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One of the most common load modes is flexure. The paper measures and models the flexural strength and modulus of a bio-polyethylene reinforced with thermos-mechanical fibers from corn stover. Moreover, the authors use modified rules of mixtures to evaluate the contribution of the reinforcements to the properties of the composite. It was found a high impact of coupling agent content on the strength of the composites, and materials with a 6% of such agent and 50% of reinforcement increased 181% the strength of the matrix, and 464% its modulus. The obtained values are noticeable higher than polypropylene and some of its composites. Micromechanics analysis shows that the effect of natural fiber reinforcement on the flexural properties of a bio-based PE is similar to the effects on a polyolefin. Thus, the use of fully bio-based composites can be proposed as a substitute for some oil-based polymers, partially bio-based materials, and their composites

Porous yttriastabilized zirconia (YSZ), in a composite with NiO, is widely used as a cermet electrode in solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). Given cycles of high temperature in these energy devices, mechanical integrity of the porous YSZ is critical. Pore morphology, as well as properties of the ceramic, ultimately affect the mechanical properties of the cermet electrode. Here, we fabricated porous YSZ sheets via freezing of an aqueous slurry on a cold thermoelectric plate and quantified their flexural properties, both for as-fabricated samples and samples subjected to thermal shock at 200 °C to 500 °C. Results of this work have implications for the hydrogen economy and global decarbonization efforts, in particular for the manufacturing of SOFCs and SOECs.

Recently, fiber-reinforced, epoxy-based, optically transparent composites were successfully produced using resin transfer molding (RTM) techniques. Generally, the production of structural, optically transparent composites is challenging since it requires the combination of a very smooth mold surface with a sufficient control of resin flow that leads to no visible voids. Furthermore, it requires a minimum deviation of the refractive indices (RIs) of the matrix polymer and the reinforcement fibers. Here, a new mold design is described and three plates of optically transparent glass fiber-reinforced polymers (tGFRP) with reproducible properties as well as high fiber volume fractions were produced using the RTM process and in situ polymerization of an epoxy resin system enclosing E-glass fiber textiles. Their mechanical (flexural), microstructural (fiber volume fraction, surface roughness, etc.), thermal (DSC, TGA, etc.), and optical (dispersion curves of glass fibers and polymer as well as transmission over visible spectra curves of the tGFRP at varying tempering states) properties were evaluated. The research showed improved surface quality and good transmission data for samples manufactured by a new Optical-RTM setup compared to a standard RTM mold. The maximum transmission was reported to be ≈74%. In addition, no detectable voids were found in these samples. Furthermore, a flexural modulus of 23.49 ± 0.64 GPa was achieved for the Optical-RTM samples having a fiber volume fraction of ≈42%., Bundesministerium für Wirtschaft und Klimaschutz

In order to further enhance the reinforcing effectiveness of polypropylene (PP) fibers on pavement concrete, waterborne epoxy (WBE) was introduced in this research and its effect on the flexural properties and freeze–thaw resistance of PP-fiber-reinforced concrete was evaluated. Compressive-strength tests, flexural-strength tests, three-point bending tests, freeze–thaw cycling tests and a scanning electron microscopic observation were carried out to analyze mainly the influence of WBE on the flexural properties and freeze–thaw resistance of PP-fiber-reinforced concrete. WBE contents of 0, 5%, 10%, 15% and 20% by weight of the cement were employed. The experimental results indicated that WBE was beneficial to improving the flexural properties of PP-fiber-reinforced concrete. With increasing content of WBE, the flexural strength and the peak load showed significant increases. Although a slight degradation in the abovementioned flexural parameters was observed when the WBE content was above 15%, the deflection at the peak, the fracture energy and the fracture toughness still showed an upward trend. In addition, the freeze–thaw resistance of PP-fiber-reinforced concrete was improved remarkably with the increasing addition of WBE content, leading to smaller mass loss and higher residual flexural strength. Moreover, microstructural images revealed that with the addition of WBE, the PP fiber/concrete interfacial bonding was effectively improved, and the concrete matrix tended to be denser as well, which provided higher resistance for crack initiation and propagation. In consideration of maximally improving the flexural properties of PP-fiber-reinforced pavement concrete, and while ensuring the compressive strength and meeting the freeze–thaw requirements, it was recommended that the content of WBE in PP-fiber-reinforced concrete should be 15%.

In recent years, serious reduction in petroleum resources and concerns about the usage of synthetic plastics have prompted global communities to accept the use of natural fibres and biopolymers in many products. Lignocellulosic fibre polymer biocomposites have attracted the attention of scientists and engineers because of their wide availability, low carbon emission and biodegradability. Currently, oil palm is one of the main crops cultivated in Malaysia and Indonesia and is regarded as a potential source of lignocellulosic fibres for biocomposites. The cellulosic content of oil palm fibres (OPFs) enhances the mechanical properties of composites. Ensuring the compatibility of OPFs as main constituents with other materials in composites for a specific applications is essential. Mechanical performance in terms of tensile, flexural and impact strength determines an OPF's compatibility. However, no comprehensive reviews focusing on the mechanical properties of OPF biocomposites have been published, and factors influencing mechanical performance, such as interfacial adhesion, stacking sequence, additive, type of polymer and fibre size have not been explored. Some studies have identified the research gaps and deduced that the potential applications of OPFs as reinforcement materials in composites have not been explored.

The development of resin-based composites (RBCs) is a delicate balance of antagonistic properties with direct clinical implications. The clear trend toward reducing filler size in modern RBCs solves esthetic deficiencies but reduces mechanical properties due to lower filler content and increases susceptibility to degradation due to larger filler–matrix interface. We evaluated a range of nano- and nano-hybrid RBCs, along with materials attempting to address shrinkage stress issues by implementing an Ormocer matrix or pre-polymerized fillers, and materials aiming to provide caries-protective benefit by incorporating bioactive fillers. The cytotoxic response of human gingival fibroblast (HGF) cells after exposure to the RBC eluates, which were collected for up to six months, was analyzed using a WST-1 assay. The microstructural features were characterized using a scanning electron microscopy and were related to the macroscopic and microscopic mechanical behaviors. The elastic-plastic and viscoelastic material behaviors were evaluated at the macroscopic and microscopic levels. The data were supplemented with fractography, Weibull analysis, and aging behavioral analysis. The results indicate that all RBCs are non-cytotoxic at adequate exposure. The amount of inorganic filler affects the elastic modulus, while only to a limited extent the flexural strength, and is well below the theoretical estimates. The nanoparticles and the agglomeration of nanoparticles in the RBCs help generate good mechanical properties and excellent reliability, but they are more prone to deterioration with aging. The pre-polymerized fillers lower the initial mechanical properties but are less sensitive to aging. Only the Ormocer retains its damping ability after aging. The strength and modulus of elasticity on the one hand and the damping capacity on the other are mutually exclusive and indicate the direction in which the RBCs should be further developed.

