X-ray micro-CT Research Articles

The tracheal system of the Common Wasp (Vespula vulgaris) – A micro-CT study

X-ray micro-CT has been used to study the tracheal system of Pre and Post hibernation Queen wasps (Vespula vulgaris) and their workers. We have compared our findings in wasps with Snodgrass’s description of the tracheal system of the honeybee as characterised by anatomical dissection. Our images, whilst broadly similar, identify the tracheal system as being considerably more complex than previously suggested. One of the 30 wasps imaged had a markedly different, previously undescribed tracheal system. Since completing this study, a large micro-CT study from the American Museum of Natural History (AMNH) has been published. This used different software (Slicer) and analysed 16bit digital data. We have compared our methods with that described in the AMNH publication, adopted their suggested nomenclature and have made recommendations for future studies.

A numerical and experimental meso-mechanical approach for the prediction of creep of concrete

A two-step meso-scale approach is proposed to predict the creep of concrete. The approach requires the creep of cement paste as input, combined with meso-scale analysis of digital images of mortar and concrete that are obtained from X-ray microCT scanning. For the generation of input data and validation of the model, a comprehensive series of creep tests are carried out on cement paste, mortar and concrete cylinders for a period of 6 months. The model uses a robust and automatic quadtree decomposition algorithm to convert digital images into meshes, which are then solved using the scaled boundary finite element method based on a continuum approach. The proposed model is separately validated on the mortar and the concrete scale respectively. In the first step, knowing the creep response of cement paste from the tests, the creep of mortar is simulated by considering it as a two-phase composite comprising of viscoelastic cement paste and elastic fine aggregates. Validation of the predicted response is obtained through comparison with the measured creep response of mortar. A similar procedure is then applied for concrete which is treated as a two-phase composite of viscoelastic mortar and elastic coarse aggregates. Finally, by accounting for damage of the mortar phase, it is demonstrated that the nonlinear creep of concrete observed at high stress levels can be attributed to material damage developed at the meso-scale.

Ballistic performance of additive manufacturing 316l stainless steel projectiles based on topology optimization method

Material and structure made by additive manufacturing (AM) have received much attention lately due to their flexibility and ability to customize complex structures. This study first implements multiple objective topology optimization simulations based on a projectile perforation model, and a new topologic projectile is obtained. Then two types of 316L stainless steel projectiles (the solid and the topology) are printed in a selective laser melt (SLM) machine to evaluate the penetration performance of the projectiles by the ballistic test. The experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles, indicating the better penetration ability of the topologic projectiles. Finally, microscopic studies (scanning electron microscope and X-ray micro-CT) are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic projectiles. An explicit dynamics simulation was also performed, and the failure locations of the residual topologic projectiles were in good agreement with the experimental results, which can better guide the design of new projectiles combining AM and topology optimization in the future.

A morphological study and the variability in the number of infraorbital foramina in the African green monkey (Grivet) (Chlorocebus aethiops) using microcomputed tomography.

Knowledge of the nonhuman primate morphology and anatomy related to craniofacial mechanoreception is essential for a fundamental understanding of the incidents that have occurred during the evolution of craniofacial features. The present study focuses on the variability in the number of infraorbital foramina and associated anatomical structures such as the infraorbital canal (IOC) and the infraorbital groove (IOG), as they are considered to play an important role in the behavioral ecology of these animals. A total of 19 skulls of Chlorocebus aethiops were analyzed. The number of infraorbital foramina was assessed macroscopically using a magnifying glass and a small diameter probe. Three dimensional(3D) projections and morphometric analysis of the infraorbital foramina, IOCs, and IOGs were performed using microcomputed tomography (micro-CT) for two skulls that represent one of the most common morphological types. Regardless of sex and body side, the most common morphological type observed in the studied species is the presence of three infraorbital foramina. The IOC takes a funnel or pinched shape. 3D projections were made to assess the course of the infraorbital vascular and nerve bundles in selected individuals. The results indicate a high morphological diversity within the species, although there appears to be a consistent distribution pattern of infraorbital neurovascular bundles in species of the Cercopithecidae family. The use of X-ray micro-CT allowed 3D visualization of the maxillary region to determine the variability of the infraorbital foramina and to track the division of the infraorbital neurovascular bundle in the case of the most common macroscopic expression of the number of the infraorbital foramen in C. aethiops, as well as the morphometric of the IOCs and IOGs which are related to mechanoreception of the primate's snout.

