Advanced Materials Research Vols. 472-475

Abstract: The micro robot that based on resonant principle can get high speed and high precision. However its leg is usually a flexible continuum with complex shapes, and its dynamic modeling is a key problem during researching this kind of robot. A method combining finite element with modal coordinates is presented, and is used to build Finite Degree Of Freedom (FDOF) model of Multi Rigid Bodies (MRD) for flexible leg of micro robot. Modal analysis of continuum model and FDOF model of MRD for flexible leg is conducted in ANSYS and ADAMS software environment respectively. Analysis results show that the two model have similar lower nature frequency and vibration modes, which verified the correctness of the FDOF model and its establish method. Based on FDOF model, the equivalent drive model of piezoelectric bimorph and system dynamic model of micro robot are build, which provides a theoretical basis for dynamic analysis of the micro robot.

Abstract: The polyaniline have been prepared in the absence and presence of magnetic field by the technique of cyclic voltammetry (CV) on 304-stainless steel electrode in H2SO4 aqueous solution of aniline (Ani). The influence of magnetic field on electropolymerization of PANI was investigated by electrochemical properties, FT-IR spectra, X-ray diffraction (XRD) and microstructure. The results indicate that the effect of magnetic field on the polyaniline is positive.

Abstract: In order to optimize the craft parameter of cold roll forming, this paper puts forward a new method reflect the law between cold roll forming force and craft parameter. The method combines artificial neural network and finite element emulation for cold roll forming, and begins with analyzing the cold roll forming to decide the main factors that have an impact on roll forming force. According to the single factor experiment method, the paper establishes the roll forming emulation model to simulate, and a BP neural network is constructed with the sample data from the simulation.

Abstract: The current research on the porthole-die aluminium alloy extrusion is presented here. The empirical method and simulation method are analyzed. Particularly, the Lagrangian Finite Element Method(FEM), Eulerian Finite Volume Method(FVM) and Arbitrary-Lagrangian Eulerian(ALE) algorithm are compared. The development of the porthole-die aluminium is educed.

Abstract: The mechanics properties and improved structure design for an advanced typical aviation pipe connection fit based on contact FEA and ANSYS have been researched in this paper. First of all, by establishing a multi-body contact FEM for a connection fit, its contact mechanics properties and the simulation method of pretension torque are discussed. Then the mechanics properties and stress distribution in working condition for the original connection fit are calculated and analyzed. In the end, in view of the deficiency of stress concentration in the original design, the structure improvement has been discussed and fixed on, and at the same time the stress analysis for the improved connection fit is carried out. The study has shown that as an effective means to design a pipe connection fit and analyze its mechanics, the simulation method of multi-body contact FEA given in the paper can be used to analyze effectively the mechanics properties, and the structure improvement to the original connection fit can effectively get a better load properties and enhance its reliability.

Abstract: Abstract. Above all, it is discussed about vibration mechanism of the pipe system in a chemical ship, according to layout feature of pipes, the finite element model of the pipe system is constructed by means of CAESARⅡ software, through analyzing internal characteristics of pipes, exciting force and valves of dynamic responses are deduced, displacement responses are tested after the pipe system is applied by exciting force, damping projects of pipes are put forward to after measuring results are compared with calculation results.

Abstract: This paper, based on the current state and problems of saving and intensive land use system of urban-rural integration in Chongqing, in which methods of theoretical approach and system analysis are applied, brings up three mechanisms as: (1) the connecting of the increase of urban construction and the decrease of rural residential area; (2) the connecting of sprawling and farmland consolidation; (3) the connecting of intensive land-use in urban-rural area. At last, the paper builds up the saving and intensive land use system of urban-rural integration follow as: (1) perfecting land surveying system; (2) strengthening land statistics system; (3) perfecting land evaluation system; (4) clearing land property right system; (5) improving land registration system; (6) refining land use system; (7) building land tax system; (8) explicating land consolidation system.

Abstract: Cracking is a serious problem in laser-clad hardfacing layers due to inhomogeneous distribution of coarse brittle phases and stress induced during rapid solidification. Tantalum carbides and borides which can form and precipitate at much higher temperatures are tentatively designed to inhibit the formation of the coarse brittle phases of chromium carbides and borides. It is found by XRD analysis that TaC, Ta4C3, TaB and Ta5B6 were formed in-situ and the coarse brittle phases were largely avoided in laser-clad Ni-based layers. It is also found that the formation sequence of these species is governed by their precipitation temperature instead of the rule determined by the standard free energy of formation. The formation of the chromium carbides and borides is inhibited due to the priority of formation of tantalum carbides and borides during rapid solidification. SEM and penetration visualization examinations show that the microstructure is markedly refined and the cracking susceptibility is significantly reduced by this method. The microhardness of the layers maintains at about 800 Hv.

Abstract: ZrO2-8wt.%Y2O3 (8YSZ) thermal barrier coatings (TBCs) were deposited by atmospheric plasma spraying (APS) on NiCoCrAlY-coated Inconel 738LC substrates. The thermal shock behavior was investigated by quenching the samples in water with temperature of 20-25°C from 950°C. To study of failure mechanism results from thermal cycling, microstructural evaluation using scanning electron microscope (SEM), elemental analysis using energy dispersive spectroscopy (EDS) and phasic analysis using x-ray diffractometry (XRD) were done. The results revealed that failure of the TBC system was due to the spallation of ceramic top coat. Thermal mismatch stress was the major factor of TBC failure in thermal shock test.

Abstract: Zn alloy die casting is easily corroded and porous, so it is hard to obtain the strong adhesion strength between the substrate and the metal coating. In this paper, Cu coatings were prepared by ultrasonic-electrodeposition on Zn alloy in a cyanide-free deposition bath containing a base agent of 1-hydroxyethylene-1, 1-diphosphonic acid (HEDPA). The effect of ultrasound on the electrochemical behavior of bath and the morphology of the coating were investigated by potential sweep and by SEM, respectively. Experimental results indicate that pre-treatments, such as electrolytic degreasing, have a remarkable influence on adhesion strength. Application of ultrasonic increases the limiting current density of cathode and enhances the throwing power of bath. Application of ultrasonic also promotes the formation of network-cross copper coating which enhances the adhesion strength between the substrate and the coating.