Positive Hybrid Effect Research Articles

Experimental study on the mechanical properties and impermeability of basalt-PVA hybrid fibre reinforced concrete

Numerous studies have indicated that the incorporation of chopped fibres can significantly improve the mechanical properties and durability of concrete. To further explore the effect of chopped basalt fibres, PVA fibres and their hybrid fibres on the improvement of concrete mechanics and impermeability, mechanical property and impermeability tests of chopped basalt fibres/PVA fibres of different lengths and hybrid ratios mixed with concrete of disparate benchmark strengths were carried out. By comparing the characteristic values of each group and their variation rules, the optimal length and hybrid ratio of the fibres were determined. The results show that the enhancement effect of chopped basalt fibres of different lengths on the mechanical and impermeability properties of concrete is different, showing a trend of first increasing and then decreasing. The enhancement effect of chopped basalt fibres on the mechanical and impermeability performance of concrete with different benchmark strengths is better than that of PVA fibres. Compared with those of the C30 plain concrete, the mechanical and impermeability properties of the chopped basalt-PVA hybrid fibre concrete significantly improve to varying degrees. When the proportion of chopped basalt fibres is greater than or equal to the proportion of PVA fibres, a positive hybrid effect on the mechanical and impermeability performance of concrete with the same benchmark strength occurs. With increasing benchmark strength, the enhancement effect of the two types of fibres on the mechanics and impermeability of the concrete decreases. The attenuation range of PVA fibres is greater than that of chopped basalt fibres, and even a reduction in the mechanical and impermeability properties of concrete occurs. This results in the enhancement effect of chopped basalt-PVA hybrid fibres on concrete mechanics as well as a significant decrease in the impermeability. The improvement rates of the compressive performance and impermeability of concrete by a single or a hybrid of the two fibres are highly similar, and the enhancement effect of the fibre compressive performance is significantly greater than that of the impermeability.

Experimental Study on Impact Performance of Basalt-Polypropylene Fiber Reinforced High-Performance Concrete.

To enhance the impact resistance of high-performance concrete (HPC), a novel efficient solution was adopted by incorporating basalt fibers (BF) and polypropylene fibers (PF) as reinforcement materials in this work. To this end, the effects of single BF (BHC) and PF (PHC) as well as their combinations (BPHPC) on the impact energy consumption, ductility ratio, and toughness factor were explored through drop weight impact test of concrete considering fiber volume contents (0.1%, 0.15%, 0.2%) to evaluate the impact resistance of the concrete. The Weibull distribution function model is used to fit the drop weight impact test results and predict the probability of failure. Moreover, the fracture-resistance enhancement mechanism of fiber is analyzed at a microscopic level. Test results showed that the number of impacts resisted by the HPC can follow well the two-parameter Weibull distribution. Compared with the single BF and single PF, the combination of 0.15% BF and 0.1% PF yields favorable impact resistance, thus exhibiting a positive hybrid effect.

Experimental investigation on the mechanical properties of cement mortar containing recycled tire crumbs reinforced with polypropylene, oil palm and banana fibers

The automotive industry discards a large number of end-of-life tires annually, creating a growing global environmental hazard. The incorporation of crumb rubber derived from waste tires into construction materials is considered one of several alternatives for sustainably reusing these waste materials. The addition of fibers as reinforcements would address the typical degradation caused by the crumb rubber in cement composites. Fibers sourced from plants and recycled synthetics offer a practical and eco-friendly reinforcement material that is both cost-effective and easy to procure. However, two challenges emerge from these choices. Firstly, natural fibers exhibit substantial regional variations, resulting in differences in their properties and inconsistent performance. Secondly, recycled materials also demonstrate variation due to disparities in production and manufacturing processes. As a result, incorporating these fibers into cement-based materials has produced conflicting outcomes due to these inherent variations, rendering practical application unfavorable. Therefore, this study attempts to promote the adoption of sustainable practices by addressing the lack of available performance-based data for the utilization of these fiber variants in the design of cement mixtures. The data would allow engineers to integrate these mixtures into commercial designs for practical in-situ construction. A total of 18 novel cement-based mixtures containing different types of fibers, chemical admixture, and discarded crumb waste were formulated and evaluated in fresh and hardened properties. A multifaceted approach was also undertaken to further hybridize the fibers and quantify the synergistic effects within the investigated cement matrice. The results indicate that the incorporation of polypropylene and oil palm fibers enhances compressive and tensile strength, although there is a general weakening observed in flexural strength. In the case of hybrid fibers, a successful combination of polypropylene and banana fibers is evident, showing a positive hybrid effect coefficient compared to a negative coefficient for polypropylene-oil palm fiber combinations.

