Advanced Materials Research Vols. 118-120

Abstract: A novel time-variant reliability model is developed after studying the traditional dynamic performance of mechanism. The expression of reliability is given based on stochastic process. A two-dimensional description of the error generating process is established by studying mechanism output kinematic accuracy. The reliability of mechanism output kinematic accuracy can be obtained according to this description. The model proposed can be used to calculate the reliability of mechanism directly, if the distribution of mechanism output kinematic accuracy is known.

Abstract: Rapid prototyping (RP) is an innovative manufacturing technology. In recent years, the research to fabricate multi-material products by RP is becoming active. In this paper, we update the recent development of process planning for multi-material RP.

Abstract: Fatigue test were performed on 2024-T62 aluminum panels with MSD cracks, and the fatigue behavior of panels with MSD was analyzed. By the experiment results, the speed of crack growth increased stably in most time of life span, and crack growth rate curves were plotted. Then a rough method was presented to evaluate fatigue life of aluminum panels based a constant geometric factor from the curves and the evaluation is useful in engeering.

Abstract: The heat transfer in solid-fluid coupling system relates to not only the heat transfer process in solid and fluid bodies but also the physical quantity exchange through the boundary. Because some boundary conditions, such as heat flux and coefficient of heat transfer, are uncertain, neither solid body nor fluid body can be separated from the coupling system when the thermal coupling analysis is carried out. A coupling analysis method based on numerical simulation codes ABAQUS and FLUENT was put forward to solve the boundary problem. The two simulation codes were controlled by the interface software which was developed to exchange the boundary conditions between solid and fluid models at each iteration step. A copper finned radiator model and its corresponding air model were built by ABAQUS and FLUENT respectively, and the heat elimination process of the radiator under forced convection conditions was investigated. The heat elimination characteristic of an aluminium radiator was also researched. By comparing with the copper radiator, it can be found that the larger the coefficient of heat conductivity is, the higher the heat elimination efficiency is.

Abstract: This paper presents a kind of all-digital integrated hydraulic actuator (IHA) unit to drive heavy load object without centralized oil tank. In order to improve the control quality of the actuation system while eliminating or reducing the disturbance, and also to solve the problem of flow rate mismatch existed in IHA with single-rod cylinder actuator, a fuzzy PID PWM controller is suggested. Simulations on the integrated hydraulic actuator unit are carried out to evaluate the effectiveness of the proposed control method when applied to hydraulic systems with various external disturbances encountered in real working conditions. Simulation results are discussed and some conclusions are given.

Abstract: On the basis of the idea that the displacement response of the structure can be expressed as superposition of normal modes of vibration multiplied by corresponding time-dependent modal coordinate, the strain response of the same structure under the same loading condition can also be regarded as a superposition of strain modes multiplied by modal coordinates, this paper presents a hybrid method for determining the dynamic stresses of railway vehicle based on the combination of experiment and numerical simulation. The calculation formulas based on strain mode superposition principle is deduced in detail. The numerical experiment shows that the dynamic stress time history can be obtained by the proposed method expediently and accurately. In addition, to meet the demand of fatigue engineer of the vehicle bogie, a software system was developed, which has a friendly, open and easily removable interface and is valuable for practical use.

Abstract: Double-tubesheets are used in heat exchangers where strict tightness is required. In this paper, finite element analysis models were established to simulate the double-tubesheets. Stresses and deformations in the tubesheets induced by pressure load were calculated and formulated. Results showed that the tube supports to the tubesheet are much stronger than considered in the commonly used heat exchanger design codes. If the design is based on accurate stress analysis using finite element method, the tubesheet thickness of heat exchangers could be significantly reduced. The two tubesheets strengthen each other especially when their spacing is short.

Abstract: The theoretical hydrodynamic pressure modeling were presented for flow of coolant fluid through the grinding zone in flood delivery grinding using roughness surface grinding wheel. The simulation results show that the hydrodynamic pressure was proportion to grinding wheel velocity, and inverse proportion to the minimum gap between wheel and work surface and the maximum pressure value was generated just in the minimum gap region in which higher fluid pressure gradient occuring. It can also be concluded the surface roughness of grinding wheel and workpiece makes the contact zone’s hydrodynamic pressure rough and unstable, i.e. the value curve considering roughness is not smooth, leading to the micro-elastohydrodynamic lubrication phenomenon.

Abstract: Excessive levels of vibration in commercial vehicles, due to excitation from the road irregularities, can lead to cargo damage and safety problems. In order to study the cargo ride safety problem, a three dimension (3D) finite element model of full vehicle was established, which differs from the previous two dimension (2D) one. The computation algorithm for acceleration power spectral density (PSD) and root mean square (RMS) was also given. For the sake of comparisons, two frames with different stiffness were given in the computations of PSD and RMS of body vertical accelerations for four excitation cases. The computed results showed that when the stiffness of the frame increases, the RMS values of the body decreases strongly at the frequency band 14-26Hz, which can effectively improve the cargo ride safety.

Abstract: A system design for a recycling process for the nano removal of the indium tin oxide (ITO) nanostructure from the color filter surface of TFT-LCD displays is presented. The low yield rate of ITO thin-films is well known in semiconductor production processes. By establishing a recycling process for the ultra-precise removal of the thin-film nanostructure, the optoelectronic semiconductor industry can effectively recycle defective products with a reduction of both production costs and pollution. In the current experiment, the major interest lies in the features of the technology and the design of an oblique cathode for the electrochemical removal process. For this process a steep gradient of the oblique cathode provides large discharge mobility and a better removal effect. A thin oblique cathode, a small gap-width between the cathode and the ITO surface, or a high flow rate of electrolyte corresponds to a higher removal rate of the ITO-layer. A large current flow combined with a high feed rate of the display also results in a fast removal rate.