also observe a nonmonotonic behavior in which the exchange bias oscillates slightly as the shell thickness increases. This phenomenon is ascribed to the dependence of the antiferromagnetic outer shell thickness variation at the expense of the simultaneous opposite variation in the ferromagnetic inner shell.

Simulation of the solidification organization of X15CrNiSi20-12 alloy castings during investment casting based on the CAFE model

In this work, the CAFE (Cellular Automata Finite Element) model was used to simulate the grain growth of X15CrNiSi20-12 austenitic stainless steel during the investment casting process, and the effects of shell thickness, shell temperature, casting temperature, and cooling rate on the solidification organization were investigated by orthogonal tests. The results show that the cooling method has an important effect on the formation of equiaxed crystals. However, the shell temperature, shell thickness, and casting temperature have a smaller effect on the formation of equiaxed crystals. A more equiaxed fine grain structure can be obtained by using a shell thickness of 7 mm, shell temperature of 1143.15 K, casting temperature of 1913.15 K, and water-cooling conditions. In addition, a decrease in the shell thickness, shell temperature, and casting temperature can lead to an increase in the grain size, while an increase in the cooling rate will lead to smaller grain size and increase the number of equiaxed fine crystals, thus improving the mechanical properties of the material.

Static and Dynamic Analysis of Re-Entry Vehicle Nose Structures Made of Different Functionally Graded Materials

High-speed aerospace applications, such as re-entry vehicles, mostly involve thin-walled structural components with a high strength-to-weight ratio and high-temperature resistant. The present novel work comprises the structural and thermal analysis of re-entry vehicle nose structures made of four functionally graded materials (FGM). Four FGM shell structures made of aluminum/silicon carbide, aluminum/aluminum oxide, Ti-6Al-4V/silicon carbide and Ti-6Al-4V/aluminum oxide have been considered for the re-entry vehicle nose. The effect of various thermal environments, as well as the linear temperature rise from metal-rich to ceramic-rich on critical buckling temperature and natural frequency have been studied. The critical buckling temperature, as well as the natural frequency of the large, thin re-entry vehicle nose structures, decrease with an increase in a uniform thermal environment, as well as linear temperature rise. The effect of shell thickness on buckling and dynamic characteristics of an FGM shell is also studied, suiting the nose of the re-entry vehicle under various linear temperature rises. The critical buckling temperature and natural frequency are quantified for several cases, and it was observed that they are significantly influenced by the shell thickness. Thus, the research intends to determine the thickness required for such thin and large shells to withstand in the re-entry thermal conditions.

Au@Cu2O core@shell nanocrystals as sustainable catalysts for efficient hydrogen production from ammonia borane

The use of Au@Cu2O core@shell nanocrystals as sustainable catalysts for efficient hydrogen (H2) production from ammonia borane (AB) is demonstrated. By combining the attributes associated with core@shell structural features and electronic interactions, Au@Cu2O exhibited remarkable performance toward AB hydrolysis. The effect of shell thickness on H2 production performance was systematically investigated. Results showed that H2 production rate increased monotonically with shell thickness, while degree of dehydrogenation of AB was subject to optimization by shell thickness. A maximal 3.0 equivalents of H2 production can be achieved by Au@Cu2O with an optimal Cu2O shell thickness. The H2 produced from AB hydrolysis on Au@Cu2O was introduced to power a fuel cell for lightening light emitting diodes. The findings from the work not only enrich the family of metal/metal oxide composite catalysts for AB hydrolysis, but also deepen the fundamental understanding of implications of core@shell structural features and electronic interactions in dehydrogenation of AB.

