Flexural Strength Of Samples Research Articles

Reinforcement of cement tiles with palm kernel shell particles as natural fibre

This study focused on the experimental investigation of the effect of palm kernel shell particulate reinforcement on the mechanical properties of cement-based tiles. Five samples of cement tiles reinforced with different compositions of kernel shell of 1440 µm particle size at predetermined moisture content were produced against a control sample to ascertain the composition that offered the best suitable properties for the functional requirements of cement tiles at reduced cost. For all the samples produced, evaluations for bulk density, apparent porosity, water absorption capacity, and flexural strength were investigated. The results showed that porosity, water absorption capacity, and apparent density decreased with an increase in the palm kernel shell compositions while bulked density increased. The variation with 80 % cement and 20 % palm kernel shell fibre reinforcement (Sample B) demonstrated optimal tile quality with apparent porosity of 10.35 %, a water absorption capacity of 5.47 %, bulk density of 1.89 g/cm3, and flexural strength of 37.21 kgF/ cm2 . It was evident that the flexural strength of sample B met the ASTMC293 standard cement tiles requirement of 35 kgF/cm2 to 40 kgF/ cm2 thus the optimal volume fraction with improved surface characteristics and recommended for applications where hard and heavy materials are used on tiles.

Experimental study on mechanical properties of FDM 3D printed polylactic acid fabricated parts using response surface methodology

The purpose of this study is to examine the mechanical properties of components produced through the Response Surface Methodology for polylactic acid, utilizing the Fused Deposition Modeling 3D printing technique. Polylactic acid is a commonly employed biodegradable polymer, making it a desirable substance for diverse applications. This study involves carrying out experiments to vary process printing parameters like layer height or thickness, part orientation, and infill density. The values of these parameters were obtained using a Response Surface Methodology Box–Behnken experimental design. The mechanical performance of the 3D Printed polylactic acid fabricated was assessed by evaluating their flexural and tensile strength. The test samples for measuring tensile and flexural strength are fabricated according to American Society for Testing and Material standards. The findings suggest that higher strength is achieved when using increased layer height and infill levels. The experimental results indicated that specimens with a filling ratio of 80% exhibited greater tensile strength, while the flexural strength of samples with 50% infill was observed to be higher. Regression analyses and multi-optimization techniques were employed to predict the experimental results. This study provides valuable insights that can significantly impact various industries. Our research on the complex interactions between process variables and mechanical properties has major implications for improving high-strength component manufacturing. As demand for dependable and efficient 3D-printed materials rises, our discoveries improve material design and manufacturing methods, making a significant contribution to the field.

Effect of Water-Solid Ratio on Physical Properties of Tobermorite Type Thermal Insulation Materials

In this paper, diatomite is used as the main raw material to prepare tobermorite type thermal insulation material. According to the characteristics of the reaction system, appropriate amount of waste aerated concrete is added to the raw materials. After adding crystal seeds into the reaction system, the crystal of the reaction products is more complete, the crystal grains are larger, and the degree of crystallization is higher. The maximum use temperature of the prepared tobermorite insulation material can reach 750°C - 850°C. If the service temperature continues to rise, the volume will shrink and cracks will easily occur, which is caused by the transformation of internal crystals. After studying the influence of water solid ratio of reaction system on the apparent density, thermal conductivity and flexural strength of samples, it can be seen that 300kg/m3 thermal insulation material can be prepared when the water solid ratio is 15:1. When the water solid ratio is 15:1, the thermal conductivity of the thermal insulation material is 0.077W/(m • K), and the flexural strength is about 0.384MPa.

