Applied Mechanics and Materials Vols. 423-426

Abstract: In pressurized water nuclear power plants, pressurizer is applied to control the primary loop’s pressure during transient processes. There are different thermodynamic models, which calculate the pressurizer’s tank pressure and water/vapor thermodynamic properties in different times. In this article, single-region and two-region models have been employed to simulation of WWER-1000 type pressurizer. Here, the obtained pressure from both models has been compared with RELAP5/Mod3 code findings. The RELAP is a thermal-hydraulic code, which has been developed and accepted throughout the world for simulating loop flows, for example pressurized water reactor (PWR) systems together with their related scaled systems. Finally, the pressure results have been compared and indicate that the presented models accuracy, are acceptable. The differences between models and RELAP code results are justifiable.

Abstract: The impulse theorem of mass center and the impulsive moment theorem relative to the center of mass and the kinematic consistency condition of studied problems are employed to investigate the friction oblique collision problem of planar moving small sphere and the friction wheel collision problem and the tube nut axial impact problem, the kinematic parameters of each problem after impact are obtained, the conclusions here can provide theoretical references to further designs of experiments and engineering design calculations.

Abstract: To simplify the internal force evaluation of portal frame being composed of non-uniform members, the force method was used to solve internal force of every key section of the non-uniform beam in portal frame with single-span. Gauss numerical integration method was used to simplify the complex integration when the deformation energy was calculated. Under the precondition of satisfied accuracy, the direct expressions of bending momentshear force and axial force of every key section of beam were obtained. The research work can be used as reference for the evaluation and design of portal frame members.

Abstract: The hard roller and soft roller are alternately arranged in the inking system of offset press. The ink vibrator is a hard roller which transmits the motion to the ink distributing roller. In order to analyze the motion mechanism of the ink roller, a model of an ink distributing roller and an ink vibrator is built up by using the software ANSYS. After the simulation of the motion, the force on the contact area of the ink distributing roller and the rotation speed of both rollers are analyzed. The result is that the ink distributing roller rotates with tangential force on the contact area and this force increases together with the rotation speed. When the two rollers rotate, the tangential elastic deformation is caused by the tangential force on contact area, and the radial deformation of the ink distributing roller is caused by the pressure. It leads to a relative sliding of the two rollers, which is mainly influenced by the rotation speed of ink vibrator and the radial deformation of ink distributing roller. Meanwhile, to verify the accuracy of the analysis, the rotation speed of the two rollers and the deformation of the ink distributing roller have been measured on a printability tester and then compared with the results of simulation. The analysis of the motion mechanism is very important to the study of printing color quality control.

Abstract: Adopted with the actual value of statistic geo-stress, using RFPA software to simulate the hydraulic fracturing of underground. The sample is treated as elastomers and simplified into plane problem, submit strength, elastic modulus, poisson ratio to weibull distribution. It could be found in figures that the size, length, extending direction of two crack is not identical. The cracks` forms grow into symmetry horizontal double-wing crack from the final result, besides, crack propagation direction is perpendicular to the direction of the minimum principal stress.

Abstract: Regarding the displacements and internal forces of Timoshenko beams as dual variables, Timoshenko beam problems were included into dual variables system. Corresponding to state transfer solution of Hamiltonian dual equation, transfer form solution of dual variables for Timoshenko beams was presented. Based on transfer form solution, element stiffness equation and the shape functions of Timoshenko beams were deduced, boundary integral equation and the fundamental solution function of Timoshenko beams were obtained, which reveal the intrinsic relationships among the finite element method, the boundary element method and dual variables system of Timoshenko beams. Based on the transfer form solution of Timoshenko beams, transfer matrix method for chain structure of Timoshenko beams was proposed. For chain beam structure problems, transfer matrix method is simple, intuitive, and has the advantages of good boundary adaptability and less calculation in solving the node variables of chain structures with recursive solution. The numerical results demonstrate the feasibility and accuracy of transfer matrix method in complex beam structure problems.

Abstract: A flexible isolation system of diesel engine was modeled to deeply study the effect of nonlinear isolators on the system response, and some cases of two-layer isolators were analyzed in ADAMS. The results show that when there are only the upper isolators with nonlinearity, the acceleration of engine block is decreased by 18.75% than that with linear isolators, and the acceleration of middle raft is decreased by 66.96% at the same time. However, when only the lower isolators are nonlinear, the acceleration of engine block is increased by 53.13%, and the acceleration of raft is decreased by 90.44%. The performance of system with all nonlinear isolators is similar to that of system only with upper nonlinear isolators.

Abstract: This study was aimed to investigate the dynamic characteristics of a multi-axis feeding stage of a milling machine. In order to clarify the influence of the guide system on the structure performance, we have proposed finite element approach to modeling the X-Y working tables with sliding and rolling guide, respectively. The results show that the machine models with sliding and rolling guides show similar vibration behavior. But the sliding guides give more constraints to the motion of working table, showing higher vibration frequency when compared to the rolling guides. This obviously indicates that the guide system significantly influences the resonant frequency and the response amplitudes of a feeding stage.

Abstract: To make the theoretical analysis of the microbial continuous culture more close to the experimental results, we consider a chemostat model with Watt type functional response and variable yield. The existence of limit cycles and Hopf bifurcation is investigated, which is useful in the further study of the oscillatory behaviors of the microbial growth in the vessel. The conditions for the global asymptotical stability of the model are obtained by Dulac criterion.

Abstract: Finite element simulation method of random vibration analysis was used for hermetically metal sealing. According to the results of the random vibration analysis and the theory of fatigue fracture mechanics, the hermetically metal sealing on the PCB plate cracking damage mechanism was analyzed. The danger point of the Von Mises stress was obtained, and the Von Mises stress - time history data was accessed through inverse Fourier transformation. And rain flow count method was used to calculate Von Mises stress-time history data of cycle count. The linear cumulative damage theory and the material S-N curve were used to calculate the fatigue life of Hermetically metal sealing.