In this study, the effects of the post-ultraviolet-curing process on the flexural, absorptive, and morphological properties of poly(lactic acid) specimens produced using a fused deposition modelling technique 3D printer were experimentally investigated. In this direction, 15, 30, 45, and 60 min post-UV-curing processes were applied to poly(lactic acid) three-point bending and absorption specimens produced at 190 and 200 °C. Three-point bending tests and morphological analyses were applied after the post-ultraviolet-curing process, and absorption tests were applied by immersing the post-ultraviolet-cured specimens in a distilled water bath for 1-, 3-day, and 1-, 2-, and 4-week exposure times. The changes in flexural strain properties for each experimental parameter were also simulated by the computer-aided finite element analysis and compared with the experimental results. It was observed that the post-ultraviolet-curing process increased the flexural strength of the poly(lactic acid) specimens produced at both 190 and 200 °C with the same increasing trend up to 30 min of exposure, and the most significant increase was determined in the specimens that were subjected to post-ultraviolet-curing for 30 min. Although the flexural strengths of the post-ultraviolet-cured specimens were higher than the non-cured specimens in all conditions, it was detected that they tended to decrease after 30 min.

The formulation and flexural properties of thin fly ash geopolymers with thickness of merely 10 mm and replacement of ladle furnace slag to fly ash in thin geopolymer were presented. The formulation was discussed in terms of NaOH molarity, solid aluminosilicates-to-liquid alkali activator (S/L) mass ratio, and alkali activator (Na2SiO3/NaOH) mass ratio. Thin fly ash geopolymers with flexural strength and Young's modulus of 6.2 MPa and 0.14 GPa, respectively, were obtained by using 12 M NaOH, S/L ratio of 2.5 and Na2SiO3/NaOH ratio of 4.0. A high Na2SiO3/NaOH ratio was implemented for thin geopolymer synthesis to produce a more viscous slurry which helped to retain the shape of a thin geopolymer. The incorporation of ladle furnace slag up to 40 wt.% reported an increment of 26% in flexural strength up to 7.8 MPa as compared to pure fly ash geopolymers and the stiffness was increased to 0.19 GPa. Denser microstructure with improved compactness was observed as the ladle furnace slag acted as the filler. New crystalline phases of calcium silicate hydrate (C–S–H) were formed and coexisted with the geopolymer matrix, which consequently enhanced the flexural strength of thin fly ash geopolymer. This proved that the ladle furnace slag has the potential to be utilised in geopolymer synthesis and will enhance the flexural properties of thin geopolymers. The flexural performance of thin geopolymers in this study was considerably good as the thin geopolymers exhibited comparatively similar flexural strengths, but a higher strength/thickness ratio as compared to geopolymers with thickness greater than 40 mm.

Syntactic foam made from hollow glass microspheres (HGM) in an epoxy matrix has proven to be a good material with a strong structural strength. Understanding filler particle size variation is important in composite material formation, especially in syntactic foam, because of its numerous applications such as aerospace, marine, and structural purposes. In this present work, the effects of particle variation in different sizes (20–24 µm, 25–44 µm, 45–49 µm, and 50–60 µm) on the mechanical properties of the syntactic foam composites with a focus on flexural strength, modulus, and fracture surfaces are investigated. The particle sizes are varied into five volume fractions (5, 10, 15, 20, and 25 vol%). The results show that the highest flexural strength is 89 MPa at a 5 vol% fraction of 50–60 µm particle size variation with a 69% increase over the neat epoxy. This implies that the incorporation of HGM filler volume fraction and size variation has a strong effect on the flexural strength and bending modulus of syntactic foam. The highest particle size distribution is 31.02 at 25–44 µm. The storage modulus E’ increased at 30 °C, 50 °C, and 60 °C by 3.2%, 47%, and 96%, respectively. The effects of wall thickness and aspect ratio on the size of the microstructure, the fracture surfaces, and the viscoelastic properties are determined and reported accordingly.

The natural fine aggregate was totally replaced by recycled fine aggregate (RFA) containing crush dust to prepare recycled high ductility cementitious composites (R-HDCC) for making full use of waste concrete and obtaining better properties. A total of 45 slab specimens in 15 groups were manufactured to systematically investigate the effects of RFA particle size distribution, RFA-binder ratio (R/B), water-binder ratio (W/B), fiber volume fraction (Vf), fly ash content (FA/B) and fiber length (Lf) on the flexural properties of R-HDCC through the third-point test. The results showed that the specimens with the RFA containing crush dust and smaller particles performed best due to the denser matrix. The specimens with a moderate R/B of 0.4 had the highest peak flexural stress whereas the specimens with a smaller R/B of 0.2 had a higher ductility and energy absorption ability. The peak flexural stress and ductility decreased with the increase in W/B, but the fiber strengthen effect was greatest for specimen with a moderate W/B of 0.35. The peak flexural stress of specimen increased continuously as Vf increased from 0 to 2.0% whereas the ductility and energy absorption ability reached maximum when Vf increased to 1.5%. Small amount of fly ash could slightly improve the peak flexural stress of specimen while the achievement of higher ductility and energy absorption ability needed a higher FA/B. Finally, the prediction models of peak flexural stress and ductility ratio of R-HDCC were proposed, which showed good agreements with test results.

It is known that carbon fibre–reinforced aluminium laminate is the third generation of fibre metal materials. This study investigates the response of carbon fibre–reinforced aluminium laminates (CARALL) under tensile loading and three-point bending tests, which evaluate the damage initiation and propagation mechanism. The 2D Hashin and 3D Hashin VUMAT models are used to analyse and compare each composite layer for finite element modelling. A bilinear cohesive contact model is modelled for the interface failure, and the Johnson cook model describes the aluminium layer. The mechanical response and failure analysis of CARALL were evaluated using load versus deflection curves, and the scanning electron microscope was adopted. The results revealed that the failure modes of CARALL were mainly observed in the aluminium layer fracture, fibre pull-out, fracture, and matrix tensile fracture under tensile and flexural loading conditions. The 2D Hashin and 3D Hashin models were similar in predicting tensile properties, flexural properties, mechanical response before peak load points, and final failure modes. It is highlighted that the 3D Hashin model can accurately reveal the failure mechanism and failure propagation mechanism of CARALL.

