Series Of Composites Research Articles

Effect of anisotropy field on the resonance frequency and reflection loss shift characteristics of barium hexaferrite ceramics

Abstract For this study, a modified barium hexaferrite based microwave and radar absorbing material was used. Synthesis and characterization of BaFe(12-2x)(MnTi)xO19 (0.1 ≤ x ≤ 1.0) have been prepared by solid state reaction method. The X-ray diffraction patterns reveal that all samples only crystallized into M-type barium hexaferrite after calcination at 1200 °C. Surface morphology images show that the hexagonal flake-like particle is formed at the initial stages of the Mn-Ti substitution level. The magnetic properties measurement reveals that the variation of magnetization values may vary based on preferable site occupation of Mn4+-Ti2+ cations to replace Fe3+ cations. The significant decrease in field coercivity (Hc) from 3.18 kOe to 0.51 kOe with the increase of Mn-Ti substitution affected the lowering values of field anisotropy (Ha). The maximum reflection loss (RL) positions of BaFe(12-2x)(MnTi)xO19 compositional series are shifted to lower frequency range following the Ha trendlines. The maximum RL value equals to 98.42% microwave absorption at 10.5 GHz has been obtained in x = 1.0 (BaFe10Mn0.5Ti0.5O19) composition.

Time Series approach to map areas of Agricultural Plastic Waste generation

Abstract. The escalating presence of plastics in agriculture has raised concerns regarding Agricultural Plastic Waste (APW). Hitherto, a lack of comprehensive plasticulture data impedes effective waste management strategies, potentially resulting in plastic pollution and contributing to microplastic formation. APW locations and quantities are pivotal for territorial planning and the formulation of public policies on waste management and land use. Remote detection of agri-plastics has garnered increased consideration, particularly in mapping plastic-mulched farmlands (PMFs) dispersed in extensive regions. This study investigates whether the use of satellite image time series can map PMFs accurately. We assessed pixel-based classification using a 16-day composite time series of Sentinel-2 imagery (S2-16D) obtained from the Brazil Data Cube project. The Plastic-Mulched Landcover Index (PMLI) was joined into S2-16D bands because it is an index focused on PMF detection. Four classifiers (RF, MLP, L-TAE, and TCNN) were compared through agreed classification metrics. The most promising outcome showed an overall accuracy of 100% employing L-TAE but with visible noise in the map. The time series enhanced accuracy while minimizing background confusion, offering a viable solution for PMF detection. The PMF map presented herein represents an initial stride toward fostering circularity in plasticulture throughout South America.

Synergistic Effects of Bismuth Oxide on the Radiation Attenuation Characteristics of Borosilicate Glasses

Abstract This work explores Bi2O3-doped borosilicate glasses' synthesis and radiation shielding characterization, and their applicability as radiation shields. The glasses are prepared via melt quenching in the composition series of 60B2O3-(22-x) SiO2-10CaO-(8+x)Bi2O3 (where x=4,8,12 and 16 mol%). The produced glasses' radiation shielding properties, such as the mass attenuation coefficient (MAC), the transmission factor (TF), and the effective atomic number (Zeff), were examined, and the effect of Bi2O3 on the samples' radiation shielding performance was explored. The glass sample with 24 mol% Bi2O3 exhibited notable efficiency in shielding against gamma radiation. This is evidenced by the favourable change in the MAC, TF, and Zeff with increasing Bi2O3 content. We examined the relation between the glass thickness and the TF, with the results revealing that the 0.6 cm thickness glass possesses the highest TF compared to a thickness of 1.2 cm, indicating that at the thickness of 1.2 cm, the glass material attenuates better compared to 0.6 cm. The relation between the glasses' density and their half value layer was also examined.

Mechanically robust, self-healing and stretchable electromagnetic shielding materials based on multi-component dynamic bonded polyurethane elastomer