Mullite Reinforced SiC/Al2O3 Composites Prepared by Microwave Sintering Based on Green Manufacturing

In the preparation process of composites, the implementation of green manufacturing technology has an important impact on improving material properties and preparation efficiency. The adopting of green manufacturing technology not only greatly reduces the energy consumption but also effectively avoids the environmental pollution. Compared with the traditional material preparation process, the material preparation process for green manufacturing is a new concept and idea. Microwave sintering is such an efficient, clean, and pollution-free preparation process, so it is widely used in the field of material preparation. By microwave sintering, the mullite reinforced SiC/Al2O3 composites with different SiC particle size were prepared from the composite powders composed of SiC particles coated with SiO2, by a sol-gel method and Al2O3 particles. The effect of SiC particle size on the microstructure, bulk density, fracture toughness, flexural strength, and thermal shock resistance of SiC/Al2O3 composites was studied. The bulk density, fracture toughness, and flexural strength were evaluated by the Archimedes method, single-side notched beam method, and three-point bending method, respectively. The thermal shock resistance of samples was investigated through the combination of water quenching and three-point bending methods. The results showed that with the increase of SiC particle size, the bulk density, fracture toughness, and flexural strength of samples all increased first and then decreased. The bulk density, fracture toughness, flexural strength, and flexural strength retention of SiC(5 μm)/Al2O3 composites were better than those of other samples, which were 2.06 g/cm3, 1.98 MPa·m1/2, 63 MPa, and 60%, respectively. The better mechanical properties and thermal shock resistance of SiC(5 μm)/Al2O3 composites are due to the formation of bridging mullite whiskers between SiC and Al2O3 particles with large length diameter ratio. Therefore, the unique sintering mechanisms of size coupling effect and local thermal aggregation effect in microwave sintering were discussed. The research results can not only provide reference for the preparation process of mullite reinforced SiC/Al2O3 composites but also for the wide application of microwave sintering technology.

Experiment and molecular dynamics simulation of functionalized cellulose nanocrystals as reinforcement in cement composites

This study evaluated the potential effect of cellulose nanocrystal and coated polyethylene fiber on the mechanical properties of mortar. Two kinds of cellulose nanocrystals (CNC) directly as Nano-materials, and indirectly as film coated onto the polypropylene fibers were employed as cement-based reinforcement materials. The fluidity, flexural and compressive strength, and the microstructure of each specimen were measured. In the direct method, mortar mixed with the CNC containing carboxyl groups (CNC-C) showed superior properties compared to the CNC containing sulfo groups (CNC-S). The addition of CNC impacted the process of hydration and compactness of hydration products. The results of X-Ray polycrystalline diffractometer (XRD) and heat of hydration showed that CNC accelerated hydration process. Energy spectrum analysis (EDS) measured ratio of calcium to silicon (C/S) of calcium silicate hydrate (C-S-H) and proved that CNC-C increased the tightness of C-S-H while CNC-S decreased. The results of scanning electron microscopy (SEM) indicated that cellulose nanocrystals were interspersed in C-S-H, forming Nano-bridge and arresting Nano-crack. In the indirect method, the maximum increase in flexural strength of sample between all groups was the specimen that adding 0.3% (volume ratio of fiber to mortar) of CNC-C coated polypropylene fibers. The flexural and compressive strength of the mortar were increased by 22.81% and 10.65% compared to the control, respectively. The results of SEM indicated that coating enhanced bond of the fibers/matrix. Molecular dynamics simulation (MD) analyzed the binding energy, microstructure, dynamic characteristics and adsorption conformation between two CNCs and C-S-H at the molecular scale. MD presented clearly that the adsorption energy between CNC-S and C-S-H was much smaller than CNC-C and C-S-H. This was identical with CNC-C enhancing the mechanical properties of the mortar and CNC-S reducing the mechanical properties.

Preparation of high-strength porous mullite ceramics and the effect of hollow sphere particle size on microstructure and properties

Porous mullite ceramics with high strength were successfully prepared by protein foaming method with fly ash hollow spheres as raw materials. When sintering temperature was increased from 1450 °C to 1550 °C, short rod-like mullite crystals in three-dimensional skeleton grew into interlocking microstructure, effectively enhancing compressive strength and flexural strength of mullite ceramic samples. Using hollow spheres with smaller particle sizes decreased open porosity of samples. However, the effect on total porosity was negligible. Moreover, smaller hollow spheres promoted a shift in median pore size of samples to smaller diameters (87.01 μm→61.66 μm→54.61 μm→36.81 μm). Both compressive strength and flexural strength of samples were significantly improved by reducing particle size of fly ash hollow spheres. Samples produced with the smallest hollow spheres (S4) exhibited low thermal conductivity of 0.401 W m−1 K−1 as well as high compressive strength of 18.10 MPa and flexural strength of 8.69 MPa. These characteristics are significantly superior to those of traditional mullite-based porous ceramics, indicating the effectiveness of the proposed preparation method.

