Papers by Keyword: Coupling

Abstract: This paper describes the speed regulation of a magnetic gear integrated permanent magnet synchronous motor. The operating principle of the motor is discussed and the torque transmission is analyzed using finite element method; hence the motor model is established. The speed regulation is analyzed under vector control, and the simulated results verify the feasibility of speed regulation control.

Abstract: Based on the friction stir welding rig,the temperature field model was established by COMSOL Multiphysics under the coupling effect of joule-heat and friction heat. The coupled temperature field distribution and variation rule of the analysis model were simulated and analyzed under current-carrying or without current. The results show that the maximum temperature mainly distributes the contact area of the pin tool and work piece. The distribution of the temperature and isothermal layer with current is basically same with non current. The temperature distribution area of shoulder with current gets larger than without current condition. Under the constant welding velocity,axial force,rotation velocity and displacement,the maximum temperature produced by coupling function of joule-heat and friction heat is much higher than the one,which engendered by friction heat.

Abstract: For the numerical simulation of sheet metal forming processes, the commercial finite element software packages are among the most commonly used. However, these software packages have some limitations; in particular, they essentially contain phenomenological constitutive models and thus do not allow accounting for the physical mechanisms of plasticity that take place at finer scales as well as the associated microstructure evolution. In this context, we propose to couple the Abaqus finite element code with micromechanical simulations based on crystal plasticity and a self-consistent scale-transition scheme. This coupling strategy will be applied to the simulation of rolling processes, at different reduction rates, in order to estimate the evolution of the mechanical properties. By following some appropriately selected strain paths (i.e., strain lines) along the rolling process, one can also predict the texture evolution of the material as well as other parameters related to its microstructure. Our numerical results are compared with experimental data in the case of ferritic steels produced by ArcelorMittal.

Abstract: Failure develops and propagates through a structure via a complex sequence of competing micro-mechanisms occurring simultaneously. While the active mechanism of surface debonding is the source of loss of stiffness and cohesion, friction between cracked surfaces, upon their closure, acts as a passive dissipation mechanism behind the quasi-brittleness and hence can increase the toughness of the material under favorable loading conditions. In order to numerically study damage propagation, the constitutive response must be able to faithfully capture, both qualitatively and quantitatively, one of the signature characteristic of failure: the energy dissipation. In this paper, we present an interface decohesive model for discrete fracture that is able to capture the apparent enhancement of interfacial properties that is observed when transverse compressive loads are applied. The model allows to seamlessly account for the additional frictional dissipation that occurs when the loading regime involves transverse compression, whether during debonding or after full delamination. This constitutive model is then used to successfully predict the response of realistic engineering structures under generalized loading conditions as demonstrated with the numerical simulation of a fiber push-out test.

Abstract: Using torque telemetry system to test the mechanical drive system of rolling mill,it is found that the torsional vibration and current signal in the electric drive system have the same obviously vibration frequency. The model of cycloconverter, synchronous motor and mechanical drive system of rolling mill are built and analysed by Matlab/Simulink and ANSYS.The simulation results show when the harmonic torque frequency and the torsional vibration natural frequency of for mechanical drive system are equal or close, the strong torsional vibration arouse It is proved that the convertor output current harmonics can induce the electromechanical coupling vibration of main mechanical drive system under the certain conditions.

Abstract: A nondestructive inspection system has been developed using the active thermography technology. However the solder defects can not be distinguished directly from the thermal images captured by IR camera because of the heating non-uniformities. The principal component analysis is explored to identify the defects of the solder bumps accurately and effectively. Thermal contrast image is obtained by subtracting source distribution map from the original thermal image. The hot spots corresponding to 16 solder bumps are segmented. The pixels with the thermal contrast values ranging from 0.18°C to 0.20°C are counted, and the maximum and the minimum of the pixel value are found out respectively, which are used in the principal component analysis. The missing bump is identified by the first principal component score. The results show that it is effective using the principal component analysis in active thermography for defects inspection of solder bumps in microelectronic packaging.

Abstract: In this paper we introduce cross tree and block mathematical principles into the design of database system, divide the time sequence and storage space of computer database system, establish the mathematical model and algorithm of computer resources database system, and design the test database system. In this paper, we use high performance interface of Display Port, by way of coupling to communicate on two port control, and use RHEL 6.2 Linux virtual machine to do simulation experiment on process of database system. Through the simulation we find the API which is called by Read, Close, Mmap, Stat, Fstat is similar. It is consistent with the actual situation, and verifies the reliability of the program. Finally, we apply the database system to the network database construction of sports literature resources in the new town of Poyang Lake area. It reaches the effect that sport resources are shared by all. It provides technical support for the application of computer database system.

Abstract: Based on the heterogeneity of rock, the application of the theory of elastic damage mechanics, the Biot seepage mechanics and the theory of effective stress, considering the rock damage before and after the crack extension and penetration, the numerical calculation model using software RFPA is established in this article. Through the simulation research of rock specimens under the conditions of different osmotic pressure difference of seepage damage law, results show that the permeability coefficient of the rock and the crack, expansion and penetration is directly related to, but also affected by the failure mode of the rock. Permeability changes obviously lags behind the rock damage and crack or fissure extension, permeability of kick also lags behind the peak strength of rock.

Abstract: Using the finite element ANSYS workbench platform Hydrodynamic Diffraction and Hydrodynamic Time Response Module, taking a self-elevating offshore mooring location as a study case for the corresponding value calculated the dynamic response of the platform. Studied in the wind, waves and currents under load, platforms and mooring ropes coupled motion in case of time-domain response analysis, and get mooring ropes mooring and platform displacement force-time curve. Methods discussed in this paper have a certain reference value for offshore platform mooring positioning.

Abstract: This paper presents a mutual mode entropy algorithm to quantify the degree of coupling between two simultaneous acquisition of beta rhythm EEG time series. Applying the algorithm to calculate beta rhythm EEG and hypothesis testing, the results show that coupling degree was significantly different between different physiological states which indicating that mutual mode entropy can be used to analyze the coupling between the time series. The mutual mode entropy also can be parameter measuring brain state which can be applied to assist future clinical evaluation of brain function.