Experimental investigations on the fatigue behavior of hybrid basalt/glass fiber epoxy composites

AbstractTo expand the applications of hybrid fiber composites in structural engineering applications, it is essential to study their fatigue behavior. The tensile and fatigue performance of unidirectional hybrid basalt/glass epoxy composites made with vacuum‐assisted resin infusion molding are investigated in this research. The sequencing influence on tensile properties was assessed using the two configurations of basalt/glass fiber epoxy hybrid fiber composites, namely GBBBG and BGBGB, having nearly equal volume fractions. According to the test results, hybrid fiber composites showed a positive hybrid effect on their tensile strength. Both hybrid layups showed higher tensile strengths (3.5% to 10.5%) than GFRPs and BFRPs. The GBBBG laminate has slightly higher fatigue resistance than BGBGB laminate under tension–tension (T–T) fatigue. Scanning electron microscopy (SEM) images verify the fatigue failure modes, which include fiber, matrix cracking, delamination, and debonding. The DMA analysis showed the lower adhesion efficiency of hybrid fiber composites, signifying lower damping properties.

EXPERIMENTAL ANALYSIS OF THE EFFECT OF THE WOVEN ARAMID FABRIC ON THE STRAIN TO FAILURE BEHAVIOR OF PLAIN WEAVED CARBON/ARAMID HYBRID LAMINATES

Remarkable advances in the research and development of micro/mini Unmanned Aerial Vehicles (UAVs) seek thin, lightweight and strong materials for their structural applications. As these structures involve various loading conditions in both the in-plane and through-the-thickness directions during their life cycle, the assurance of the structural stability in each direction is deemed mandatory. The woven Aramid fibers as high strain materials (HSM) are known to improve the through-the-thickness impact strength. However, the addition of the HSM can affect the overall tensile behavior of composite laminates. This study investigates the effect of the woven Aramid fiber on the in-plane tensile behavior of Carbon/ epoxy laminates. Laminates are fabricated using an easy and cost-effective Vacuum Assisted Resin Infusion Molding (VARIM) setup. A uniaxial tensile test was conducted to analyze the tensile behavior of Carbon/Aramid hybrid composites. The effect of adding the woven Aramid layer and the Carbon fabric sequence on the tensile modulus, strain to failure and modulus of toughness are investigated in this study. The results revealed that the presence of Aramid has a positive hybrid effect on the failure strain, exhibiting pseudo-ductile behavior with a compromise in the tensile modulus of the virgin Carbon/epoxy laminate.

Study on impact properties of carbon/kevlar fiber hybrid composites

AbstractIn this article, carbon/kevlar hybrid composites were prepared using Vacuum Assisted Resin Infusion (VARI). The sandwich structure with plain carbon weave fabric as the core layer and plain kevlar weave fabric as the surface layer was selected as reinforcement and the solution of epoxy resin and curing agent was selected as matrix. The low velocity impact experiment and compression after impact (CAI) experiment were carried out on the samples at different hybrid ratio and different temperatures, and the mechanical response on the impact loads were analyzed respectively. The results show that the specimen can limit the delamination defect expansion of the surface kevlar fiber as the carbon fiber used as the core layer, which reduce the delamination defect area and improve the impact resistance of the sample. The toughness of the sample improves the brittle failure mode, that is, the sample still has a certain bearing capacity after the load exceeds the maximum strength, the sandwiched composites presents a positive hybrid effect. With the increase of temperature, the matrix was obviously softened, the macromolecular movement in the system was intensified, the three‐dimensional network macromolecular structure of the matrix and the fiber/matrix interface properties were damaged, and the mechanical properties showed an obvious downward trend. As far as the influences of hybrid ratio and temperature on impact behavior of composite are concerned, it lay a theoretical foundation for the industrial application of carbon/kevlar hybrid composites.Highlights The sandwiched structure was used to design the composites, which greatly improves the impact properties of the specimens. The impact properties and compression after impact properties at different hybrid ratios and different temperatures were studied. Based on the hybrid effect and temperature effect, the impact failure mechanism of the sample was analyzed.

