Kinds Of Fiber Materials Research Articles

Failure analysis and evaluation for cracked concrete beam reinforced with CFRP

With the development of material technology, many kinds of fiber materials have been exploited. In all these fiber materials, carbon fiber reinforced plastic (CFRP) is widely used in civil engineering. First, in this paper the reinforcement performance and failure of cracked concrete beam reinforced with CFRP are studied by digital image correlation method. Secondly, a simple method for the evaluation of reinforcement effect for cracked concrete beam reinforced with CFRP is proposed and verified by experimental results. The reinforcement effect for cracked concrete beam reinforced with CFRP can be evaluated in the service process without specimen damage by this method. Finally, the effects of the bond defect of CFRP on reinforcement effect are studied by this evaluation method. This method plays an important role in the safe application of concrete beams reinforced with CFRP.

Study on the performance of a novel dew-point evaporative cooler based on fiber membrane automatic wicking

A dew point evaporative cooler with fiber membrane coated in the wet channel for improving wettability was proposed in this paper. Firstly, Coolplus with the best performance was selected by comparing four kinds of fiber materials. Then, the cooling performance of the cooler was studied at different experimental conditions. It was found that the cooler showed excellent cooling effect at high temperature, low humidity and velocity. The temperature was decreased slowly along the flow direction of primary air. When inlet temperature, relative humidity and velocity were in the range of 25∼40, 40%∼70% and 1 ∼ 2m/s at the condition of 14 water temperature, the maximum temperature drop was 8.35, the cooling capacity per unit area was between 59.7 and 149.4W/m2, and the wet bulb efficiency and dew point efficiency was increased from 42% and 25% to 92% and 76%. When the water temperature was raised from 14 to 28, the temperature drop was only decreased from 8.35 to 6.82. Therefore, the influence of water temperature on the cooling effect is insignificant. The best conditions of temperature 40, relative humidity 40%, velocity 1m/s and water temperature 20 were suggested. Finally, comparison with a similar case was conducted to evaluate the proposed cooler.

Effect of modified sepiolite and carbon fiber composite on performance of oil-well cement and mechanism analysis

Sepiolite fiber (HPS), as a cheap and environmentally friendly mineral fiber material, has good application value in toughening filler of oil well cement stone and is the best substitute for toxic asbestos material. However, due to the defects of conventional industrial HPS such as low purity, poor dispersion, it will produce great incompatibility with cement slurry, which will adversely affect its performance. In this paper, conventional industrial HPS was treated with activation modification. The changes of surface groups of sepiolite before and after modification and the actual dispersion effect in aqueous solution were studied by FTIR and dispersion state of aqueous solution. In addition, the effects of modified sepiolite fibers (H-HPS) and carbon fibers (C-Fibers) on oil well cement were also investigated. The mechanism of the micro-morphology of the toughened cement paste was analyzed. The results show that the dispersion and suspension of H-HPS in aqueous solution have been greatly improved. The rheological test results of cement paste also support the improvement. At the same time, the optimum mixing ratio of the two materials was screened out by synergistic study with C-Fibers. It was found that the composite fiber cement slurry system synthesized the advantages of the two kinds of fiber materials, and the toughening effect was obviously better than that of the modified cement paste with a single admixture. From the analysis of SEM, it can be seen that HPS in the composite fiber cement slurry system fills in micro-voids on the one hand, and forms a uniformly dispersed network structure on the other hand, The C-Fibers in the system can effectively dissipate the tensile energy of the fracture interface of cement paste by interacting with hydration products, thus reducing the filtration of cement paste and improving the bulk toughness of cement paste.

Experimental and numerical investigation of the properties of the Hot Mix Asphalt Concrete with basalt and glass fiber

In the recent decades, different kinds of fiber materials are used for improving the asphalt mixture performance. Meanwhile, different kinds of fiber are used excessively due to their desirable physical and chemical properties and their easier application. The main purpose of this research is to evaluate the characteristics of the asphalt mixture while using basalt fiber and glass fiber. In order to provide asphalt samples, these two types of fibers are used in different percentages. In this way, 42 samples (with different percentages of fiber and bitumen) were made using Marshal Hammer. In the next step, while constructing 63 asphalt samples using a gyratory device, then mix asphalt conventional tests include the determination of indirect tensile strength, moisture sensitivity test, and resilient modulus and creep tests performed. The results of this research indicate that using these two types of fibers increased the percentage of optimum bitumen and marshal resistance. At best, adding 0.1% glass fiber resulted in 13% increase in marshal resistance. Ultimately, ANFIS method was employed to predict the result of the experimental test and the possibility of using neural network method have been evaluated to predict the laboratory result.     

Influence of Reinforcing Materials on the Properties of Woven Spacer Fabric Composite Sandwich Panels

Two kinds of fiber materials, glass fiber and technical polyester filament were used to design six different kinds of woven spacer fabrics. Then in the space of the fabric the polyurethane foam was filled and on the surface of the fabric the epoxy resin was combined by means of handle paste shaping craft to build the composite panels. The flexure and compression performance of the composite panels were measured. The experimental results showed that the difference of the materials influenced the properties of compression and flexure to some extent.