Stretchable self-healing electromagnetic interference (EMI) shielding materials can automatically restore their original performance after mechanical damage, and can still maintain over 20 dB EMI shielding effectiveness (EMI SE) under tensile state. In this work, a series of highly stretchable self-healing polyurethane elastomer PUBNS-X was prepared by introducing dynamic disulfide bonds, boronic ester bonds and boron-nitrogen coordination (B-N) on the polyurethane main chain. It was found that B-N coordination significantly increased the elongation at break and the tensile strength. The high dynamic reversibility of boronic ester, disulfide bond and B-N coordination bond synergistically endowed PUBNS-X with excellent temperature-triggered self-healing properties. The mechanical properties of PUBNS-X can be restored to more than 90 % at 60 °C. The pre-assembled silver nanowires (AgNWs) conductive network was then introduced into the polyurethane surface by taking advantage of the fluidity of the dynamically bonded polyurethane backbone to obtain a series of stretchable self-healing electromagnetic shielding composites (AgNWs/PUBNS-Y). The results showed that the EMI SE of AgNWs/PUBNS-Y can reach ∼55 dB, and the conductivity can be restored to 82 % of the original value after healing at 60 °C. The investigation of the electromagnetic interference shielding performance of composites under different strains showed that the EMI SE of AgNWs/PUBNS-3 can still maintain 20 dB under 90 % strain. These composites will have broad potential applications in the fields of flexible wearable electronic products, bionic intelligent materials and soft robots.

Poly(Vinylidene Fluoride‐Hexafluoropropylene) Composites With Carbon Based Nanofillers for Electromagnetic Interference Shielding

ABSTRACTIn the current work, a series of flexible polymer matrix composites (PMCs) based on poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP) as the polymer matrix and carbon nanofillers, namely single‐walled nanotubes (SWCNT) or carbon blacks (CB), were fabricated via a facile preparation method of blending and solution casting. The electrical conductivity, morphology, dielectric constant, mechanics, and electromagnetic interference (EMI) shielding properties of the composite films were adjusted by varying the carbon type (CB = Ketjenblack, Vulcan, or SWCNT = Tuball) and amount (0.1–15 wt%). The influence of the conductive nanofillers on the EMI shielding effectiveness (SE) and microwave absorbing properties in the X‐band frequency range (8–12 GHz) were investigated. By increasing the carbon content, the EMI shielding properties of the composite films were improved due to an increase in the magnitude of the electromagnetic properties. As the loading of these carbon fillers approach the percolation threshold, the dielectric constant of the composite can dramatically increase because of the construction of a microcapacitor network. However, these nanofillers/polymer composites generally have high dielectric loss near the percolation threshold due to the direct connection between carbon nanofillers. The PVDF‐HFP/Tuball composite particularly contributed low dielectric loss to the electromagnetic (EM) wave, resulting in excellent microwave absorption properties with a SE per unit thickness of 337.5 dB/mm and 2.5× less weight compared with conventional aluminum with the same SE, demonstrating the promise of using these materials as practical EMI shields.

Constructing high-performance bulk thermoelectric composites by incorporating uniformly dispersed fullerene sub-nanoclusters

Sub-nanomaterials possess unprecedented size-dependent properties compared to conventional nanomaterials, which endow them with great potential in catalysis, biomedicine, sensors, and so on. However, their applications in thermoelectrics are unknown due to poor thermal stability and low yields. Herein, we construct a series of thermoelectric composites by incorporating highly thermally stable and commercial fullerene sub-nanoclusters (C60 or C70). We find that sub-nanoclusters as the second phase can conduce to optimized carrier concentration through charge transfer at interfaces while the carrier mobility is significantly enhanced due to atom orbital hybridization and size-dependent electrical scattering mechanism. Furthermore, the ultra-low thermal conductivity of C60 due to its distorted chemical bonding and sub-nanometer pore, and the interfacial thermal resistance greatly suppress the phonon transport. Consequently, the 0.15 mol% C60/Bi0.4Sb1.6Te3 realizes an ultra-high ZT of ∼1.6 at 373 K, an excellent thermoelectric conversion efficiency of ∼7.4%, and a huge cooling performance of ∼73 K. This work demonstrates the application of sub-nanomaterials in thermoelectrics and may shed light on other fields such as electronic devices, thermal management, and fullerene chemistry.

Efficient photocatalytic activity over α-MnS/ZIF-67 p-n junction: Revealing the synergistic effects of exposed crystal facets and built-in electric field mechanism

In this investigation, we explored two series of composites comprising p-type α-MnS with selectively exposed {001} or {111} facets, coated with n-type ZIF-67 nanoparticles, to enhance the photocatalytic activity on Rhodamine B (RhB) degradation. The influence of the crystal facet orientation and the p-n junction on the photocatalytic efficacy was also well studied. The α-MnS/ZIF-67 composites displayed enhanced separation of charge carriers and superior light absorption capabilities, benefiting for efficient photocatalysis. The composites with cubic α-MnS morphology exhibited a pronouncedly higher photocatalytic activity relative to those with octahedral α-MnS morphology. The composition of α-MnS with ZIF-67 constructed the formation of a p-n junction with build-in electric field, extending the response into the visible region and promoting the mobility of charge carriers, thereby improving the photocatalytic performance. Our findings revealed that superoxide radicals (O2-) were the major reactive species in the photocatalytic degradation process. This study contributes novel insights into the development of high-performance and stable metal-organic framework (MOF)-based photocatalysts through the crystal facet engineering and the construction of p-n junctions.

