Fiber Mass Fraction Research Articles

Study on mechanical properties and molecular simulation of nano‐SiO2‐modified hybrid fiber reinforced polymer bar under the dry and alkaline environment

AbstractFiber reinforced polymer (FRP) bars have received extensive promotion and application in the structural engineering. However, due to the limitations inherent in using single material, FRP reinforced concrete structures often encounter issues, such as brittle failure and inadequate energy dissipation, particularly in complex natural environments and under various loading conditions. In this study, the preparation of nano‐SiO2‐modified carbon/basalt hybrid FRP bars was carried out using the pultrusion‐winding process and ultrasonic treatment. The objective was to investigate the influence of the fiber volume ratio and mass fraction of nano‐SiO2 on the mechanical properties of FRP bars under drying and alkaline conditions. Molecular dynamics simulations were performed to construct interface models between fibers and epoxy resin in order to elucidate the toughening mechanism of nano‐SiO2 and the degradation mechanism in alkaline conditions. The research results show that elevating the substitution rate of carbon fibers and incorporating nano‐SiO2 doping bring about alterations in the brittle fracture characteristics of BFRP bars and enhance the post‐yield performance and interlaminar shear properties of hybrid FRP bars, concurrently mitigating the degradation of mechanical properties induced by exposure to alkaline solutions. MD simulations indicate that the addition of nano‐SiO2 improves the binding rate of hydrogen bonds between BF and epoxy resin, resulting in a higher interfacial energy between BF/epoxy resin compared to CF/epoxy resin. Moreover, nano‐SiO2 effectively mitigates the impact of alkaline solutions on the formation of interfacial hydrogen bonds. The findings of this study serve as a valuable reference for the design and application of FRP reinforced concrete structures.Highlights Nano‐SiO2 modified B/CFRP bars made via extrusion‐winding & ultrasonic treatment. Improved mechanical properties and plastic deformation in Nano‐SiO2 modified B/C FRP bars. Nano‐SiO2 inhibits B/CFRP bars degradation in alkaline solution. Nano‐SiO2 bind more at BF/epoxy than CF/epoxy interface. Nano‐SiO2 reduces alkaline solution effect on interfacial H‐bonding.

Fodder and seed productivity of the bonfire awnless of the selection of Omsk agrarian scientific center

The study was conducted in 2019–2023 in the Omsk region in order to assess the feed and seed productivity of varieties of bonfire awnless selected of the Omsk Agrarian Scientific Center and the selection of the most promising material from the studied material for further use in breeding work. The material was varieties SibNIISHoz-189 (standard), SibNIISHoz-88, Titan, SibNIISHoz-99, Elbrus and Effect. Three cycles were carried out: summer sowing in 2019, 2020 and 2021, accounting years, respectively, 2020–2021; 2021–2022 and 2022–2023. During the experiments, the yield of green mass and absolutely dry matter, seed productivity were evaluated, biochemical analyses of the green mass of varieties were carried out to determine the content of the mass fraction of protein and fiber. In all years of the research, during the growing season, increased air temperature was noted, exceeding the long-term average data by 1.6…1.8 ºС and a large deficit of precipitation. The GTC values by year were: 2020–0.60; 2021–0.56; 2022–1.02; 2023–0.85, with the optimal –1.13. On average, over 3 cycles of research, a significant excess over the standard was characterized by: in terms of green mass yield – varieties SibNIISKhoz-88 and SibNIISKhoz-99 (9.6 and 7.3 % of st.); in terms of absolutely dry matter yield – SibNIISKhoz-88, SibNIISKhoz-99, Titan and Effect (7.8…11.1 % to st.); in terms of seed yield – SibNIISKhoz-99, Elbrus, Effect and Titan (16.5…22.8 % to st.). The mass fraction of protein in the green mass of the Effect variety, on average, over 3 evaluation cycles significantly exceeded the standard by 0.8 %, while the fiber content was at the standard level.