Hybrid composite samples with different carbon and glass fiber layers arrangement were produced by resin transfer molding (RTM) in an attempt to disclose the effects of low temperature on their flexural and low velocity impact behavior. Flexural tests were carried out at T = −50°C and the failure modes were examined, while impact tests, always at T = −50°C, were performed at penetration and at indentation in the range from 10 J to 30 J. The damage extension was accurately evaluated by ultrasonic non-destructive testing. The results were then compared with the room temperature ones obtained in a previous paper to highlight the influence of the temperature. The compression after impact tests were carried out at room temperature for samples previously impacted at both room and low temperature to assess the damage tolerance of the different hybrid configurations. Stacking sequence was found to govern both the flexural and impact behavior of laminates. At low temperature, the flexural strength and modulus values improved over the corresponding room temperature values irrespective of the stacking sequence, while an easier damage propagation and less residual strength were detected in dynamic loading.

Purpose: The objective of this study was to evaluate the physical and mechanical properties of a short fiber-reinforced resin composite: everX-Posterior and compare it with two bulk-fill composites, namely, Filtek Bulk-fill and Beautifil-Bulk, which are intended for large posterior restorations. Methods: Investigated properties were flexural strength, flexural modulus, surface roughness, volumetric shrinkage and depth of cure. Scanning electron microscopy images of each specimen after the flexural test were used for cross-sectional comparison. Results were analyzed using ANOVA following Tukey post-hoc test. Results: Flexural strength of everX-Posterior was comparable with two other resin composites, showing higher flexural modulus. EverX-Posterior showed the highest surface roughness after polishing and the lowest volumetric shrinkage (2.29%) among all composites used in this study. Data also showed that the everX-Posterior depth of cure was 4.24 mm, which was the highest among the three groups. Conclusion: Based on the results of this study, it was concluded that everX-Posterior as a short fiber-reinforced composite showed improvements and satisfactory performance in mechanical and physical properties, which make it a reliable base material candidate for large posterior restorations., Journal of Oral Science, 63(2), pp. 148-151; 2021

Near infrared spectroscopy is non-invasive and may be applied as a rapid and cost effective technique for assessment of quality parameters of timber. Near infrared spectra of Tectona grandis (teak) wood samples were collected before measuring physical (density, equilibrium moisture content) and strength (flexural and compressive) properties using conventional methods. Partial least squares regression was used to develop calibration models between measured wood properties and near infrared data. The best near infrared spectra pre-processing methods differed by property. Linear calibration models with high R², low error and high ratio of performance to deviation values were observed from partial least squares analysis for different wood properties. These linear models may be applied for rapid and precise estimation of the properties examined in testing and evaluation procedures for commercially valuable teak wood.

Employment of natural fiber for the filament of fused deposition modeling (FDM) can be found in numerous studies from different areas. However, the presence of fiber such as kenaf in polymer filament could cause mechanical properties degradation with regard to the fiber loading owing to low compatibility between natural fiber and polymer matrix. Therefore, this study aims to study the mechanical properties of three-dimensional (3D)-printed structures of composites specimens with varying volume percentages of kenaf fiber. From the tensile and flexural testings, the findings revealed decrements in the tensile strength and modulus of kenaf fiber-reinforced ABS (KRABS) composites from 0 to 5% contents of kenaf fiber which were 23.20 to 11.48 MPa and 328.17 to 184.48 MPa, respectively. The raising amount of kenaf fiber at 5 to 10% raised the tensile strength and modulus from 11.48 to 18.59 MPa and 184.48 to 275.58 MPa, respectively. Flexural strength and modulus of KRABS composites were decreased at to 5% from 40.56 to 26.48 MPa and 113.05 to 60 MPa, respectively. With further kenaf fiber addition from 5 to 10%, the flexural strength and modulus were increased from 26.48 to 32.64 MPa and 60 to 88.46 MPa, respectively. These results were supported by the finding from the morphological analysis, where the presence of porosity and fiber pull out implied the poor interfacial bonding between kenaf fiber and ABS matrix. This study has successfully demonstrated the tensile and flexural performances of different volume percentages of KRABS composites filament for FDM through experimental research.

This paper elucidates the influence of borax decahydrate addition on the flexural and thermal properties of 10 mm thin fly ash/ladle furnace slag (FAS) geopolymers. The borax decahydrate (2, 4, 6, and 8 wt.%) was incorporated to produce FAB geopolymers. Heat treatment was applied with temperature ranges of 300 °C, 600 °C, 900 °C, 1000 °C and 1100 °C. Unexposed FAB geopolymers experienced a drop in strength due to a looser matrix with higher porosity. However, borax decahydrate inclusion significantly enhanced the flexural performance of thin geopolymers after heating. FAB2 and FAB8 geopolymers reported higher flexural strength of 26.5 MPa and 47.8 MPa, respectively, at 1000 °C as compared to FAS geopolymers (24.1 MPa at 1100 °C). The molten B2O3 provided an adhesive medium to assemble the aluminosilicates, improving the interparticle connectivity which led to a drastic strength increment. Moreover, the borax addition reduced the glass transition temperature, forming more refractory crystalline phases at lower temperatures. This induced a significant strength increment in FAB geopolymers with a factor of 3.6 for FAB8 at 900 °C, and 4.0 factor for FAB2 at 1000 °C, respectively. Comparatively, FAS geopolymers only achieved 3.1 factor in strength increment at 1100 °C. This proved that borax decahydrate could be utilized in the high strength development of thin geopolymers.

The price of material is an important factor when selecting the additive polymer procedure. In selective laser sintering (SLS), the price can be reduced by the recycling of material, i.e., with different shares of original and recycled material, as well as by the orientation of the product during manufacturing. Numerous tests warn that orientation in the direction of z axis should be as low as possible to reduce the total price of the product. The product also has to satisfy the influence of atmospheric conditions to which it is exposed during its lifetime, i.e., UV radiation and humid environment. UV light, with sun being its most common source, and average humidity in different parts of the world can be approximately from 20% to 90%, depending on time, day and geographic location. In this work, the test specimens have been made of original, mixed and 100% recycled material and then exposed to the influences of UV radiation and water absorption. After having been exposed to atmospheric conditions for a longer time, the mechanical properties of the polyamide products made by selective laser sintering were tested. The results show that exposure to UV radiation reduces tensile elongation at all ratios of recycled material and orientation of 70–90% except in the z direction, while in flexural deformation it is the other way around. The effect of water was observed only between the 7th–14th day of absorption with a decrease in strength until the deformation did not change.

