Advanced Materials Research Vols. 785-786

Abstract: The deformation behavior of particulate reinforced metal matrix composites (PRMMCs) under monotonic and cyclic loadings was simulated by FEA method. Base on the cohesive zone model, the effect of the interface between particle and matrix was considered. Then, the finite element simulation of the PRMMCs with an ideal interface and weak interface was compared with corresponding experimental results. It is shown that: with a weak interface been considered in the finite element simulations, the resistance of PRMMCs to the ratcheting strain was reduced, which gets more closed to the experimental results.

Abstract: Carbon nanotubes (CNTs) doped TiO₂/glass fiber reinforced plastics (GRP) hybrid materials were prepared by first step sol-gel and then hand lay-up method, using modified CNTs doped tetrabutyl titanate as precursor. The results showed that TiO₂ component as the inorganic material, could improve the high temperature stability of the GRP, and the latticework structure of the hybrid material could disperse the CNTs well and prevented them from gathering at high temperature.

Abstract: The subject of this paper is option analysis of the use of geopolymers as matrixes to repair mortars designated for rehabilitation of reinforced concrete structures. Due to their specific properties, geopolymers show a high potential mainly for special applications. Rehabilitation of reinforced concrete structures exposed to extreme conditions is a field in which it is possible to effectively take advantage of geopolymers ́ exceptional properties. In this particular case, we focus on comparing the behaviour of polymer-cement materials commonly used in the rehabilitation of reinforced concrete structures and the one of geopolymer-based mortars.

Abstract: Polyimide foams (PIF) contained carbon black were prepared from polyimide precursors by inflation process. The structure, compressive strength and heat-resistance of the PIF were studied. The FT-IR results confirmed the successful synthesis of PIF. T_g value of PIF with different content carbon black was over 255°C.With the increasing of carbon black content, T_g of PIF decreased. PIF decomposition temperature (T_d 5%) was higher than 540°C,while the compression strength of PIF about 0.12MPa with low content carbon black.

Abstract: A sub-micron spherical powder material-micro bead, which has good water reduction, filling and enhancement effect, could be used as active mineral admixture in high-strength concrete. The affection of micro bead on the hydration temperature rise, mechanical properties, and shrinkage properties of high-strength concrete were studied, and the results showed that: micro bead could reduce the highest temperature peak of concrete, and at the low water-cement ratio, its small dosage could develop the compressive strength of concrete, and after instead of silica fume with suitable dosage, it could reduce the shrinkage of high-strength concrete.

Abstract: A generalized higher-order global-local theory was presented. The transverse shear stresses can be got directly through the constitutive equation without using the equilibrium equation. The second derivative of interpolation function was deduced. The hammer integration of triangular area coordinate method was applied to solve the multiple integration problem of the element stiffness matrix. The order choice of numerical integration was discussed and results obtained through two different integration orders were compared. The flow of how to compile a FORTRAN program was given. A moderately thick composite laminated plate was analyzed via finite element method (FEM) based on the theory and results were compared with that of Paganos three-dimensional elasticity. It shows that the interlaminar stresses are accurate for moderately thick laminated plates.

Abstract: In the present paper we used the global Gaussian collocation method and trigonometric shear deformation theory to analyze free vibration of laminated composite plates. Natural frequencies computed by the present method are found to agree well with those from some available published results.

Abstract: As a natural nanomaterial, the bentonite is widely used in industry and engineering, and it is used in the anti-seepage (infiltration) project in civil engineer because of its low permeability. The micro-pore structure characteristics of the bentonite with the different dehydration methods are measured by Mercury Intrusion Porosimetry (MIP) in this text. Then the effects of the dehydration methods on the micro-pore structure characteristics of bentonite are analysed and the detailed reasons of the test errors are given. The results of the research have certain referential value for the application of the bentonite in civil engineering and play a guiding role on how to reduce the errors and to improve the authenticity and the reliability of the test.

Abstract: In this paper the governing equations of cross-ply symmetric laminated composite plates are derived based on the trigonometric shear deformation theory. Generalized Navier type solutions are obtained to predict the free vibration behavior of cross-ply symmetric laminated composite plates. The analytical solutions of natural frequencies are obtained for thick and moderately thick plates as well as for thin plates, and compared with some available results in other papers. Through numerical examples, the high accuracy of present method for free vibration analysis of cross-ply symmetric laminated composite plates is demonstrated.

Abstract: Using the cylinder to take 2L as sample from five equidistant azimuthally and the center point to weight. Wash away the cement slurry in sample thoroughly first. Put the rest into the container full with water and churn. Then, collect the suspended fiber using the square-hole sieve of 75 um aperture. Churn it as more as possible to make sure of collecting whole fiber in samples. Wash clear and dry under 105±5 Celsius degree to constant weight. After cooling to room temperature then weight them respectively and accurate to 0.01g. The dispersion performance will be qualified if the dispersion relative error between arithmetic average value of synthetic fiber content and theoretical calculated value is from -10% to 10%. The concrete test steps is as per “Cement Concrete and Mortar Synthetic Fiber GBT21120-2007”. Slump、slump flow of all the fresh concrete were tested to determine the fresh properties of fiber reinforced concrete. The mixing proportions are listed in Table 1, All the strength tests were carried out following the Chinese standard GB/T 50081-2002. Resistance to chloride ion penetration was measured according to ASTM C1202 (Rapid determination of the Chloride Permeability of Concrete) at the curing age of 7d、28 days using a proportion of the Φ100mm × 50mm cylinders. The early crack resistance test is according to the fiber reinforced concrete testing standards CECS 13-2009. It can be concluded that the working performance of composite fiber concrete are better compared with the single mixed concrete. It is obvious that the spread degree is being larger as the increasing of cellulosic fiber based on the certain adulterate amount. Fiber incorporation has little influence on concrete 7 d 、28 d age compression strength. The 7d and 28d splitting tensile strength、flexural strength were enhanced by incorporation of fibers. The addition of fiber improved the resistance ability of 7d and 28d fiber concrete chloride penetration to a great extent. It improved the ability of corruption resistance from seawater and extended the life of concrete and hence promoting the wide spread usage in marine project. Fiber incorporation delayed the occurrence of early crack and controlled the development of cracks, which made the concrete plastic shrinkage crack width and the maximum crack areas reduced.