Influence of complex enzyme drug and phytase on growth, digestibility and use of nutrients of wheat and soya compound feed and mineralization of the drumstick in broiler chickens

Plant feeds contain anti-nutritional factors. Thus, non-starchy polysaccharides are poorly digested and can serve as a barrier to enzyme access to nutrients. Phytate can form a complex with other divalent cations (Ca, Mn, Mg, Fe, Zn), amino acids. Phytate is the largest reserve of phosphorus in plants, but this compound cannot be effectively absorbed by poultry, which requires the inclusion of expensive inorganic sources of phosphorus in feed. The purpose of the research was to evaluate the possible effects of separate and combined inclusion of the complex enzyme drug Sunzyme (matrix as an ingredient) and the phytase-containing enzyme drug Sunface 5000 (matrix in nutritional value) on the digestibility and absorption of nutrients of wheat and soybean compound feed by broiler chickens. During the experiment, 204 day-old broiler chickens were divided according to the principle of analogues into 4 groups of 51 heads in each. The broiler chickens of the control group received compound feed without enzyme drugs, the 1st experimental group received compound feed with Sanzyme (matrix as an ingredient), the 2nd experimental group received compound feed with Sanzyme (matrix as an ingredient) and Sunface 5000 (matrix in nutritional value), the 3rd experimental group received compound feed with Sunface 5000 (matrix in nutritional value). Compound feeds were fed from one day to 42 days of age. In order to determine the digestibility of the main nutrients in compound feeds of broiler chickens aged 35–42 days, a physiological experiment was carried out based on the results of which a animal science analysis of the fed compound feeds and litter was carried out using generally accepted methods. When studying feed and litter, the mass fraction of dry matter, crude protein, crude fat, fiber, nitrogen-free extractives, ash, calcium and phosphorus were determined. It was found that compared with the control group broiler chickens received Sunzyme and Sunface 5000 had higher coefficients of digestibility and nutrient utilization of wheat and soybean compound feeds and as a result achieved a high average final live weight with low feed intake per unit of gain during the rearing period.

Pore fractal characteristics and ANN model of polyacrylonitrile fiber reinforced concrete under the synergistic effects of freeze-thaw and erosion

The degradation of the concrete pore structure is a major concern among scholars due to its negative impact on durability. This study conducted a salt freezing test on polyacrylonitrile fiber concrete (PANFRC) using a composite freeze-thaw medium consisting of Na2SO4, MgSO4, and NaCl (5 % + 5% + 3.5 %). The pore volume fractal dimension was determined by analyzing the T2 spectrum obtained through nuclear magnetic resonance technology. The study explored the influence of different types of pores on frost resistance and developed an artificial neural network-based machine learning model to predict macroscopic frost resistance using the pore volume fractal dimension. The experimental findings indicate that plain concrete exhibits a density loss of 4.67 % upon failure, whereas the density loss in PANFRC is reduced to less than 3 %. The frost resistance durability index is observed to improve as the fiber mass fraction increases within specific ranges. Notably, when the fiber content surpasses 1.2 kg/m³, the durability factor (DF) can be effectively doubled. Drawing from the concept of freeze-thaw cycles, a novel frost-thaw erosion damage model was developed, which incorporates the influence of fiber content under the combined action of freeze-thaw cycles and erosion. The analysis of pore dimensions reveals that the fractal characteristics become more pronounced with the increase in pore size, although this does not extend to the micro-pore range (i.e., those smaller than 0.1 μm). In comparison to other machine learning algorithms, the ANN demonstrates its superiority by establishing a meso-macro transfer prediction model with enhanced generalization capabilities.

ОТЗЫВЧИВОСТЬ ГИБРИДА КУКУРУЗЫ НУР НА ЛИСТОВЫЕ ПОДКОРМКИ КАРБАМИДОМ И СТИМУЛЯТОРОМ РОСТА ИЗАГРИ ВИТА В ПОЧВЕННО-КЛИМАТИЧЕСКИХ УСЛОВИЯХ РЕСПУБЛИКИ ТАТАРСТАН

