Distribution Of Fibers Research Articles

Distributions of coarse aggregate and steel fiber in ultra-high performance concrete: Migration behavior and correlation with compressive strength

The vertical distribution of coarse aggregates and steel fibers in ultra-high performance concrete (UHPC) both at fresh and hardened states was investigated to unveil their migration behavior and the correlation with compressive strength. To fulfill this purpose, customized design of specimens and tailored test method were developed. Specimens with two sizes (3–5 mm and 5–10 mm) and varying content (0–50 %) of coarse aggregate and different volume fraction of steel fiber (0–2 %) were proportioned. It was found that higher amount of coarse aggregates was located in the lower part whereas more steel fibers and voids were observed in the upper region of the specimens. Increasing the content of coarse aggregates resulted in worsened uniformness of its distribution, while incorporating steel fibers up to 2 % by volume imposed negligible effects on the heterogeneity. Migration of different phases primarily occurred during the fresh state. Compressive strength of the specimens at the middle layers was up to 30 % higher than those at the top and bottom layers. The inferior compressive strength was primarily ascribed to the worsened distribution of CAs and higher voids in the top layer.

Fabrication and Characterization of Electrospun Ocimum sanctum and Curcumin-Loaded Nanofiber Membrane for the Management of Periodontal Disease: An In Vitro Study.

Background Periodontal disease is a chronic inflammatory condition that gradually deteriorates the supportive tissues of teeth, eventually leading to tooth loss. Mechanical debridement stands as the gold standard method for treating periodontitis. However, antimicrobial therapy is recommended for optimal results when used alongside mechanical debridement. Numerous studies have investigated local drug delivery as an adjunct to mechanical debridement of affected tooth surfaces. Ocimum sanctum exhibits anti-inflammatory, antioxidant, and antimicrobial properties. Similarly, curcumin, as documented in the literature, demonstrates a broad spectrum of anti-inflammatory and antimicrobial effects. Electrospinning has demonstrated itself to be a highly effective method for fabricating drug-loaded fibers. Electrospun nanofibers containing Ocimum sanctum and curcumin are expected to exhibit greater efficacy due to their increased surface area, facilitating the dispersion of larger quantities of drugs, and their ability to control drug release when employed as a local drug delivery system. This study aims to fabricate and characterize the properties of nanofiber membranes loaded with Ocimum sanctum and curcumin using the electrospinning technique. Methods About 50 mg each of Ocimum sanctum and curcumin were blended with 15% polyvinyl alcohol and 2% chitosan polymer in a 4:1 ratio and left to stir overnight. A 10 mL syringe was filled with this solution, and an 18 G blunt-end needle charged at 15.9 kV was used for extrusion. Continuous fibers were collected onto a collector plate positioned 12 cm from the center of the needle tip, at a flow rate of 0.005 mL/min. The morphology of the fabricated membrane was assessed through scanning electron microscopy (SEM), the strength of the material was assessed through tensile strength analysis using INSTRON, an Electropuls E3000 Universal Testing Machine(INSTRON, Norwood, MA), and the drug release pattern was analyzed using Jasco V-730 UV-visible spectrophotometer(Jasco, Easton, MD). Results The morphology of this nanofiber showed a random distribution of fibers with no bead formation. The average diameter of the membrane was 383±102 nm, and the tensile strength of this material was 1.87 MPa. The drug release pattern showed an initial burst release of Ocimum sanctum, followed by a controlled release in subsequent hours. However, curcumin showed very little drug release because of its solubility. Conclusion In summary, the Ocimum sanctum and curcumin-loaded nanofibers exhibited robust tensile strength, a controlled drug release profile, and uniform drug distribution within the nanofiber membrane. Consequently, it can be concluded that curcumin nanofibers and electrospun Ocimum sanctum serve as valuable agents for local drug delivery in the treatment of periodontitis.