Mechanical Properties of Reactive Powder Concrete with Coal Gangue as Sand Replacement.

Coal gangue (CG) represents a huge amount of industrial solid waste in China, and usually is used as a coarse aggregate to produce low-strength coal-gangue-based concrete. In this paper, in order to prove the possibility to obtain a higher-strength concrete with a higher CG utilization rate, reactive powder concrete (RPC) with coal gangue as a sand replacement at different replacement ratios was studied. RPC samples were prepared by replacing natural river sand (RS) with CG sand at different CG/RS weight ratios from 0–100% at intervals of 25%. Mechanical tests were carried out, and the microstructure features of RPC samples at 28 days were characterized. The test results showed that strong back shrinkage of strength existed. On days 7 and 14, the flexural strengths of samples with CG/RS replacement ratios of 0–75% fluctuated around the mean value. Strengths of samples with a CG/RS replacement ratio of 100% dropped off. However, on day 28, the flexural strengths of samples with CG were all lower than the strengths of samples on days 7 and 14. The flexural strengths and compressive strengths of the RPC with a CG/RS replacement ratio of 100% on day 14 were 14.09 MPa and 37.03 MPa, respectively, which decreased to 6.42 MPa and 28.44 MPa, respectively, on day 28. Compared with natural river sand, CG sand reduced the working performance, compressive strength, and flexural strength of RPC. Microscopic analysis showed that on day 28, increasing the CG replacement ratio could inhibit cement hydration, weaken the interface transition zone, and lead to the degradation of the RPC’s performance. Modification of CG sand would be helpful to obtain higher-strength concrete.

Study of corrosion property and mechanical strength of eco-friendly fabricated superhydrophobic concrete

The complex corrosive environment in the ocean and the hydrophilicity of concrete often leads to corrosion of the rebars in concrete. Endowing concrete with superhydrophobicity is an effective measure to prevent the internal rebars from being corroded. Here, an eco-friendly green method was proposed for fabricating superhydrophobic concrete by adding non-toxic lauric acid into concrete to reduce surface energy and covering stainless steel mesh to obtain rough hierarchical structures. The superhydrophobic concrete exhibited WCA of 153° and WSA of less than 10°. The corrosion property of fabricated concrete immersed into simulated seawater for different time was studied. The results show that the superhydrophobic concrete possesses better corrosion resistance to internal rebars than ordinary concrete. The compressive and flexural strengths of samples with different curing ages were studied. This eco-friendly green method for fabricating superhydrophobic concrete with corrosion resistance may have good application prospects in coastal engineering.

Experimental research on ductility enhancement of ultra-high performance concrete incorporation with basalt fibre, polypropylene fibre and glass fibre

The research aims to enhance the ductility characteristics of ultra-high performance concrete fibre material (UHPC-FM) comprising with different micro-synthetic fibres such as basalt fibre (BF) polypropylene fibre (PPF) and glass fibre (GF). As a sequence, consecutive dosages of these fibres such as 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% of volumetric fractions were introduced into the mixes for preparing the UHPC-FM to achieve the goals. The observed results showed that both the type and amount of added fibres influenced on the properties of fresh and hardened UHPC-FM concretes. In addition, higher contents of fibre filament (FFs) resulted a decreasing trend in flow of fresh UHPC-FM mixtures, where pastes with PPF demonstrated the highest fluidity property. Moreover, compressive strength (CS) increased upon addition of 0.5% FFs and linearly decreased for introducing the higher amounts. Compared with the control specimen (UHPC-A0), the flexural strength of samples containing 2.5% BF, PPF and GF increased by 20.8%, 26.9%, and 27.9%, respectively. Modulus of rupture increased by 20.04% in case of BF, 24.92% for PPF and 26.05% for GF when compared with reference sample (8429.5-kN). Toughness indexes of BF, PPF and GF based UHPC-FM samples were around 4.64, 4.75 and 4.86 times higher respectively, in comparison to the control specimens. The microstructure observation and drying shrinkage test illustrate fiber can modify UHPC well, which corroborated the results of mechanical properties exactly. In addition, the results of the current test can be applied for ultra-high-performance (UHPC) panels and vibration-free UHPC material.