The feed potential of the universal early-maturing hybrid corn Nur was studied in the conditions of the Ancestral region of the Republic of Tatarstan on gray forest heavy loamy soils. The content of humus in the arable layer was characterized as increased by 4.4 %, mobile phosphorus as very high - more than 377 mg/kg, exchangeable potassium increased – 124 mg/kg. The soil had a medium reaction close to neutral (pH 6.3). Meteorological conditions in 2023 were characterized as arid with a lack of precipitation during the growing season of corn. To obtain high-quality feed from corn, different corn nutrition systems were studied: without fertilizers, background N16P16K16, background N16P16K16 + urea leaf dressing in the 5-7 leaf phase, background N16P16K16 + Izagri Vita leaf dressing in the 5-7 leaf phase, background N16P16K16 + Izagri Vita leaf dressing in the 5-7 leaf phase and cob formation. Izagri Vita is a growth stimulant with trace elements. Improving the nutritional conditions of corn extends the growing season by 2-3 days. Corn responds positively to the application of mineral fertilizers and carrying out leaf fertilization with carbamide. This technique ensures the formation of the highest plant height (159.7 cm) and leaf area (42.19 thousand m2/ha). The largest aboveground mass was formed on the von NPK+ variant Izagri Vita 44.50 t/ha. Biometric indicators of corn also improved on fertilized food backgrounds. The highest yield of green mass was obtained on the variants background NPK and background NPK + Izagri Vita (2 phases) (45.81 and 41.88 t/ha). The increase in yield from the applied mineral fertilizers amounted to 16.25 and 12.31 t/ha. Better nutrition of corn provides a more nutritious feed from corn. The NPK background variant had the highest mass fraction of dry matter (86.3 %), crude fiber (35.0 %), and NPK background + From graphite, where the mass fraction of nitrogen was 20.5 g/kg, crude protein 128.2 g/kg, phosphorus 1.0%.

The role of flexural particles in the shear flow of pine residue biomass: An experiment-informed DEM simulation study

An experiment-informed discrete particle simulation study was performed to investigate the role of flexural particles in the shear flow of milled pine residues. Physical pine anatomical fraction samples were tested in an FT4 powder rheometer. A chip model for bark/stem chips and a fiber model for needles were proposed for DEM. The FT4 simulations show mixed fibers/chips require higher force and torque to drive shear flow than pure chips or fibers. The mass fraction and flexibility of fibers reveal nonlinear inter-dependency on impacting the shear flow of mixed fibers/chips. Polydisperse fibers well match the needle-rich samples on the flow attributes, while polydisperse mixed fibers/chips agree reasonably with the bark/stem-rich samples. The DEM study indicates that the flowability of pine residue biomass is determined collectively by various material attributes of the anatomical fractions, which must be considered when developing preprocessing methods for conversion-ready biomass with adequate material handling performance.

Использование семян льна-долгунца при производстве безалкогольного пива «Светлое»

Research is presented on replacing part of the barley malt with flax seeds in the production of beer wort and its effect on physicochemical parameters. The greatest value for the duration of saccharification and filtration was obtained with the addition of 4% fiber flax seeds. The duration of saccharification increased from 5 to 15 minutes, and the duration of filtration from 75 to 180 minutes. When replacing barley malt with 1% fiber flax seeds, the acidity and mass fraction of moisture do not exceed the GOST requirements. The use of fiber flax seeds in the production of beer wort did not affect the transparency of the finished product, but a pleasant nutty smell and mild taste appeared. The production of beer wort, the optimal proportion of flax seeds when replacing barley malt is 1%. Since when it increases to 4%, the acidity and mass fraction of moisture in the wort do not meet the requirements of GOST, this may affect the quality of the finished product and its shelf life. The results obtained must be taken into account in the further development of the non-alcoholic beer recipe. Keywords: FIBER FLAX, BARLEY MALT, BEER WORTH, NON-ALCOHOLIC BEER

Preparation and Properties of Gradient Sound-Absorbing Composites with Waste Feathers

