Institute of Fundamental Technological Research

Dobrzański J., Stupkiewicz S., Towards a sharper phase-field method: A hybrid diffuse–semisharp approach for microstructure evolution problems, COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING, ISSN: 0045-7825, DOI: 10.1016/j.cma.2024.116841, Vol.423, No.116841, pp.1-23, 2024

Abstract:
A new approach is developed for computational modelling of microstructure evolution problems. The approach combines the phase-field method with the recently-developed laminated element technique (LET) which is a simple and efficient method to model weak discontinuities using non-conforming finite-element meshes. The essence of LET is in treating the elements that are cut by an interface as simple laminates of the two phases, and this idea is here extended to propagating interfaces so that the volume fraction of the phases and the lamination orientation vary accordingly. In the proposed LET-PF approach, the phase-field variable (order parameter), which is governed by an evolution equation of the Ginzburg–Landau type, plays the role of a level-set function that implicitly defines the position of the (sharp) interface. The mechanical equilibrium subproblem is then solved using the semisharp LET technique. Performance of LET-PF is illustrated by numerical examples. In particular, it is shown that, for the problems studied, LET-PF exhibits higher accuracy than the conventional phase-field method so that, for instance, qualitatively correct results can be obtained using a significantly coarser mesh, and thus at a lower computational cost.

Keywords:
Microstructure evolution,Interfaces,Laminate,Phase-field method,Finite element method

Darban H., Elastostatics of nonuniform miniaturized beams: Explicit solutions through a nonlocal transfer matrix formulation, International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2024.104054, Vol.198, No.104054, pp.1-18, 2024

Abstract:
A mathematically well-posed nonlocal model is formulated based on the variational approach and the transfer matrix method to investigate the size-dependent elastostatics of nonuniform miniaturized beams. The beams are composed of an arbitrary number of sub-beams with diverse material and geometrical properties, as well as small-scale size dependency. The model adopts a stress-driven nonlocal approach, a well-established framework in the Engineering Science community. The curvature of a sub-beam is defined through an integral convolution, considering the bending moments across all cross-sections of the sub-beam and a kernel function. The governing equations are solved and the deflections are derived in terms of some constants. The formulation uses local and interfacial transfer matrices, incorporating continuity conditions at cross-sections where sub-beams are joined, to define relations between constants in the solution of a generic sub-beam and those of the first sub-beam at the left end. The boundary conditions are then imposed to derive an explicit, closed-form solution for the deflection. The solution significantly simplifies the study of nonuniform beams with multiple sub-beams. The predictions of the model for two limiting cases, namely local nonuniform and nonlocal uniform beams, are in excellent agreement with the available literature data. The flexural behavior of nonuniform miniaturized beams, composed of two to five different sub-beams and subjected to different boundary conditions, is studied. The results are presented and discussed, emphasizing the effects of the material properties, nonlocalities, and lengths of the sub-beams on the deflection. It is demonstrated that the flexural response of nonlocal nonuniform beams is more complex than local counterparts. Unlike the local beams, dividing a nonlocal uniform beam into multiple sub-beams and then reconnecting them changes the overall stiffness of the beam. The study highlights the potential to design nonuniform miniaturized beams with specific configurations to control their flexural response effectively.

Keywords:
Small-scale beam,Transfer matrix method,Multi-material,Size effect,MEMS,NEMS

Kalita D., Mulewska K., Jóźwik I., Zaborowska A., Gawęda M., Chromiński W., Bochenek K., Rogal Ł., Metastable β-Phase Ti–Nb Alloys Fabricated by Powder Metallurgy: Effect of Nb on Superelasticity and Deformation Behavior, METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN: 1073-5623, DOI: 10.1007/s11661-023-07285-5, pp.1-17, 2024