Thermodynamic Formation and Three-dimensional Characterization of MnS–MgAl<sub>2</sub>O<sub>4</sub> Composite Inclusions in Steel

The distribution and morphology of inclusions in steel have an important effect on the quality of steel. It has been proved that the oxide inclusions can be modified into small and dispersed spinel inclusions by adding proper amount of Mg in steel. The MnS-MgAl2O4 composite inclusions are formed with the core of MgAl2O4 inclusions during the solidification process of molten steel, which has deforming ability and can improve the properties of materials steel. However, the investigation of the control of the composite inclusions is limited by the lack of understanding structure of the inclusions. In this study, the Mg treated steel samples were prepared by induction furnace in this study. In the experiment, SEM-EDS was used to characterize the samples, and thermodynamic calculations were used to describe the evolution mechanism of inclusions and MnS-MgAl2O4 composite inclusions formed in steel samples with different Mg contents. The atomic mismatch calculated between MnS and MgAl2O4 proves that they can nucleate effectively. The three-dimensional (3D) morphology of the composite inclusion of MnS-MgAl2O4 in steel samples were observed by using the X-ray Micro-CT in the beamline of BL16U2 at Shanghai Synchrotron Radiation Facility (SSRF). It is proved that MnS and MgAl2O4 phases exist in the form of co-associated, which is valuable for the control of composite inclusions in steel. The current work provide a powerful method to analyze the detailed structure of the composite inclusions in the steel.

Experimental investigation of the air blast performance of hybrid composite skinned sandwich panels with X-ray micro-CT damage assessment

This research investigates the performance of interlaminar hybrid composites as the skins of composite sandwich panels under blast loading with the aim of promoting delamination between dissimilar plies for energy absorption. The deformation of the composite panels was captured using high-speed digital image correlation (DIC). High-speed full-field DIC enables failure to be captured at the moment it occurs across the entire panel. X-ray micro-CT imaging was used to assess the post-blast damage sustained by particular areas of interest from each panel, which were selected based on DIC results. The combination of full-field DIC and detailed X-ray micro-CT scanning enabled a unique comparison of both the global and localised blast resilience of hybrid and conventional composite sandwich panels to be performed.Following a single blast load, the extent of damage to the Hybrid-3B skinned sandwich panel was found to lie between that of GFRP and CFRP skinned sandwich panels. X-ray micro-CT scanning of these panels reveals that there is no continuous damage path through the skin thickness of Hybrid-3B, whereas the GFRP and CFRP panels sustain damage in every ply.Following repeat blast loading, the Hybrid-4 skinned sandwich panel suffered from a front skin crack spanning the length of the panel. Post-blast compressive strength testing reveals that this skin crack and resulting core crack acted as a stress relief, limiting the damage sustained elsewhere in the panel.It was concluded that Hybrid-3B results in a good trade-off between strength and stiffness and is advantageous over conventional CFRP and GFRP panels under a single blast load. Under repeated loading Hybrid-4 offers advantages over Hybrid-3B. Finally, the design of the support structure can significantly aid in blast resilience, and, a holistic approach considering both panels and support should be taken when designing for blast resilience.

X-ray micro-CT based computation of effective diffusivity of metabolic gases in tomato fruit

The effective diffusivity is a key engineering property of fruit that affects transport of metabolic gases and, hence, ripening. It strongly depends on the microstructure of the fruit. In bulky fruit such as tomato, porosity and pore structure differ between tissues and change during maturation and ripening. Knowledge of the relationship between gas diffusivity and microstructure of tomato will aid management and control of postharvest operations. By using mathematical models of mass transport that incorporate the 3-D microscopic tissue geometry obtained from micro-computed tomography (μ-CT), the relationship between microstructural features and gas diffusivity may be computed in a direct way. In this study, a previously validated pore-scale network model (PNM) was used to simulate the effective gas diffusivity of O2, CO2 and ethylene for five types of tomato fruit tissues (i.e., outer mesocarp, inner mesocarp, septa, placenta and columella) at different maturation and ripeness stages. The effective gas diffusivity of the placenta and columella was large during the entire ripening process as these tissues contained more interconnected open intercellular spaces. The effective diffusivity of the inner mesocarp increased with increasing porosity during ripening while the microstructural changes of the outer mesocarp lagged compared to those of the inner mesocarp region, resulting in a delayed increase of the effective gas diffusivity with ripening. Regression models between the effective diffusivity of O2, CO2 and ethylene as a function of porosity, open porosity or tortuosity were established. This study provides a quantitative basis for further gas exchange modeling in intact tomato fruit to predict their ripening process.