To make full use of waste feather resources, waste feather fiber/polybutanediol succinate gradient sound-absorbing composites were prepared by a hot-pressing process with waste feather fiber as a reinforcing material and polybutanediol succinate as a matrix material. It can be applied to construction and other fields. The influence of gradient waste feather fiber mass fraction, gradient material density, and gradient material thickness on the sound-absorbing performance was studied, and the sound-absorbing mechanism of the material was analyzed. To determine the average sound-absorbing coefficient, maximum absorbing coefficient, and noise reduction coefficient as the evaluation index, the gradient sound-absorbing composites with waste feathers were compared with market common porous sound-absorbing materials with polyester fiber and wool fiber. The maximum sound-absorbing coefficient of the gradient sound-absorbing composites with waste feathers was 0.860; the average sound-absorbing coefficient was 0.408; the noise reduction coefficient was 0.393; and the noise reduction grade was IV. The sound-absorbing band was wide, and gradient sound-absorbing composites with waste feathers can be applied over a wide range.

ФИЗИКО-ХИМИЧЕСКИЕ СВОЙСТВА ФЕРМЕНТИРОВАННЫХ КОМБИКОРМОВ В ЗАВИСИМОСТИ ОТ СПОСОБА ПРИГОТОВЛЕНИЯ

The article presents the results of a comparative study of the physicochemical parameters of fermented compound feed consisting of 40% brewer's grains, 20% wheat bran, 20% sunflower cake, 20% mushroom substrate. Prepared in two ways: the first way – the compound feed composed of native ingredients was fermented, the second – the compound feed composed of pre-fermented ingredients. In the compound feed composed of fermented ingredients, in comparison with the compound feed fermented in full, the mass fraction of moisture, crude fat, soluble carbohydrates, starch and crude fiber was higher; the mass fraction of crude protein and exchange energy was lower.

Influence of the thermal expansion on the surface quality of coated and non-coated natural-fiber-reinforced composites

Natural fiber reinforced plastics (NFRP) are increasingly used as a sustainable material alternative to glass or carbon fiber reinforced plastics in lightweight solutions. Visible and/or decorative coated components must meet high surface qualities and defects such as fiber print-through due to different expansion behavior of fiber and matrix are not permitted. Various studies investigate the expansion behavior of NFRP under the influence of temperature and humidity on mechanical properties. In contrast, there are no studies that relate these properties to decoratively coated NFRP and the importance for surface quality. The present study aims to fill this gap using a flax fiber reinforced bio-based epoxy resin (FFRP) manufactured by resin transfer molding process (RTM). The surface roughness and the coefficient of thermal expansion (CTE) were determined as a function of the fiber mass fraction. Further, FFRP and carbon fiber reinforced plastics (CFRP) were decoratively coated and subjected to an alternating climate test. The results showed that reducing the fiber mass fraction of an FFRP to 40 % and using a glass-fiber non-woven on the surface, in combination with 50 % fiber mass fraction, were the most promising methods for reducing roughness in the uncoated state. In addition, the FFRP exhibited an increased CTE longitudinally of 11 ppmK−1 and transversely of 105 ppmK−1 to the fiber direction compared to the CFRP (5 and 79 ppmK−1), along with increased roughness of Ra 0.8 compared to 0.6. The effect of fiber print-through was shown for all variants by the stress in the alternating climate test.

Photosynthetic activity - as a factor in the formation of yield and quality of the new grain fodder oat variety Irtysh 33