Large-amplitude vibrations of thick cantilevered circular cylindrical shells containing still fluid

In the present study, for the first time, thick and moderately thick shells with clamped-free boundary conditions are modeled according to the third-order shear theory with thickness stretch. Then using Lagrange relations, the governing differential equations of the system in terms of shell–fluid​ interaction are derived and the solution method of the equations is also presented. The linear and nonlinear free vibration of cantilevered circular cylindrical shell containing quiescent fluid is investigated and the effects of shell thickness, length and fluid relative height are studied. In linear free vibration analysis, it was observed that the presence of fluid reduces the fundamental frequency of the system and the number of circumferential waves of the fundamental mode, especially in the thin shell. Also, increasing the height of the fluid, strengthens the decreasing fundamental frequency of the system. In nonlinear analysis, it was found that the presence of fluid, mainly weakens the nonlinear behavior in the thin/thick shell. Also, it was found that with increasing shell thickness, the effect of fluid on the nonlinear behavior of the system decreases, and the shell behavior is more dominant in the system. In addition, the presence of fluid has mainly reduced the peripheral contraction of the shell caused by the large amplitude circumferential waves, so that peripheral contraction approaches zero in the fully filled thin shell.

Tunable SERS activity of Ag@Fe3O4 core-shell nanoparticles: Effect of shell thickness on the sensing performance

Surface enhanced Raman spectroscopy (SERS) with enormous advantages has emerged as a powerful tool for both highly sensitive structural detection of analytes and imaging applications. Among various multifunctional nanomaterials for SERS substrate, nanocomposites of magnetic and plasmonic materials deliver both SERS effect and magnetic manipulation capacity, and thereby, have practical advantages for trace analysis in a broad range of fields. Herein, we investigate the SERS performance of different-sized Ag@Fe3O4 core-shell nanoparticles (NPs) obtained by controlling the Fe precursor concentration in a facile one-pot solvothermal synthesis method. The surface morphology, composition, structure, optical and magnetic properties are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-Vis spectroscopy, and electrochemical techniques. The small shell thickness and high shell porosity of the smallest NPs significantly improve the mass diffusion and therefore SERS performance, making it an ideal substrate for highly sensitive detection of methylene blue (MB) and crystal violet (CV) organic pollutants. Quantitative SERS measurements using the Ag@Fe3O4 NPs are successfully demonstrated with MB as probe analytes. Due to the presence of a porous Fe3O4 shell, the Ag@Fe3O4 NPs showed outstanding SERS sensing performance with a linear concentration range from 10−7 to 10−10 M and the limit of detection (LOD) of 3 × 10−10 M. Moreover, the Ag@Fe3O4 core-shell nanocomposite exhibits high reproducibility and reliability and can be a promising candidate for SERS sensing systems.

Magnetocaloric Effect and Magnetic Properties of Core-Shell Ferrimagnetic Spherical Nanoparticle: A Monte Carlo Study

In this work, a Monte Carlo simulation based on the Metropolis algorithm has been applied to investigate the magnetic properties and the magnetocaloric effect (MCE) of a ferrimagnetic nanoparticle, with a core-shell structure. The magnetic properties of ferrimagnetic nanoparticle were shown, the influences of the interface and shell couplings on both compensation and critical temperatures were examined and the effect of shell thickness was elucidated. The MCE was obtained by calculating the magnetic entropy change (−ΔS m ) using the Maxwell relation. The shell coupling J sh , the antiferromagnetic interface coupling J int , and the ferromagnetic shell thickness R sh of the nanoparticle impact the MCE. Our findings could pave the way for enhancement of the MCE of the present system, controlled by the variation of the magnetic interactions and external magnetic field.

DEM Analysis of the Mechanical Role of Backfill of Jointed Masonry Fan Vaults: Results of Virtual Experiments

ABSTRACT Fan vaulting is a magnificent innovation of English Gothic architecture that has been admired since the 14th century. However, how this breathtaking structural form works under mechanical loads (like self-weight and support displacement) is still poorly understood. One of the many interesting open issues is the mechanical role of backfill. This paper studies how the existence and the height of the backfill affect the horizontal and vertical reactions expressed on the fan vault by the tas-de-charge and the lateral longitudinal wall. In order to analyse this, discrete element models are prepared for small-span and large-span fan vaults constructed of jointed masonry, with Voronoi-shaped elements forming the backfill, and then the structures are submitted to self-weight and gradually increasing quasi-static outwards support displacements. The ratio of horizontal versus vertical reactions is applied to quantify how stable these vaults are in the case of different levels of backfill. The effect of shell thickness is also addressed.