Investigation of mode I fracture behavior of copper slag-SFRSCC

This study has examined how coarse CS (copper slag) aggregates (20–60 %) and HESFs (hooked-end steel fibers) (0.1–0.5 %) affect the performance, microstructure, and fracture/mechanical features of SCCs (self-compacting concretes) under pure loading mode I. To estimate the SCC ductility, fracture toughness and fracture energy behavior, use has been made of common specimens such as ENDB, ENDC and SCB and the Work Fracture Method. According to the results, adding CS (up to 30 %) improves the efficiency and strengthens the microstructure and mechanical properties. While 0.3–0.5 % SFs affect the fresh concrete properties negatively, they affect those of the hardened concrete positively and increase the mechanical properties. At high CS and SF values, fracture parameters weaken slightly due to improper fiber distribution and bad SF-CS locking and interaction effects. The WFM yielded close fracture features for ENDB specimens, but those of ENDC specimens were more than the actual values. SCB specimens were more suitable than others because they were prepared easily, consumed less material and were modeled better under pure mode I. According to the results, ALK (Active Learning Kriging) models estimated the fracture characteristics with high accuracy and yielded a correlation coefficient in the 0.87–0.95 range.

Second harmonic generation microscopy, biaxial mechanical tests and fiber dispersion models in human skin biomechanics

Advanced numerical simulations of the mechanical behavior of human skin require thorough calibration of the material’s constitutive models based on experimental ex vivo mechanical tests along with images of tissue microstructure for a variety of biomedical applications. In this work, a total of 14 human healthy skin samples and 4 additional scarred skin samples were experimentally analyzed to gain deep insights into the biomechanics of human skin. In particular, second harmonic generation (SHG) microscopy was used to extract detailed images of the distribution of collagen fibers, which were subsequently processed using a three-dimensional Fourier transform-based method recently proposed by the authors to quantify the distribution of fiber orientations. Mechanical tests under both biaxial and uniaxial loading were performed to calibrate the relevant mechanical parameters of two widely used constitutive models of soft fiber-reinforced biological tissues that account for non-symmetrical fiber dispersion. The calibration of the models allowed us to identify correlations between the mechanical parameters of the constitutive models considered. Statement of significanceConstitutive models for soft collagenous tissues can accurately reproduce the complex nonlinear and anisotropic mechanical behavior of skin. However, a comprehensive analysis of both microstructural and mechanical parameters is still missing for human skin. In this study, these parameters are determined by combining biaxial mechanical tests and SHG stacks of collagen fibers on ex vivo healthy human skin samples. The constitutive parameters are provided for two widely used hyperelastic models and enable accurate characterization of skin mechanical behavior for advanced numerical simulations.

Force model of ultrasonic empowered minimum quantity lubrication grinding CFRP

As a weight-reducing material in aerospace applications, carbon fiber reinforced polymer (CFRP) requires precision grinding to ensure the accuracy and assembly of mating positioning surfaces. However, achieving low-damage machining of CFRPs remains challenging. Flood cooling reduces the mechanical properties, while dry grinding deteriorates the surface integrity, making minimum quantity lubrication (MQL) a viable alternative. However, nanolubricants struggle to penetrate the grinding area due to gas barrier obstruction. Consequently, a new CFRP grinding approach using multiangle 2D ultrasonic vibration-empowered nanolubricant MQL was proposed. An analytical force model is crucial for optimizing machining strategies and adjusting parameters. The aim is to reveal grinding mechanics and develop a force model under different ultrasonic and lubrication-cooling conditions. First, a uniform random fiber distribution model and a grinding wheel model were established, and the mechanical properties of the interface were predicted. Then, the intermittent grinding behavior and dynamic stiffnesses of the multiangle 2D ultrasonic vibration-assisted grinding (UVAG) system were investigated based on the geometric kinematics of the grains' trajectory. Furthermore, based on the deformation deflection curve, bending fracture force models for 45°, 90°, and 135° fibers were established with different contact and boundary conditions. The material removal mechanisms of shear and tension-compression buckling in 0° CFRP grinding were revealed, and an elliptical contact normal force model was established. The interlayer shear in 45° CFRPs was analyzed. The longitudinal compressive matrix cracking and fiber shear fracture in the 90° CFRPs were elucidated. Fiber microbuckling and fiber bundle removal of 135° CFRPs were investigated. Finally, grinding force models with different fiber orientation angles (FOAs) were interconnected and experimentally assessed. Experimental assessments demonstrated that the grinding force model has acceptable estimation error and effectively captures the mechanics of CFRPs with different FOAs.