Fast-cure epoxy resin systems allow being manufacturing of composite parts in minutes. However, the brittle nature of the polymer limits its usage due to crack initiation and growth. Nanofillers are widely used to enhance the epoxy resin’s mechanical performance. However, final mechanical properties are typically governed by the process parameters, including curing temperature and time; therefore, the curing behavior of nano-integrated composites should also be characterized. Thermally exfoliated graphene oxide (TEGO) has a significant influence on the mechanical properties of the polymer matrix, even at low percentages. This study introduced TEGO into the fast cure epoxy resin system, and the cure kinetics was analyzed using dynamic differential scanning calorimetry (DSC). TEGO modification increased the curing time, but the system still maintains fast cure properties. Dynamic mechanical analysis (DMA) illustrated that the glass transition temperature (Tg) of TEGO-fast cure epoxy nanocomposite increased by 10°C. Moreover, flexural tests revealed that flexural stress was increased by 12.85% with even a low percentage of TEGO addition. Fracture surfaces were analyzed by scanning electron microscopy, and toughening mechanisms were addressed.

Present research work deals with the various date palm fibres (DPF) loading (0%, 40%, 50%, and 60% by wt%) as reinforced material in phenolic composites. DPF reinforced phenolic composite were manufactured by hand lay-up technique and characterized mechanical (tensile, flexural and impact), morphological, and dynamic mechanical properties to evaluate optimum fibre loading of composites. It is observed that incorporation of 50% DPF loading improved tensile modulus and impact properties but reduce tensile strength, flexural strength and modulus. Scanning electron microscope investigated the interfacial bonding of fibre and matrix in composites. Storage modulus of DPF composites improved and 50% DPF loading illustrated highest storage modulus. Loss modulus increased when DPF was reinforced, 40% fibre loading showed highest Tg for loss modulus but Tg of 50% fibre loading was very close to the composite with 40% fibre loading. Tan delta of DPF composites display low value whereas increasing the fibre loading, the Tg of damping factor were increased. The obtained results concluded that 50% DPF composites have better mechanical and thermal properties with better interfacial bonding between fibres and matrix. This material can be use as insulation material in buildings, false ceiling and walls.

The increasing interest towards environmentally friendly materials for economic reasons and to comply with ever more stringent environmental requirements has allowed the flax fibres to gain an extraordinary interest in the development of new polymer composites. In fact, among plant fibres, the flax ones, given their low density, are characterised by specific mechanical parameters even higher than those of E-glass fibres. However, the application of composites reinforced with natural fibres remains confined to non-structural components. This matter is due to the requirement of important challenges resolution such as their intrinsic hydrophilicity and poor interfacial adhesion with hydrophobic polymer matrices, widely used for their easy processability, economy and lightness. In this context, this research has been focused on the flexural and low-velocity impact properties of polypropylene-based laminates, containing woven flax fibres and subjected to a pre-selected hygroscopic ageing protocol. The presence of a coupling agent, polypropylene-grafted-maleic anhydride, was considered too. Mechanical results, integrated with micrographic observations and visual inspections, provide useful details about the potential use of the studied materials already screened in the nautical field.

The quantitative study of the structure and properties relationship in cellular materials is mostly limited to cell diameter, cell density, skin layer thickness, and cell size distribution. In addition, the investigation of the morphology is generally carried out in two dimensions. Therefore, the interrelation between morphological properties and mechanical characteristics of the foam structure has remained in an uncertain state. In this study, during the physical foaming process, a foam morphology is locally created by using a mold equipped with a core-back insert. The variation in morphology is obtained by modifying the mold temperature, injection flow rate, and blowing agent content in the polymer melt. X-ray microtomography (μCT) is used to acquire the 3D visualization of the cells structure. The Cell Distribution Index (CDI) is calculated to represent the polydispersity in cell size distribution. The relationship between the wide range of morphological qualities and relevant flexural properties is made explicit via a statistical model. According to the results, the morphology, particularly cell shape, characterizes the mechanism of the linear elastic deformation of the closed-cell foams. IR-thermography reveals the bending failure of cellular structures in the tensile region despite the differences in cell diameter.

This paper presents the experimental and analytical studies to investigate the effect of concentrated butt-joints on the flexural properties of laminated bamboo-timber flitch beam (BTFB, or bio-flitch beam). The experimental results reveal that the concentrated butt-joints significantly reduce the flexural strength of the BTFB. They also suggest that the failure mechanism of the BTFB with or without concentrated butt-joints are completely different but less evidence shows an obvious effect of the butt-joints on the modulus of elasticity in bending. In addition, laminated bamboo lumber with concentrated butt-joints is found to be unsuitable for structural applications. The analytical predictions are in close agreement with the experimental results that demonstrate the potentials of the proposed analytical model as a forensic investigation instrument to estimate the strength reduction of the structure, if the butt-jointed laminated bamboo was, unfortunately, used in construction.

The hybridization of natural and synthetic fibers leads to composites’ optimum mechanical properties. In this study, an attempt was made to study the effect of the stacking sequence on PBS-based Glass-Jute (GJ) hybrid composites. Six types of hybrid composite, each containing five different layers of jute and glass fabric, were manufactured by the compression molding method. Mechanical properties, such as tensile, flexural, and impact resistance were studied and analyzed in detail. The surface characterization of the composites was performed through scanning electron microscopic images. The moisture absorption properties were also investigated by immersing the composites in distilled water for one week at ambient temperature. The TGA test was conducted to study their thermal properties. The experimental results showed that the stacking sequence of the fiber layers has a significant effect on the overall performance of GJ hybrid composites. Among the hybrid GJ composites, composites with glass fiber layers on their outer surfaces showed optimum mechanical, thermal, and water resistance properties.

