Applied Mechanics and Materials Vols. 105-107

Abstract: Using the ultrasonic fatigue test method, the influence of subjection to plasma nitriding surface modifications on the ultra-high cycle fatigue behavior of Ti-6Al-4V was investigated, then a comparison with corresponding behaviors of the normal Ti-6Al-4V was made. The results show the S-N curve of Ti-6Al-4V with plasma nitriding surface modifications still continuously declines, no conventional fatigue limit exists for Ti-6Al-4V. Plasma nitriding surface modifications enhance surface hardness, but they make the material fatigue strength decrease by about 17 %. The fractography of fatigue failure has been observed by scanning electron microscopy. The observation shows that fatigue failure initiates from internal of specimen after the fatigue life of 10⁸ cycles and fatigue cracks mainly initiate from the surface of specimen before the fatigue life of 10⁸ cycles.

Abstract: Using Fe (NO₃)₃ as modifying agent, a new porous environmental ceramic filter is modified at surface to pre-treat slightly-polluted water. It can effectively reduce organic substances in subsequent processes, thus enhance the quality of water output. The iron oxide / modified ceramic filter media was manufactured by heating vaporization, and the optimal modification conditions were as follows: pH value is seven, Fe (NO₃)₃ density is 2mol/L, and roasting temperature is 550 centigrade. Compared with plain ceramic filter media, the removal rate of COD was enhanced six to eight times. The surface morphology of filter media was inspected by SEM, which showed that the iron oxide film, being fine particles, was attached to the ceramic filter. This is beneficial for enhancing adsorption capability. The matter species of iron oxide film were analyzed by XRD, result showed that it contains α-Fe₂O₃ and α-FeOOH, which is helpful for adsorbing and removing organic substances in water.

Abstract: Composite circular steel tubes- with and without epoxy infill for three different grades of concrete are tested for ultimate load capacity and axial shortening , under axial monotonic loading for compression. Steel tubes are compared for different lengths, cross sections and thickness. Specimens were tested separately after adopting Taguchi’s L9 (Latin Squares) Orthogonal array in order to save the initial experimental cost on number of specimens and experimental duration. DOE (Design of Experiment) approach was adopted. Results were generated using Taguchi’s method-a new technique to get mean effects plot. Analysis was carried out using ANOVA (Analysis of Variance) technique with the assistance of Mini Tab v15- a statistical soft tool. Results were verified after conducting preliminary nine combination experiments as per L9 orthogonal array and linear regression models were developed. Comparison for predicted and experimental output is obtained from linear regression plots. To know the implications of different factors on circular composite columns with and without epoxy, surface contours were also generated. From this research study it is concluded that ,Regression models which were developed with minimum number of experiments based on Taguchi’s method predicted the axial load carrying capacity very well and reasonably well for at ultimate point. Cross sectional area of steel tube has most significant effect on ultimate load carrying capacity. Also it is observed that, as length of steel tube increased- load carrying capacity decreased.

Abstract: In contemporary electronic technology era, the volume of electronic equipment and printed circuit board reduced so dramatically that the requirements of heat dissipation and insulation increase thereafter. In this research, γ-aminopropyltriethoxysilane (KH550)-treated boron nitride (BN) powder was used as a filler to modify epoxy composites. Effects of the BN particle size and concentration on the thermal conductivity of composites were investigated. SEM image showed the treated BN filler dispersed well in the composite matrix. Moreover, the thermal conductivity was enhanced as the BN concentration was increased. Similar phenomenon was also observed when the filler particle size was reduced. Results indicated that with increasing amount of BN addition, the composites’ thermal conductivity showed a nearly linear increase. When the mass fraction of BN was 30% and its particle size was 220 nm, the thermal conductivity reached 3.4 W/(m•k), which was 17 times as high as that of pure EP resin.