An Efficient Algorithm for Exact Segmentation of Large Compositional and Categorical Time Series

ABSTRACTChange‐point detection, also known as signal segmentation, is an essential preprocessing step in many applications, ranging from industrial monitoring to bioinformatics. In short, it consists in finding the temporal boundaries of homogeneous regimes in long and non‐stationary time series. While this area of research is active, most existing methods are designed for Euclidean data. However, in many practical scenarios, the collected time series are compositional, meaning that each observation belongs to the probability simplex (the set of non‐negative vectors whose components sum to one). In this work, we propose an algorithm detecting change‐points in large compositional signals with an underlying piecewise stationary model. We cast the change‐point detection task as a discrete optimization problem, whose solution is shown to converge to the true change‐points. We introduce a new and time‐efficient dynamic programming algorithm that solves exactly this problem. To limit the number of operations, we describe a novel pruning rule that allows us to reduce the set of candidate change‐point indices. Our method is tested on a thorough simulation study, which confirms its efficiency. Additionally, we apply our method to a human activity segmentation task, highlighting the necessity for such novel techniques compared to standard algorithms.

Microstructure and Selected Properties of Al2O3 Matrix Composites Fabricated by Pulse Plasma Sintering of Al2O3 and Pre-composite Powder (NiAl–Al2O3)

Paper-related production of composite materials from Al2O3-pre-composite powder (NiAl–10 wt pct Al2O3). PPS allowed for forming ceramic–intermetallic composites. MA produced the pre-composite powder. Six series of composites were made, differing in temperature (1200 °C, 1300 °C, 1400 °C) and content of pre-composite powder (2.5 and 5 wt pct with respect to the amount of Al2O3). Highest hardness was obtained for composite series sintered at 1300 °C. Both series, with various pre-composite powder content, had a value of 20.8 to 20.9 GPa. Samples containing 2.5 wt pct pre-composite powder sintered at 1200 °C were highest KIC value of 4.72 ± 0.34 MPa·m0.5. Interestingly, the same value was obtained in composites containing 5 wt pct pre-composite powder sintered at 1300 °C. For both series with different pre-composite powder content, sintering at 1400 °C obtained the highest strength. For composites containing 2.5 wt pct pre-composite powder, splitting tensile strength value was 255.98 MPa, while for samples with 5 wt pct, pre-composite powder was 264.01 MPaGraphical

Flexible MOF@fabrics composites: The in-situ growth of metal-organic frameworks on cotton and selectively adsorption of gold(III) from aqueous solution

Metal-organic frameworks (MOFs) show great potential applications in dealing with heavy metal pollution due to their unique large specific surface area, tunable pore size, and diverse active groups. However, the powder form of MOFs has suffered from the disadvantages of difficult recycling and secondary contamination after adsorption of heavy metals, which seriously limits their practical application. Therefore, in this work, we prepared a series of bifunctional zirconium-based MOFs cotton fabric composites (MCFC) via in situ growth of MOFs on carboxylated cotton fabric, exhibiting large specific surface area, adjustable pore size, and effective adsorption ability. The prepared CF-UiO-66-(OH)2-FA shows an excellent adsorption efficiency of Au(III) more than 99.990 %, and the saturated adsorption amount is up to 190.98 mg·g−1 at 25 °C. Meanwhile, the kinetic experiment analysis demonstrated that the Au(III) adsorption behavior of MCFC follows pseudo-second-order (PSO) kinetic model. More importantly, it also exhibits great selectivity in adsorbing Au(III) from the mixture of multiple metal ions coexisted solution. The results of adsorption thermodynamics and adsorption isotherms indicate that adsorption is monolayer and a spontaneous, exothermic process. And the ideal adsorption and separation process could be finished by quickly filtrating with a single or multi-layer MCFC. Excellent adsorption performance even after four cycles of adsorption. Therefore, the fabricated MCFC shows great processability, flexibility, collectability and reusability in adsorbing and recycling precious metal ion from wastewater.