Abstract:
This study investigates the effect of Nb concentration on the mechanical properties, superelasticity, as well as deformation behavior of metastable β-phase Ti–Nb alloys produced via powder metallurgy. The alloys were fabricated through mechanical alloying, followed by consolidation using hot pressing. The resulting microstructure comprises fine β-phase grains with TiC carbide precipitates at the grain boundaries. The study reveals non-linear variations in the values of yield strength for the manufactured materials, which were attributed to the occurrence of various deformation mechanisms activated during the loading. It was found that the mechanisms change with the increasing concentration of Nb in the manner: stress-induced martensitic transformation, twinning, slip. However, all these mechanisms were activated at a reduced concentration of Nb compared to the materials obtained by casting technology previously reported in the literature. This is most probably associated with the elevated oxygen content, which affects the stability of the parent β-phase. The study revealed that superelasticity in Ti–Nb-based alloys prepared using powder metallurgy may be achieved by reducing the content of β-stabilizing elements compared to alloys obtained by conventional technologies. In this study, the Ti–14Nb (at. pct) alloy exhibited the best superelasticity, whereas conventionally fabricated Ti–Nb alloys displayed superelasticity at an Nb concentration of approximately 26 at. pct. The developed material exhibited a non-conventional, one-stage yielding behavior, resulting in a superelastic response at significantly higher stresses compared to conventionally fabricated Ti–Nb alloys.

Kaszyca K., Marcin C., Bucholc B., Błyskun P., Nisar F., Rojek J., Zybała R., Using the Spark Plasma Sintering System for Fabrication of Advanced Semiconductor Materials , Materials, ISSN: 1996-1944, DOI: 10.3390/ma17061422, Vol.17, No.1422, pp.1-15, 2024

Abstract:
The interest in the Spark Plasma Sintering (SPS) technique has continuously increased over the last few years. This article shows the possibility of the development of an SPS device used for material processing and synthesis in both scientific and industrial applications and aims to present manufacturing methods and the versatility of an SPS device, presenting examples of processing Arc-Melted- (half-Heusler, cobalt triantimonide) and Self-propagating High-temperature Synthesis (SHS)-synthesized semiconductor (bismuth telluride) materials. The SPS system functionality development is presented, the purpose of which was to broaden the knowledge of the nature of SPS processes. This approach enabled the precise design of material sintering processes and also contributed to increasing the repeatability and accuracy of sintering conditions.

Keywords:
spark plasma sintering, arc melting, semiconductor materials, half-Heusler, bismuth telluride, cobalt triantimonide, SHS, SPS

Strojny-Nędza A., Pietrzak K. Z., Jóźwik I., Bucholc B., Wyszkowska E., Kurpaska Ł., Grabias A., Malinowska A., Chmielewski M., Effect of Nitrogen Atmosphere Annealing of Alloyed Powders on the Microstructure and Properties of ODS Ferritic Steels, Materials, ISSN: 1996-1944, DOI: 10.3390/ma17081743, Vol.17, No.8, pp.1-19, 2024

Abstract:
Oxide Dispersion Strengthened (ODS) ferritic steels are promising materials for the nuclear power sector. This paper presents the results of a study on the sintering process using the Spark Plasma Sintering (SPS) technique, focusing on ODS ferritic steel powders with different contents (0.3 and 0.6 vol.%) of Y2O3. The novelty lies in the analysis of the effect of pre-annealing treatment on powders previously prepared by mechanical alloying on the microstructure, mechanical, and thermal properties of the sinters. Using the SPS method, it was possible to obtain well-densified sinters with a relative density above 98%. Pre-annealing the powders resulted in an increase in the relative density of the sinters and a slight increase in their thermal conductivity. The use of low electron energies during SEM analysis allowed for a fairly good visualization of the reinforcing oxides uniformly dispersed in the matrix. Analysis of the Mössbauer spectroscopy results revealed that pre-annealing induces local atomic rearrangements within the solid solution. In addition, there was an additional spectral component, indicating the formation of a Cr-based paramagnetic phase. The ODS material with a higher Y2O3 content showed increased Vickers hardness values, as well as increased Young’s modulus and nanohardness, as determined by nanoindentation tests.

