Addition Of Short Fibers Research Articles

Mechanical Properties and Performance of 3D-Printed Acrylonitrile Butadiene Styrene Reinforced with Carbon, Glass and Basalt Short Fibers.

This paper presents the results of experimental investigation of the mechanical characteristics of 3D-printed acrylonitrile butadiene styrene (ABS) and its modifications reinforced with different types of short-fiber fillers: carbon, glass, and basalt. Elastic modulus, tensile and bending strength, as well as fracture toughness were determined in series of mechanical tests for samples produced with different manufacturing parameters, such as nozzle diameter and infill angle. It was found that the use of ABS filament reinforced with the short fibers can significantly improve the mechanical properties of 3D-printed devices when the infill angle is oriented along the vector of the applied load. In such a case, the elastic modulus and tensile strength can be increased by more than 1.7 and 1.5 times, respectively. The use of a larger nozzle diameter led to the growth of tensile strength by an average of 12.5%. When the macroscopic load is applied along the normal to the printed layers, the addition of short fibers does not give much gain in mechanical properties compared to pure ABS, which was confirmed by both standard tensile and fracture toughness tests. The surface of the fractured samples was examined using scanning electronic microscopy, which allowed us to make conclusions on the type of defects as well as on the level of adhesion between the polymeric matrix and different types of short fibers.

Effect of Fibres on Physico-Mechanical Properties of Bulk-Fill Resin Composites.

To measure the flexural strength (FS) of bulk-fill resin composites and assess their long-term water absorption and solubility properties with and without the inclusion of short glass fibres. One resin composite, everX Flow with fibres, and four commercially available bulk-fill composites without fibres, namely, PALFIQUE, Activa, SDR Plus, and Filtek Bulk Fill One, were tested. Six specimens (2 × 2 × 25 mm) were fabricated for each material and stored in water for 1 day and 30 days to measure the flexural strength using a three-point bending test. To evaluate water absorption and solubility, circular disks measuring 15 × 2 mm (n = 5) were immersed in water for 60 days, and their weights were recorded periodically. After 60 days, the specimens were dried for an additional 21 days to determine solubility. Flexural strength values ranged from 101.7 to 149.1 MPa. Significant distinctions were observed among the resin composites at the onset of the study (p < 0.05). The highest FS value was identified in everX Flow, while ACT exhibited the lowest (p < 0.05). However, the flexural strength values exhibited a significant decrease with increased storage time (p < 0.05), except for ACT, which demonstrated a noteworthy increase. Concerning water absorption and solubility, ACT displayed the highest absorption, while the range of solubility varied from -0.88 to 5.8 μg/mm3. ACT also had the highest solubility, whereas everX Flow exhibited negative solubility. The addition of short fibres, along with potential differences in matrix composition, enhanced the flexural strength of everX Flow. However, the substantial reduction in flexural strength observed in everX Flow and SDR following exposure to water corroborates the manufacturers' recommendation to apply a conventional resin composite cap on these materials.

Simultaneously improve the mode II interlaminar fracture toughness, flexural properties, and impact strength of CFRP composites with short aramid fiber interlaminar toughening

AbstractThis work mainly focuses on the mode II interlaminar fracture behavior of carbon fiber composite that was interlaminar toughened by short aramid fiber modified epoxy resin. The short fibers were first dispersed in the epoxy matrix and then in the laminate interlayer area during the lamination process. The ENF test evaluated the Mode II interlaminar fracture toughness of laminates. The results show that mode II interlaminar fracture toughness increases with the addition of short fibers. When the fiber content is 10 g/m2, the toughening effect is the best at 2437.72 J/m2, which is about 61.8% higher than the untoughened sample. The toughening mechanism of CFRP laminates by adding short fibers was observed by mode II fracture surface SEM images. In addition, flexural properties and Charpy impact properties of short fiber modified resin interlayer toughened laminates were also studied. The results showed that with this method, flexural properties and impact strength were improved to a certain extent, proving that this method is an effective interlaminar toughening method.