Multi-stage image registration based on list-mode proton radiographies for small animal proton irradiation: A simulation study

We present a multi-stage and multi-resolution deformable image registration framework for image-guidance at a small animal proton irradiation platform. The framework is based on list-mode proton radiographies acquired at different angles, which are used to deform a 3D treatment planning CT relying on normalized mutual information (NMI) or root mean square error (RMSE) in the projection domain.We utilized a mouse X-ray micro-CT expressed in relative stopping power (RSP), and obtained Monte Carlo simulations of proton images in list-mode for three different treatment sites (brain, head and neck, lung). Rigid transformations and controlled artificial deformation were applied to mimic position misalignments, weight loss and breathing changes. Results were evaluated based on the residual RMSE of RSP in the image domain including the comparison of extracted local features, i.e. between the reference micro-CT and the one transformed taking into account the calculated deformation.The residual RMSE of the RSP showed that the accuracy of the registration framework is promising for compensating rigid (>97% accuracy) and non-rigid (∼95% accuracy) transformations with respect to a conventional 3D-3D registration. Results showed that the registration accuracy is degraded when considering the realistic detector performance and NMI as a metric, whereas the RMSE in projection domain is rather insensitive.This work demonstrates the pre-clinical feasibility of the registration framework on different treatment sites and its use for small animal imaging with a realistic detector. Further computational optimization of the framework is required to enable the use of this tool for online estimation of the deformation.

Viscoelastic characterisation of additively manufactured composites with nylon matrix: Effects of type and orientation of fibres

This study investigates the viscoelastic performance of additively manufactured (AM) nylon and nylon-matrix composites reinforced with short and continuous fibres with three different fibre orientations: longitudinal, transverse, and quasi-isotropic. Dynamic mechanical analysis under a frequency sweep of 1–100 Hz along with tensile tests used to determine the Young's modulus and X-ray micro-CT for evaluation of microstructural porosity were employed to fully describe the viscoelastic behaviour of the composites. Generally, the addition of fibres increased the storage modulus of most composites. The composites revealed increased porosity and fractography using a scanning electron microscope on the tensile specimens demonstrated poor fibre-matrix bonding. These factors, along with the fibre orientation, had a complex effect on the loss modulus of the composite structures. Overall, the addition of fibres reduced the damping factor of the composite specimens compared to pure AM nylon samples. The quantified parameters, including those of the Prony series, can be used in numerical simulations supporting the design and optimisation of AM components.

Fractal Analysis of Coal Pore Structure Based on Computed Tomography and Fluid Intrusions

As a non-homogeneous porous medium, the structural complexity of coal directly affects pore structure parameters and gas percolation characteristics, which in turn determine the fractal dimension of coal samples. Among them, the specific surface area of coal largely determines the complexity of the pore structure and is closely related to coal and gas protrusion hazards. To investigate the relationship between the fractal dimension of coal and its specific surface area, we analyzed the pore structure of coal samples using low-temperature nitrogen adsorption, the mercury pressure method, and X-ray micro-computed tomography (CT) experiments. By calculating the fractal dimension of coal and reconstructing it in three dimensions, the morphological characteristics and distribution of pores can be described qualitatively and quantitatively. The fractal dimension of coal samples was found to increase exponentially with the specific surface area based on measurements of large pores and mesopores via the mercury pressure method and those of small pores and micropores using the nitrogen adsorption method. X-ray micro-CT experiments revealed that the fractal dimension of large pores (i.e., >2 μm) conformed to this pattern.