Facile fabrication of 3D-printed cellulosic fiber/polylactic acid composites as low-cost and sustainable acoustic panels

This work presents a green, cost-effective and eco-friendly strategy to reduce noise pollution by developing biopolymer-based 3D-printed acoustic panels. We successfully fabricated two series of composites by varying the weight percentage (wt%) of cellulose fibers of water hyacinth (WH) and pineapple leaf (PAL), with polylactic acid (PLA) as the matrix via the heat-press method. All samples were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Physico-mechanical properties, including hardness, tensile, and impact strength, were improved with increasing fiber loading. Filaments of 1 wt% water hyacinth fibers (WHFs) in PLA (1 WHF/PLA) and 1 wt% pineapple leaf fibers (PALFs) in PLA (1 PALF/PLA) were prepared and tested for 3D printability. The sound absorption coefficients (α) of the 3D-printed panels were investigated from 500 to 5000 Hz sound frequency range. The 3D-printed 1 WHF/PLA and 1 PALF/PLA acoustic panels achieve a maximum α (α-max) of 0.55 and 0.83 at 5000 and 4000 Hz, respectively, featuring the first work to report α-max > 0.5 at low fiber loadings in the high-frequency sound range. The tensile strength of the 3D-printed versions is significantly higher than non-3D-printed counterparts and commercial acoustic absorbers. Our data suggest the prepared 3D-printed panels are excellent candidates for acoustic applications at high-frequency noises. This study exhibits a facile, environmentally benign and sustainable approach to construct highly efficient and mechanically robust biopolymer-based 3D-printed sound-proof panels, which have promising potential as green engineering materials. Interestingly, this research also proposes a mitigation technology for the freshwater invader, Eichhornia crassipes (water hyacinths).

Preparation and ferroelectric properties of metal-organic frame lithium ion liquid crystal composites

ABSTRACT Two series of lithium ion liquid-crystalline composites (LCCs) containing metal-organic frame (MOF) materials were fabricated via a self-assembly process by use of poly(4-styrenesulfonic acid) lithium polymers, a cholesteryl-based liquid-crystalline monomer with terminal sulphonic acid group, and Fe-MIL-53_NH2. The chemical structure, chiral smectic C mesophase and ferroelectric property of the LCCs were characterised by various instruments, and the effect of liquid crystal monomer and lithium polymers on the ferroelectric property were investigated. The cholesteryl-based liquid crystal monomer presents a dominant role in the ferroelectric property of the LCCs, in which the asymmetric carbon atoms are responsible for the spontaneous polarisation. For the LCCs, the mechanical properties and porous loading characteristics of liquid crystal polymer are improved by the MOF materials, and the lithium-ion polymer connects the liquid crystal monomer with the MOF by ionic bond and improves the polarity of the material. When the electric field changed from −10 V and 10 V, the maximum residual polarisation strength (Pr) of the LCCs reached 74.82 nC/cm2. Because the LCCs showed excellent ferroelectric and mechanical properties, it has some potentials of application in the field of ferroelectric materials.

Long-term investigation on the daily variability of microplastic concentration and composition - Monitoring in the effluent of a wastewater treatment plant

The discharge of treated wastewater into receiving waters by wastewater treatment plants (WWTPs) is considered as one of the main pathways for microplastics (MPs) to enter the environment. To gain a better understanding of the temporal variability of MPs in WWTP effluents, this study investigated the concentration and composition (size, shape and polymer type) of MPs in the effluent of a German WWTP over the course of one month. 24-hour mixed samples were collected daily by a custom built automated sampling unit for MPs. Particles and fibers ≥11 μm were analyzed using Fourier transform infrared microspectroscopy. The MP concentration showed large daily fluctuations and ranged between 9.64 103 m−3 and 8.44 104 m−3 MPs over the study period. However, there was no significant correlation between the MP concentration and the precipitation or discharge from the WWTP. In contrast to the MP concentration, the MP composition in terms of size and shape was consistent over the study period. There were strong correlations between the time series of the polymer types polypropylene, polyethylene, polystyrene, polyester, ethylene-vinyl-acetate, cellulose artificially modified as well as the polymer cluster acrylates/polyurethanes/varnish. The time series of polyamide showed no significant correlation with the time series of any other polymer type. This study established a one month long high-resolution time series of MP concentration and composition, and thus provides a valuable basis for future research on the temporal variability of MP inputs into the environment from WWTP effluents.