The purpose of the research is to assess the influence of photosynthetic activity of the new promising oat variety Irtysh 33 on the formation of its yield and quality of green mass. The experiments were performed in 2017-2022. The soil of the experimental plots is ordinary leached chernozem with a humus content of 5.7…7.5 %. The experiment was carried out in 4 repetitions. The seeding rate is 4 million viable seeds/ha. The area of the plots is 10 m2. The object of research is a new promising oat variety Irtysh 33, the standard variety is Orion. Optimal moisture supply was observed in 2019 (hydrothermal coefficient = 1.10), excess moisture in 2018 (hydrothermal coefficient = 1.39), and dry conditions in 2017, 2020-2022. (hydrothermal coefficient = 0.58-0.77). On average, over the period of research, the variety Irtysh 33 was characterized by a more developed leaf apparatus (35.5 and 24.9 % higher than the standard for leaf surface area in the sweeping and flowering phases, respectively). The new variety was characterized by an increased mass fraction of dry biomass, exceeding the Orion standard by 14.6 % in the heading phase and by 10.2 % in the flowering phase. The Irtysh 33 variety provided photosynthetic potential 30 % higher than the standard. The new variety generated forage yields that were 7.3 and 3.2 t/ha higher than the standard in the heading and flowering phases, respectively. An increased quality of forage mass of the Irtysh 33 variety in the heading phase was also noted - higher than the standard for the mass fraction of protein by 0.4 %, for protein collection by 1.07 t/ha and 0.7 % lower than the standard for the mass fraction of fiber. Indicators of photosynthetic activity had a direct impact on the formation of the yield and quality of green mass of the Irtysh 33 variety, depending on the development phase. From spawning to flowering, the role of accumulation of dry biomass on the formation of the mass fraction of fiber (from r=0.515±0.02 to r=0.684±0.103, respectively) and yield (from r=0.479±0.008 to r=0.602±0.015) increased, as well as the role of net productivity of photosynthesis (for the accumulation of dry biomass from r=0.115±0.004 to r=0.419±0.017; for yield from r=0.460±0.020 to r=0.601±0.051). The average direct degree of conjugation of the assimilation surface of the leaf with the mass fraction of protein, noted in the sweeping phase (r=0.640±0.19), in the next phase changed to the average reverse (r= -0.508±0.021).

Improvements in Mechanical and Shape-Memory Properties of Bio-Based Composite: Effects of Adding Carbon Fiber and Graphene Nanoparticles.

Shape-memory carbon fiber (CF) polymer composites reinforced with graphene nanoplatelets (GnPs) as a filler based on a bio-based V-fa/ECO copolymer were prepared at different graphene GnPs and CF mass fractions using the hand lay-up and hot-pressing methods. The obtained composite specimens were subjected to flexural, dynamic mechanical, and shape-memory analyses. The obtained results revealed that the flexural strength and modulus were improved by the addition of the GnPs and CF due to the improvement in the interfacial adhesion and fiber reinforcement with up to 3 wt.% GnPs and 60 wt.% CF. Additionally, appreciable improvements in the shape-memory performance were achieved with the addition of the GnPs, where values of up to 93% and 96% were recorded for the shape fixity and recovery, respectively. The shape-memory performance was affected by the fiber mass fraction, with the composites retaining the shape-memory effect albeit with a significant drop in performance at higher fiber mass fractions. Lastly, the specimens at 40 wt.% CF and 3 wt.% GnPs were determined to be the optimum compositions for the best performance of the bio-based SMP composite.

Compression properties and constitutive model of short glass fiber reinforced poly-ether-ether-ketone (PEEK)

To analyze the deformation behavior of short glass fiber-reinforced poly-ether-ether-ketone (SGFR-PEEK) under various conditions through numerical simulations, it is crucial to construct a constitutive model that can describe its stress–strain behavior over a wide range of strain rates and temperatures. In this study, quasi-static compression tests were conducted on SGFR-PEEK composites with varying mass fractions, and dynamic tests were performed using a Split Hopkinson Pressure Bar to acquire the material's compressive stress–strain response under quasi-static and dynamic conditions. The results indicate that, under compression, the yield stress of SGFR-PEEK composites increases with an augmentation in glass fiber content, rises with increasing strain rate, and decreases with elevated temperature. Based on experimental findings, a modified Johnson–Cook constitutive model was established to characterize the mechanical performance of SGFR-PEEK. In comparison to the traditional Johnson–Cook intrinsic structure model, the modified model takes into account the glass fiber mass fraction as comprehensively as possible and better predicts the material's flow behavior at high strain rates. Finally, this modified constitutive model was implemented in the ABAQUS software using the user-defined subroutine VUMAT to simulate the compression behavior of SGFR-PEEK composites under different loading conditions, and the model was validated. This research provides valuable insights for the practical application of SGFR-PEEK composites in engineering.