Keywords:
spark plasma sintering, ODS ferritic steel, mechanical alloying, Mössbauer spectroscopy, nanoindentation

Pietrzyk-Thel P., Jain A., Bochenek K., Michalska M., Basista M. A., Szabo T., Nagy P., Wolska A., Klepka M., Flexible, tough and high-performing ionogels for supercapacitor application, Journal of Materiomics, ISSN: 2352-8478, DOI: 10.1016/j.jmat.2024.01.008, pp.1-41, 2024

Abstract:
Ionogels are an attractive class of materials for smart and flexible electronics and are prepared from the combination of a polymer and ionic liquid which is entrapped in this matrix. Ionogels provide a continuous conductive phase with high thermal, mechanical, and chemical stability. However, because of the higher percentage of ionic liquids it is difficult to obtain an ionogel with high ionic conductivity and mechanical stability, which are very important from an application point of view. In this work, ionogel films with high flexibility, excellent ionic conductivity, and exceptional stability were prepared using polyvinyl alcohol as the host polymer matrix and 1-ethyl-3-methylimidazolium hydrogen sulfate as the ionic liquid using water as the solvent for energy storage application. The prepared ionogel films exhibited good mechanical stability along with sustaining strain of more than 100% at room temperature and low temperature, the ability to withstand twisting up to 360° and different bending conditions, and excellent ionic conductivity of 5.12 × 10−3 S/cm. The supercapacitor cell fabricated using the optimized ionogel film showed a capacitance of 39.9 F/g with an energy and power densities of 5.5 Wh/kg and 0.3 kW/kg, respectively confirming the suitability of ionogels for supercapacitor application.

Keywords:
Ionic liquid, Gel polymer electrolyte, Ionic conductivity, 1-Ethyl-3-methylimidazolium hydrogen sulfate, Supercapacitors

Kucharski S. J., Maj M., Ryś M., Petryk H. M., Size effects in spherical indentation of single crystal copper, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, ISSN: 0020-7403, DOI: 10.1016/j.ijmecsci.2024.109138, Vol.272, pp.1-15, 2024

Keywords:
Hardness, Lattice rotation, Plasticity, Strain Gradient

Deshpande S., Bordas S., Lengiewicz J. A., MAgNET: A graph U-Net architecture for mesh-based simulations, Engineering Applications of Artificial Intelligence, ISSN: 0952-1976, DOI: 10.1016/j.engappai.2024.108055, Vol.133 B, No.108055, pp.1-18, 2024

Abstract:
In many cutting-edge applications, high-fidelity computational models prove to be too slow for practical use and are therefore replaced by much faster surrogate models. Recently, deep learning techniques have increasingly been utilized to accelerate such predictions. To enable learning on large-dimensional and complex data, specific neural network architectures have been developed, including convolutional and graph neural networks. In this work, we present a novel encoder–decoder geometric deep learning framework called MAgNET, which extends the well-known convolutional neural networks to accommodate arbitrary graph-structured data. MAgNET consists of innovative Multichannel Aggregation (MAg) layers and graph pooling/unpooling layers, forming a graph U-Net architecture that is analogous to convolutional U-Nets. We demonstrate the predictive capabilities of MAgNET in surrogate modeling for non-linear finite element simulations in the mechanics of solids.

Keywords:
Geometric deep learning, Mesh based simulations, Finite element method, Graph U-Net, Surrogate modeling

Kowalczyk-Gajewska K., Maj M., Bieniek K., Majewski M., Opiela K.C., Zieliński T.G., Cubic elasticity of porous materials produced by additive manufacturing: experimental analyses, numerical and mean-field modelling, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-023-00843-z, Vol.24, pp.34-1-34-22, 2024