Effects of Hard Twisted Yarn on Mechanical Property in Fiber Structural Hybrid Composite Materials

In this study, we have extended the concept of fiber hybrid and proposed fiber structural hybrid composite as the new concept. Fiber structural hybrid is defined as reinforcements consist from same kinds of fiber materials with different structure such as the fineness, the twisting state, and etc. In this study, the concept of the fiber structural hybrid was applied to the glass woven fabric composite and fiber structural hybrid composite materials with different twisting count and twisted structure were fabricated. By static tensile test and Finite Element Method (FEM) considering of the internal structure, the effects of the difference in twisting state of weft fiber on the initial fracture of fiber structural hybrid composites were investigated. In tensile test, it was clarified that tensile modulus and initial fracture stress were decreased by the increase in the twisted count and the number of doubling. In FEM, apparent interfacial strength inside of weft fiber bundle was decreased by the increase in twisting count and apparent interfacial strength was increased by the increase in number of doubling. From these results, initial fracture can be designed by applying the fiber structural hybrid concept to the composite materials, and the safer structural material can be realized.

A general polyconvex strain‐energy function for fiber‐reinforced materials

AbstractThe continuum mechanical modeling and numerical simulation of fiber‐reinforced materials, such as carbon‐fiber‐reinforced plastics or collagenous biological tissues, are of great interest in the field of material science. In this regard, various strainenergy functions have been proposed to capture the inherent anisotropy of these types of materials ranging from simple exponential functions applied in biomechanics [5] to more sophisticated formulations based on the theory of invariants [8]. The goal of this contribution is to present an alternative ansatz, which basically adopts the general idea of the wellestablished isotropic hyperelasticity law of Ogden [7]. In particular, a polynomial strain‐energy function formulated in the fiber stretch is proposed, which allows the description of the general nonlinear elastic response of various kinds of fiber materials, such as collagen, nylon or sisal, in a very concise form. Moreover, the formulation still meets the requirements of a stress‐free reference state and material stability, whereas the number of material parameters is kept to a minimum. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Capillary electrochromatography using fibers as stationary phases

Fiber-packed capillary columns have been evaluated in chromatographic performance in capillary electrochromatography (CEC). The change of electroosmotic flow (EOF) velocity and selectivity using different kinds of fiber materials was examined. Although the EOF velocity among the different fiber packed columns was almost the same, retention of parabens was larger on the Kevlar®-packed column than on the Zylon®-packed one, and was larger on the as-span-type fiber-packed column than on the high-modulus-type packed one. Using 200 νm ID × 5 cm Kevlar® packed column combined with a 100 νm ID × 20 cm precolumn capillary and a 530 νm ID × 45 cm postcolumn capillary, the separation of three parabens within 30 s was achieved. Other compounds were also separated in a few minutes by the fiber-packed CEC method.

Capillary electrochromatography using fibers as stationary phases.

Fiber-packed capillary columns have been evaluated in chromatographic performance in capillary electrochromatography (CEC). The change of electroosmotic flow (EOF) velocity and selectivity using different kinds of fiber materials was examined. Although the EOF velocity among the different fiber packed columns was almost the same, retention of parabens was larger on the Kevlar-packed column than on the Zylon-packed one, and was larger on the as-span-type fiber-packed column than on the high-modulus-type packed one. Using 200 microm ID x 5 cm Kevlar packed column combined with a 100 microm ID x 20 cm precolumn capillary and a 530 microm ID x 45 cm postcolumn capillary, the separation of three parabens within 30 s was achieved. Other compounds were also separated in a few minutes by the fiber-packed CEC method.

Sound Absorption Characteristics of Fiber Assemblies

The influence which several factors relating to the make-up of a fiber assembly have on sound absorption characteristics was investigated by measuring the normal incident absorption coefficients of fiber assemblies from 250 to 2, 000c/s at intervals of 1/3 octaves. The results obtained are:(1) There are two other types of absorption characteristics besides the well-known viscosity resistance type (I). One is a fibrous resonance type (II), of which the absorption characteristics show resonance absorption at low frequency but which, in a high frequency range, belongs to type (1). The other is an intermediate type (III), which is between (I) and (II).(2) The absorption characteristics of a fiber assembly belong to type (I) if the fibers are arranged parallel to the direction of the propagation of the sound wave. The air in the fiber assembly plays a part in the absorbing action. If the fibers are arranged so as to divide the air space in the assembly into small sections, the value of its absorption coefficient is high.(3) It is experimentally estabished that the absorbing mechanism of a fiber assembly comes mainly from the frictional action between the surface of fibers and the air in the assembly. Fiber assemblies are equal to one another in their absorption characteristics if the fibers are the same in total surface area, even it they differ in length or fineness.(4) To increase the absorption coefficient of a fiber assembly in a low frequency range, it is better to increase its thickness than to reduce its porosity. The thickness of a fiber assembly has an effective value which increases the absorption coefficient to a maximum for a certain frequency and a certain porosity degree.(5) The relation between a certain frequency (f) and a certain effective porosity (Pe), which porosity increases the absorption coefficient at that frequency to a maximum value, is shown as follows: f=K(100-Pe)-1.3 where K is a constant which is decided by the kind of fiber material, its fineness, the fiber orientation and the thickness of the fiber assembly. If K is obtained experimentally at a certain frequency, the value of Pe for every frequency is calculable by the above equation. There is the most effective porosity (Pme) giving the greatest value among the maximum absorption coefficients in Pe of all frequencies.The larger the total surface area is, the greater Pme is and the lower the frequency is.