Multiphase hybrid model and thermal insulation simulation of elytra-mimetic ceramic fiber aerogel

In our previous work, the coaxial electrostatic spinning method was applied to construct nanofiber/SiBCN ceramic aerogel with an elytra-mimetic structure. The material presented excellent mechanical, insulation, oxidation resistance, and other properties. Based on preliminary experiments and literature reports, the integrated heat transfer behavior of nanofiber/SiBCN composite ceramic aerogels in high-temperature environments was affected by several factors, such as coaxial fiber size properties, fiber particle content, interactions, and spatial distribution. Moreover, the above factors overlapped and interacted with each other, and it was hard to generalize a clear law of action through traditional experiments and characterization. Therefore, the paper constructed a representative volume unit (RVE) model based on the complex spatial distribution characteristics of composite aerogels, using fractal theory, Rosseland equation theory, and multiphase model theory. This paper investigated the fiber and particle content, the size characteristics of the coaxial fibers, and the overall heat transfer process in high-temperature environments using the finite element method. The finite element simulated the effective thermal conductivity of multiphase aerogel composites under multiple parameters, such as fiber occupancy, fiber core-shell diameter ratio, temperature, and heat transfer mode. We obtained the property parameters of the complex composition of the material through fractal theory. The model was combined with finite elements to study the fiber particle content, the size characteristics of coaxial fibers, and the integrated heat transfer process in high-temperature environments. The fibers improved the absorption and reflection of thermal radiation with increasing fiber mass fraction, leading to improved ability of ceramic fiber aerogel to extinguish light. The fibers had a larger area to absorb and reflect thermal radiation. Based on the excellent extinction ability of SiC fibers, the composite ceramic aerogel had improved thermal performance at a specifically fiber-to-shell diameter ratio through a comprehensive multifactor simulation analysis.

Thermal Performance and Environmental Analysis of a Brick Based on Traditional Gypsum Plaster Reinforced with Date Palm fibres

Timchemt is a traditional plaster that has been used for a long time and until today in the construction of the Ksar of Ouargla through their facility of obtaining and realization. In addition to that, because of the use of industrial building materials, nature is carried out by the toxic gases that are produced in factories when these materials are manufactured. So to minimize these negative effects on our planet and to encourage the use of local materials from the Saharan region, we have studied this material to improve its characteristics and to replace the others, especially because it is natural and does not harm the environment. The main objective of this paper is the improvement of the thermal properties of gypsum plaster by mixing it with date palm fibres in order to be used in wall and ceiling mortars. The thermal conductivity, thermal diffusivity, and thermal effusivity of the studied samples were measured using a steady hot plate. The obtained results show that the increase in the mass fraction of date palm fibres resulted in a significant improvement consisting of a reduction of the material's thermal properties. This reduction was up to 36% for the thermal conductivity, 13% for the thermal diffusivity, 23% for the thermal effusivity, and 16% for the volumetric thermal capacity.

Numerical study of paraffin and glass fiber composites for thermal management of lithium‐ion battery packs

AbstractPhase change materials (PCMs) have garnered significant interest in the field of passive cooling for lithium‐ion batteries in recent years due to their simple structure, low cost, and stable performance. This paper introduces a passive thermal management strategy based on nonuniform paraffin (PA) and glass fiber for battery modules. It explores the impact of glass fiber on the thermal conductivity and structural strength of PA, as well as the thermal management performance of the composite phase change battery module that combines the two materials. The findings reveal that the composite phase change module with a glass fiber mass fraction of 60%, operating at a discharge rate of 3C, maintains a temperature 0.76°C lower than that of the air‐cooling module. This reduction results in a decreased maximum temperature difference between the modules from 7.3 to 5.0°C and a decrease in the maximum temperature ratio from 16.9% to 11.6%. Moreover, compared to the PA phase change module, heat transfer to adjacent cells decreases by approximately 10% during thermal runaway, effectively suppressing thermal propagation. Additionally, the incorporation of glass fiber in this scheme enhances the compressive strength of the module by a factor of 9.81. This study presents a novel method to address the thermal management needs of batteries for heat dissipation and thermal insulation.

Mechanical Properties of Bio-Based Sandwich Composites Containing Recycled Polymer Textiles.