Mechanical responses of buoyant bio-inspired foamed concrete structures

This work proposes a new type of lightweight cellular foamed concrete (FC) inspired by natural cellular structures with controllable mechanical properties for different prefabricated engineering applications. The 3D printed formworks are inspired by the lattice structure and triply periodic minimal surface (TPMS) architectures, including gyroid and primitive prototypes. These 3D printed sacrificial thermoplastic Polylactic Acid (PLA) formworks were then infiltrated with two types of foamed concrete with different densities of 600 kg/m3 and 800 kg/m3 and subjected to uniaxial compressive loadings. Furthermore, the X-ray computed tomography (CT) scan was conducted on the prefabricated structures to further observe the PLA-foamed concrete contact region and to investigate the air void characteristics. Numerical simulation was employed for further investigation on the structural performance and failure mechanism of three bio-inspired structures (TPMS-Primitive, -Gyroid, and strut-based lattice). By both numerical and experimental investigations, the gyroid cellular structure yields the highest compressive capacity, followed by the primitive and lattice structures, respectively. Furthermore, based on the X-ray micro-CT scan, the bio-inspired architecture of the moulds showed a significant effect on the size and distribution of air voids, which highly influenced the compressive strength of the infiltrated foamed concrete.

Embodied latch mechanism of the mandible to power at ultra-high speed in the trap-jaw ant Odontomachus kuroiwae.

Rapid movements of limbs and appendages, faster than those produced by simple muscle contraction alone, are generated through mechanical networks consisting of springs and latches. The latch plays a central role in these spring-loaded mechanisms, but the structural details of the latch are not always known. The mandibles of the trap-jaw ant Odontomachus kuroiwae closes the mandible extremely quickly to capture prey or to perform mandible-powered defensive jumps to avoid potential threats. The jump is mediated by a mechanical spring and latch system embodied in the mandible. An ant can strike the tip of the mandible onto the surface of an obstacle (prey, predator or ground) in order to bounce its body away from potential threats. The angular velocity of the closing mandible was 2.3×104rads-1 (1.3×106degs-1). Latching of the joint is a key mechanism to aid the storage of energy required to power the ballistic movements of the mandibles. We have identified the fine structure of two latch systems on the mandible forming a 'ball joint' using an X-ray micro-computational tomography system (X-ray micro-CT) and X-ray live imaging with a synchrotron. Here, we describe the surface of the inner section of the socket and a projection on the lip of the ball. The X-ray live imaging and movements of the 3D model show that the ball with a detent ridge slipped into a socket and over the socket ridge before snapping back at the groove edge. Our results give insight into the complex spring-latch systems that underpin ultra-fast movements in biological systems.

Finite-Element Modelling Based on Optical Coherence Tomography and Corresponding X-ray MicroCT Data for Three Human Middle Ears.

Optical coherence tomography (OCT) is an emerging imaging modality which is non-invasive, can be employed in vivo, and can record both anatomy and vibrations. The purpose here is to explore the application of finite-element (FE) modelling to OCT data. We recorded vibrations for three human cadaver middle ears using OCT. We also have X-ray microCT images from the same ears. Three FE models were built based on geometries obtained from the microCT images. The material properties and boundary conditions of the models were obtained from previously reported studies. Tympanic-membrane (TM) vibration patterns were computed for the three models and compared with the patterns measured using OCT. Frequency responses were also computed for all three models for several locations in the middle ear and compared with the OCT displacements and with the literature. The three models were compared with each other in terms of geometry and function. Parameter sensitivity analyses were done and the results were compared among the models and with the literature. The simulated TM displacement patterns are qualitatively similar to the OCT results. The simulated displacements are closer to the OCT results for 500Hz and 1kHz but the differences are greater at 2kHz. This study provides an initial look at the combined use of OCT measurements and FE modelling based on subject-specific anatomy. The geometries and parameters of the existing FE models could be modified for individual patients in the future to help identify abnormalities in the middle ear.

Wood-Decaying Fungi: From Timber Degradation to Sustainable Insulating Biomaterials Production.

Addressing the impacts of climate change and global warming has become an urgent priority for the planet's well-being. In recent decades the great potential of fungal-based products with characteristics equal to, or even outperforming, classic petroleum-derived products has been acknowledged. These new materials present the added advantage of having a reduced carbon footprint, less environmental impact and contributing to the shift away from a fossil-based economy. This study focused on the production of insulation panels using fungal mycelium and lignocellulosic materials as substrates. The process was optimized, starting with the selection of Trametes versicolor, Pleurotus ostreatus, P. eryngii, Ganoderma carnosum and Fomitopsis pinicola isolates, followed by the evaluation of three grain spawn substrates (millet, wheat and a 1:1 mix of millet and wheat grains) for mycelium propagation, and finishing with the production of various mycelium-based composites using five wood by-products and waste materials (pine sawdust, oak shavings, tree of heaven wood chips, wheat straw and shredded beech wood). The obtained biomaterials were characterized for internal structure by X-ray micro-CT, thermal transmittance using a thermoflowmeter and moisture absorption. The results showed that using a wheat and millet 1:1 (w/w) mix is the best option for spawn production regardless of the fungal isolate. In addition, the performance of the final composites was influenced both by the fungal isolate and the substrate used, with the latter having a stronger effect on the measured properties. The study shows that the most promising sustainable insulating biomaterial was created using T. versicolor grown on wheat straw.