Hybrid effect on tensile, flexural, and quasi-static punch shear behavior of jute/ramie and jute/flax reinforced hybrid composites

Abstract The high specific properties and environmental durability of synthetic fibers make them a popular choice for reinforcing lightweight composites. Unfortunately, they are often limited by their poor biodegradability and high cost. Nevertheless, natural fibers are critical in industrial applications due to their environmental and economic benefits. This study investigated the tensile and flexural behavior of natural hybrid jute/ramie and jute/flax composites with different stacking sequences. A quasi-static punch shear test was also performed to understand their deformation behavior. Jute, ramie, and flax composites have also been fabricated for comparison. Tensile and flexural tests showed a positive hybrid effect in some samples, whereas flax–jute hybrid composites in two different stacking sequences exhibited a synergistic effect. While a maximum improvement of 37.99 % was achieved in the tensile test, this rate was 64.81 % in the flexural test with these hybrid composites. According to punch shear experiments, punch geometry and stacking sequence considerably impact punch shear strength, energy absorption capacity, and deformation.

Influence of hybrid steel-polyacrylonitrile fibers on the mechanical toughness and freeze-thaw resistance of sulfoaluminate cement composites

Sulfoaluminate cement (SAC), an environmentally friendly low-carbon cement, is commonly applied for rapid repair and construction. However, limited studies were conducted to elevate the performance of SAC-based materials by using the hybrid fiber modification, especially the durability. This study investigated the mechanical behaviors and freeze-thaw (F-T) resistance of SAC-based materials with hybrid steel-polyacrylonitrile (PAN) fibers, as well as their enhancement mechanism characterized using X-ray computed-tomography (CT) and scanning electron microscope. The results showed that incorporating hybrid fibers remarkably increased the flexural and compressive toughness of mortars, with steel fibers contributing the most critically. The fiber hybridization also significantly enhanced the F-T resistance of mortars, with PAN fiber being the main contributor. Specifically, the use of hybrid fibers caused a 61.0% improvement in the relative dynamic elastic modulus of mortars after 300 F-T cycles. CT scanning demonstrated that incorporating PAN fibers reduced the porosity of mortars and restrained the initiation and propagation of microcracks, while uniformly and randomly distributed steel fibers interspersed between macrocracks. Morphology observation illustrated that PAN fiber addition was conducive to enhance the anchoring force of steel fiber. Accordingly, the hybrid steel-PAN fibers contributed to suppress cracking at different scales and achieved a positive hybrid effect. At last, the results of this work provide a promising design solution for SAC-based composites to achieve better toughness and frost resistance.

Characterization of mechanical properties, efficiency, and design considerations for the additive manufacturing of hybrid composites with continuous fibers

The integration of continuous fibers into additively manufactured plastic components greatly enhances their mechanical properties. Nonetheless, a challenge lies in the limited adaptability of these properties to specific loading scenarios. To address this issue, present research aims to exploit the hybridization of additively manufactured composites, combining diverse fiber materials within a single component. Specifically, fabricating continuous fiber-reinforced hybrid composites through material extrusion enables high flexibility in adapting local fiber materials. To further the understanding of the effects of hybrid fiber reinforcement in additively manufactured plastic parts, this study investigates how distinct stacking sequences in hybrid and non-hybrid PA6-based composite components, reinforced with carbon and glass fibers, affect deformation and failure behavior. Mechanical properties are assessed using tensile, flexural, and impact tests, in conjunction with an analysis of cost and weight efficiency. The results unveil a distinct correlation between stacking sequences and the mechanical properties of additively manufactured composites. While the hybrid samples predominantly exhibit slight negative hybrid effects, a positive hybrid effect of 96.4 % is achieved in terms of impact toughness with an optimized stacking sequence. With the exception of impact strength, specimens reinforced solely with carbon fibers frequently demonstrate a remarkable ratio between mechanical properties, weight, and cost, whereas hybrid composites exhibit a balanced compromise across all tested mechanical properties. Building upon the obtained results, three comprehensive design approaches are introduced and applied, demonstrating the new design possibilities arising from the combination of hybrid composites and additive manufacturing. The developed design approaches and material combinations can be used for a wide range of lightweight construction applications.