Abstract:
Although the elastic properties of porous materials depend mainly on the volume fraction of pores, the details of pore distribution within the material representative volume are also important and may be the subject of optimisation. To study their effect, experimental analyses were performed on samples made of a polymer material with a predefined distribution of spherical voids, but with various porosities due to different pore sizes. Three types of pore distribution with cubic symmetry were considered and the results of experimental analyses were confronted with mean-field estimates and numerical calculations. The mean-field ‘cluster’ model is used in which the mutual interactions between each of the two pores in the predefined volume are considered. As a result, the geometry of pore distribution is reflected in the anisotropic effective properties. The samples were produced using a 3D printing technique and tested in the regime of small strain to assess the elastic stiffness. The digital image correlation method was used to measure material response under compression. As a reference, the solid samples were also 3D printed and tested to evaluate the polymer matrix stiffness. The anisotropy of the elastic response of porous samples related to the arrangement of voids was assessed. Young’s moduli measured for the additively manufactured samples complied satisfactorily with modelling predictions for low and moderate pore sizes, while only qualitatively for larger porosities. Thus, the low-cost additive manufacturing techniques may be considered rather as preliminary tools to prototype porous materials and test mean-field approaches, while for the quantitative and detailed model validation, more accurate additive printing techniques should be considered. Research paves the way for using these computationally efficient models in optimising the microstructure of heterogeneous materials and composites.

Keywords:
Pore configuration, Anisotropy, Elasticity, Micro-mechanics, Additive manufacturing

Witecka A., Pietrzyk-Thel P., Krajewski M., Sobczak K., Wolska A., Jain A., Preparation of activated carbon/iron oxide/chitosan electrodes for symmetric supercapacitor using electrophoretic deposition: A facile, fast and sustainable approach, JOURNAL OF ALLOYS AND COMPOUNDS, ISSN: 0925-8388, DOI: 10.1016/j.jallcom.2024.174040, Vol.985, No.174040, pp.1-15, 2024

Abstract:
In this research, electrophoretic deposition (EPD) was employed to prepare a porous composite film (ACF electrode) consisting of 90 wt% activated carbon particles, 10 wt% iron oxide nanoparticles, and a chitosan as binder in a facile, fast, and sustainable manner. This micro-mesoporous composite film, with a thickness of ∼45 µm and a surface area of ∼208.1 m2g−1, was coated on a stainless steel substrate. The SEM and TEM investigations proved the homogeneous distribution of carbon microparticles and iron oxide nanoparticles in the deposit, while the EDX, XRD, Raman spectroscopy, and XPS confirmed the chemical composition. ACF electrodes were also used in a symmetric two-electrode cell configuration with a sandwiched gel polymer electrolyte - PVdF(HFP)-PC-Mg(ClO4)2 and revealed a specific capacitance of ∼54.4 F g−1, along with satisfactory energy and power density of ∼4.7 Wh kg−1 and 1.2 kW kg−1, respectively, and excellent electrochemical stability up to ∼10,000 cycles (with merely 8.5% decay by the 5000th cycle). Obtained results confirmed the stability of the used system and its possible application in the field of energy storage and conversion.

Witecka A., Schmitt J., Courtien M., Gerardin C., Rydzek G., Hybrid mesoporous silica materials templated with surfactant polyion complex (SPIC) micelles for pH-triggered drug release, Microporous and Mesoporous Materials, ISSN: 1387-1811, DOI: 10.1016/j.micromeso.2023.112913, Vol.365, No.112913, pp.1-13, 2024

Abstract:
New Surfactant PolyIon Complex (SPIC) micelles were assembled by electrostatic complexation of an antibacterial cationic surfactant, cetylpyridinium chloride (CPC), and a double hydrophilic block copolymer (DHBC) containing a neutral comb block of poly(oligo(ethylene glycol)) methyl ether acrylate (PEOGA) and a weak polyacid block of poly(acrylic acid) (PAA). The corresponding SPIC micelles, with a CPC/PAA core and a PEOGA corona, were successfully used as structure directing and functionalizing agents in a soft and sustainable sol-gel strategy, yielding hybrid mesoporous silica (MS) materials with a monomodal pore size distribution centred at 2.8 nm. The influence of synthesis parameters, including the pH, concentrations and ratios of components, was systematically investigated. The obtained hybrid MS materials were intrinsically functional, with PEOGA blocks anchored in silica walls via H-bonding, while weak polyacid blocks, complexed with CPC, were confined within the mesopores. The response of the materials to pH changes (pH 7.4, 4.2 and 3) indicated remarkable stability of the anchored DHBC, while CPC was selectively released under the acidic conditions typical of orodental biofilm microenvironments. This result is noteworthy, since the release of encapsulated amphiphilic drugs into water is less favorable than that of hydrophilic drugs. Owing to the control of their pore and functionality properties, ordered hybrid silica materials templated and functionalized with SPIC systems will be materials of choice for developing pH-responsive biomedical devices using wet processing techniques