Cracking Diagnosis in Fiber-Reinforced Concrete with Synthetic Fibers Using Piezoelectric Transducers

The addition of short fibers in concrete mass offers a composite material with advanced properties, and fiber-reinforced concrete (FRC) is a promising alternative in civil engineering applications. Recently, structural health monitoring (SHM) and damage diagnosis of FRC has received increasing attention. In this work, the effectiveness of a wireless SHM system to detect damage due to cracking is addressed in FRC with synthetic fibers under compressive repeated load. In FRC structural members, cracking propagates in small and thin cracks due to the presence of the dispersed fibers and, therefore, the challenge of damage detection is increasing. An experimental investigation on standard 150 mm cubes made of FRC is applied at specific and loading levels where the cracks probably developed in the inner part of the specimens, whereas no visible cracks appeared on their surface. A network of small PZT patches, mounted to the surface of the FRC specimen, provides dual-sensing function. The remotely controlled monitoring system vibrates the PZT patches, acting as actuators by an amplified harmonic excitation voltage. Simultaneously, it monitors the signal of the same PZTs acting as sensors and, after processing the voltage frequency response of the PZTs, it transmits them wirelessly and in real time. FRC cracking due to repeated loading ad various compressive stress levels induces change in the mechanical impedance, causing a corresponding change on the signal of each PZT. The influence of the added synthetic fibers on the compressive behavior and the damage-detection procedure is examined and discussed. In addition, the effectiveness of the proposed damage-diagnosis approach for the prognosis of final cracking performance and failure is investigated. The objectives of the study also include the development of a reliable quantitative assessment of damage using the statistical index values at various points of PZT measurements.

Numerical Simulations of Components Produced by Fused Deposition 3D Printing.

Three-dimensional printing technology using fused deposition modeling processes is becoming more and more widespread thanks to the improvements in the mechanical properties of materials with the addition of short fibers into the polymeric filaments. The final mechanical properties of the printed components depend, not only on the properties of the filament, but also on several printing parameters. The main purpose of this study was the development of a tool for designers to predict the real mechanical properties of printed components by performing finite element analyses. Two different materials (nylon reinforced with glass or carbon fibers) were investigated. The experimental identification of the elastic material model parameters was performed by testing printed fully filled dog bone specimens in two different directions. The obtained parameters were used in numerical analyses to predict the mechanical response of simple structures. Blocks of 20 mm × 20 mm × 160 mm were printed in four different percentages of a triangular infill pattern. Experimental and numerical four-point bending tests were performed, and the results were compared in terms of load versus curvature. The analysis of the results demonstrated that the purely elastic transversely isotropic material model is adequate for predicting behavior, at least before nonlinearities occur.

Estimation of thermal conductivity of short fiber composites

The present study deals with estimation of effective thermal conductivity of short fibers with polymer composites. This work proves enhancing the thermal conductivity property of composites can be achieved with the addition of short fibers (glass) whose thermal conductivity is more than the matrix material. In this work short glass fibers of 3 mm in length used and added in a proportions ranging of 0%, 2%, 4%, 6% by volume fraction and polyester resin as matrix material and have been prepared by simple hand Lay-up technique. The apparatus is used to find thermal conductivity is Lee’s Disc apparatus. And to validate the apparatus, experiment has been carried out to determine the thermal conductivity of existing material (glass) whose thermal conductivity is known. Thus experimentally determined values of the composite are then compared with the analytical models such as Rule of mixture (ROM), Maxwell model and Bruggeman model. Further finite element analysis (FEA) is used to determine effective thermal conductivity of the composite materials using commercially available software ABAQUS. From the obtained experimental results, numerical results and FEA results, it can be observed that there is a gradual increase in effective thermal conductivity of the composites with the addition of glass fiber content. This study also proves that FEA is a best method to validate and to compare with experimental results of the investigation. And with this unique increased thermal conductivity property and light weight composites can be used in many sophisticated applications.