Effect of Zirconia Silica Nanofibers on Flexural Strength of Feldspathic Ceramic - An Experimental Study.

Background:Dental ceramics exhibit good optical and esthetic properties due to their translucency. Feldspathic ceramic is the most widely used veneering ceramic with brittleness, which accounts for most of its failure. Hence, this study was done to evaluate and compare the flexural strength of feldspathic ceramic reinforced with zirconia-silica nanofibers in the ratio of 2.5, 5, and 7.5 wt% with conventional feldspathic ceramic.Materials and Methods:According to ISO 6872, a master die was prepared from which resin bars were fabricated with 4.0 mm in width × 1.2 mm thickness × 25.0 mm length, Zirconia-silica nanofibers were produced by sol-gel electrospinning go around with calcination and blended with feldspathic ceramic through ball milling method. The samples were prepared with 0, 2.5, 5, 7.5 wt% nanofibers reinforced ceramic. The flexural strength of the samples was evaluated using three-point bending test.Results:The flexural strength values of zirconia-silica nanofibers reinforced ceramic groups were higher than control group. There was a gradual increase in the flexural strength values of felspathic ceramic groups with increase in wt% of nanofibers.Conclusion:The flexural strength of feldspathic ceramic samples reinforced with zirconia-silica nanofibers by 5 and 7.5 wt% were statistically significant compared to control, whereas the flexural strength of 2.5 wt% was statistically insignificant compared to the control group.

Fabricated and analyzed the mechanical properties of textile waste/glass fiber hybrid composite material

Natural fibers are getting attention from researchers and academicians to utilize in polymer composites due to their eco-friendly nature and sustainability. The investigation of hybrid composite has been amalgamated and high structural performance. This paper has presented the fabrication and analysis of textile waste/glass fiber hybrid composite material's mechanical properties. The samples were fabricated by the hand lay-up method and pressing strategy. Five samples were prepared which are pure resin, textile waste fiber only layer (T/T/T), textile waste/glass fiber/textile waste layer (T/G/T), glass fiber/textile waste/glass fiber layer (G/T/G) and glass fiber only layer (G/G/G) composite. The mold was prepared locally in the workshop. The specimen was cut from the manufactured test agreeing to the ASTM standard for mechanical properties tests such as tensile test, flexural test, and impact test. The experimental results justify that textile waste fiber's effect is improved mechanical properties from pure resin composite. For instance, tensile strength was improved by 31.1% and modulus of elasticity was increased by 38.3%. The Flexural strength of sample G/T/G is 95% greater than T/T/T sample. T/G/T's tensile strength is recorded 64 MPa and G/T/G has recorded 52.33 MPa. The flexural strength and flexural modulus of the G/T/G composite are given 173.1 MPa and 32.63GPa, respectively. During the impact test, the textile wastes fabric to decrease the composite's impact strength is decreased. The highest water absorbed is shown G/T/G hybrid composite. The composites are immersed for 168 h in cube until at equilibrium state.

Mechanical Properties of Mortars Reinforced with Amazon Rainforest Natural Fibers.