Changes in the Cutaneous Nerve Fiber Staining and Distribution of PGP9.5 in Clinically Uninvolved Skin in Leprosy Patients after Completion of Multidrug Therapy and Assessing PGP9.5 as a Marker of Treatment Response.

Subclinical involvement of nerves may sometimes be present much before the overt clinical manifestations become apparent. Protein gene product (PGP) 9.5, a ubiquitin-C-terminal hydrolase, has been widely used as a marker to study the involvement of peripheral nerve fibers in many diseases. To evaluate the change in cutaneous nerve fiber staining and distribution from pre-treatment and post completion of multidrug therapy through the expression of PGP9.5 and to assess PGP9.5 as a marker of treatment response. In this prospective single-center observational study, skin biopsy was taken in patients with leprosy, having areas of nerve function impairment (NFI), based on findings of nerve conduction studies (NCSs), but not having lesions or impaired tactile or thermal impairment clinically. The thin nerve fiber density in the clinically normal skin in areas supplied by nerve showing changes of sensory neuropathy was evaluated to study the density of the fibers. A second biopsy was taken at the end of treatment from a site near the previous site to assess the changes in intra-epidermal nerve fiber staining and distribution. Thirty-three patients were recruited in the present study (24 males and 9 females). Pre-treatment, 27 patients had abnormal NCSs, while six patients did not have any evidence of neuropathy on NCSs. Staining for nerve fibers using PGP9.5; in the epidermis was positive in five patients pre-treatment and 11 patients post treatment (P = 0.181). Staining in the dermis revealed positivity in 14 pre-treatment, which increased to 18 post treatment (P = 0.342). Adnexae showed positivity in five patients pre-treatment and increased to 17 post treatment (P = 0.005). A reduced PGP9.5 staining in the epidermal, dermal, and adnexal regions was seen in leprosy patients, which improved post treatment. Thus, PGP9.5 may serve as a marker of NFI and treatment response.

ECOLOGICAL AND FUNCTIONAL COMPARISON OF WOOD ANATOMY ON SOME TREE GENERA IN THE SOUTHERN NIGERIA

This work aimed at utilizing wood anatomical traits to assess the compatibility or suitability of 9 species in the families where they belong since the earlier classification depended only on morphological characters and also to possibly deduce the permeability of their vessel lumen during wood treatment with preservatives of equal or different viscosity. Comparative stem anatomy of tree taxa Antiaris toxicaria Lesch. (Moraceae), Ficus exasperate Vahl. (Moraceae), Milicia excelsa Welw. (Moraceae), Dacryodes klaineana Lam. (Burseraceae) Canarium schweinfurthii Engl. (Burseraceae), Dacryodes edulis Lam. (Burseraceae), Erythrophleum suaveolens Taub. (Fabaceae), Pelthophorum pterocarpum De Cand. (Fabaceae), Pterocarpus soyauxii Taub. (Fabaceae) was studied. Observations on the transverse, radial-longitudinal and tangential-longitudinal sections showed that there were vast variations and few similarities in the vessel, axial parenchyma, ray cell and storied fibre distributions within and across families. Variations across the three ecological zones were found. The highest vessel diameter occurred in C. schwenfortii with 222.84µm (Burseraceae) followed by F. Exasperate with 196.42 µm (Moraceae) and P. pterocarpum with 187.23 µm (Fabaceae) across the three ecological zones. Vessel diameters were in direct proportion with the amount of rainfall while vessel frequencies were in negative proportion with the amount of rainfall across the ecological zones. Qualitative properties were not significantly affected by either temperature or rainfall.

