Applied Mechanics and Materials Vols. 457-458

Abstract: We protocol to research and develop sport biomechanics quick response system for vault technical training, which quick analyzes vault techniques of athletes by using pressure plate on vault board to collect data of step position and strength, combined with synchronous acquisition of coxa joint kinematic parameters. This is helpful to improve the technical training effective of vault gymnast. We use a regular camera to shoot the positive side of athletes. At the same time the pressure plate is placed on vault board to collect dynamic data. Use MATLAB as a development platform, and input the video image of the athletes. The software automatically recognizes tracking coxa joint colored blocks, records the coordinates, and calculates position shift, velocity and other statistics of coxa joint accordingly. Pressure plate with built-in software BioWare can export pressure data and save it as a .txt format. Through programming, MATLAB can read kinetic data of pressure plate in .txt format, and synchronically analyze vault gymnasts movement with tracking kinematics data of coxa joint trajectory. Researching and developing this system is generated from practically overcoming the difficulty in vault training. The features of this system are to collect and analyze data with simplicity and quickness. This system is mainly comprised by normal camera equipment and pressure plate, which can provide a technical diagnose report with kinematics and kinetics parameters in one time vault exercise. For coaches and gymnasts, this report can be used as reference to provide improvement comments in vault daily training, as well as enhance effectiveness and efficiency of vault technical training.

Abstract: The tight sandstone formation usually has natural fracture, which is the foundation of effective development using hydraulic fracturing. The conventional reservoir productivity simulation method don't adapt to it. In this paper, Warren & Root model was used for describing infinity tight fractured reservoir model with vertical hydraulic fractures. Then, assuming the fracture length and the width does not vary with time and formation pressure, fracture seepage equation was obtained in base of the one-dimensional flow Darcy percolation equation and continuity equation. By Stehfese, a method of numerical inverse transformation, production performance simulation model was established for natural fractured tight sandstone reservoir. Taking for actual example from Daqing oilfield, affection of characteristics of natural fractures and artificial fracture parameters on productivity of natural fractured tight sandstone reservoir were analyzed. Elastic storability ratio has a greater influence than interporosity flow coefficient. It was the core technique for the gas reservoir to effective development by large amount of fluid and low sand ratio.

Abstract: In order to better analyze the load resonant characteristic of thrust vector servo mechanism of spacecrafts, multiple DOF mathematical models were established. Combined with the need of simulated actual conditions for ground tests, a comprehensive load simulator containing mechanical and hydraulic load was presented. The simulation results show that, the dynamic characteristics of output load displacement of the simulator is in agreement with the characteristics of actual system. The simulation and experimental results verify the feasibility of this load simulator structure, which could provide design reference for developing equipment of thrust vector control system for ground tests.

Abstract: With the development of oilfield exploration, the performance of electric submersible pump (ESP) has been enhanced very fast. It requires testing techniques develop at the same time. The most outstanding question is the testing of high temperature and pressure ESP. A testing well was drilled in Daqing in 1992. It keeps the water liquid state on 150 centigrade by high pressure. This system can simulate operational mode 3000 meters under the ground. But many new ESPs have been produced these years. The quondam testing system couldnt meet the testing requirement. A new testing system is desiderated eagerly. This paper developed a high temperature and pressure ESP testing experimentation system. Hydraulic/thermodynamic analysis calculation has been carried on. Friction resistance from constant pressure point to the suction inlet of hot water pump and the ESP in heating-forced cycle and experimentation primary cycle are calculated respectively. Keeping the water liquid state on 180 centigrade, constant pressure value was fixed on 2.5 MPa. The heat load is calculated including the heat that the water in the system and the equipment need and the heat loss. In order to protect ESP from emanating too much heat to keep the temperature and pressure of the system steady, heat exchange system has been designed. Cold load and heat exchange square have been calculated. Friction resistance and the size of the cold water cistern have been calculated. These provide necessary academic foundation for the testing experimentation of high temperature and pressure ESP.

Abstract: This paper presents a new method which combined multi-body dynamics theory and finite element technology to calculate transient stress of the crankshaft of the large-scale reciprocating compressor. On the basis of multi-body dynamics theory, the kinematical simulation of the crankshaft, the connecting rod, the piston and other components were performed, and thus to get the vibration modal of the crankshaft. So we can judge whether the crankshafts torsional resonance will happen, as well as get the real loads on the crankshaft when it worked. Then the transient stress of the crankshaft can be calculated using finite element technology. Comparing to traditional stress calculating methods, this new method not only considers the variable inertia which caused by reciprocating masss movement, but also can calculate the integrated vibration stress of crankshaft in three directions, including torsion, lateral and axial. Therefore, this method can describe dynamic characteristics of the crankshaft more accurately and more entirely.

Abstract: According to the characteristics of the marine pipelines, we present a kind of ships in-pipe reconnaissance robot for different types of pipes. Finish an optimized design for the adjusting mechanism by mechanics analysis of the metamorphic mechanism, and by the analysis of overcoming obstacles performance, the robot can not only adapt to different types of pipes, but also has good obstacle surmounting abilities. No doubt it improves the stability and reliability of the robot. The force and movement trajectory of the robot is obtained by using ADAMS, which carries on the kinematics analysis. Simulation results show that the robot can pass through 330 ~ 486 mm (diameter) pipes smoothly and can pass 5 mm circular obstacle by spring within the scope of the traction.

Abstract: In order to reveal the change rule of vibration acceleration during micro-end-milling straight groove, the single-factor and orthogonal experiments are employed to confirm the influence of milling parameters on vibration acceleration. On this basis, the relation equation between milling parameters and vibration accelerations is built. The result show that, the vibration acceleration along the width of groove is bigger than that of feed direction and it will increase rapidly with the improve of cutting speed; the predicted result of vibration acceleration is in good accordance with test result, therefore the relation equation can be used to predict vibration acceleration.

Abstract: In the paper, the steady-state steering dynamics model of the cars is firstly established. Then, three degree of freedom model of double row angle contact ball bearing is established. Based on the mathematical model and load spectrum, wheel hub bearing unit service life is calculated and estimated. The analysis results of the service life influencing factors have an important guiding significance for the design and use of hub bearing unit.

Abstract: Based on the proppant index, a production forecast method for thick oil-bearing formation fracturing was deduced. And combined with NPV methodology, treatment scale of multistage pump-off propped fracturing can be optimized. The effects of treatment parameters, such as injection stages, pumping interval, pumping rate, the ratio of pre and post stage pumping rate, on the fracture geometry, conductivity and production were simulated and analyzed. It reveals that two injection stages, 5 minutes of pumping interval and consistent pumping rate contribute to the highest annual cumulative production. Moreover, the injection stages make the most significant influence on production. Optimization results, applied to Kunbei Oilfield, achieved satisfactory application effects. The single well average production was enhanced by7.92 t/d, the stimulation ratio was 13.56, and the stimulation validity was about 270 days.

Abstract: The gluing control system designed for production plants to manufacture flap-disks was investigated using programmable logic controller (PLC) and servo. The system has been mainly developed to achieve efficient gluing for the back cover. It is implemented by a PLC, a human-machine interface (HMI), a positioning module and sensors, as well as servo amplifiers and motors. Issues was discussed in this paper, such as connection of the hardware, working mechanism design, capacity selection of servo motors, high-speed and uniform gluing, means of pre-opening and delayed-shutoff for the needle valve and etc. Hardware and software was developed for the system and high-precision gluing was achieved. The device has been provided for industrial applications, which has greatly improved the production quality and efficiency.