Abstract: To the exacting underwater engineering and waterproof projects, the impervious performance of concrete plays a crucial role in the whole project. XYPEX is a special crystalline powder waterproof material, it is new and effective which is widely used in the basements, dams and other waterproof projects. Adding steel fiber into concrete, the strength of concrete will obviously be improved. The paper makes a comparison of the compressive strength, splitting strength and impermeability test of concrete specimens with two different materials-XYPEX (waterproof material) and steel fiber, and also studies the effect of the two different materials on concrete compressive strength, splitting strength, impermeability and relevant laws, along with discussing the reaction mechanism because of the addition of this two materials.

Abstract: Studies were conducted on the production of silane modified kaolinite/silica core-shell nanoparticles (SMKS). The SMKS nanoparticles were prepared via the sol–gel technique using tetraethyl oxysilane (TEOS) as the precursor to form silica shells on the surface of kaolinite particles followed with silane treatment. TEM of the unmodified kaolin (ORK) and SMKS revealed that a layer of ultrafine silica particles were deposited on the kaolinite surface to form a new kind of core–shell structure particles.

Abstract: Abstract. In this paper, the elasto-plastic dynamic analysis on the steel spatial arch truss with 90m span and 0.1rise-span ratio is carried out under earthquake wave with SAP2000. In the analyses, the geometric and material nonlinear effects are considered simultaneously based on the plastic-hinge theory. Under the action of EL-centro wave with the peak increasing gradually, its elasto-plastic dynamic responses have been obtained. The results show that its failure mode under the earthquake action is elasto-plastic dynamic buckling; that its critical peak acceleration of EL earthquake wave when applied in X direction is 635gal, and is 465gal when applied in Z direction; The ratio of its maximal node horizontal displacement and its rise height is 1/486, and its displacement ductility coefficient is 1.029 and the ratio of its bars with plastic hinge appearing when buckling is 0.7% when EL-Centro waves applied on structure in X direction; The ratio of its maximal node vertical and its structural span is 1/604, and its displacement ductility coefficient is 1.022 and the ratio of its bars with plastic hinge appearing when buckling is 2.8% when EL-Centro waves applied in Z direction.

Abstract: In the present paper, an accurate 3D finite element model is presented for bucking analysis of soft-core rectangular sandwich plates. The sandwich plate is composed of three layers: top and bottom skins and core layer. Finite element model of the problem has been constructed in the ANSYS 11.0 standard code area. The effect of geometrical parameters of the sandwich plate is studied. Comparison of the present results with those of plate theories confirms the accuracy of the proposed model. The overall buckling loads calculated by FE model are higher than that of the accurate results and the maximum discrepancy is less than 10 percent.

Abstract: The study uses distilled water as test liquid, investigates the wettability of modified asphalt with silane coupling agent DB-570 by sessile drop method, measures the contact angel of modified asphalt with different amount of coupling agent based on LB-ADSA model by ADSA software, and also calculates the surface tension of modified asphalt. The study analyzes asphalt membrane by SEM. The results show that the static contact angle of distilled water in the surface of modified asphalt increased with the addition of coupling agent, the adhesion of asphalt and aggregate enhanced after modification, the asphalt membrane become much more complete.

Abstract: With the growing global energy crisis, development of economic and land-efficient construction structural system became an significant subject in Civil Engineering field. Under this context, material and structural test and theoretical analysis research is meaningful on new energy-saving building material, glazed hollow bead insulation concrete. In this paper, one mix design that meet insulation requirements of the energy-saving project on coefficient of heat conductivity and compressive strength have been chosen. Under the uniaxial status, prism samples of above mix design have been selected to do compression strength and deformation tests; Systemic analysis of the relationship between the strength and deformation for glazed hollow bead insulation concrete has been carried through, and some results have been provided, including the stress-strain constitutive relationship of glazed hollow bead insulation concrete with grade c35, prism compressive strength, strain, initial elastic modulus, residual strength, ductility, etc.