Investigation on fiber fracture mechanism and milling force model of CF/PEEK by ultrasonic milling

Ultrasonic milling can achieve high machining efficiency and surface quality on CF/PEEK composites due to its advantages of low cutting force, high material removal rate, improved surface quality, long tool life, and eco-friendly machining technology. This method is widely used in many scenarios such as aerospace, navigation, and new types of weapons. However, the changes in fiber fracture mode and the effects of fiber friction caused by high-frequency ultrasonic vibration cannot be ignored. To study this, first, a fiber fracture model is constructed based on experiments to describe the fiber fracture mechanism. Then, the machined surface and subsurface are analyzed to establish the relationship between feed speed and fiber deformation depth. Increasing the feed can increase the fiber deformation depth by 3.17 times. Finally, an analysis of the single fiber fracture mechanics is carried out and a force model is created that considers the friction between the tool tip and the fiber during ultrasonic milling. The predictive force model, integrated with the fiber distribution, was validated against experimental results, showing a maximum force error of 5.722 %. This model effectively explains the fracture mechanism of CF/PEEK fibers during ultrasonic milling at the microscopic level.

Secondary debris resulting from concrete slabs subjected to contact detonations – Spatial velocity distribution and influence of steel fibers

Secondary debris resulting from concrete slabs subjected to contact detonations – Spatial velocity distribution and influence of steel fibers

A novel in-situ micro-mechanical testing of paper fracture and its stochastic network model

Understanding and simulating the evolution of fracture in cellulose-based paper materials is vital for many eco-sustainable applications of packaging solutions. In this work, we conduct an integrated experimental-statistical mechanics analysis to elucidate how the microstructural mechanisms govern the fracture behavior of paper. We employ in-situ tensile tests combined with confocal microscopy to observe and analyze key microstructural phenomena, such as fibers’ activation and recruitment, and progressive tensile failure of unnotched paper samples under uniaxal loading. The developed stochastic mechanics critical cross-section model to treat the cellulose fiber network is able to decouple the stochastic morphological parameters from the constitutive model of the fibers. Notably, it robustly predicts the anisotropic properties of paper materials in the machine direction (MD) and cross-machine direction (CD) as a direct consequence of the different statistical distribution of fibers’ orientation, for the same fiber constitutive model. The proposed approach is finally employed to get an insight into the role of the main morphological parameters, local/non-local fibers’ strain redistribution, and finite elasticity of fibers on the whole mechanical behavior of paper.

Sustainable mortar reinforced with recycled glass fiber derived from pyrolysis of wind turbine blade waste

Pyrolysis technology has recently made significant progress in recycling millions of tons of wind turbine waste (WTB). Short fibers represent its main product (∼70 wt%), which needs further studies to explore its future applications. In this context, this work aims to the valorization of the recycled glass fiber (rGF) derived from pyrolysis of WTB (at 550 °C) in the production of rGF-reinforced mortar composite (rGF/M) for sustainable building applications. The research began by subjecting the derived rGF to sieving (rGFs), washing (rGFw), and oxidation (rGFo) pretreatments for purification and removing any impurities, organic residues, and char particles. Afterward, the chemical degradation of the treated rGF in a strong alkaline cement solution with pH = 14 was studied for up to 90 days. In parallel, the mortar composite samples were fabricated at 1 wt% of the treated rGF batches (rGFr, rGFw, and rGFo) to study the effect of different pretreatments on their microstructure, dispersion, compressive strength, flexural strength, and water absorption capabilities behavior after different curing periods (28 and 90 days). The results showed that rGFo (7.84%) showed a lower degradation rate versus rGFw (16.41%) and rGFr (30.76%). Meanwhile, the highest curing period (90 days) contributed to improving the properties of the mortar composites in general, especially in the case of using rGFo which led to improved compressive strength (15%) and reduced absorption coefficient (38%) and cumulative water content (32%) with a uniform distribution of short fibers in the matrices and a slight increase in flexural strength compared to control mortar sample (8.6 MPa). While rGFs provides better flexural strength (9.3 MPa) with a 12% improvement. Based on these results it can be concluded that rGFo has high potential in sustainable building materials with high competition with virgin glass fiber.