IMPACTS ON MECHANICAL PERFORMANCE OF STRUCTURAL CONCRETE REINFORCED WITH SISAL FIBERS

It is a laboratory research with the objective of studying the viability of the use of sisal fibers in the structural concrete composition, studying its influence on the mechanical performance of the concrete. The tests were performed to measure the strength of two cementitious matrices, one conventional and one with addition of the fibers, in relation to tensile stresses in flexion, axial compression and water absorption, and, finally, a comparison was made between the obtained results. The tests showed that the addition of short fibers of sisal provided an increase of 18.62% in the characteristic compressive strength and 30% in the flexural tensile strength; it was also observed that this addition made the concrete mixture drier.

Mechanical Properties of Short Fiber-Reinforced Geopolymers Made by Casted and 3D Printing Methods: A Comparative Study.

The main objective of this article is to develop ceramic-based materials for additive layer manufacturing (3D printing technology) that are suitable for civil engineering applications. This article is focused on fly ash-based fiber-reinforced geopolymer composites. It is based on experimental research, especially research comparing mechanical properties, such as compressive and flexural strength for designed compositions. The comparison includes various composites (short fiber-reinforced geopolymers and plain samples), different times of curing (investigation after 7 and 28 days), and two technologies of manufacturing (casted and injected samples—simulations of the 3D printing process). The geopolymer matrix is based on class F fly ash. The reinforcements were green tow flax and carbon fibers. The achieved results show that the mechanical properties of the new composites made by injection methods (simulations of 3D technology) are comparable with those of the traditional casting process. This article also discusses the influence of fiber on the mechanical properties of the composites. It shows that the addition of short fibers could have a similar influence on both of the technologies.

Research Of Mixer Rotors Speed On Mixing Process Of Short Fiber-rubber Composites

Mixer rotor speed is one of the important factors which effects the mixing process and mixer rotor speed of SFRC greatly. The effects of different mixer rotor speed on mixing process of SFRC have been researched by experiments. In the paper, the mixer rotor speed was changed from 50rpm to 80rpm respectively. And also the addition of short fibers was about 0phr∼6phr. The experimental results indicated that SFRC had better physical and mechanical properties as mixer rotor speed was about 70rpm, and the addition of short fibers was about 3phr.

Effects Of Roof Bolt Pressure On Properties Of Short Fiber And Rubber Composite Material

Roof bolt pressure is one of the important factors which impacts the mixing process and roof bolt pressure of SFRC greatly. The effects of different roof bolt pressure on mixing process of SFRC have been researched by experiments. In the paper, the roof bolt pressure was changed from 0.3MPa to 0.6MPa respectively. And also the addition of short fibers was about 0phr∼6phr. The experimental results indicated that SFRC had better physical and mechanical properties as roof bolt pressure was about 0.6MPa, and the addition of short fibers was about 3phr.

Experimental study on preparation of short fiber and rubber composites using top ram pressure

Top ram pressure is one of the important factors, which impacts the mixing process and top ram pressure of SFRC greatly. The effects of different top ram pressure on mixing process of SFRC have been researched by experiments. In the paper, the top ram pressure was changed from 0.3MPa to 0.6MPa respectively. And also the addition of short fibers was about 0phr∼6phr. The experimental results indicated that SFRC had better physical and mechanical properties as top ram pressure was about 0.6MPa, and the addition of short fibers was about 3phr.

Research of Physical and Mechanical Properties of SFRC by Top Ram Pressure

Ram pressure is one of the important factors which impacts the mixing process and top ram pressure of SFRC greatly. The effects of different top ram pressure on mixing process of SFRC have been researched by experiments. In the paper, the top ram pressure was changed from 0.3MPa to 0.6MPa respectively. And also the addition of short fibers was about 0phr~6phr. The experimental results indicated that SFRC had better physical and mechanical properties as top ram pressure was about 0.6MPa, and the addition of short fibers was about 3phr.

Experimental study of cooling water temperature on properties of short fiber and rubber composites

Cooling water temperature is one of the important factors, which effects the mixing process and cooling water temperature of SFRC greatly. The effects of different cooling water temperature on mixing process of SFRC have been researched by experiments. In the paper, the cooling water temperature was changed from 20°C to 50°C respectively. Also the addition of short fibers was about 0phr∼6phr. The experimental results indicated that SFRC had better physical and mechanical properties as cooling water temperature was about 40°C, and the addition of short fibers was about 3phr.

