Advanced Materials Research Vols. 139-141

Abstract: In allusion to the problem that the newly developed pumping units using for automotive power steering gear assembly can not clean the inside oil, the paper takes the key flow channel as the research object, establishes the 3D geometrical model, meshes it, and then uses the Fluent software to simulate and analysis the flow. After setting different working conditions as diverse pressures of the import and export, the paper gets some visual results of the flow velocity vector and the flow pressure vector. At last, according to the characteristic diagrams of the flow received from the stimulation, the paper gives some theoretically explanation to the phenomenon of remaining a small quantity of oil and provides an important basis to set some important parameters of the pumping machine. Meanwhile, it gives some reference significance for the optimization design of steering gear.

Abstract: This paper aims at the structures of heavy gas turbine rotor’s support, the analyze method of fluid-solid couple and that of thermal-solid couple is adopted to simulate by ANSYS CFX, by compared with the deformation of the different structures of their support, it sums up that the tangential support is the best structure. Furthermore, the deformation of the tangential support under different conditions is analyzed, such as the different temperature of gas and the ultimate load of shaft, that supports the research of the working mechanism of the sliding bearing and the dynamic characterization, and finally the research achievements are expanded to apply the study of the stability of shaft power, providing a basis for the study and development of the future’s gas turbine technology.

Abstract: Aiming at a large marine diesel engine, a mathematical model for the 3-D elastohydrodynamic lubrication analysis of piston ring-cylinder liner was presented. The average Reynolds equation and asperity contact approach were combined with the elastic deformation equation. The asymmetry in the circumferential direction, gas blowby and the effect of temperature and pressure on the oil density and viscosity were considered. The 3-D wear simulation of piston ring-cylinder liner was performed when the diesel engine was operated under warm start and cold start conditions, respectively. The 3-D distribution rules show that the first gas ring has the biggest wear loss, and the maximum wear loss of cylinder liner occurs in the vicinity of TDCF. Finally, the results matched well with the wear measurements, and it indicates the present method is effective and can help engineers to improve the tribological performance of the diesel engine.

Abstract: A pressure pulsations reactive attenuator for controlling hydraulic system was investigated through theoretical and experimental means. The attenuator consists of many “mass-spring-damp” lumped parameter vibration systems with different natural frequency. Through the fluid-structure coupled vibration, the fluid vibrations are converted into structure vibrations. And on this device, the filter attenuation model was established and the simulation results show that, changing the system flow pulse frequency (from 186 Hz to 225 Hz) near to the resonance frequency (236 Hz) of a certain lumped parameter vibration system, the attenuator has a good effect because of component resonance attenuating hydraulic pulsation energy. To verify the correctness of simulation results, the experiment is tested and the results are homology. It provides a new practical technique for hydraulic system vibration control.

Abstract: Mould-repair is an important task in the mould production and depends especially upon the experience of the engineer. It is much full of subjectivity and uncertainty. How to find the knowledge of mould repair and establish the mould repair solving project is an important problem for all the injection mould manufacturers in the industry. Using the Bayesian networks reasoning to help the technician establish the mould-repair solving project was put forward. The mould-repair Bayesian networks (MRBN) reasoning model was established according to the characteristic of mould-repair solving project. The reason control tactic of the process plan system and the reasoning engine of MRBN were designed. The application example about the shrinkage, ill-full injection, gas-obstructed is presented to prove the correctness of the method. The conclusion shows that it can help the engineers analyze the cause of problem well and recommend some more useful solutions.

Abstract: The pressure distributions in cavitations nozzle of three different structures were studied by Hydromechanics theory, the models and mashes were completed by using Gambit software, for the conditions of the inlet pressure to 20MPa and the outlet pressure to 0.1MPa, the flow field within cavitations nozzles is simulated based on the standard k-ε model and the SIMPLE algorithm with Fluent. The result of numerical simulation is consistent with that of analytical calculation. Simulation results show that the flow has a strong shear effect with the surrounding medium in the diffuser, resulting in significant negative pressure, which is conducive to the formation of cavitations bubbles. The angle nozzle is best selected for impinging streams cavitations reactor on this basis in the paper.

Abstract: The collision characteristics of the truck fences are very important to occupant safety in car, when the car’s front collisions the tail of truck. This study is a kind of the truck fence structure and simulates its crash. First, simulates the original truck guards. Second, improves the truck fence, and the truck fence is simulated by ANSYS / LS-DYNA. Finally, the simulation results and unimproved simulation results are compared. The results show that the dynamic response characteristics (deformation, velocity and acceleration) and the absorb energy (interna energy and kinetic energy) of the improved model are significantly enhanced.

Abstract: The multi-body system analysis has become one of the main simulation techniques to calculate the kinematics characteristics of a car suspension under wheel travel or to build a virtual prototype model of a vehicle in order to predict the vehicle dynamics performance. The modeling of twist beam rear suspensions is always difficult for the unique structural behavior of this component. A non-linear method based on multi-body dynamics software (ADAMS/Car) was used to represent the twist beam within the suspension system. The kinematics characteristic analysis of the rear suspension was realized by means of ADAMS/Car. The main suspension parameters (toe angle, camber angle and wheel track variation) were calculated by changing wheel travel. The result shows that the method of suspension kinematics analysis by using ADAMS/Car can be used in the design of suspensions conveniently.

Abstract: The mechanical equipment faults result from parts failure in the period of service time, due to reassembly and maintenance, the reliability model for mechanical equipment is broken, so it is necessary to research and estimate the safety reliability of mechanical system. Based on the time-to-failure density function of parts, the mechanical system reliability model is constructed to track the change course of age structure of part population for the mechanical systems that are reassembled and maintained. By means of simulation of the system reliability model, concerned parameters with mechanical systems service life are defined, it is discussed how the time-to-failure density function have influence on the service life for mechanical systems undergoing reassembly and maintenance. It is significant to estimate reliability and failure rate of systems and to establish reasonable maintenance policies.

Abstract: According to the demand of exploiting the poor-thin oil layer in Daqing oilfield, Y422 retrievable fracture bridge plug is designed. Match usage of this bridge plug and other instruments can fracture multiple oil reservoirs with one-trip string, which is characterized by simple technology and safety operation. This bridge plug has realistic significance and practical value for improving oilfield economic benefits and provides an extensive application prospect. After setting process, the slips brace the bridge plug whose performance have a directly influence on the oil well productivity and production safety. In order to make sure that the bridge plug slips can meet the anchoring requirement, the actual working state of the slips system was analyzed by using finite element software, and the stress distribution rules were obtained. The results provide theoretical basis for optimizing slip structure and improving working reliability.