Male brodice uobičajeno se izrađuju od polimernih kompozita ojačanih nerazgradivim staklenim vlaknima. Lanena vlakna usporedivih su mehaničkih svojstava, a uz biorazgradivost njihova je prednost i što se dobivaju iz obnovljivih izvora. U ovom radu izrađeni su kompoziti na bazi epoksidne smole ojačane različitim brojem slojeva biaksijalno orijentiranih lanenih vlakana i istražen je utjecaj broja slojeva na rastezna svojstva kompozita. Analizirana su i savojna svojstva te međuslojna smična čvrstoća. Dobiveni podaci uspoređeni su sa zahtjevima Hrvatskog registra brodova (HRB) za polimerne kompozite ojačane staklenim vlaknima. Istraživanje je pokazalo kako rastezna svojstva i savojni modul neovisno o broju slojeva zadovoljavaju zahtjeve HRB-a. Savojna čvrstoća i prividna međuslojna smična čvrstoća su tek malo niže od propisanih. Kompoziti s više od sedam slojeva vlakana imaju viši maseni udio vlakana i višu istezljivost, a kritična svojstva pri savojnom opterećenju su im slabija nego kod tanjih. Povećanjem udjela smole postigla bi se bolja impregnacija vlakana i uravnoteženost svojstava koja bi zadovoljila zahtjeve HRB-a. Small boats are usually made of polymer composites reinforced with non-degradable glass fibers. Flax fibers have comparable mechanical properties, and in addition to biodegradability, their advantage is that they are obtained from renewable sources. In this paper, composites based on epoxy resin reinforced with different number of layers of biaxially oriented flax fibers were made and the influence of the number of layers on the tensile properties of composites was investigated. Bending properties and interlayer shear strength were also analyzed. The obtained data were compared with the requirements of the Croatian Register of Shipping (CRS) for glass fiber reinforced polymer composites. The research showed that the tensile properties and the bending module, regardless of the number of layers, meet the requirements of CRS. Flexural strength and apparent interlayer shear strength are only slightly lower than prescribed. Composites with more than seven layers of fibers have a higher mass fraction of fibers and higher elongation, and their critical bending properties are weaker than those of thinner ones. Increasing the resin content would achieve better fiber impregnation and a balance of properties that would meet the requirements of CRS.

The paper focused on the experimental characterization of the hybrid composites of basalt, carbon, and glass fibers with epoxy resin. Five different composite panels: name Basalt/Epoxy (BE), Carbon/Epoxy (CE), Glass/Epoxy (GE), Basalt-Glass/Epoxy (BGE), and Basalt-CarbonGlass/Epoxy (BCGE), were manufactured using Vacuum Assisted Resin Transfer Molding (VARTM) techniques in the laboratory of Mechanical Engineering, Konya Technical University. The tensile and flexural tests specimens are prepared using a PST 650 Jigsaw cutter. The sample preparation and testing are per ASTM D3039 and ASTM D7264 standards. The tensile and threepoint tests were conducted using an Instron 8801 universal testing machine with a 100 KN capacity. The tensile stress, modulus of elasticity, and % elongation at the break of BGE hybrid composites are higher than those of GE composites. In addition, the flexural stress and flexural modulus of BGE are higher than the BE composite, which has the lowest flexural properties of other composites.

In this study, a bamboo stick board with rotary-cut bamboo veneers was successfully fabricated. Additionally, vacuum heat (VH) treatment, which is a popular thermal modification method, was used to modify bamboo sticks. Therefore, the effects of different VH treatment temperatures on the dimensional stability and flexural properties of bamboo stick boards with and without bamboo veneers were investigated. For all boards, as the temperature increased to 220 °C, the thickness change rate and equilibrium moisture content decreased, and the flexural properties increased. The results exhibited that VH treatment improved the dimensional stability and flexural properties of the boards. Furthermore, the board with veneers had lower flexural properties and higher thickness swelling after water absorption than the board without veneers (BSB). The results indicated that bamboo veneer caused low flexural properties and high thickness swelling of the board compared to the BSB. However, the bamboo veneer played an aesthetic role in the appearance of the bamboo stick board.

To test the acoustic performance of fiber-reinforced composites for replacing wood, an acoustic vibration test method is developed. For evaluation of the test method, composites are manufactured using hemp and ramie embedded in epoxy, through vacuum-assisted resin infusion molding. The effects of the most important factors, i.e., impulse, relative humidity (RH), and specimen thickness, on the acoustic vibration response of the composites are systematically studied. The magnitudes of the impulses, represented by different masses of the dropping balls, seem to have little influence on the shapes of the acoustic vibration curves, although the intensity of the spectra increases as the impulse increases. The RH influences the spectrum shape significantly due to variation in the Young’s modulus and density of the material upon absorption of moisture. The specimen thickness also greatly affects the testing results. The specific dynamic modulus, acoustic radiation damping coefficient, and acoustic impedance change a little as the impulse magnitude and RH change, but decrease substantially as the specimen thickness increases. The specific dynamic modulus can be linearly correlated with the flexural modulus of a material.

The novel reactive methylmethacrylate (MMA) thermoplastic resin (commercially known as Elium® resin) is the first liquid thermoplastic resin which is curable at room temperature. This resin is a competitive solution against traditional epoxy-based composites. In this work, novel non-crimp (NC) glass fabric/MMA resin composites were manufactured using a vacuum infusion process. Cellulose microcrystals (CMCs) were dispersed in the resin to improve the fibre/matrix interface and the composite properties. CMCs were first dispersed in the resin using an ultrasonication process and then the CMC/MMA resin suspension, mixed with a peroxide initiator, was infused into the reinforcing fabric. The amounts of CMCs dispersed in the resin were 0.5%, 1% and 2% (of the weight of the resin). The influence of CMCs on the interlaminar shear strength (interface), flexural properties, abrasive wear and dynamic-mechanical behaviour was thoroughly investigated. From the mechanical characterisation, it was observed that the addition of 1% CMC to the NC glass/MMA resin composites improved the flexural strength, interlaminar shear strength and wear performance by 30.77%, 38.04% and 22.27%, respectively as compared to the neat glass/MMA resin composite. Above this amount of CMC (i.e., 1 wt%), the properties started to degrade as a result of CMC agglomeration.

Bu çalışma, polivinil klorür (PVC) köpük çekirdek ve E-cam elyaf takviyeli polimer tabakalardan oluşan asimetrik sandviç kirişlerin üç nokta ve dört nokta eğilme davranışları hakkında ayrıntılı bir araştırma sunmaktadır. Sandviç kirişlerin eğilme yükü-sehim davranışı ve hasar mekanizması üzerindeki orta düzlem asimetrisinin etkileri incelenmiştir. Sandviç kirişlerin eğilme ve kayma rijitlik değerlerini hesaba katan basit analitik ifadeler, numunelerin hasar yükünü, kiriş orta-nokta sehmini ve eşdeğer eğilme rijitliğini tahmin etmek için önerilmiş ve deneysel sonuçlar ile doğrulanmıştır. Yükleme yönünü değiştirerek, asimetrik kirişlerin eğilme davranışı kontrol edilebilir. Yükleme tarafında, kalın veya yüksek düzlem içi mekanik özelliklere sahip yüzey tabakasının kullanılması, üst yüzey tabakasında basma hasarı gecikmesine neden olmuştur. Uygulanan formül kayma deformasyonlarını hesaba katmadığı için etkin eğilme rijitliği değerleri yüksek tahmin edilmiştir. Birinci mertebe kayma deformasyon teorisi, elastik bölgede sandviç kirişlerin orta açıklık deplasman değerlerinin tahmin etmek için kullanılmış ve deneysel sonuçlarla iyi bir uyum göstermiştir., This study presents a detailed investigation on the three-point and four-point bending behaviour of asymmetric sandwich beams composed of polyvinyl chloride (PVC) foam core and E-glass fibre reinforced polymer face sheets. The effects of mid-plane asymmetry on the bending load-displacement behaviour and failure mechanism of the sandwich beams were examined. Simple analytical expressions accounting for flexural and shear rigidities of the sandwich beams were proposed to predict the failure load, mid-span deflection and equivalent bending stiffness of the specimens and validated against experimental results. By shifting the loading direction, the flexural behaviour of asymmetric beams may be controlled. On the loading side, the use of face sheet with thick or high in-plane mechanical characteristics resulted in a delay in compressive failure of the top face sheet. The effective bending stiffness was overestimated since the applied formula did not account for shear deformations. First-order shear deformation theory was used to estimate the mid-span displacement values of sandwich beams in elastic regime and showed good agreement with the experimental results.