Keywords:
Double hydrophilic block copolymer, Cooperative self-assembly, Surfactant-polyion complex micelle, Stimuli-responsive nanomaterials, Sustainable, Sol-gel synthesis

Entezari E., Velazquez J., Lopez D., Zuniga M., Mousavisogolitappeh H., Davani R., Szpunar J., An experimental and statistical study on the characteristics of non-metallic inclusions that serve as hydrogen-induced crack nucleation sites in pipeline steel, Engineering Failure Analysis, ISSN: 1350-6307, DOI: 10.1016/j.engfailanal.2023.107695, Vol.154, No.107695, pp.1-15, 2024

Abstract:
This study consists of a statistical study to identify spatial distribution parameters of non-metallic inclusions (NMIs) at hydrogen-induced cracking (HIC) nucleation sites in both low-strength and high-strength steel pipes. The electrochemical cathodic charging method was used to induce HIC in pipeline steel plates, and the nucleation of the HIC was monitored using straight beam ultrasonic testing. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to evaluate the shape, size, area fraction, and separation distance of NMIs. The hydrogen microprint technique (HMT), electron backscattered diffraction (EBSD) analysis, and finite element (FE) stress analysis were performed to characterize HIC nucleation sites. The findings showed that cubical and spinal NMIs, characterized by strong hydrogen trapping capacity due to high misfit strain and von Mises stress, are favored sites for HIC nucleation. The main finding of this study is that the shape and sharpness of NMIs are the factors that determine when NMIs will be a HIC nucleation site, rather than size, as generally accepted.

Keywords:
Hydrogen-induced cracking, Statistical study, Non-metallic inclusions, Hydrogen microprint technique, Finite element stress analysis

Ciurans-Oset M., Flasar P., Jenczyk P., Jarząbek D. M., Mouzon J., Akhtar F., Role of the microstructure and the residual strains on the mechanical properties of cast tungsten carbide produced by different methods, Journal of Materials Research and Technology, ISSN: 2238-7854, DOI: 10.1016/j.jmrt.2024.04.067, Vol.30, pp.3640-3649, 2024

Abstract:
Cast tungsten carbide (CTC) is a biphasic, pearlitic-like structure composed of WC lamellae in a matrix of W2C. Besides excellent flowability, spherical CTC powders exhibit superior hardness and wear resistance. Nevertheless, the available literature generally fails to explain the physical mechanisms behind such a phenomenon. In the present work, the microstructure and the mechanical properties of the novel centrifugally-atomized spherical CTC have been extensively investigated. This material exhibited an extremely fine microstructure, with WC lamellae of 27–29 nm in thickness and bulk lattice strains of 1.0–1.4 %, resulting in a microindentation hardness of 31.4 ± 1.6 GPa. The results of this study clearly show that centrifugally-atomized CTC is mechanically superior to both spheroidized CTC and conventional cast-and-crushed CTC. In addition, the effect of a series of heat treatments on the bulk fracture toughness and the fatigue life of entire CTC particles was also investigated. The reduction of residual stresses in the bulk of particles upon annealing dramatically increased the indentation fracture toughness, whereas the bulk microindentation hardness remained essentially unaffected. Regarding the fatigue life of entire particles under uniaxial cyclic compressive loading, local phase transformation phenomena at the surface of the particles upon heat treatment were concluded to play the most critical role. Indeed, the cumulative fatigue damage was minimized in surface-carburized CTC powders, where compressive stresses were induced at the outermost surface.