Research on the Electrosensitivity and Electrothermal Properties of Intelligent High-Performance Concrete Materials.

In order to enhance traditional building materials, High-performance concrete (HPC) is being modified by adding carbon and basalt fibers with volume contents of 0.75-1.25% and 0.15-0.35%, respectively. The original mechanical properties are maintained while developing the material's intelligent self-sensing and self-heating functions, which are tested for pressure sensitivity and bending sensitivity, and with electrothermal tests. The results demonstrate that carbon fiber can significantly reduce the matrix resistivity of high-performance concrete, reaching the percolation threshold at a content of 1%. The inclusion of basalt fibers in the material results in a decrease in resistivity. However, the addition of mixed fibers leads to improved mechanical-electrical sensitivity under compression and bending, with a positive hybrid effect. The optimal contents for carbon fiber and basalt are 0.75% and 0.3%, respectively. In electrothermal tests, the specimen can reach a temperature of 104.5 °C with a heating rate of 25.86 °C/h, indicating the potential for self-monitoring and the electric melting of ice and snow. These findings provide support for the intelligent improvement of building structures in the new era.

Tensile, impact, and the damping performance of woven flax‐carbon hybrid polyamide biocomposites

AbstractFiber hybridization is suggested to enhance the properties of fiber‐reinforced composites. Regarding the matrix, thermoplastic alternatives to conventional thermosets are needed to balance mechanical performance and sustainability. We combined woven flax and carbon fibers with a polyamide 11 matrix into a hybrid biocomposite and studied its manufacturing process as well as its impact, tensile, and damping properties. Mechanical damage was investigated using scanning electron microscopy and X‐ray computed tomography. Hybridization significantly improved the tensile properties: 233% higher modulus and 432% higher strength than pure flax composites and 19% higher failure strain than pure carbon composites. Additionally, the hybrid composites exhibited a positive hybrid effect with respect to the impact resistance, characterized by higher displacement at maximum impact force and occurrence of combined damage mechanisms. Although the damping behavior of the hybrid composites remained inferior to that of pure flax composites, their damping factor was 20% higher than that of pure carbon composites. These results provide valuable insights into the mechanical performance of carbon‐flax hybrid composites.Highlights Enhanced mechanical performance and impact resistance in woven flax‐carbon/PA11 hybrid biocomposite compared to nonhybrid reference composites. Superior tensile modulus and strength of hybrid biocomposite than pure flax fiber composite, and greater failure strain than pure carbon fiber composite. A positive hybridization effect in impact properties with a greater displacement at maximum force and higher dissipated impact energy, indicating enhanced ductility and fracture toughness. Improved damping behavior in hybrid biocomposite compared to the pure carbon composite.

An experimental and numerical study on the hybrid effect of basalt fiber and polypropylene fiber on the impact toughness of fiber reinforced concrete

As the civil aviation industry advances, higher requirements are put forward for the performance of airport cement pavement. The frequent takeoffs and landing of aircraft will cause continuous and large impact load on airport pavement, and combined with long-term natural factors, there will be various structural diseases. These diseases not only affect the service life of pavement, navigation safety. To enhance the impact resistance and durability of concrete, the incorporation of fiber has proven an effective approach, and basalt fibers (BF) and polypropylene fibers (PF) are selected as reinforcement materials in this study. Firstly, the effects of single BF and hybrid BF and PF on the mechanical properties of concrete were explored through compressive and flexural tests considering fiber volume contents (0.1%, 0.15, 0.2%) and lengths (6 mm, 9 mm, 12 mm). Then, the drop hammer impact test method, recommended by ACI committee 544, was refined to evaluate the impact resistance toughness of concrete. Finally, the numerical simulation of the impact test was established to explain the concrete impact damage mechanism. The results show that under less than 0.15% volume content, the single BF can effectively enhance the compressive strength, flexural strength, and impact resistance of concrete. Compared with the single BF, the combination of 12 mm BF and 6 mm PF yields favorable results, encompassing improved mechanical properties and impact resistance, thus exhibiting a positive hybrid effect. The increase in PF length (9 mm) leads to a reduction in compressive strength but an improvement in flexural strength and impact resistance. The simulation of the impact test is constructed and the accuracy is confirmed by comparing the impact times and failure patterns of the specimens. The tensile damage of plain concrete is much greater than the compressive damage, and the cracks will spread rapidly from the upper surface to the lower surface. Compared with plain concrete, the crack width of hybrid fiber reinforced concrete is larger, but the damage degree is more uniform. Fiber can absorb a large amount of impact energy, reduce the emergence of micro-cracks, and improve the impact toughness and toughness coefficient of concrete.