Polyurethane cement composite is a new organic–inorganic composite material with high strength, corrosion resistance, and fast curing. It is a complement and alternative to traditional cement materials. The flexural properties of polyurethane cement composites are the basic mechanical index of the material. In order to study the flexural properties under different temperature loads, a molecular model was established, the chemical reaction process of polyurethane cement and the temperature response mechanism was analyzed, and the preparation process of polyurethane cement was proposed. Then, bending tests were carried out in strain-controlled mode to obtain the specimens’ bending strength and stiffness modulus under different temperature loads. The test results showed that the tensile strength of polyurethane cement decreased first, then increased, and finally decreased with the increase in temperature, while the bending stiffness modulus decreased with the increase in temperature. Combined with the theoretical derivation, the damage mode of the samples under different temperature loads was analyzed, and the “L-type” damage strain curve was obtained. The results showed that the proposed theory could effectively explain the mechanism of action and flexural properties of polyurethane cement composites under temperature loading, which is a significant improvement to the application of polyurethane cement composites in practical engineering.

Fused Filament Fabrication (FFF) is a popular additive manufacturing process to produce printed polymer components, whereby their strength is highly dependent on the process parameters. The raster angle and infill pattern are two key process parameters and their effects on flexural properties need further research. Therefore, the present study aimed to print test specimens with varying raster angles and infill patterns to learn their influence on the in-plane and edgewise flexural properties of acrylonitrile–butadiene–styrene (ABS) material. The results revealed that the highest in-plane and edgewise flexural moduli were obtained when printing was performed at 0° raster angle. In comparison, the lowest values were obtained when the printing was executed with a 90° raster angle. Regarding the infill pattern, the tri-hexagon pattern showed the largest in-plane modulus, and the quarter-cubic pattern exhibited the greatest edgewise flexural modulus. However, considering both the modulus and load carrying capacity, the quarter-cubic pattern showed satisfactory performance in both planes. Furthermore, scanning electron microscopy was used to investigate the failure modes, i.e., raster rupture, delamination of successive layers and void formation. The failure occurred either due to one or a combination of these modes.

In this paper, experiments and finite element analysis methods were adopted to study the flexural performance of shape memory alloy hybrid composites (SMAHC). The effect of embedding content and position of shape memory alloy (SMA) wire on the flexural properties of composite laminates was analyzed, and the optimal content and position of SMA wire were obtained. The optimal number of SMA wires for SMAHC laminates (B-2) is four. Compared with GFRP laminates, the flexural modulus of B-2-4 laminates increases by 5.19%, while the strength decreases by 5.76% on average. The finite element model of the SMAHC laminate was established by using ABAQUS finite element analysis software, and the validity of the model was verified by the comparison between the simulation results and the experimental results. The microscopic morphology results show that the weak interface between the matrix and SMA has a certain influence on the flexural performance of SMAHC specimens.

Glass fibre-reinforced polyphenylene sulphide composites were prepared by hot-pressing glass fibre fabrics and polyphenylene sulphide resins. The effects of different polyphenylene sulphide resin forms on the properties of the composites were investigated using scanning electron microscopy, dynamic mechanical analyser, pendulum impact tester and universal testing machine. The results showed that different polyphenylene sulphide resin forms had nearly no effect on the glass transition temperature of the composites, which are all located at about 100 °C. Compared with other polyphenylene sulphide composites, the bending strength of polyphenylene sulphide film composites was the highest, reaching 314.58 MPa, and the impact strength of polyphenylene sulphide particle composites was the highest, reaching 245.4 KJ/m2. The bending strength and impact strength were calculated using a standard fraction, and the highest standard fraction was obtained when the ratio of polyphenylene sulphide film to particle was 1:2. The impact strength and bending strength could be obtained. The impact strength reached 229.8 KJ/m2, and the bending strength reached 284.16 MPa.

This work reports on the use of low-cost pineapple leaf fiber (PALF) as an alternative reinforcing material to the established, commonly used material for prosthetic socket fabrication which is carbon-fiber-reinforced composite (CFRC) due to the high strength and stiffness of carbon fiber. However, the low range of loads exerted on a typical prosthetic socket (PS) in practice suggests that the use of CFRC may not be appropriate because of the high material stiffness which can be detrimental to socket-limb load transfer. Additionally, the high cost of carbon fiber avails opportunities to look for an alternative material as a reinforcement for composite PS development. PALF/Methyl Methacrylate-based (MMA) composites with 0°, 45° and 90° fiber orientations were made with 5–50 v/v fiber volume fractions. The PALF/MMA composites were subjected to a three-point flexural test to determine the effect of fiber volume fraction and fiber orientation on the flexural properties of the composite. The results showed that 40% v/v PALF/MMA composite with 0° fiber orientation recorded the highest flexural strength (50 MPa) and stiffness (1692 MPa). Considering the average load range exerted on PS, the flexural performance of the novel composite characterized in this work could be suitable for socket-limb load transfer for PS fabrication.

The reinforcing effect of graphene oxide (GO) in enhancing the flexural strength and flexural modulus of aramid fiber (AF)/epoxy composites were investigated with GO-AFs at a weight fraction of 0.1-0.7%. The flexural strength and flexural modulus of the composite reached 87.16 MPa and 1054.7 MPa, respectively, which were about 21.19% and 40.86% higher than those of the pure epoxy resin, respectively. In addition, the flexural properties and interfacial shear strength (IFSS) of composite reinforced by GO-AFs were much higher than the composites reinforced by AFs due to GO improved the interfacial bonding between the reinforcement material and matrix.