Keywords:
Cast tungsten carbide, Microindentation hardness, X-ray diffraction, Lattice microstrains, Dislocation density, Compression

Gaurav A., Das A., Paul A., Jain A., Boruah B., Jalebi M., Could halide perovskites revolutionalise batteries and supercapacitors: A leap in energy storage, Journal of Energy Storage, ISSN: 2352-152X, DOI: 10.1016/j.est.2024.111468, Vol.88, No.111468, pp.1-22, 2024

Abstract:
Metal halide perovskites have rapidly emerged as a revolutionary frontier in materials science, catalyzing breakthroughs in energy storage technology. Originating as transformative entities in the field of solar cells, these perovskites have surpassed conventional boundaries. This comprehensive review embarks on a journey through the intriguing potentials of energy storage, driven by the exceptional properties of perovskite materials. We delve into three compelling facets of this evolving landscape: batteries, supercapacitors, and the seamless integration of solar cells with energy storage. In the realm of batteries, we introduce the utilization of perovskites, with a specific focus on both lead and lead-free halide perovskites for conciseness. Leveraging superior electrical properties such as high ionic conductivity (ranging from 10−3 to 10−4 Scm−1 for Li-ion) and diverse structural dimensions coupled with remarkable diffusion coefficients (2.68 × 10−8 cm2s−1 and 3.63 × 10−9 cm2s−1) for Chloride and Iodide-based halide perovskites, respectively, we explore the immense potential of perovskites as electrodes compared to other host materials such as layered oxide, carbon, etc., specifically for Al-ion, Zn-ion, and Li-ion batteries application, paving the way for the next generation of energy storage devices. In the domain of supercapacitors, we discuss the application of halide perovskites, highlighting both their advantages and limitations. We also provide a brief overview of the significant progress made in the supercapacitor domain using perovskite materials over the years. Additionally, we venture into unexplored territories, emphasizing the potential integration of solar cells and energy storage systems, delving into innovative concepts such as photo-accelerated capacitors/supercapacitors and photo-accelerated batteries. Importantly, we presented a detailed analysis of the impact of the perovskite composition on different energy storage applications. Ultimately, we outline the significant advantages, recognize the existing limitations, and stimulate imagination concerning the boundless future potential of halide perovskites in the energy storage domain, fostering a scientific and innovative perspective that contributes to the ongoing research and practical application of perovskite materials.

Keywords:
Metal halide perovskite, Energy storage, Battery, Supercapacitors, Perovskite solar cells-batteries

Staszczak M., Urbański L., Cristea M., Ionita D., Pieczyska E.A., Investigation of Shape Memory Polyurethane Properties in Cold Programming Process Towards Its Applications, Polymers, ISSN: 2073-4360, DOI: 10.3390/polym16020219, Vol.16, No.2, pp.219-1-219-20, 2024

Abstract:
Thermoresponsive shape memory polymers (SMPs) with the remarkable ability to remember a temporary shape and recover their original one using temperature have been gaining more and more attention in a wide range of applications. Traditionally, SMPs are investigated using a method named often “hot-programming”, since they are heated above their glass transition temperature (Tg) and after that, reshaped and cooled below Tg to achieve and fix the desired configuration. Upon reheating, these materials return to their original shape. However, the heating of SMPs above their Tg during a thermomechanical cycle to trigger a change in their shape creates a temperature gradient within the material structure and causes significant thermal expansion of the polymer sample resulting in a reduction in its shape recovery property. These phenomena, in turn, limit the application fields of SMPs, in which fast actuation, dimensional stability and low thermal expansion coefficient are crucial. This paper aims at a comprehensive experimental investigation of thermoplastic polyurethane shape memory polymer (PU-SMP) using the cold programming approach, in which the deformation of the SMP into the programmed shape is conducted at temperatures below Tg. The PU-SMP glass transition temperature equals approximately 65 ◦C. Structural, mechanical and thermomechanical characterization was performed, and the results on the identification of functional properties of PU-SMPs in quite a large strain range beyond yield limit were obtained. The average shape fixity ratio of the PU-SMP at room temperature programming was found to be approximately 90%, while the average shape fixity ratio at 45 ◦C (Tg − 20 ◦C) was approximately 97%. Whereas, the average shape recovery ratio was 93% at room temperature programming and it was equal to approximately 90% at 45 ◦C. However, the results obtained using the traditional method, the so-called hot programming at 65 ◦C, indicate a higher shape fixity value of 98%, but a lower shape recovery of 90%. Thus, the obtained results confirmed good shape memory properties of the PU-SMPs at a large strain range at various temperatures. Furthermore, the experiments conducted at both temperatures below Tg demonstrated that cold programming can be successfully applied to PU-SMPs with a relatively high Tg. Knowledge of the PU-SMP shape memory and shape fixity properties, estimated without risk of material degradation, caused by heating above Tg, makes them attractive for various applications, e.g., in electronic components, aircraft or aerospace structures.