Effect of fiber volume fraction on hybrid effects of tensile properties of unidirectional aramid/carbon fiber hybrid composites

AbstractAramid/carbon fiber hybrid reinforced polymer (A/CHFRP) composites were prepared via compression molding to obtain carbon‐fiber‐reinforced polymer (CFRP) composites with better toughness. Based on the existing theoretical model, the effects of the carbon fiber volume fraction on the properties of the A/CHFRP were studied using thermal gravimetric analysis (TGA), tensile tests, and scanning electron microscopy (SEM) analysis. According to the TGA results, the hybrid fiber improved the thermal stability of the CFRP. With increasing carbon fiber content, the thermal stability of the A/CHFRP composites also increased. The tensile results showed that the A/CHFRP composite with a carbon fiber volume fraction of 22.7% exhibited “pseudo‐ductility,” with the failure strain 54.09% higher than that of the CFRP composite. With increasing carbon fiber content, the ductility of the A/CHFRP composites decreased. The elastic modulus of the A/CHFRP composites conformed to the prediction model of the rule of mixtures (ROM). The strength was found to fall in the triangular area surrounded by the ROM and the bilinear ROM and exhibited a positive hybrid effect. The SEM results showed that the tensile failure modes of the A/CHFRP composites were mainly fiber and resin matrix debonding and fiber fracture. Brittle fracture of the carbon fibers was observed in the A/CHFRP composites, while aramid fibers appeared to peel off and silk crimp for ductile failure. Thus, this study provides a theoretical basis for toughening CFRPs.Highlights The volume ratio of the two fibers affects the hybrid effect of A/CHFRP. The thermal stability of A/CHFRP increases with increasing carbon fiber content. The carbon fiber volume ratio of 22.7% in A/CHFRP exhibited pseudo‐ductility. A/CHFRP exhibiting a failure strain 54.09% higher than that of the CFRP. The strength prediction of A/CHFRP depends on the failure mode.

Hybrid effect of polyethylene fibre and nano-calcium carbonate on the flowability and strength of a geopolymer composite

Using geopolymer composites to reduce the use of Portland cement can decrease carbon dioxide emissions. The focus of this study was on improving the strength of a geopolymer composite by assessing the positive hybrid effect of nano-calcium carbonate (NCC) and polyethylene fibres (PFs) of different lengths (6 mm and 12 mm). Fresh and hardened properties, including flowability and strength, were investigated to evaluate the hybrid effect. Generally, the hybrid effects from the PFs of different lengths and NCC were negative for flowability, but the hybrid effects were positive on strength. The combination of 12 mm PF + 6 mm PF + 1% NCC was found to have the highest hybrid effect on bending strength, resulting from the good fibre–matrix bond. The bending strength of the PF-reinforced geopolymer composite was assessed based on a new regression coefficient (A), which takes into account the hybrid effect, the fibre–matrix bond strength and fibre dispersion. The new model for the bending strength of PF-reinforced geopolymer composites introduced in this paper is simpler and more effective than previous models provided in the literature.

Impact Resistance of 3D-Printed Continuous Hybrid Fiber-Reinforced Composites.