In this study, the graphene nanoplatelets (GNP)/carbon fabric (CF)/epoxy (EP) hybrid laminated composites were fabricated via electrophoretic deposition (EPD) followed by hand lay-up assisted vacuum bagging technique. GNP were dispersed in two different colloidal suspensions, i.e., distilled water (DW) and N-dimethyformamide (DMF), and the effect of EPD GNP onto CF surface were investigated. The finding indicated that the electrophoretic mobility (EM) of GNP is slightly slower in DMF due to the higher viscosity of DMF (0.92 mPa.s) compared to DW (0.89 mPa.s). Zeta (ξ) potential of GNP were slightly higher in DMF, revealing the non-polar behaviour of GNP being easily dispersed in DMF due to its low polar and hydrogen-bonding strength. However, the higher current intensity was observed for the GNP-DW suspension, implying higher dielectric constant of DW adequate for effective deposition of GNP onto CF surface as confirmed via field-emission scanning electron microscopy (FESEM). The GNP-DMF/ CF/EP composites exhibit the highest flexural properties compared to GNP-DW/CF/EP composites. These findings proved the colloidal dispersibility of GNP in DW and DMF suspensions, respectively used in EPD govern the flexural properties of GNP/CF/EP hybrid laminated composites.

To improve the flexural properties of cemented soils reinforced with fibers and avoid their brittle failure when subjected to complex loading conditions, a simple and cost-effective technique was explored to facilitate their application in retaining walls. In this study, how different fiber surface modifications, i.e., alkali treatment, acid treatment and silane coupling agent treatment, as well as different fiber contents, i.e., 0%, 0.25%, 0.5% and 1%, affect the bending properties of cemented soils was investigated by conducting three-point bending tests on notched beams. The digital image correlation (DIC) technology was used to examine the crack propagation process and the strain field distribution of cracks in specimens in the flexural tests. The results show that all fiber surface modifications increased peak strength and fracture energy, for example, the fracture energy of specimens AN1, AH1 and AK1 was increased by 180.4%, 121.5% and 155.4%, respectively, compared to PVA1. In addition, the crack tip strain, crack propagation rate and the initial crack width of the modified specimens were lower than those before modification. Lastly, scanning electron microscope (SEM) and mercury intrusion porosimetry tests were adopted to reveal the mechanism of bending performance in cemented soils reinforced by fiber surface modifications.

Date palm waste is an abundant agricultural residue in Tunisia and can be used for plastic reinforcement. Moreover, its use in plastic composites can help to reduce dependence on fossil resources for material production. In this work, the valorization of date palm residues was studied by employing high-yield processes following mechanical, chemical, and enzymatical treatments. Fibers obtained by soft chemical treatment with sodium hydroxide and enzymatic treatment with xylanases and pectinases were evaluated for their use in the reinforcement of plastic materials. The flexural strength property, truly relevant for structural, construction, automotive, or other market sectors, was adopted to assess the reinforcing potential of the fibers. Polypropylene was effectively reinforced with date palm fibers (60 wt.%), exhibiting a flexural strength increases of 80% (73.1 MPa), 93% (78.5 MPa), and 106% (83.9 MPa) for mechanical, chemical, and enzymatic fibers, respectively. The different treatments had an impact on the chemical composition of the fibers, and by extension on the final properties of the composites. The holocellulose content could provide good interfacial adhesion using a coupling agent, whereas the lignin content improved the dispersion of the phases. Two interesting outcomes were that the flexural performance of enzymatic fibers was like that of wood composites, whereas the specific flexural strength was comparable to that of glass fiber composites. Overall, the present work has shown the potential behind date palm waste in the composite sector when a specific property or application is desired. Novel treatments have been used for greater fiber compatibility, increasing the sustainability of the process, and improving the applicability of the palm residue.

Continuous carbon fibre-reinforced thermoplastic composites have convincing anisotropic properties, which can be used to strengthen structural components in a local, variable and efficient way. In this study, an additive manufacturing (AM) process is introduced to fabricate in situ consolidated continuous fibre-reinforced polycarbonate. Specimens with three different nozzle temperatures were in situ consolidated and tested in a three-point bending test. Computed tomography (CT) is used for a detailed analysis of the local material structure and resulting material porosity, thus the results can be put into context with process parameters. In addition, a highly curved test structure was fabricated that demonstrates the limits of the process and dependent fibre strand folding behaviours. These experimental investigations present the potential and the challenges of additive manufacturing-based in situ consolidated continuous fibre-reinforced polycarbonate.

Environmentally friendly composite plates intended for load-bearing applications were prepared and systematically characterized in terms of mechanical performances and morphological features. Sample plates combining two extrusion grades of bio-polyamide 11, one of which is plasticized, and two basalt fiber fabrics (plain weave and twill architectures) were obtained by film stacking and hot pressing, and their mechanical properties were investigated by quasi-static flexural and low-velocity impact tests. The comparative analysis of the results, also interpreted by the bending damage analysis, through optical microscope observations, and impact damage analysis through visual inspection and indentation measurements demonstrate that, besides interfacial adhesion issues, the mechanical performance of the laminates need to be optimized through a careful selection of the constituents in the light of the final application. In particular, if the goal is a gain in impact strength, the use of the plasticized matrix is beneficial, but it brings about a loss in stiffness and strength that can be partially compensated by properly selecting a more performing fiber fabric architecture. The latter must also be easily permeated by the matrix to enhance the efficiency of stress transfer from the matrix. Overall, our results can be exploited for the development of bio-composites for particularly demanding applications.

ss Superior mechanical properties are the most needed in today’s new-made composites. Epoxy resins good properties make it a good choice to be used for making composites with desired requirements. However often, the inherent properties of the polymer alone are insufficient to meet the structural demands of an application. The major concern for polymeric material is its structural stability under constant loadings for long-term service. Targeting these issues, the current work investigates experimentally the flexural and creep behavior of polymer nanocomposites. For this purpose, different sets of polymer nanocomposites of epoxy resin (EPR) mixed with differing amounts of calcium titanate (CaTiO3) nano-particles and glass fiber (GF) were prepared. The flexural strength, flexural modulus, deflection at the peak were determined. Besides, the creep behavior was monitored by testing different samples for a duration of 24 ​h and the results show that good creep behavior was attended by adding glass fibre. Also, it was noted that the flexural strength at yield increases with increasing filler amount from 1 ​wt% to 7 ​wt%. However, the flexural strength at peak increases with increasing of filler up to 5 ​wt%. Moreover, by adding GF the flexural strength at the peak has a fluctuating change from decreasing to increasing at 0.1 ​wt % GF while adding 0.2 ​wt % of GF gives a continuous increase in strength.