CHMP4B contributes to maintaining the follicular cells integrity in the panoistic ovary of the cockroach Blattella germanica.

The Endosomal Sorting Complex Required for Transport (ESCRT) is a highly conserved cellular machinery essential for many cellular functions, including transmembrane protein sorting, endosomal trafficking, and membrane scission. CHMP4B is a key component of ESCRT-III subcomplex and has been thoroughly studied in the meroistic ovaries of Drosophila melanogaster showing its relevance in maintaining this reproductive organ during the life of the fly. However, the role of the CHMP4B in the most basal panoistic ovaries remains elusive. Using RNAi, we examined the function of CHMP4B in the ovary of Blattella germanica in two different physiological stages: in last instar nymphs, with proliferative follicular cells, and in vitellogenic adults when follicular cells enter in polyploidy and endoreplication. In Chmp4b-depleted specimens, the actin fibers change their distribution, appearing accumulated in the basal pole of the follicular cells, resulting in an excess of actin bundles that surround the basal ovarian follicle and modifying their shape. Depletion of Chmp4b also determines an actin accumulation in follicular cell membranes, resulting in different cell morphologies and sizes. In the end, these changes disrupt the opening of intercellular spaces between the follicular cells (patency) impeding the incorporation of yolk proteins to the growing oocyte and resulting in female sterility. In addition, the nuclei of follicular cells appeared unusually elongated, suggesting an incomplete karyokinesis. These results proved CHMP4B essential in preserving the proper expression of cytoskeleton proteins vital for basal ovarian follicle growth and maturation and for yolk protein incorporation. Moreover, the correct distribution of actin fibers in the basal ovarian follicle emerged as a critical factor for the successful completion of ovulation and oviposition. The overall results, obtained in two different proliferative stages, suggest that the requirement of CHMP4B in B. germanica follicular epithelium is not related to the proliferative stage of the tissue.

New insights into the mechanical behavior and enhancement mechanism of micro-steel-fiber-reinforced recycled aggregate concrete through in-situ 4D CT analysis

Micro-steel-fiber-reinforced recycled aggregate concrete (MSFR-RAC), an innovative and environmentally friendly construction material, is gaining traction in civil engineering due to its superior performance and sustainability. This study utilized in-situ CT tests to investigate the strength and deformation variations in MSFR-RAC influenced by micro-steel fibers. Calculation models for the fiber influence factor (FIF) on peak stress, peak strain, and ultimate strain were proposed, and the optimal volume fraction threshold for steel fibers was determined. Using CT scanning and 3D reconstruction, the internal pore structure, crack evolution, and spatial distribution of steel fibers were analyzed. The interaction mechanism between steel fibers and the concrete matrix was established based on crack evolution patterns. The results demonstrate that steel fibers significantly enhance the microscopic structure and mechanical performance of MSFR-RAC. This study provides essential technical and theoretical support for the design and application of MSFR-RAC in construction.

Influence of reconstruction uncertainty in fiber orientation distribution on the effective elastic constants of composites reinforced with discontinuous fibers: a Monte Carlo simulation study

The orientation distribution of fibers in discontinuous fiber composite materials is influenced by various factors associated with the manufacturing process. Predicting fiber orientation distribution can be achieved through software simulation of the process or experimental methods, such as X-ray computed tomography. As uncertainties related to the reconstruction of fiber orientation distribution may be unavoidable in practical cases, this paper investigates the impact of some of these uncertainties on the effective elastic constants of composites through Monte Carlo simulations. The primary objective of this study is to address how the ratio of fiber detection and the measurement error of individual fiber orientation influence the orientation tensors and effective elastic constants. To predict the elastic properties of composites under various scenarios of fiber orientation distributions, a micromechanical model incorporating an orientation averaging procedure has been used. Three cases of different fiber orientation distributions have been analyzed. The conducted Monte Carlo simulations enabled the presentation of a quantitative description of the uncertainty associated with the reconstruction of the orientation distribution of fibers, including the effective elastic constants. The resulting distributions of orientation tensors and elastic constants have been analyzed and discussed.

