Applied Mechanics and Materials Vols. 633-634

Abstract: Considering the elastic-plastic and creep behavior of the material of bolted joint, and the nonlinear variation of its properties with temperature, this paper proposed a one-dimensional mathematical model for predicting clamp load variation with cyclic elevated-temperature. Then, relevant factors which may affect the process are studied, and some measures to enhance the threaded fitting reliability are proposed.

Abstract: This paper by taking the hypersonic speed wing surface as the research object, according to the basic theory of thermal mode analysis, calculates and analyzes the influence of temperature variation on model vibration characteristics. According to the analysis, the structural natural vibration characteristics can be influenced by different temperature loads obviously. As for the 7075 root fixed wing surface model under the temperature range of 150K~500K, the basic linearity of frequencies of different order modals decreases with the rise of temperature; The structural frequency decreases sharply with the rise of temperature when the temperature is higher than 500K.

Abstract: Modal is the natural vibration characteristic of mechanical structures, and each modal has its specific natural frequency, damp radio and modal shape. Modal of vibration is the natural and total character of elastic structures. By modal analysis, the structure’s characters of different principal modal within a impressionable frequency range can be understanded, and is an important method in terms of structure’s dynamic design and machinery fault diagnosis. It provides basis for vibrating characteristics analysis, vibrating fault diagnosis of the systems, or forecasting and analyzing the dynamic characteristics of noncircular gear.

Abstract: The inlet connection of a centrifugal compressor is a bent pipe, and a straight pipe is installed between the bent pipe outlet and impeller inlet. The effect of different lengths of the straight pipe on the aerodynamic noise of a centrifugal compressor is numerically simulated. Theresult show that it’s essential to value the inlet bent pipe’s position in the inlet and outlet aerodynamic design. With the increase of straight pipe’s length, the noise radiated from the inlet decreases. When the length is over the pipe diameter, it has little effect on the outlet noise. The increase of straight pipe’s length also makes the circumferential noise decrease. The noise is distorted at approximately 90 ° in the rotational direction of the volute tongue. The sound power level of the compressor decreases to a constant value with the length over the pipe diameter. In the engineering application on aerodynamic noise, the straight pipe’s length before impeller inlet should be longer than the pipe diameter.

Abstract: Power characteristic and damper effectiveness of the vibration damper for 1250mm² Conductor is analysed by laboratory test. Resonance frequency, power dissipation and protectable span of the vibration damper are given in the test results, which indicates that power characteristic of the vibration damper meets the requirements of the industry standard and can provide a reference for anti-vibration design of 1250mm² conductor, and the protectable span of the damper is 141m.

Abstract: The security assessment of large underframe on car body is proposed through the SINTAP/FITNET method and with the help of numerical simulation technology of finite element based on some EMU powered car in service at present. The security and reliability of the underframe structure is predicted. The defect tolerance that the underframe is ‘fitness for service’ is put forward in this paper. The result shows that the crack shape a/c has little impact on the security with the semielliptic surface cracks assumption. In addition, the security assessment on dangerous areas and critical crack sizes are acquired based on the assumption a/c=0.2. The critical crack sizes of the dangerous area 1, area 2 and area 3 are about 5 to 5.5 millimeters, while the unilateral penetrate crack size of the area 4 reaches 40 millimeters. The structures are suit for service as the risk of brittle failure is extremely small.

Abstract: The reliability design method is considered based on the EMU application in our country. It is verified that the vehicle reliability obeys the exponential distribution according to the statistical testing principles and practical data statistics of some high-speed EMU, in addition, the reliability after a period of time of operation, or to say, the operational time which meet demand of the certain reliability requirement, is predicted. The reliability assessment for the EMU operating for a period of time is proceed on the basis of the suggestion table of failure rate levels obtained through quantities of statistics. Apart from this,suggestions about reliability design is proposed based on the given condition of failure rate levels. The method can be used as one of reliability assessment indicator of EMU in the future.

Abstract: The principle of balancing a high speed cantilever rotor at full speed has been put forward by low-speed and high-speed balancing. The portable field dynamic balancing instrument based on the microcontroller is discussed from the hardware, the software and the signal process in detail. With the developed instrument, the whole-machine balancing experiment was conducted on a saucer-separating centrifuge RJ-460. The vibration of the saucer-separating centrifuge decreased from 3.8mm/s to 0.3mm/s at 1200r/min and decreased from 9.8mm/s to 0.6mm/s at 7200r/min. The experimental results indicated that the principle of balance is correct and the designed instrument is reliable and promising.

Abstract: The “SG” is a large inertial confinement fusion (ICF) project that is building in china. Its essential working principium is stimulating the nuclear material in the target ball by shooting with laser, then the ICF will produce large numbers of fusion energy which is controllable. The laser is lead and transmited primary by mirror which is clamped by mirror frame in the shooting range system.For the needs of precision when shooting, there are some strict demands to the dynamic characteristics of the mirror frame. This paper designed a machine model of a array mirror frame which is quad intergrated, and simulation analysis on dynamic characteristics of the mirror frame .

Abstract: This paper introduces the solution for calculating the divergence dynamic pressure of wing under subsonic speed based on static aeroelasticity. Several groups of results (q ~ θ values) are calculated and the divergence dynamic pressure can be obtained through two methods, i.e. making q ~ θ value curves or deducing divergence dynamic pressure formula based on the characteristics of equilateral hyperbola. According to several groups of calculated data, the error caused by the two methods is minor and can be ignored basically.