The addition of natural fibers used as reinforcement has great appeal in the construction materials industry since natural fibers are cheaper, biodegradable, and easily available. In this work, we analyzed the feasibility of using the fibers of piassava, tucum palm, razor grass, and jute from the Amazon rainforest as reinforcement in mortars, exploiting the mechanical properties of compressive and flexural strength of samples with 1.5%, 3.0%, and 4.5% mass addition of the composite binder (50% Portland cement + 40% metakaolin + 10% fly ash). The mortars were reinforced with untreated (natural) and treated (hot water treatment, hornification, 8% NaOH solution, and hybridization) fibers, submitted to two types of curing (submerged in water, and inflated with CO2 in a pressurized autoclave) for 28 days. Mortars without fibers were used as a reference. For the durability study, the samples were submitted to 20 drying/wetting cycles. The fibers improved the flexural strength of the mortars and prevented the abrupt rupture of the samples, in contrast to the fragile behavior of the reference samples. The autoclave cure increased the compressive strength of the piassava and tucum palm samples with 4.5% of fibers.

Influences of Printing Pattern on Mechanical Performance of Three-Dimensional-Printed Fiber-Reinforced Concrete.

Underperformed interfacial bond and anisotropic properties are often observed in three-dimensional-printed concrete, where the printing pattern is unidirectional. Such issues could be potentially alleviated by replicating microstructures of natural materials or applying different architectures, where printed layers are arranged into unique and unconventional patterns. Furthermore, the quest to develop printing methods for highly complex or self-support concrete architecture could benefit from these nature-inspired patterns. In this work, the influences of different architectural arrangements of layers on mechanical properties of hardened concrete on compressive and flexural strengths are investigated. Specifically, unidirectional (0°), cross-ply (0°/90°), quasi-isotropic (0°/ ± 45°/90°), and helicoidal patterns (with pitch angles of 10°, 20°, and 30°) are used to create unidirectional, bidirectional, and multidirectional layers in printed objects without and with 0.75% by volume of 6 mm-long steel fibers. The experimental results demonstrate considerable improvements in the flexural strengths of nontraditional specimens without steel fibers over the unidirectional control with a few exceptions. Among investigated patterns, the quasi-isotropic demonstrates significant influences in both compressive and flexural responses of printed concrete samples without steel fibers. The addition of steel fibers leads to noticeable improvement on both compressive and flexural strengths of samples in any pattern compared with their counterparts without fibers. Besides, the inclusion of steel fibers into unconventional layups (cross-ply, quasi-isotropic, and helicoidal patterns) leads to the alleviation of directional dependence of mechanical properties, which is a limitation of the unidirectional samples with fibers. Of all helicoidal patterns, the one with a 10°-angle layup is shown to be more beneficial to the flexural strength enhancement and damage resistance in bending. X-ray microcomputed tomography measurements are performed to visualize the direction and distribution of fibers.

Dual filler functionally graded polymermaterials – manufacturing process and characteristics

ABSTRACT Functionally graded material (FGM) are a composite material which consists of filler material and matrix. FGM properties vary along the composition gradient. Common FGMs employs one type of filler material with specific properties. The application of two types of filler materials makes an opportunity to achieve the advantages of two types of filler materials, simultaneously. This study focuses on the FGMs with two types of filler materials and polyester resin (polymer) as a matrix. In this regard, the centrifugal technique is employed to fabricate dual filler functionally graded polymer materials (DF-FGPM). Copper-Silicon Carbide and Iron-Fused Alumina are used as two cases of dual filler materials. The microstructure and flexural strength of samples are evaluated using the image processing method and three-point bending test (according to ASTM D790), respectively. The results of particle distribution showed the different behavior of particles which can enhance surface and volumetric properties, simultaneously. Also and because of the importance of the interfacial layer in the composite structure, developed FGM presented achievements in the B type of loading during the three-point bending test.

