Advanced Materials Research Vols. 875-877

Abstract: This paper proposes a cycle time design rule for a certain kind of time-constraint and re-entrant automatic production line. A computation model of the productive time and productivity is presented. Then, the cycle time under different schemes according to a real technology process is given. The design rule of this kind of line is deduced by a lot of simulations at last.

Abstract: To study the release process of micro-rocket system of small object, a novel model and numerical simulation is proposed. The structure and the work principle of the micro-rocket release system are explored. The release model is constructed using solid rocket theory, and including gap between objects and project canal. The theoretical methods are presented for the constructional design of micro-rocket releasing system of small object.

Abstract: The seismic responses under the action of far-fault and near-fault ground motions of the bridge tower structure of the long-span cable-stayed bridge are numerically discussed by means of the model of the bottom consolidation of the column. The results show that the responses of tower of the cable-stayed bridge correlate well with the properties of the ground motions. The seismic responses of the model have much larger values under the near-fault velocity pulse-like ground motions than those of the counterpart. The frequency of system reduces as the flexibility of structure decreases because of the rigid foundation; The displace response of tower shows that the rigid foundation has little influence on the seismic response of the cable-stayed bridge, while the acceleration response of the tower implies that rigid foundation has adverse effect. Thus, consideration of the soil-pile-superstructure interaction can be meaningful both in theory and reality during the seismic design of long-span cable-stayed bridge structure.

Abstract: In this paper the topology of the grid-connected regenerative electric drive systems (REDS) and the performances of the integral state feedback current controller of the front-end three-phase power inverter are presented. The proposed control was successfully implemented by the author on a quasi direct AC-AC converter with Proportional-Integral current controllers and the simulation test has been performed for the modified integral state feedback current controllers based on the Matlab/Simulink software. The comparative results between the actual current controller topology and that of the conventional PI current controllers of the AC-AC power converter are reported. Moreover, the solution presented in this paper adds supplementary benefits to power system besides the conventional state feedback control: the designed input filter assures zero steady state error and an adequate component is added for the dynamic rejection of the load disturbance. Because it uses the integral component, the control structure has robust capabilities to disturbance actions.

Abstract: As one of the key components, the feeder coil terminal box (ctb) of the international thermonuclear experimental reactor ( iter) covered with an internal 80[K] thermal radiation shield, provides the 4.5[K] environment and houses the interconnection of the magnet systems with the cryo-plant, the power supplies, the data acquisition system and the local cryogenic components. This paper presents a finite element analysis of fluid-solid heat transfer on thermal shields for iter pf (poloidal field) feeders coil terminal box (ctb), especially for cooling-pipes and his connection with panel firstly. The main objective of this analysis is to evaluate the heat-shielding effects of design layout and operating parameters of helium cooling-pipes with cfd (computational fluid dynamics) techniques. The model and method do not only consider the temperature distribution as well as the pressure dropping, also the deformation caused by thermal stress. Based on the results, the heat transfer in the ctb thermal shields has been studied and the detail design confirmed.

Abstract: The machining deformations caused by the release and redistribution of original residual stresses were studied by the theoretical analysis and finite element method. The research results show that the release and redistribution of original residual stresses result in machining distortion of the plate part. There exists an optimal value of material removal amount according to original residual stresses. When the amount of the material removed exceeds the optimal value, the machining deformation can be controlled effectively.

Abstract: In the last twenty years, we assist to a total transformation of the façades cladding technology with low thickness stone elements. The old conception of the anchorage component is exceeded and approach us a new production of systems and accessories for the connection of stone elements with a high degree of performances. In the field of the building façades cladding, using low thickness stone slabs, it is being developed the art of connections. This paper summarizes a research experience in which we focused a methodological model for the technological design of the façades cladding, using low thickness stone elements.

Abstract: The present study is a preliminary effort which investigates the effect of different sequences of composite materials on the Von Mises stress and stress concentration factor on a simple thin cracked plate. Our approach is to reduce the design of cylinder under internal pure pressure to that of a cracked metal plate reinforced by different sequences layers of composite subjected to a tensile loading. Four reports of the length of the crack front (a) with respect to the thickness (t) of the structure were analyzed. The increased ratio (a/t) from 10% to 40% positively influences the values of stress intensity factors and the Von Mises stress. Finally, the numerical results show that the reinforced the cracked structure with composite layers has greatly reduced the stress intensity factor at the crack tip based on fiber orientations.

Abstract: A two-scale method able to carry out a macroscopic failure analysis of a composite structure in presence of microscopic mixed mode interface crack initiation, is proposed. The method is able to accurately predict local failure quantities (fiber/matrix interfacial stresses, energy release and mode mixity for an interface crack) in an arbitrary cell from the results of a macroscopic homogenized analysis. Microscopic crack initiation is thus analyzed by using a coupled stress and energy failure criterion in term of these local quantities. Numerical results are obtained for a plane strain model of a locally periodic fiber-reinforced composite material subjected to shear loading and characterized by initially undamaged fiber/matrix interfaces. Predictions for the critical load factor and interface crack length at crack onset obtained by the proposed model are compared with those obtained by means of a direct simulation.

Abstract: In this paper, we present a novel approach for calculating chemical reaction rates based on molecular collision theory, in which molecular collision cross sections are calculated by averaging over all reactive trajectories from ab initio molecular dynamics simulations. The molecular collision radius is determined by both reactive and non-reactive trajectories of molecular dynamics under constant temperature. Thus, both steric and temperature effects have been take into account for molecular collision cross sections. We have applied this approach to calculate reaction rates of reactions KO+CO==K+CO₂, KO+C==K+CO, and K₂O+CO₂==K₂CO₃ under high temperature. It also shows that under higher temperature, the probabilities of a successful reaction resulting from particle collision are low, because the products are not stable.