Keywords:
polyurethane shape memory polymer, cold programming, thermal expansion, shape fixity, shape recovery

Mousavisogolitappeh H., Amini C., Efficient homogenization of honeycomb sandwich panels using orthotropic core simplification and Finite Element-based method: A comparative study, Journal of Composite Materials, ISSN: 0021-9983, DOI: 10.1177/002199832412404, pp.1-13, 2024

Abstract:
Composite materials, particularly honeycomb composites, are widely utilized in various industries, including aerospace, due to their high energy absorption against the impact and exceptional strength-to-weight ratio. This study aims to leverage the plastic and elastic properties of these materials to develop a simplified numerical model that incorporates orthotropic properties for core modeling. By doing so, the need for detailed honeycomb structure modeling is eliminated, resulting in reduced computational costs and time. A comprehensive three-dimensional finite element model, accounting for structural intricacies, is presented based on experimental data from a reputable source (isotropic model) and its equivalent finite element model (orthotropic model). The model is validated by the experimental results, demonstrating good agreement. The study also investigates parameters such as energy absorption, the internal energy of the core and faces, maximum displacement, and maximum contact force under low-velocity impact scenarios with spherical and cylindrical projectiles. These findings highlight the effectiveness of the orthotropic model, particularly in showcasing greater energy absorption in the core of the sandwich panel when subjected to a cylindrical impactor.

Keywords:
honeycomb, sandwich panel, homogenization, finite element analysis, impact

Jain A., Michalska M., Enhanced electrochemical properties of multiwalled carbon nanotubes modified with silver nanoparticles for energy storage application, MATERIALS CHEMISTRY AND PHYSICS, ISSN: 0254-0584, DOI: 10.1016/j.matchemphys.2024.129200, Vol.317, No.129200, pp.1-9, 2024

Abstract:
This work reports an easy, straightforward, and cost-effective method to synthesize a composite material using multiwalled carbon nanotubes (MWCNTs) and silver nanoparticles (Ag NPs) for application as an electrode in supercapacitors. The objective of this work was to enhance the charge transfer mechanism in supercapacitor cells by introducing the conductive particles in the MWCNT framework. The pivotal studies, like scanning (SEM), and transmission (TEM) electron microscopy, X-ray diffraction (XRD), Raman, and X-ray photoelectron (XPS) spectroscopy confirmed the formation of the composite as well as a successful deposition of Ag NPs on MWCNT. The surface area of the composite was evaluated by using the N2 adsorption-desorption studies and it was found to be of the order of 358 m2 g−1. Electrochemical studies were performed using a two-electrode system. Magnesium ion-based polymer gel electrolyte was used as an electrolyte material. The single electrode-specific capacitance was observed to be ∼31.9 F g−1 with power density and energy density values of ∼4.4 kW kg−1 and 1.2 Wh kg−1, respectively, at a current density of 0.46 A g−1. The cell was stable up to ∼5000 charge-discharge cycles with ∼96% of capacitance retention at the end of 5000 cycles.

Keywords:
Supercapacitor, Gel polymer electrolyte, MWCNTs

Olusegun S., Souza Guilhermina de O., Sutuła S., Osial M., Krajewski M.^♦, Pękała M., Sobczak K., Felis E., Krysiński P., Methotrexate anti-cancer drug removal using Gd-doped Fe3O4: Adsorption mechanism, thermal desorption and reusability, Groundwater for Sustainable Development, ISSN: 2352-801X, DOI: 10.1016/j.gsd.2024.101103, Vol.25, pp.1-9, 2024

Keywords:
Adsorption,Thermal desorption,Gd-doped Fe3O4,Methotrexate