Elasto-plastic behavior and failure of thick GLARE laminates under bending loading

Mechanical properties of thick GLARE1-9/8 laminates with unidirectional structure are investigated. Three-point bending tests are conducted to determine the elasto-plastic behavior and flexural strength of samples with different length. Effective longitudinal and interlaminar shear moduli of GLARE are measured based on various span method. Failure loads and failure mechanisms are determined within the range of the samples’ span-to-thickness ratio L/h=3.5...27. Micro/meso-mechanical models are involved for the analysis of experimental data. It is shown, that found values of elastic moduli agree well with simple analytical models, while the non-linear deformations of GLARE under high loading levels should be described accounting for plastic effects that arise in aluminum sheets as well as in GFRP layers. Change of failure mechanisms is accurately predicted based on the developed elasto-plasticity model involving maximum stress and maximum strain criteria. Size effects for the apparent interlaminar shear strength (ISS) of GLARE laminates are explained accounting for anisotropy and inelastic deformations of GFRP layers. It is shown, that true ISS evaluated based on the proposed model is closed to those one determined by the double-notched shear test.

Combined effect of compaction and clay content on the mechanical properties of adobe brick

Iran is one of the oldest countries in the world, benefiting from adobe-based architecture. The present study investigates the effect of dynamic compaction on mechanical properties of adobes using clayey-silty soils from Ardakan city, Yazd, Iran, with a focus on the compressive, tensile and flexural strengths in relation with the particle size distribution of the earth. However, it is found that the results of this mechanical stabilization are in function of the mineralogical compositions as well. In this regard, adobe samples in the control and experimental (compacted) groups were made with six soil types of six different mines, and their physical, mineralogical, and chemical characteristics were determined. Compressive, tensile, and flexural strengths of samples were examined, and the mechanical strength of the unbaked adobe bricks was correlated with the physical properties of the soils. The laboratory studies confirmed the direct relationship between dynamic compaction and mechanical strength. The results showed that soil compaction in the experimental adobes results in an increase of compressive strength by 79.43 %, tensile strength by 42.42 %, and flexural strength by 75.00 % compared to control adobes which lacks compaction. So, dynamic compaction is an acceptable method for manufacturing earthen materials such as adobe according to the required standards.

Preparation and properties of porous silicon nitride ceramics with polymethyl methacrylate as pore-forming agent

Porous Si3N4 ceramics were prepared by adding polymethyl methacrylate (PMMA) as pore-forming agent, combined with cold isostatic pressing and pressureless sintering at nitrogen atmosphere. The composition of phases, microstructure, density and porosity, flexural strength, dielectric properties of samples with different content of PMMA were studied in this paper. With an increase of PMMA content, the density and flexural strength of samples were decreased, while the porosity and dielectric properties were improved. Two types of pores in the sample were found in the experiment, the micropores formed by β-Si3N4 bridging, while the macropores formed by the pore-forming agent, and the macropores were the main factor for reducing the flexural strength and improving the dielectric properties by increasing porosity. When the PMMA content was 15 wt%, the comprehensive performance of sample was optimal, the porosity of 33.49%, the flexural strength of 103.62 MPa, the dielectric constant of 5.82 and dielectric loss tangent of 6.0 × 10−3.

Resistencia a la flexión del poliéter éter cetona poliéter de alto rendimiento en comparación con la aleación de metal base y la cerámica de circonio

Optimal flexural strength is a critical prerequisite for prosthetic frameworks. This study aimed to assess the flexural strength of polyether ether ketone (PEEK) polymer compared to a base metal alloy and high-strength Zirconia ceramic commonly used in prosthodontic treatments. Materials and Methods: In this in vitro, experimental study, 10 bar-shaped samples measuring 18×5×2mm were fabricated of each the PEEK polymer, nickel-chromium base metal alloy and zirconia ceramic. Half of the samples in each group were subjected to 5000 thermal cycles between 5°C - 55°C with 20 seconds of dwell time and 20 seconds of transfer time to simulate oral conditions. All samples then underwent three-point bending test. Two-way ANOVA followed by Tukey’s test were applied to compare the mean flexural strength of the groups with and without thermocycling at 0.05 level of significance. Results: The flexural strength of base metal alloy, Zirconia and PEEK was 1387.70±45.50 MPa, 895.13±13.99 MPa and 192.10±5.37 MPa, respectively. The difference was significant among the groups (p<0.001). Thermocycling had no significant effect on the flexural strength of samples in any group (p=0.306). Conclusion: PEEK high-performance polymer had a lower flexural strength than base metal alloy and Zirconia ceramic, and its flexural strength was not affected by thermocycling. PEEK seems to be able to resist masticatory forces in the oral cavity pending further in vitro and clinical studies.