Production of the cylinder head and crankcase of a small internal combustion engine using metal laser powder bed fusion

This effort investigates the use of metal additive manufacturing, specifically laser powder bed fusion (LPBF) for the automotive and defense industries by demonstrating its feasibility to produce working internal combustion (IC) engine components. Through reverse engineering, model modifications, parameter selection, build layout optimization, and support structure design, the production of a titanium crankcase and aluminum cylinder head for a small IC engine was made possible. Computed tomography (CT) scans were subsequently used to quantify whether defects such as cracks, geometric deviations, and porosity were present or critical. Once viability of the parts was established, machining and other post-possessing were completed to create functional parts. Final X-ray CT and micro-CT results showed all critical features fell within ±0.127 mm of the original equipment manufacturer (OEM) parts. This allowed reassembly of the engine without any issues hindering later successful operation. Furthermore, the LPBF parts had significantly reduced porosity percentages, potentially making them more robust than their cast counterparts.

Framework of magnetostrain responsive Ni–Mn–Ga microparticles driving magnetic field induced out-of-plane actuation of laminate composite

Ni–Mn–Ga single crystals (SC) exhibiting a giant magnetic field induced strain (MFIS), resulting from twin boundaries rearrangements, are excellent materials for novel actuators although enhanced brittleness and high costs are remaining the issues for applications. In polycrystalline state Ni–Mn–Ga alloys show small MFIS due to grain boundary constraints. By simple size reduction of the mentioned materials it is hardly possible to create quasi-two-dimensional MFIS actuators on the microscale with a pertinent out-of-plane performance. In pursuit of the trend for next generation materials and functions by design, in the present work we have developed a laminate composite as a prototype of microactuator with the out-of-plane stroke being driven by a framework of magnetostrain responsive Ni–Mn–Ga microparticles. The laminate consisted of the layer of crystallographically oriented Ni–Mn–Ga semi-free SC microparticles sandwiched between bonding polymer and Cu foils. Such design provided a particles isolation with a minimum constraint condition from the polymer. MFIS of the individual particles and the whole laminate composite was investigated by X-ray micro-CT 3D imaging. Both particles and laminate exhibited the same recoverable out-of-plane stroke produced by the particles´ MFIS of around 3% under 0.9 T. The developed microactuator design is promising for applications in the areas of micro-robotics, optical image stabilization in cameras, pumps for microfluidics etc.

Cobalt-Doped Mesoporous Silica Coated Magnetic Nanoparticles Promoting Accelerated Bone Healing in Distraction Osteogenesis.

Large bone abnormalities are commonly treated using distraction osteogenesis (DO), but it is not suitable for a long-term application; therefore, there is an urgent need for adjuvant therapy that can accelerate bone repair. We have synthesized mesoporous silica-coated magnetic nanoparticles doped with cobalt ions (Co-MMSNs) and assessed their capacity to quicken bone regrowth in a mouse model of DO. Furthermore, local injection of the Co-MMSNs significantly accelerated bone healing in DO, as demonstrated by X-ray imaging, micro-CT, mechanical tests, histological evaluation, and immunochemical analysis. In vitro, the Co-MMSNs exhibited good biocompatibility and induced angiogenic gene expression and osteogenic development in bone mesenchymal stem cells. And the Co-MMSNs can promote bone regeneration in a rat DO model. This study demonstrated the significant potential of Co-MMSNs to shorten the DO treatment duration and effectively reduce the incidence of complications.