Improving the resilience of 3D-printed composites through material extrusion technology (MEX) is an ongoing challenge in order to meet the rigorous requirements of critical applications. The primary objective of this research was to enhance the impact resistance of 3D-printed composites by incorporating continuous hybrid fibers. Herein, continuous virgin carbon (1k) and Kevlar (130D and 200D) fibers were used with different weight and volume fractions as reinforcing fibers to produce hybrid and non-hybrid composites for impact resistance testing to obtain energy absorption with different impact energies: 20 J, 30 J, 40 J, and 50 J. Moreover, 0°/90° fiber orientations were used. Hybrid composites with combinations of PLA + CF + 130D KF and PLA + CF + 200D KF showed higher impact resistance, less damaged areas (71.45% to 90.486%), and higher energy absorption (5.52-11.64% more) behaviors compared to PLA + CF non-hybrids. CT scan images provided strong evidence to resist the fracture and breakage patterns, because the stiffness and elongation properties of the fibers acted together in the hybrids specimens. Furthermore, positive hybrid effects of the PLA + CF + KF hybrids also showed an ideal match of toughness and flexibility in order to resist the impacts. In the future, these hybrids will have the potential to replace the single type of composites in the fields of aerospace and automobiles.

An investigation of the hybrid effect of pre-absorbed lightweight aggregate and basalt-polypropylene fiber on concrete performance

Although fibers have been extensively adopted to modify the mechanical performance of concrete containing lightweight aggregate (LWA), the composite impact of fibers and LWA’s internal curing has not been addressed yet. In this study, a comprehensive investigation of basalt-polypropylene (BF-PF) fiber reinforced lightweight aggregate concrete was carried out to investigate the interactions between BF-PF fibers and LWA’s internal curing, considering multiple LWA contents and BF:PF ratios. Results showed that adding LWA benefited the flexural strength but lowered the compressive strength, as the multi-pore structure of LWA increased the porosity and pore size of concrete while the internal curing of LWA optimized the overall pore structure. Nonetheless, adding BF-PF fibers could alleviate LWA’s negative effect on compressive strength given that a positive hybrid effect was identified between LWA and BF-PF fibers. The discharged water from LWA benefited cement hydration and contributed to an increased Ca(OH)2 content in the paste and a lowered Ca/Si ratio in the interfacial transition zone, thereby enhancing the bond between BF-PF fibers and the paste. Given a fixed fiber volume, increasing the PF ratio was more conducive to concrete’s post-cracking behavior while increasing the BF ratio benefited concrete’s pore structure. Furthermore, a multi-dimensional evaluation accommodating fresh properties, mechanical performance, pore characteristics, cost and environmental sustainability indicated that a mix of 20% LWA and 0.20% fiber at a BF:PF ratio of 3:1 was the optimum one. The results demonstrate the enhancing mechanism of fiber reinforced lightweight aggregate concrete, providing insight into concrete design in practical engineering.

Hybrid all-cellulose reinforcement in polypropylene matrix biocomposites for injection moulding - influence of particle geometry and volume fraction on hybrid effect

The presented study is focused on evaluation of influence of reinforcement volume fraction and geometry on the occurrence of positive hybrid effect by the hybridisation of man-made cellulose fibres (rayon viscose) with cellulose microparticle fillers applied in polypropylene matrix. Four volume fractions of reinforcement were used at 1:1 combination of short man-made cellulose fibres with cellulose microfillers of different aspect ratio. The highest volume fraction was applied for a comparison of four types of cellulose microfillers characterised by different aspect ratios. Proportional volume content of compatibiliser to volume of reinforcement and manufacturing conditions were maintained for all composites. Positive hybrid effect present in tensile and flexural performance was found to result from different factors such as: favourable combination of reinforcement owing to their similar stress–strain characteristic, decreased void fraction, slightly improved orientation of short rayon viscose fibres in hybrid and reduced relaxation of stresses during deformation.