Polymer blends is a well-established and suitable method to produced new polymeric materials as compared to synthesis of a new polymer. The combination of two different types of polymers will produce a new and unique material, which has the attribute of both polymers. The aim of this work is to analyze mechanical and morphological properties of bio-phenolic/epoxy polymer blends to find the best formulation for future study. Bio-phenolic/epoxy polymer blends were fabricated using the hand lay-up method at different loading of bio-phenolic (5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%) in the epoxy matrix whereas neat bio-phenolic and epoxy samples were also fabricated for comparison. Results indicated that mechanical properties were improved for bio-phenolic/epoxy polymer blends compared to neat epoxy and phenolic. In addition, there is no sign of phase separation in polymer blends. The highest tensile, flexural, and impact strength was shown by P-20(biophenolic-20 wt% and Epoxy-80 wt%) whereas P-25 (biophenolic-25 wt% and Epoxy-75 wt%) has the highest tensile and flexural modulus. Based on the finding, it is concluded that P-20 shows better overall mechanical properties among the polymer blends. Based on this finding, the bio-phenolic/epoxy blend with 20 wt% will be used for further study on flax-reinforced bio-phenolic/epoxy polymer blends.

To investigate the residual bending strength of a corroded H-shaped steel beam in an underground coal mining environment, the law governing the degradation of the mechanical properties of corroded steel was first investigated through tensile testing. Subsequently, a four-point bending test was conducted on corroded H-shaped steel beams. The influence of the corrosion rate and sustained loading ratio on the residual bending performance of a corroded H-beam was investigated. The results reveal that the uniform corrosion and uneven corrosion of the steel occurred simultaneously. Additionally, pits with a small size appeared on the steel surface and the number of these pits increased with the corrosion time. Four different fracture modes were observed after the tensile test, and the yield strength and ultimate strength of the corroded steel decreased as the corrosion rate increased. In the bending test, the failure mode of the corroded H-shaped steel beam was not changed by the corrosion. The bearing capacity, stiffness, and ductility of the corroded H-shaped steel beams decreased with the increase in the corrosion rate, and the sustained loading further decreased the bearing capacity. Finally, a simple method for assessing the yield load and ultimate load of corroded H-shaped steel beams is proposed.

Environmentally friendly composite plates intended for load-bearing applications were prepared and systematically characterized in terms of mechanical performances and morphological features. Sample plates combining two extrusion grades of bio-polyamide 11, one of which is plasticized, and two basalt fiber fabrics (plain weave and twill architectures) were obtained by film stacking and hot pressing, and their mechanical properties were investigated by quasi-static flexural and low-velocity impact tests. The comparative analysis of the results, also interpreted by the bending damage analysis, through optical microscope observations, and impact damage analysis through visual inspection and indentation measurements demonstrate that, besides interfacial adhesion issues, the mechanical performance of the laminates need to be optimized through a careful selection of the constituents in the light of the final application. In particular, if the goal is a gain in impact strength, the use of the plasticized matrix is beneficial, but it brings about a loss in stiffness and strength that can be partially compensated by properly selecting a more performing fiber fabric architecture. The latter must also be easily permeated by the matrix to enhance the efficiency of stress transfer from the matrix. Overall, our results can be exploited for the development of bio-composites for particularly demanding applications.

In this paper, the effects of stacking sequence and ply orientation on the mechanical properties of pineapple leaf fibre (PALF)/carbon hybrid laminate composites were investigated. The hybrid laminates were fabricated using a vacuum infusion technique in which the stacking sequences and ply orientations were varied, which were divided into the categories of cross-ply symmetric, angle-ply symmetric, and symmetric quasi-isotropic. The results of tensile and flexural tests showed that the laminate with interior carbon plies and ply orientation [0°, 90°] exhibited the highest tensile strength (187.67 MPa) and modulus (5.23 GPa). However, the highest flexural strength (289.46 MPa) and modulus (4.82 GPa) were recorded for the laminate with exterior carbon plies and the same ply orientation. The fracture behaviour of the laminates was determined by using scanning electron microscopy, and the results showed that failure usually initiated at the weakest PALF layer. The failure modes included fibre pull-out, fibre breaking, matrix crack, debonding, and delamination.

The paper deals with the mechanical degradation of composite material components in seawater at room temperature. In particular, this study compares quasi-static and dynamic behaviour of carbon fiber/vinyl ester components, dry and water saturated in a saline environment at 3% to simulate the seawater exposition. At this regard, short-beam shear, flexural and low-velocity impact tests were systematically performed before and after the conditioning of the material under examination. Finally, the damage of the impacted specimens was carefully analyzed by visual inspections and ultrasound investigations. Despite a very low water absorption, the analyses allow to highlight different phenomena, reflecting on variations in the mechanical properties and in the extent of the damage of the investigated samples.

Chiang Mai Dental Journal, 42, 3, 57-64

The aim of the present study is to evaluate the physical properties of endodontically treated teeth restored with five different restorative techniques and materials. Hundred and forty extracted human molar teeth were used. In addition to five restoration groups, specimens with no restorations were used as the negative control, and intact molar teeth were used as the positive control. For flexural strength tests, material specimens were made from 5 different materials using a mould according to ISO 4049 standards. One-way ANOVA revealed that the fracture resistance was significantly affected by the restoration type. SFRC group showed the best fracture resistance values, while lowest values were seen in the GWF group. The test results of flexural strength showed values between 140 and 184 MPa and modulus of elasticity between 6.33 and 18.89 GPa ( p < 0.05 ). Under the limits of this study, results showed that SFRC can be used to increase the fracture resistance of ETT.

Experimental investigations were carried out to determine the mechanical properties of fine concrete with short AR-glass fibers including the effects of fiber content and length. Also, the basalt fiber textile reinforced concrete (BTRC) sheets with short AR-glass fibers were tested under four-point bending, and the effects of the number of fiber textile layer and fiber length on the flexure properties were emphatically analyzed. The results show that the mechanical properties of fine concrete with fibers were mainly related to fiber length and content, the mechanical properties of fibers reinforced fine concrete increase with the increase of fiber length, and the comprehensive mechanical properties of fine concrete materials are the best when the AR-glass fiber content is about 5%. The flexure performance tests of BTRC sheets show that the strength and the deformation capacity of sheets increase with the increase of the number of fiber textile layers. The short AR-glass fibers can also effectively improve the strength and deformation capacity of BTRC sheets, and the cracking load and ultimate displacement can be respectively increased by up to 106% and 268% compared with BTRC sheets without short fibers. For the multi-fiber compound reinforced concrete sheets, the fiber textile can provide tension in the desired direction, and the short AR-glass fibers can improve the cracking resistance and toughness of sheets.