A multi-method approach for the investigation of termite mound structures (Kalahari Basin, Botswana)

Fungus-growing termites (FGT) are important agents in subtropical and semiarid ecosystems for the biological and geological modifications they bring through the construction of their mounds. In order to survive and thrive, the mounds are designed to host the Termitomyces fungus in pre-set conditions of humidity and temperature. The interior structure of FGT mounds has only been scarcely studied in the scientific literature, making knowledge about mound morphology and development incomplete. In this study, a relic FGT mound in northern Botswana was analyzed using a combination of electrical resistivity tomography (ERT), particle size distribution (PSD), X-ray computed microtomography (X-ray micro-CT), and soil micromorphology methods. Specifically, we set out to investigate (i) whether changes in the measured soil resistivities reflect expected changes between the various functional compartments of the mound; (ii) what changes in soil texture and structure are associated with the resistivity variations; and (iii) whether this information can be used to better understand the mound compartments and their development. Our results suggest that ERT may eventually provide an attractive and efficient method to investigate the interior structure of FGT mounds that is non-destructive. The use of ERT does not require to remove the epigeal of the mound. The modifications brought by FGT to the texture and structure of the soil, respective to the function of each mound compartment, can increase resistivity of up to three orders of magnitude. Further, the work presented in this paper helps to (i) identify processes involved in the sediment transfer between the mound and its surroundings, (ii) increases the understanding of mound morphology, and (iii) show that fungus-growing termitaria affect durably savanna landscape. Finally, this study demonstrates that ERT is a pertinent non-destructive method to investigate mound structure.

Characterization and analysis of alumina clusters in steel by X-ray Micro-CT

The properties of steel are affected by the non-metallic inclusions. It is critical to control the morphology of inclusions for producing the high-quality steel. However, due to the morphology of inclusions is complex and diverse, it is difficult to reveal the real morphology of inclusions by using the traditional two-dimensional (2D) observation method, and making it hard to quantitatively analyze the size and morphology of inclusions. In this study, the three-dimensional (3D) morphology of the alumina clusters in steel samples was observed by using the X-ray Micro-CT in the beamline of BL16U2 at Shanghai Synchrotron Radiation Facility (SSRF). Avizo software was used to reconstruct the 3D morphology of the alumina clusters, which intuitively shows the actual morphology of alumina clusters. The accuracy of 2D and 3D observation methods is discussed based on the stereological analysis of individual alumina cluster. A series of parameters were defined to characterize the morphological characteristics of the alumina clusters based the 3D observation. The fractal theory was introduced to quantitatively describe the morphological of alumina clusters. In the current study, the 2D fractal dimension of alumina clusters was determined as 1.64. The complexity of 3D morphology of alumina clusters was analyzed by 3D fractal dimension and shape factor. The current work provides an effective method for quantitative description of the morphology and spatial distribution of inclusions, which provides an important reference for effective control of alumina inclusions.

Manufacturability of functionally graded porous β-Ti21S auxetic architected biomaterials produced by laser powder bed fusion: Comparison between 2D and 3D metrological characterization.

Functionally graded porous structures (FGPSs) are attracting increasing interest in the manufacture of prostheses that benefit from lower stiffness and optimized pore size for osseointegration. In this work, we explore the possibility of employing FGPSs with auxetic unit cells. Their negative Poisson's ratio was exploited to reduce the loss of connection between prosthesis and bone usually occurring in standard implant loaded under tension and therefore undergoing lateral shrinking. In addition, to further improve osseointegration and mitigate stress shielding effects, auxetic FGPSs were fabricated in this work using a novel β-Ti21S alloy characterized by a lower Young's modulus compared to traditional α + β Ti alloys. Specifically, two different auxetic FGPSs with aspect ratio equal to 1.5 and angle θ of 15° and 25° with a relative density (ρr) gradient of 0.34, 0.49, 0.66 and of 0.40, 0.58, 0.75 were designed and printed by laser powder bed fusion. The 2D and 3D metrological characterization of the as-manufactured structures was compared with the design. 2D metrological characterization was carried out using scanning electron microscopy analysis, while for the 3D characterization, X-ray micro-CT imaging was used. An undersizing of the pore size and strut thickness in the as-manufactured sample was observed in both auxetic FGPSs. A maximum difference in the strut thickness of -14 and -22% was obtained in the auxetic structure with θ = 15° and 25°, respectively. On the contrary, a pore undersizing of -19% and -15% was evaluated in auxetic FGPS with θ = 15° and 25°, respectively. Compression mechanical tests allowed to determine stabilized elastic modulus of around 4 GPa for both FGPSs. Homogenization method and analytical equation were used and the comparison with experimental data highlights a good agreement of around 4% and 24% for θ = 15° and 25°, respectively.