Applied Mechanics and Materials Vol. 483

Abstract: In this study, to simulate the grinding process for rolled homogeneous armor steel (RHA) 4043, a single-grain cutting process is modeled using a three-dimensional (3-D) numerical model, which is developed using a coupled finite element (FE) - smoothed-particle hydrodynamics (SPH) approach. The proposed numerical model is then employed to investigate the influences of grain negative rake angle (-22°, -31°, and-45°) as well as high and super-high cutting speed ranged from 100 m/s to 260 m/s in the cutting processes. The numerical results show the cutting forces are much lower and the maximum chip thickness is much larger when using a smaller grain negative rake angle.

Abstract: A new method of parallel projection galvanometer scanning (PPGS) is presented, as a low-cost, flexible, trans-scale solution for laser material processing on freeform surfaces. The parallel projection transformation is used for mapping three-dimensional space curves to terraced two-dimensional plane graphics that each one is suitable for traditional galvanometer scanning method. For implementation of the PPGS method, a parallel projective laser scanning system with the combination of galvanometer and telecentric lens is needed, that the laser is directed along the space curve path on freeform surface part without deviation when the x-y axis galvanometer is scanning the mapping graphic path of the parallel projection plane. In practice, the existing 3D galvanometer scan system, "3+2" and rob-scan system are alternative choices in different application situations.

Abstract: Normal form theory is very useful for direct bifurcation and stability analysis of nonlinear differential equations modeled in real life. This paper develops a new computation method for obtaining a significant refinement of the normal forms for high dimensional nonlinear systems. In the theoretical model for the nonlinear oscillation of a composite laminated piezoelectric plate under the parametrically and externally excitations, the theory of normal form is applied to find the explicit formulas of normal forms associated with a double zero and a pair of pure imaginary eigenvalues.

Abstract: Orthogonal experiment method was used on DC CMT welding of AZ31B magnesium alloy sheet. The tensile test was carried out on the CMT5305 microcomputer control universal testing machine .The effect regular of welding current, arc length correction and welding speed on tensile strength and elongation was analyzed and acquired the optimal combination of process parameters. That is, welding current is 62A, arc length correction is +30% and welding speed is 50cm/min. The microhardness test on joints was carried out. Its found that the curve of microhardness is "W" shaped and the micro-hardness of HAZ is minimum and that of weld zone is maximum.

Abstract: To investigate the effective permittivity of composites composed of ellipsoidal inclusions, three-dimension numerical models for ellipsoidal inclusions distributed randomly are built with the finite-element modeling software Comsol Multiphysics. After calculating the effective permittivity for different cases and comparing the results with analytical results from the Maxwell-Garnett mixing rule, we find that the finite-element method has an advantage in detecting details of the interaction among inclusions, which have some impacts on the effective permittivity and could not be accurately taken into account in the analytical model. The finite-element method is expected to solve more complex problems on electromagnetic computation.

Abstract: This paper gets a further study to cladding of Ni-based Titanium Carbide in the surface of die steel of 718, This paper introduces the effect of laser process parameters on the titanium carbide and nickel solid solution and cemented carbide in cladding layer; on that basis, this paper studied the effect of the different of powder paving thickness, laser power and scanning velocity and other parameters on microstructure and properties of cladding layer. By controlling the powder-bed depth, using suitable laser cladding power and scanning speed, we can get the cladding layer of compact structure, no holes or no cracks. Experiments were carried out to get suitable process parameters, and analyzed its mechanism. It has certain significance guiding to improve the laser cladding of 718 die steel quality,

Abstract: In new dry way predecompostion cement production, after preheating, raw meal comes into a calciner, and occurs decomposition reaction, then freshly generated CaO comes into a solid-phase reaction process in the kiln. The three stages are closely related and interacted on each other. The formation rate of clinker mineral phases is closely related to the activity of CaO generated by the decomposition reaction, and high activity CaO is helpful to accelerate the formation of mineral phases and decrease the corresponding calcining temperature. However, there are large differences in activity values of CaO gennerated under various calcination conditions, and differet activated CaO has a different effect on the solid-phase reaction and dynamics of clinker formation. In this paper, in order to study the influence of different decomposition temperatures on the activity of generated CaO during solid-phase reaction, the content of free CaO after the reactions between the decomposition products of limestone under different calcination temperatures and SiO₂ was determined by chemical analysis, and the content of CaO involved in the reaction was calculated. The results show that at the limestone decomposition temperature of 900oC, the content of CaO participated in the reaction in clinker was increased, CaO activity was increased, these all were beneficial to the chemical reaction. Excessive decomposition temperature can decrease the reaction activity of CaO, so an appropriate decomposition temperature is necessary to make the majority decomposition of raw meal completed in the calciner, and ensure that generated CaO maintained a better activity state into the kiln to participate in the solid state reaction.

Abstract: Take Waugh-Type (NH₄)₆[MnMo₉O₃₂] •8H₂O absorbed on diatomite and prepared supported solid catalyst. The properties of the catalyst were studied through the synthesis of benzyl acetate. The appropriate reaction conditions were obtained by orthogonal test: mole ratio of acetic acid to benzyl alcohol was 2.5:1.0, the catalyst dosage was 1.6g, the water carrying agent toluene dosage was 2.5ml, reaction time was 150min, esterification yield was 87.4%. The catalyst are high catalytic activity and non- polluting, and could be reused.

Abstract: The lignite resource is rich in Xilingol League in Inner Mongolia. The two new methods were achieved to preparation activated carbon which used lignite as raw material. Firstly, the lignite was acidized by hydrochloric acid to prepare activated carbon. The catalytic materials in the ash as calcium, magnesium, iron and other elements were significantly reduced after that and the activated speed of the coal was significantly lower than the original coal, which are conducive to the development of uniform porous carbonized compound and decrease the hole broken. And a better surface area and adsorption properties of activated carbon was obtained. Secondly, with the carbonization and activation temperature at 800°C and 45 min, we can get the activated carbon with the excellent adsorption performance through fluidized catalysis of lignite.