Applied Mechanics and Materials Vol. 422

Abstract: This paper elaborates much security menace of using gas and analysises defect of products now available, and advance a new normally closed type safety valve for gas, it can effectively prevent much security menace which was caused by the aging of the rubber tube and leak of the joints of the pipes. Design of structure and control circuit of the valve are introduced in this paper. And the security of this valve was tested and proved by experiment. In the Mechanical Innovative Design Competition for National College Students in 2010, this design gained the national first prize. Its practicability and innovativeness were highly acknowledged and appreciated by the industry experts and got patent for utility models in the same year.

Abstract: A concept of solar chimney utilizing solar panels for building passive ventilation is proposed in this paper. First, CFD Numerical analyses were conducted to test the feasibility. Major dimensional parameters were considered in the simulation and meaningful air flow rates were observed under normal conditions. Experiments were conducted to confirm the concept and to understand the physical mechanism of the phenomenon by air buoyancy. Based on the results of the study, the proposed solar panel chimney and its advantages are worth of further investigation. Based on this innovative concept, the rooftop solar panel could be re-arranged, grouped and boxed to form an effective solar panel chimney, to serve as passive ventilation system without much cost and fully utilize the solar power.

Abstract: Apparent rotational angular acceleration exist in the stepper motor operation processing, the stepper motor torque angle characteristics were described and the mathematical model of motor are constructed; The actual angular acceleration of stepper motor on single-step operation is measured by self-developed rotating angular acceleration sensor, the experimental results show that the angular acceleration fluctuations of stepping motor on three single clap operation are little greater than on six clap operation, and there are return oscillations of motor on three single clap operation are obviously more than on six clap operation; Finally, the experimental phenomenon reasons are analyzed, and the corresponding conclusions are obtained.

Abstract: This paper describes the optimization approach of a three stage solid propellant launch vehicle configuration from existing solid rocket motors (SRM). The optimal launch vehicle (LV) is capable of delivering a small satellite of 100 kg to a circular low earth orbit of 400, 500 and 600 km altitude. The overall LV configuration and the trajectory profile were optimized simultaneously, thus the existing SRM parameters for first, second and three stages, vertical flight time, launch maneuver variable, maximum angle of attack, coasting time between first and second stage and the second coasting time between second and third stages were optimized. A genetic algorithm global optimization method has been implemented to perform the analysis, the algorithm consider mixed integer continuous variables. The results show that the proposed optimization approach was able to find the optimal solution for all three variants with very acceptable values, and the approach proved to be reliable for conceptual design level.

Abstract: Based on SL1126 internal combustion engine, using development mode based on secondary development with the underlying language (VC++6.0) and large scale software package, we study the overall structure of simulation system of internal combustion engine assembling, and build the parameterized model of internal combustion engine. And then, with the model, we perform transient analysis on the crank-link mechanism of the internal combustion engine via many-body dynamics, getting the life, velocity and change pattern of acceleration of piston. The analysis data can direct the improvement of internal combustion engine.

Abstract: For the mechanical transmission system, the torque measurement of rotating machinery has important significance to the research and development of products test、to analysis the quality inspection safety and to the control optimization. For the complex composition of the present torque measurement, this paper puts forward a simple structure torque measurement system, and it has high measurement precision. First, the grating photoelectric output signals are converted into square wave signal, then system measurement method is accepted through the relationship of the two square wave signal phase, which has corresponding relation to the twist angle of the sensor shaft. The experimental platform is constructed based on field programmable gates array (FPGA) and MCU, the non-contact torque measurement is realized through the designation of measurement system software. This method has practical value and it is expected to be used widely.

Abstract: Torque changes of mechanical equipment are important information for its status, it is a necessary way to test whether various dynamic mechanical power output reached the design standard, and it is also an important sign to test whether the product is qualified. the application of the torque sensor and its market prospect were introduced in this paper, and the status of domestic and foreign torque measuring methods are discussed, including a variety of new structure torque sensor and the corresponding measuring systems, at last, the prospects for the future development of torque measurement were put forward.

Abstract: Compatibility of different wiring system in the same building is usually needed to guarantee security and flexibility. In this paper, the compatibility problem of TN and IT system is deeply researched. Firstly, the TN and IT system is introduced. Then three schemes of the TN and IT system compatibility are proposed based on transfer switch, insulating transformer and neutral point for earth isolation using zero-sequence reactor, which is used to realize the isolation for earth of the transformer neural point.

Abstract: Pneumatic transmission system structure is complex and procedural abstraction. The system can also be difficult to test the intuitive way. Effective design and test means become one of important content in pneumatic system design. This paper introduces the FluidSIM software environment pneumatic transmission system design and simulation function and design milk packing line pressure drive system. It is proved that the system is feasible.

Abstract: Currently, the result of automatic assembly sequence planning shows bad practicality of engineering, and the assembly experience is not being fully utilized. For solving the problem, this paper introduces the double bases cooperating mechanism to aid the planning of the assembly process. By standardizing characteristic attribute of parts, the expert knowledge base that based on semantics is established. The expert knowledge base will assist the process of automatic assembly sequence planning. Desktop virtual reality technology is utilized for simulating the process of assembly operations. The status information of operations is fed back to the database for mining and learning, thus this progressive reasoning sequence meets the requirements of engineering, the final result of planning is stored into the database as an index case, it can provides a reference for subsequent similar assembly. Finally, the effectiveness of the method is verified by the example.