In this paper, sandwich composites were produced by compression moulding techniques, and they consisted of regenerated cellulose fabric (rayon) and bio-based polypropylene (PP) to form facings, while virgin and recycled polyamide (PA) textiles were used as core materials. To compare the mechanical performance between sandwich composites and typical composite designs, a control composite was produced to deliver the same weight and fiber mass fraction from rayon and PP. To evaluate the influence of recycled textile on the mechanical properties of the composites, a series of flexural, low velocity impact (LVI) and tensile tests were performed. It was found that the incorporation of thicker PA textile enhanced the bending stiffness by two times and the peak flexural force by 70% as compared to those of control. Substitution of a layer of recycled textile for two layers of rayon provided a good level of impact energy absorption capacity (~28 J) and maximum force (~4893-5229 N). The tensile strength of the four sandwich composites was reported to be in the range of 34.20 MPa and 46.80 MPa. This value was 91.90 for the control composite. The 2D cross-section slices of the composite specimens did not show any evidence of fiber tow debonding, fiber bundle splitting, or delamination.

In-line measurement of fiber mass fraction using Terahertz spectroscopy for a function-oriented quality assurance of glass fiber sheet molding compound

Glass fiber sheet molding compounds are a popular fiber-reinforced polymer because of their good processability. Both fiber mass fraction (FMF) and fiber orientation distribution significantly determine the mechanical properties of manufactured components. Local random variations in both properties occur during prepreg production and molding. This contribution expands a non-destructive measurement model for local FMF using Terahertz spectroscopy towards multiple specimen thicknesses. A thorough measurement uncertainty analysis according to the Guide to the Expression of Uncertainty in Measurement (GUM) shows an uncertainty reduction by 70 % compared to the uncertainty resulting from the manufacturing process. Measurement times of 0.5 s qualify the methodology for an in-line application. Integrating the measurement results into a parametrized, component-specific finite element model reduces the root mean squared error between physical experiments and simulations by 33 and 54 % compared to simulations with nominal fiber mass fractions.

Microscopic failure characteristics and critical length of short glass fiber reinforced composites

Short glass fiber reinforced composites (SGFRC) are frequently used to manufacture parts with complex surfaces by injection or compression molding. It was found that the length of fibers is often reduced during the manufacturing processes. To understand the causes of the change in fiber length, ex-situ 3D CT images are taken from tensile experiments to extract the information of the microstructure of the SGFRC, including fiber length, orientation and breakage. In the calculation of the critical length, the Kelly model is modified to include the effect of the stresses at fiber ends and the mechanical effect of internal pore defects on the composites. It is found that the microscopic interaction of short fibers breaks longer fibers, until they are shorter than the critical length. Through comparisons, it is found that the modified Kelly model is more accurate in predicting critical length of short fibers. In this study, micro-failure modes, such as fiber pulling out, interface debonding, matrix damage and pore destruction, are all characterized by micro-CT and scanning electronic microscope to analyze the complex failure mechanisms. The micro failure modes are mainly attributed to the micro geometric features and mass fraction of short fibers.

Studing of the composition of plant raw materials for the development of a recipe for a new type of feed

The article examines the chemical composition of some types of grain crops – wheat, bran, barley to identify the most nutritious of them, mixed with a feed additive to obtain highly nutritious feed for cattle. According to laboratory studies, the selected raw materials exceed the most common types of feed in terms of mineral content. Bran has the best indicators of vitamin and mineral composition, but the content of fiber and ash in them is higher than in wheat and barley, which can negatively affect the digestibility of ruminants. Wheat has the lowest indicators in terms of the content of the mass fraction of fiber and ash: fiber – 10.44%, ash – 1.57%. The content of the mass fraction of fat in the studied raw materials is in the range of 2.13-3.62%. Consequently, 3.5-4% of animals or a mixture of animal and vegetable fats protected from decay in the rumen can be added to the cow's diet. Comparing the data obtained with the minimum requirements for fodder crops and feed quality in the production of milk and beef, the compliance of the actual results with the requirements of regulatory documents was revealed. Based on the data obtained, it is concluded that it is possible to use this raw material as the main raw material for the development of compound feed with increased nutritional value.