Atomic-level structural engineering of La-doped CoMoP composite for enhanced overall water splitting

A series of La-doped CoMoP composites were fabricated through an in-situ phosphorization strategy with La–CoMo layered double hydroxide (LDH) as precursors. The homogenous dispersion of metal ions within the LDH structure facilitated the creation of a uniformly atomic-level La-doped CoMoP composite. Among these, the 5 % La-doped CoMoP exhibited the best performance, requiring only 41 mV overpotential for hydrogen evolution reaction (HER) and 303 mV for oxygen evolution reaction (OER) to reach a current density of 10 mA cm−2. For overall water splitting, it achieved a current density of 10 mA cm−2 at a cell voltage of just 1.61 V and maintained a stable performance over 24 h. The modulation effect of rare-earth elements, combined with the synergistic interactions among transition metal ions, contributes to its excellent bifunctional electrocatalytic performance.

Defining the boundaries of the meaning of ornamental compositions in the art of the Pazyryk culture

The article is devoted to the analysis of the semiotic field of the term "ornamental composition" in the context of definitions of ornament and composition in the art of the Pazyryk culture and its historiography. The subject of the study is ornamental compositions from elite burials of the Pazyryk culture of different periods of its development – the early Second Bashadar kurgan and the Tuekta burial ground and the late Pazyryk burial ground. In addition, the paper examines the specifics of the use of the terms "composition" and "ornament" in order to highlight the history of their meanings, as well as analyzes certain provisions of theoretical works on the study of the theory of composition and ornament. The purpose of the study is to identify the components of the semantic field of an ornamental composition related to the field of interaction of the composition with the viewer, and not to the field of meaning of specific figurative images. The article proposes using the method of formal analysis in combination with some provisions of the Gestalt approach described in the works of E. Gombrich and R. Arnheim to analyze a series of ornamental compositions with and without figurative images in the art of the Pazyryk culture. The scientific novelty of the study is predetermined by the absence in the Russian historiography of works describing the specifics of the meaning of ornamental composition in the context of visual perception in the art of the Pazyryk culture. The researchers note that the significance of ornaments in Pazyryk art could be related to the meaning of multi-figure compositions (when zoomorphic images are included in the ornament) and reflect the worldview of the bearers of the Pazyryk culture, or the types of symmetry used in the construction of ornaments could reflect the social structure of society. However, in both of these trends, the analysis of an ornamental composition without figurative images remains outside the scope as a structural and semantic, integral work of art interacting with the viewer. As a result of the research, the assumption is put forward that it is possible to designate a single semantic field for ornamental and multi-figure compositions in Pazyryk art. Clarifying and expanding the scope of the ornamental composition allows us to identify a single specificity of interaction with the viewer of both figurative and non-figurative images of Pazyryk art, to emphasize the game element in the nature of culture.

Fabrication of core-shell structural Y@VTMS-DVB composites with enhanced hydrophobicity for toluene capture under humid environment

Zeolite Y serves as an effective adsorbent for VOCs capture due to its ordered porous structure, exceptional thermal stability, chemical resistance and fine-tune key properties. However, the hydrophilicity caused by the low SiO2/Al2O3 ratio seriously limits its industrial application, especially in humid environments. In this work, a series of core-shell composites Y@VTMS-DVBn were prepared through surface grafting and copolymerization. A variety of characterizations were utilized to study the structural and morphological changes of the prepared samples. The dynamic breakthrough adsorption experiment showed that the toluene uptake was significantly improved from 1.77 mg/g to 53.09 mg/g under 30 % relative humidity. Moreover, the core-shell composite exhibited excellent regeneration properties, the adsorption capacity remained 90 % under wet conditions after 6 cycles of regeneration. Adsorption kinetic analysis revealed that the adsorption behavior of toluene on the prepared adsorbents was primarily physical adsorption. These results show that the core-shell composite is a promising candidate for VOCs removal in industrial application.