Effects of Cooling Water Temperature on Physical and Mechanical Properties of SFRC

Cooling water temperature is one of the important factors which effects the mixing process and cooling water temperature of SFRC greatly. The effects of different cooling water temperature on mixing process of SFRC have been researched by experiments. In the paper, the cooling water temperature was changed from 20°C to 50°C respectively. And also the addition of short fibers was about 0phr∼6phr. The experimental results indicated that SFRC had better physical and mechanical properties as cooling water temperature was about 40°C, and the addition of short fibers was about 3phr.

Investigation on mechanical properties of pineapple leaf–based short fiber–reinforced polymer composite from selected Indian (northeastern part) cultivars

The natural fiber–reinforced polymer composites gaining substantial importance in recent years due to their unique properties compared to synthetic composites. In India (especially northeastern part), cultivars and industries mostly focus on pineapple fruits, leaving leaf to mainly compost or burn and decay as an agro waste. In this article, pineapple leaf–based (variety type Kew or Giant Kew from Silchar, Assam, India) short fiber–reinforced polymer composites as a function of fiber composition and composite thickness on mechanical properties are analyzed. In this regard, short pineapple leaf fibers (≈ 1 mm to 2 mm) as reinforcement + epoxy resin (Lapox (L12) resin + K6 hardener) as matrix material are used for composites. Subsequently, six different fiber compositions (as 0, 1, 5, 10, 15, and 20 wt%) with composite specimen’s thickness (as 3 and 5 mm) are prepaid. Later, mechanical properties like tensile strength, flexural strength, and toughness and hardness values for each of the composite specimens are evaluated. The result shows that the addition of short fiber can improve the mechanical properties and found in all the cases composites with 10% of reinforcement + at 5-mm thickness show better performance than the other combinations.

Flexural response of basalt textile reinforced concrete with pre-tension and short fibers under low-velocity impact loads

The flexural properties of basalt textile reinforced concrete (BTRC) specimens with pre-tension, short carbon, steel, and AR-glass fibers were investigated through three-point bending in a utilizing drop-weight impact setup. The flexural impact parameters, such as flexural strength, flexural modulus, ultimate strain, maximum strain, and energy absorption capacity, were determined under different impact velocities. The flexural strength and toughness of the BTRC specimens without pre-tension significantly increased when the impact velocity (1.0–3.0 m/s) and layers of basalt textiles were increased. By contrast, the flexural modulus initially increased and subsequently decreased with increasing impact velocity, whereas the loading rate exerted a marginal influence on the ultimate strain and the maximum strain. When the basalt textile had four reinforcement layers, the BTRC reinforced with 0.5 vol% of short carbon fiber or short steel fiber exhibited varied different flexural responses under different impact velocities (1.0–4.0 m/s); in particular, the BTRC reinforced with short steel fibers had a higher maximum strain. In addition, pre-tensioned BTRC with different short fibers were tested under an impact velocity of 1.0 m/s. The flexural strength decreased as the short carbon fiber and glass fiber contents increased. The highest flexural strength was observed in the pretensioned specimen with 0.5 vol% of short glass fiber and three layers of basalt textile. The addition of short fibers in cement matrix, the number of textile layer used as reinforcement, the pretension on textile, and the impact velocities used in the tests can significantly affect the flexural impact behavior of BTRC specimens. The Weibull parameters were analyzed to quantify the degree of variability in the flexural strength.