Mechanical, elution, and antibacterial properties of simplex bone cement loaded with vancomycin

Prosthetic joint infection (PJI) is one of the most devastating failures in total joint replacement (TJR). Infections are becoming difficult to treat due to the emergence of multi-drug resistant bacteria. These bacteria produce biofilm on the implant surface, rendering many antibiotics ineffective by compromising drug diffusion and penetration into the infected area. With the introduction of new antibiotics there is a need to create benchmark data from the traditional antibiotic loaded bone cements. Vancomycin, one of the commonly used antibiotics, shows activity against Methicillin-resistant Staphylococcus aureus (MRSA) and S.epidermidis. In our study, vancomycin added to bone cement was evaluated for elution properties, antimicrobial properties, and mechanical properties of the bone cement. Vancomycin at five different loading masses (0.125, 0.25, 0.5, 1.0 and 2.0 g) was added to 40 g of Simplex™ P cement. Addition of vancomycin affected the mechanical properties and antimicrobial activity with significant differences from controls. Flexural and compression mechanical properties were compromised with added vancomycin. The flexural strength of samples with added vancomycin of 0.5 g and greater were not greater than ISO 5833 minimum requirements. 2.0 g of vancomycin added to bone cement was able to eliminate completely the four bacterial strains tested. 2.0 g of vancomycin also showed the highest mass elution from the cement over a 60-day period. Given the reduced flexural strength in samples with 0.5 g and greater of added vancomycin and the inability of vancomycin in amounts less than 2.0 g to eliminate bacteria, this study did not find an ideal amount of vancomycin added to Simplex™ P that meets both strength and antibacterial requirements.

Self-Healing Performance Comparison Between Two Promising Vascular Vessel Systems of the Wind Turbine Blade

Hollows produced by wires and borosilicate tubes are two significant approaches for the storage and transport of healing agent for self-healing wind turbine blades. To compare the performance for the two approaches, sheet samples and prototype blades were molded with vacuum-assisted resin transfer molding (VARTM) and max-flexural strength was evaluated before and after the self-healing process. One millimeter outer diameter with 0.5 mm inner diameter borosilicate tubes were used to store and transport the healing agent. Dicyclopentadiene was used as the healing agent and Grubbs' first-generation catalyst was used to initiate polymerization. To obtain the same structure of the tube, a lost-wax method was applied twice to form hollows with 1 mm outer diameter and 0.5 mm inner diameter. Since the samples need to be heated to form the hollows, the effect of the heating process on flexural strength was investigated. The flexural strength of the samples showed to be enhanced with the heating process. The percentage improval for flexural strength was 14.18% at 120 °C, 21.79% at 135 °C, and 10.89% at 150 °C. The growth trend continued until 135 °C and decreased after 135 °C. The toughness of the samples was also weakened. With the heating process, the initial and post self-healing flexural strength between samples with tubes and samples with hollows showed little difference. The recovery percentage of samples with tubes was 81.55%, while that of samples with hollows was 81.92%. Without the heating process, the initial and post self-healing flexural strength between samples with tubes and samples with hollows also showed little difference. The recovery percentage of samples with tubes was 89.52%, while that of samples with hollows was 89.46%. The space between the tubes/hollows greatly affected the flexural strength. The flexural strength of samples with a larger space between tubes/hollows was higher than that of samples with a smaller space between tubes/samples. For the prototype wind turbine blade, the initial and post self-healing flexural strength followed the same trend. For samples with hollows, the ratio of the inner diameter to outer diameter can be close to one so the walls can be very thin improving storage and transport efficiency.