Fabrication of temperature-regulated sorbitol/mannitol-doped copper oxides derived from a Cu complex and their photocatalytic properties

In this study, a series of composites containing copper oxide (CuxO) particles doped with sorbitol/mannitol, namely Cu/CuxO@C (x = 1 or 2), was successfully derived from a novel copper complex ([Cu(IPZ)2Cl2] (Cu-Complex), where IPZ = 4-Iodopyrazole) by pyrolysis method and exploiting the stability and modulation of the coordination sites of sorbitol/mannitol, which exhibited excellent photocatalytic properties. The results showed that Cu/CuxO@C possessed high efficiency in degrading rhodamine B (RhB), gentian violet (GV), methyl orange (MO) and Congo red (CR) dyes under UV irradiation, and the degradation effect was gradually enhanced with the increase of calcination temperature. The structural and chemical states of the materials were characterised in detail. Furthermore, the effects of experimental factors such as catalyst dose, solution pH, and inorganic anions on dye degradation efficiency were investigated. The photocatalytic mechanism study demonstrated that the primary oxygen-active substance was superoxide radical (·O2-). The electron transport hypothesis explains the effective separation of electrons and holes within a substance. The Cu/CuxO@C composite was regarded as a potential photocatalyst for dye wastewater treatment due to its high photocatalytic efficiency, reusability, and universality, offering a novel solution to environmental and energy issues.

Effect of Yb2O3 doping on the thermal and mechanical properties GdAlO3-Gd2Zr2O7 composite with eutectic composition

Rare earth zirconates exhibit potential as thermal barrier coatings, but their limited toughness impedes their widespread use. To address this issue, rare earth aluminates are regarded as effective toughening agents for zirconates. However, the thermal conductivity of composites containing rare earth aluminates and zirconates tends to rise. To mitigate this issue, we have developed a series of Yb2O3-doped GAO-GZO composites. The introduction of Yb2O3 results in the formation of a fluorite phase, with Yb3+ ions occupying Gd sites in both GAO and GZO components. Although the fracture toughness remains relatively unchanged, the hardness of the composite improves. The thermal conductivity decreases with increasing Yb2O3 content due to enhanced phonon-defect scattering. Additionally, the coefficient of thermal expansion is reduced due to the stronger Yb-O bonding compared to Gd-O. This study presents a viable strategy for regulating the mechanical and thermal properties of rare earth zirconates reinforced with aluminates through defect engineering.

Noetherian rings of composite generalized power series

Abstract Let A ⊆ B A\subseteq B be an extension of commutative rings with identity, ( S , ≤ ) \left(S,\le ) a nonzero strictly ordered monoid, and S * = S \ { 0 } {S}^{* }\left=S\backslash \left\{0\right\} . Let A + 〚 B S * , ≤ 〛 = { f ∈ 〚 B S , ≤ 〛 ∣ f ( 0 ) ∈ A } A+[\kern-2pt[ {B}^{{S}^{* },\le }]\kern-2pt] =\{f\in [\kern-2pt[ {B}^{S,\le }]\kern-2pt] \hspace{0.33em}| \hspace{0.33em}f\left(0)\in A\} . In this study, we determine when the ring A + 〚 B S * , ≤ 〛 A+[\kern-2pt[ {B}^{{S}^{* },\le }]\kern-2pt] is a Noetherian ring. We prove that when S S is a strict monoid, if A + 〚 B S * , ≤ 〛 A+[\kern-2pt[ {B}^{{S}^{* },\le }]\kern-2pt] is a Noetherian ring, then A A is a Noetherian ring, B B is a finitely generated A A -module, and S S is finitely generated. We also show that if B B is a finitely generated A A -module over a Noetherian ring A A and ( S , ≤ ) \left(S,\le ) is a positive strictly ordered monoid, which is finitely generated, then A + 〚 B S * , ≤ 〛 A+[\kern-2pt[ {B}^{{S}^{* },\le }]\kern-2pt] is a Noetherian ring.

Damage Assessment of Sheet Molding Compound Composites

The investigation focuses on the initiation and progression of damage in SMC (Sheet Moulding Compound) composites subjected to tension. These composites consist of a polyester matrix reinforced with randomly oriented short C glass fibers. Damage monitoring is conducted using the acoustic emission technique. To assess the influence of surface density on damage in SMC, three series of composites with surface concentrations of 300 g/m2, 450 g/m2, and 600 g/m2 are tested. Based on stress-strain curves, the main mechanical properties of the different composites are determined. Additionally, the analysis of the collected acoustic emission data enabled us to determine the damage thresholds in the different studied composites. While tensile tests and the acoustic emission technique allowed us to determine important composite parameters, further research is necessary to comprehensively discern the various damage modes.