Mechanical performance of aramid/glass fiber hybrid weft-knitting-reinforced composites under low-velocity impact

In response to the defects of easy delamination, poor impact resistance, and low toughness in laminates, intra-layer aramid/glass hybrid weft-knitted reinforced composites without lamination were designed and prepared. This paper investigated the tensile, bending, and impact response of aramid/glass hybrid weft-knitted reinforced composites. Homogeneous and hybrid composites with glass: aramid hybrid ratios of 1:1, 2:1, 3:1, and hybrid modes of transverse hybrid, oblique hybrid, and vertical interlocking hybrid were prepared by vacuum resin transfer molding (VARTM) technique. The tensile and bending properties were evaluated from stress, modulus, and strain/deflection, and a scanning electron microscope (SEM) was employed. The impact response was analyzed from peak force, maximum displacement, and energy absorption. The results confirm that interlacing brittle glass yarns with aramid yarns exhibits a positive hybrid effect. The ratios of 50%, 33%, and 25% aramid fiber in the transverse hybrid enhanced the longitudinal strength by 72.86%, 52.13%, and 22.01%. The mechanical properties of the oblique hybrid are similar in warp and weft direction; by contrast, the other two hybrid methods demonstrate mechanical anisotropy. This article implements the preparation and mechanical properties research of non-laminated hybrid composites based on weft-knitted structures, which broadens the design and selection of prefabricated components for hybrid composites.

Hybridization effect of silane treated basalt fiber on the mechanical, thermal and morphological properties of polypropylene/bamboo composite

AbstractThe aim of present work summarizes the synergistic effect of basalt fiber on mechanical, thermal and morphological behavior of PP/bamboo composite. The basalt fibers were varied at four different levels 5, 10, 15 and 20 wt% which replaces the bamboo fiber at 40 wt% while keeping both the fibers content constant at 40 wt%. PP/bamboo composite and PP/bamboo/basalt hybrid composites were fabricated through melt compounding of PP (polypropylene), PP‐g‐MA (grafted maleic anhydride polypropylene), alkaline treated bamboo fiber and silane treated basalt fiber, followed by injection molding. The addition of silanized basalt fiber in PP/bamboo composite linearly increased the tensile and flexural related properties while the impact strength decreased with the increase in basalt fiber. Theoretical modeling for tensile strength and modulus indicate the positive hybrid effect of basalt fiber. Results obtained from differential scanning calorimetry (DSC) indicated that the crystallinity of the neat PP increased with the incorporation of both the bamboo and basalt fiber. The Thermal degradation results showed that the PP/bamboo composite degraded earlier while the hybrid composite at 5 wt% basalt fiber showed highest thermal stability as compared to neat PP. Dynamic mechanical analysis (DMA) results exhibited that the viscoelastic properties enhanced with the addition of bamboo and basalt fiber. Scanning electron microscopy (SEM) micrographs on the tensile fractured surface revealed random orientation and wetting of basalt and bamboo fibers in PP matrix.

Tailorable mechanical and energy absorption behaviors of 3D printed continuous hybrid fiber reinforced composites

Abstract3D printing of continuous fiber‐reinforced thermoplastic composites (CFRPCs) has expanded potential structural application in recent years. However, it is still challenging to tailor the mechanical and energy absorption properties of 3D‐printed composites to fulfill the requirements for critical application conditions. Herein, hybrid fiber (HF) reinforced composites have been prepared by 3D printing of CFRPCs and investigated on the mechanical and energy absorption behaviors. Continuous virgin carbon fibers (CF), Kevlar fibers (KF) (130 Deniers (D), and 200 Deniers (D)) and E‐glass fibers (GF) were used as reinforcing fibers to produce hybrid and non‐hybrids composites. Hybrid composites with different combination of CF + GF, CF + 130D KF, and CF + 200D KF showed tailorable behaviors, such as flexural modulus (16,691.74, 20,372.38, and 19,017.44 MPa), tensile modulus (15,022.6, 16,269.41, and 15,320.58 MPa). And energy absorption behaviors of CF + 130D KF and CF + 200D KF were tailored in both tensile (18,865.25 and 20,302.07 N‐mm, respectively) and bending (3594.54 and 3570.80 N‐mm, respectively) tests compared to other composites which will be ideal for energy absorption applications. Moreover, CF + GF showed tailored strength which could be used in the need of high stiffness. SEM images were providing strong evidence to resist the fracture and breakage patterns, by tailoring the stiffness and elongation properties of fibers in hybrids specimens. Furthermore, positive hybrid effects of CF + KF hybrids in tensile and bending tests were also showing an ideal match of toughness and flexibility. In future, these cost and weight effective hybrids will have potential to apply in aerospace and automobile.