Replacing stitching and weaving in natural fiber reinforcement manufacturing, part 1: mechanical behavior of unidirectional flax fiber composites

ABSTRACTThis paper presents a novel natural fiber reinforcement manufacturing approach, based on a combination of short flax fibers and unidirectional flax yarns inspired by a papermaking process. The short fibers are used as a binder, replacing weaving and stitching used in textile-based reinforcements. The tensile and compressive properties of three different composites, in both longitudinal and transverse directions, were studied in order to highlight the effect of the mat binder. The presence of short fibers in the composite resulted in a slight decrease of about 10% of the longitudinal tensile modulus and strength. However, the transverse tensile properties are almost doubled. A similar trend was obtained in compression loading, where the addition of short fibers decreases the compressive modulus and strength. Particularly, the compressive strength in the yarn direction was more influenced by the presence of short fibers and was reduced by 30% compared to a decrease of 10% in the case of tensile loading. Here again, the transverse modulus was slightly increased, even if no effect was observed on the transverse compressive strength. The presence of the short fibers also shows a significant positive effect on the fracture behavior in tensile loading. The fractured surface is more uniform and presents a reduction of the splitting and crack formation along the unidirectional yarn direction.

Mechanical and tribological properties of short glass fiber and short carbon fiber reinforced polyethersulfone composites: A comparative study

Abstract The polyethersulfone (PES) composites incorporated with short carbon fibers (SCFs) and short glass fibers (SGFs) were manufactured, and their mechanical and tribological properties were comparatively investigated. The tensile and flexural strengths of SCF/PES composites increase monotonically with increasing the SCF content while those of the SGF/PES composites initially increase dramatically but the strengths approaches a plateau when the SGF content is over 5 vol%. The Young’s and flexural moduli of both SGF/PES and SCF/PES composites exhibit a monotonic increase behavior with increasing the fiber content and achieve the maximum improvements of 128.7%, 227.2%, 165% and 234% with the introduction of 30 vol% short fibers. The addition of SGFs results in a monotonic increase of the friction coefficient and a maximum increase of 48.8% is achieved with 30 vol% SGFs. By contrary, the friction coefficient of SCF/PES composites decreases with the addition of SCFs and a maximum drop of 29.8% compared with that of pure PES is reached with the addition of 20 vol% SCFs. The wear resistance of PES composite is greatly improved by the incorporation of either SGFs or SCFs. The specific wear rates of the PES composites decrease significantly with the addition of short fibers, and the maximum reduction of 71.4% and 95.7% is achieved with the addition of 20 vol% short fibers. When cost is primary consideration while strength, modulus and tribological performance are secondary considerations for end users, SGFs are superior over SCFs; otherwise; SCFs are superior over SGFs.

Modeling and Predicting the Stress Relaxation of Composites with Short and Randomly Oriented Fibers.

The addition of short fibers has been experimentally observed to slow the stress relaxation of viscoelastic polymers, producing a change in the relaxation time constant. Our recent study attributed this effect of fibers on stress relaxation behavior to the interfacial shear stress transfer at the fiber-matrix interface. This model explained the effect of fiber addition on stress relaxation without the need to postulate structural changes at the interface. In our previous study, we developed an analytical model for the effect of fully aligned short fibers, and the model predictions were successfully compared to finite element simulations. However, in most industrial applications of short-fiber composites, fibers are not aligned, and hence it is necessary to examine the time dependence of viscoelastic polymers containing randomly oriented short fibers. In this study, we propose an analytical model to predict the stress relaxation behavior of short-fiber composites where the fibers are randomly oriented. The model predictions were compared to results obtained from Monte Carlo finite element simulations, and good agreement between the two was observed. The analytical model provides an excellent tool to accurately predict the stress relaxation behavior of randomly oriented short-fiber composites.

Punching shear behavior of lightweight fiber reinforced concrete slabs

The ultimate behavior of thin reinforced concrete structures, such as slabs, can be governed by punching due to point loads. This premature brittle failure mode can occur in bridge deck slabs, often subjected to severe conditions of loads concentrated in small areas, and characterized by a reduced thickness. In this kind of structures, a proper punching reinforcement is not applicable, but the local and global behavior can be improved by the addition of short fibers. Three full-scale slabs, simulating bridge decks, were tested in the Laboratory of the University of Rome Tor Vergata, to investigate the effect of lightweight fiber reinforced material on the punching shear resistance. Furthermore, ashes coming from the combustion of Municipal Solid Waste (MSW), with pozzolanic reaction, were added to the concrete mix. The obtained results are presented, discussed and compared with the MC2010 provisions.