Revealing pore size distribution in cellulose and lignin-cellulose man-made fibers – effect of draw ratio and lignin content

There are limited methods available for measurement of the porosity of cellulose fibers, even more so for obtaining a pore size distribution. Conventional pore analysis methods require dry samples, with intact pores. However, pores in cellulose fibers collapse when dried from water and thus present a challenge for sample analysis. Furthermore, the pore collapse is partially irreversible which should be accounted for in the analysis. In this study, analysis of pore structure was carried out in the wet state with thermoporometry and also for critical point dried samples, analyzed with N2 sorption. This study determines the effect of fiber lignin content and certain spinning parameters on the pore size distribution of spun fibers before and after drying. It could also be concluded that solvent exchange, drying from a non-polar solvent will result in an altered pore size distribution, with a total pore volume greater than if dried from water, however not representative of the never-dried state. It is concluded that thermoporometry together with the water retention value (WRV) measurement is a powerful combination to acquire insights to the pore size distribution of spun fiber.

Ultrarapid soldering Cf/Al by inactive solder by ultrasonic assistance

Ultrasonic vibration was applied when soldering carbon fiber-reinforced aluminum composites (Cf/Al) in this work. The effects of ultrasonic action time on joint formation, carbon fiber distribution, and mechanical properties of the joints were studied. Results show that, with the assistance of ultrasonic vibration, inactive solder can wet the carbon fiber within dozens of seconds at low temperature (250 °C). Short ultrasonic action time leads to minor erosion of aluminum substrate, thereby restricting the movement of carbon fibers into joint. Extensive erosion of the aluminum occurs with prolonged ultrasonic action time. A uniform distribution of carbon fibers in joint is achieved at 60 s. Wetting of carbon fiber is characterized by amorphous-nanocrystalline oxides on its surface, which can be attributed to the elevated temperature and pressure induced by the cavitation of the solder. Extending ultrasonic time enhances the hardness and the shear strength of the joint. The failure cracks propagate through the substrate when ultrasonic time exceeds 15 s. This work provides referential value when soldering materials with low surface energies.

Study on crack resistance of basalt fiber reinforced asphalt mixture modified by titanate coupling agent based on digital image correlation

Basalt fiber is widely used in pavement engineering for its strong mechanical properties, while its smooth surface can cause it to slip within the asphalt mixture, weakening the overall structure. In addressing this issue, this study explores the application of a titanate coupling agent (TCA) for surface treatment of the fibers. The aim was to enhance the interfacial adhesion between the fiber and the asphalt, consequently improving the crack resistance of the fiber-asphalt mixture. This study delves into the modification mechanism and chemical grafting process of TCA, employing scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Furthermore, digital image correlation (DIC) was utilized to dynamically monitor the semicircular bending test (SCB) specimens under full loading conditions, facilitating a comprehensive evaluation of the damage evolution process. Through comparative analyses of load-displacement profiles, full-field strain, displacement, and crack development, alongside the characterization of the fracture process zone (FPZ), a multi-scale quantitative assessment was conducted on the cracking characteristics of the asphalt mixtures. Throughout the damage evolution process, the toughening and crack-blocking effects of the modified fibers were extensively evaluated. Concurrently, SEM was employed to observe the fiber distribution and microscopic morphology of the fracture surface, shedding light on the mechanism of action of TBF (Treated basalt fiber) from a microscopic perspective. The augmentation of TBFAM (Treated basalt fiber Asphalt Mixture) is systematically elucidated, demonstrating that, in comparison with the other two asphalt mixtures, TBFAM exhibits prolonged microcrack formation time and a slower rate of crack propagation. The strain at the crack initiation point increased by 1.45 %, with a concurrent 2.49 % increase in the high strain area, indicative of its superior crack resistance. TCA facilitates the generation of a biomimetic coating via chemical grafting, thereby enhancing the surface structure of basalt fibers and fortifying the fiber-asphalt interface bonding ability. The favorable surface structure of TBF fosters a three-dimensional network within the asphalt mixture system, offering functionalities such as bridging, adsorption, toughening, and crack prevention. This impedes crack development and further bolsters the stability of TBFAM.

