Applied Mechanics and Materials Vol. 441

Abstract: An impact experiment of cantilever-type piezoelectric generator is founded in order to record and analyze the first crest of output waveform. For the first crest, the analysis results show that the impact velocity, the peak voltage and the electric energy have positive correlation. The impact velocity has little influence to electricity. With the impact amplitude raised, the peak voltage, the electricity and the electric energy will rise, however, the rate of rising will descend.

Abstract: Mechanical state has a major impact on the repairing effect of tissue-engineered cartilage. The unusual state could result in the degeneration of artificial and host cartilage. A repaired cartilage defects was simulated by finite element simulation based on fiber-reinforced biphasic model in sliding load condition. The results showed that in the surrounding area of defects Mises stress, compressive strain and pore pressure are affected by the amount of compression and modulus of materials. Inadequate modulus leads to the declining mechanical bearing ability in defected position, while excessive modulus leads to increasing difference between the pressure on the two sides of bonding surface between artificial cartilage and host cartilage. During the repair process, it is suggested to choose the artificial cartilage modulus with both reasonable bearing ability and less stress concentration should be considered, and the intensity of exercise should also decrease to reduce the amount of compression.

Abstract: A nonlinear integer programming model (NIPM) with constraints is proposed to solve the allocation of approach flight flow where ends with terminal airspace, an example of an airport terminal airspace is given, where the flow is accurately forecasted.Analysising flight delays, theres a conclusion: the results solved by NIPM is far better than the average allocation method, for the second-level airspace, NIPM can reduce two flight delays, and the allocation in each flight route tends to be equilibrium, NIPM can also provide air traffic controllers with accurate and reasonable allocation schedule.

Abstract: The technology of focused beam forming is mainly used for solving some certain problems about high-precision passive positioning in near field. In view of the problem of positioning accuracy, this paper discusses the effects of factors on the width of focused peak and its changes with the factors. The result of study shows the longer arrays length and the higher frequency band of signal and the shorter distance to the target, the narrower width of focused peak, which means the higher the positioning accuracy. The influence of the errors on the positioning accuracy is also simulated and analyzed in this paper. It turned out that, when horizontal linear array is used in the positioning, the horizontal error from the placement of array and parts of array elements no working have little effect on the positioning accuracy for the reason of the horizontal directivity of the array. The vertical errors from the placement of array, from the measurement of depth of the sea and the sound velocity impact the positioning accuracy a bit more. With the analysis of positioning accuracy, it proves that the technology of focused beam forming can realize high-precision positioning in near field. Finally, several suggestions on improving the positioning quality are offered.

Abstract: To correlate medium parameters and pressure oscillation in SRM (Solid Rocket Motor) combustion chamber, a two-dimensional axisymmetric model was developed based on the typical VKI (Von Karman Institute for Fluid Dynamics) motor. Medium temperature and working pressure as the key parameters, LES (Large Eddy Simulation) was carried out for two groups of different models. Finally, pressure evolution and its FFT (Fast Fourier Transform) results were obtained. It indicates that for SRM with the same structure, medium temperature determines the frequency of pressure oscillation, and working pressure dictates its amplitude.

Abstract: The shield tunnel method is a way that widely used in tunnel build. However, the ground surface displacement and deformation because of tunnel excavation will bring a series of affections in our engineering. By using the finite element model of different tunnel excavation depth, different elastic modulus and different tunnel diameter of the tunnel, we predicted it correctly. Finally, we get the relationship between the surface displacement and the depth of tunnel excavation, diameter, strength of soil.

Abstract: It is of great significance to adopt the reasonable scheme to repair the abrasive shaft in order to make sure the safety and stable operation of the steam turbine unit. Taking a real 600MW steam turbine generator unit with worn shaft as the target system, we employ finite element software ANSYS to establish the model of the local worn shaft segment in this paper. Two kinds of optimized processing strategies are proposed to repair the worn shaft segment, considering the situation of cutting quantity and shear stress distribution. The two proposed schemes can reduce the stress concentration of the worn shaft parts largely. The study proves that the method is feasible and can be used to processing other similar failures.

Abstract: According to the chatter phenomenon of 3^rd stand of a steelworks six-roller tandem cold mill (TCM), vertical vibration of tandem cold mill was simplified to eight degrees of asymmetric freedom mass-spring system. Virtual prototype model on vertical vibration of tandem cold mill was established and natural frequencies and main vibration mode of mill were solved by using automatic dynamic analysis of mechanical systems in software ADAMS. The modal coordinates of main vibration mode of the mill were referred firstly and obtained; the maximal mode of vibration system was found and finally discovered the fifth-octave-mode chatter was the probable vibration of the mill.

Abstract: Commercial CAD/CAM systems provide semi-automatic tools to assist the designer in the dimensioning process. Analytical solutions to injection molding problems are very rare due to thecomplexities of the governing equations, the material behavior and the cavity geometry. Study of window frame fabrication by injection moulding process was carried out with the aid of Moldflow® software. Ejector plate designs were created to compare the pros and cons of each design. The investigations were carried out on flowing, packing, cooling and costing of injection moulded window frame. Using the method, good results have been obtained for several basic geometric models.

Abstract: By using modeling and simulation technology, motion simulation and structural analysis were carried out on hydraulic manipulators structure working in the radiation environment. The results of motion simulation can test the manipulators kinematics characteristic, and provide a basis for structural optimization design.Structural analysis could be used to validate manipulators s tructure is able to withstand the movement of stress, strain or not. Manipulators structure design can be properly improved by use of the structural analysis.