Advanced Materials Research Vols. 261-263

Abstract: To prepare good physical and mechanical properties of nylon 1010/POE-g-MAH composite by melt blending. The mechanical properties and rheological behavior were measured by HAAKE- II rheometer, the scanning electron microscope (SEM) and atomic force microscope (AFM).The result shows that the impact strength increases gradually with the increase of POE-g-MAH content, the composite is pseudo plastic fluid, non-Newtonian index increases with the increase of temperature. The addition of POE-g-MAH makes the non-Newtonian index of melt decrease significantly at the same temperature.With the increase of shear rate, viscous flow activation energy takes on decreasing trend.

Abstract: In past days many researchers have been worked on the expansive soil to determine the California Bearing Ratio (CBR) values in a conventional ways, which are time consuming and require lot of manual involvements. So we the authors of this research paper attempted to develop a soft computing technique to prognosticate CBR value by using Artificial Neural Network (ANN), a data driven technique. ANN is a mathematical model inspired from the human brain’s information-processing characteristics, including the parallel processing ability. Over the last few years, the use of ANN has increased in many areas of engineering. In particular have been applied to many geotechnical engineering problems and have demonstrated some degree of success. A review of the literature reveals that ANN has been used successfully in the pile capacity prediction, site characterization and so on. In the present study the Black Cotton (BC) soil has been stabilized by using Rice Husk Ash (RHA) and cement, several experiments have been conducted for different mix combinations under soaked condition. From the obtained results, it is observed that the CBR value of BC soil increases with the addition of RHA and cement combination. The soaked CBR value found to be maximum for the mix of BC soil + 15% RHA + 12% cement. The present study deals with collection of input data base from experimental results, ANN’s training and its testing are adopted to fix the appropriate weighted matrix (Illustrated in Fig (1)) which in turn Prognosticates the CBR value. Experimental results have been compared with the CBR values prognosticated by using ANN and comparison graphs also plotted (Illustrated in fig (4)). The results of this study will contribute for the prognostication of CBR, which will assist a geotechnical engineer in estimation of CBR, with minimum effort.

Abstract: In this paper, we investigate the CO₂ carbonation on porous materials such as the cement paste mortar. Our scientific goal is to model the CO₂ carbonation effect on the porous cement mortar by the micro-dilatation theory and to determine the chemo-mechanical stress development due to the chemical reactions. In fact, this phenomenon will modify not only the pH value of the cement paste but also the micro-structure due to collapsing pore-network. Based upon the micro-dilatation theory originally proposed by Cowin and Nunziato, four unknown parameters related to the micro-structure will be determined for the cement mortar using the semi-empirical method and numerical modeling. The experimental carbonation tests on two different types of cement paste (CEMI and CEMIII) have been realized to capture carbonated affected zones and to measure their shrinkage deformations.

Abstract: With the fast development of modern industry, the fact that coal dominates the main energy structure will not change for a long time. While the output of coal gangue has accounted for 15%~20% in that of coal. Therefore, coal gangue has become one of the greatest contributions to industrially discharged solid waste in China currently. Nowadays the comprehensive utilization ratio is less than 20%, so there is so much room for the activity and comprehensive utilization of coal gangue. In this article, coal gangue in Tongchuan stimulated by thermal, mechanical and chemical activation has been used as supplementary gelatinize material in cement. The optimal activated ways and technological parameter have been selected by the test of strength, fluidity, water requirement for normal consistency of cement paste, and stability. Also XRD and SEM are used to discuss the change of microstructure which has taken place in activated coal gangue preliminarily.

Abstract: The Mg-12Gd-2Y-0.5Sm-0.5Sb-0.5Zr (wt.%) alloy was prepared by casting technology. The microstructure was investigated after solution and aging treatment (i.e. T6 heat treatment). Tensile tests were performed at a crosshead speed of 1 mm/min at ambient and elevated temperature atmosphere. The results show that the aged alloy was mainly composed of α-Mg matrix, Mg₅Gd phase and dispersed long-period ordered β' precipitates. At 523K, the alloy has shown the superior tensile strength (i.e. 345.5 MPa). The strength mechanism was solution strengthening of RE and precipitation strengthening of dispersive LPO structure β' and stable Mg₅Gd precipitates in Mg matrix.

Abstract: Based on thermodynamics, a constitutive model for magnetic shape memory alloy (MSMA) is developed under biaxial magnetic field. Considering the driving force provided by Gibbs free energy and resistive force during martensite reorientation, a kinetic equation is got. Of special concern is the influence of biaxial magnetic field on martensite reorientation for a Ni₂MnGa single-crystal specimen. The theoretical results are in agreement with experimental data. Some useful conclusions can be obtained.

Abstract: A finite element model of not wholly quenched steel fatigue specimen is established. Hardness value of some distance to work piece surface are assumed different and cyclic strength coefficients of different zones are different, both is assumed to be proportional to hardness value. Elasto-plastic finite element analysis was carried out for this model. According to the stress-strain distribution on transverse section, the effect of not wholly quenched on fatigue crack initiation life is analyzed.

Abstract: The performance research of Friction Stir Weld’s Joints of Aluminum Alloy under different welding parameters is very necessary and valuable in the engineering. Two points is proposed in this paper. One is the new fracture criterion using the function curve of the value of critical crack opening displacement (|CODc|) as a fracture parameter, the other is using critical crack opening angle (CTOA) as a fracture parameter.

Abstract: The grain refining of C-Mn steel on CSP line was investigated in this paper. The grain size was about 100μm after rolling by stand F1 and then decreased all the way of the rolling process(stands F2-F6) to 15μm. The strengthening mechanisms, grain refinement strengthening, solution strengthening, precipitation strengthening and dislocation strengthening, were figured out to develop a physical metallurgy model for prediction of the properties. It was noted that there is an agreement between the predicted properties and the measured ones of the steel.

Abstract: Machined titanium chips are normally recycled as non-ferrous scrap metal, however, one approach is to recycle titanium chips to construct as lightweight sandwich panel with high energy absorption capabilities. The development of advanced ballistic protection systems that are lightweight while still providing superior energy absorption capacities is a challenge. This study reports the ballistic impact performance of sandwich panel made of Kevlar woven fabric and recycled materials, namely, titanium chips. Titanium is a lightweight material compared with steel however possesses much stronger energy absorption. Sandwich panels were constructed using titanium chips, together with layers of Kevlar woven fabric and a polymeric material. The enhancement of Kevlar woven fabric with titanium chips further strengthens sandwich panel especially in ballistic impact performance. Ballistic impact tests using a nitrogen powered gas gun firing projectiles with impact velocities range from 300 - 350 ms^-1 was carried out. Bonding of the titanium chips with a polymeric material is crucial for the overall ballistic performance. This study proved that reduction in layers of Kevlar fabric is possible by substitution of lightweight material such as titanium chips as energy absorption materials.