Viscosity‐coupled curing simulation model for L‐shaped composites considering flow and compaction

AbstractComputational methods provide effective tools for the prediction of the curing behavior of composites, especially for large‐scale complex composite structures. The flow‐compaction analysis during curing receives insufficient attention in current studies. In this work, an integrated framework considering the heat transfer, the cross‐linking reaction, the flow and compaction, and the stress–strain module is established. A comprehensive resin flow termination criterion is proposed. L‐shaped composites with a stacking layer of [45/90/−45/0]s were fabricated, and the good agreement between the experimentally measured and the numerically predicted contour data validated the current model. Compared with Hubert's model, the prediction accuracy of the thickness and fiber volume content increases by 4.24% and 3.92%, respectively. Correlation analysis between the fiber volume ratio predicted by numerical methods and experimental results (94% for this method, −41% for Hubert's model) demonstrates the well‐capture of nonuniform fiber distribution in curved composites for the current strategy. The overall framework provides an accurate and promising tool for the prediction of the curing behavior of complex composite components.Highlights An integrated numerical methodology is proposed considering the resin flow and compaction. The viscosity‐temperature coupled feature of resin is considered in the permeability coefficients. A comprehensive resin flow termination criterion is proposed for an accurate prediction. The resin content, thickness, and spring‐in angle of L‐shaped laminates are characterized. The good correlation between the experimental and numerical results validates this method. Compared with the model proposed by Hubert, the prediction accuracy improves.

Research and Development of New Polylactic Acid (PLA) Fiber Concrete Materials and Performance Research

Polylactic acid (PLA) fiber concrete has broad application prospects in the field of building materials. This article summarizes the current research status of fiber-reinforced concrete and its importance in improving the mechanical properties of cement-based materials. In view of the modification of the physical properties of PLA fiber, experimental research is conducted to improve its mechanical properties, solve the problem of natural degradation, and explore the application of anti-corrosion materials. In terms of concrete preparation technology, experiments were carried out to study uneven fiber distribution and compatibility with cement slurry to determine the optimal proportion and processing technology. Mechanical property tests and theoretical studies have shown that fiber type and length have a significant impact on the performance of concrete, and it is necessary to further explore the mechanical properties of the transition zone between the fiber and the concrete matrix. Aiming at the durability, fire resistance and other issues of PLA fiber concrete, relevant experimental research plans were proposed. Finally, the mechanical properties of ultra-high toughness PLA fiber concrete were optimized by improving the mix design, optimizing fiber type and dosage, and surface treatment technology. These research results provide an important reference for the wide application of ultra-high toughness PLA fiber concrete in building structures.

Investigative studies on natural fiber reinforced composites for automotive bumper beam applications

The automotive sector wants lighter, recyclable, degradable, and sustainable composite materials. In the last few decades, natural fiber composite has been used in a wide range. The natural plant-based fibers are reinforced into polymeric composite materials, giving significant mechanical properties compared to conventional material. This work selects flax and sisal fibers due to higher strength and Young’s modulus. Mechanical behavior such as tensile, flexural, and impact strength are evaluated. Mechanical behavior results are considered in the simulation to determine the performance of an automotive bumper beam. The tensile strength of the flax composite is 90% higher than that of the sisal composite. Flexural strength is 17% higher in a flax composite, whereas energy absorption is nearly identical in a flax and sisal composite. The flax composite has a maximum 204.9 MPa tensile strength, 157.98 MPa flexural strength, and 45 J energy absorption. The mechanical behavior results are validated with simulation results in the ANSYS workbench for static analysis. The results indicate that the flax fiber reinforced composite with 43:57 of a flax-matrix ratio performs better as it can be used as a structural material. A morphological study shows the uniform distribution of matrix material and fiber orientation.