Advanced Materials Research Vols. 591-593

Abstract: The dynamic environmental test of spacecraft products plays an important role to guarantee the reliability. Dynamic environment of spacecraft mainly generated in the launch phase, has short effect time, so the transient characteristics of spacecraft products are very important. In this paper, the dynamic test purposes of different developed stages (mainly include structural model phase and flight model phase)are sorted out, evaluation contents of spacecraft products are summed up relative to the dynamic test purposes and evaluation criteria are setup corresponding the evaluation contents. Though it, the transient characteristics of spacecraft products are evaluated which provides a reference for judging the reliability of spacecraft products.

Abstract: Deck-temperature-rising technology is the new technology that solves the antifreeze and deicing problems of ship deck. In this paper, the special experimental device was designed, and the influence laws of this new technology in different deck area were studied. Comparative experiments were done with the deck area at 18*22cm2, 26*22cm2 and 32*22cm2. The experimental results show that with the same initial temperature of water and deck surface, the deck area has significant impact on this new technology. The larger the deck area is, the greater the warming amplitude and the better warming effect can be achieved. For example, the warming amplitude is about 1.7°C as the deck area is 32*22cm2, while the warming amplitude is only about 0.6°C as the deck area is 18*22cm2. This conclusion will be valuable in further studies on this new technology.

Abstract: In view of the difficult balance of inertia force for the slider-crank mechanism, on the basis of analyzing inertia force of the slider-crank mechanism, a new balancing method of inertia force was proposed for the slider-crank mechanism with small linkage ratio, the rotary mass and the moving mass had replaced the mechanism mass, the inertia force of rotary mass was balanced by rotary weight counterbalance, a spring was disposed by slider, it provided variable elastic force and balanced the inertia force of moving mass. Then the balancing method was analyzed deeply and the theoretical derivation was made, the results show that this balancing method would achieved approximately balance for inertia force of the slider-crank mechanism with small linkage ratio.

Abstract: High speed motorized spindle plays an important role in high speed grinding. However, for high-speed machining, the spindle system usually generates excessive vibration due to the high speed and large mass. The vibration transfers to the bed of grinding machine and affects the precision of machining. To analyze and control the vibration generated by the spindle system, this paper develops a dynamic model for the high-speed spindle system, and further analyzes the eccentricity and the mass of the spindle system which affects the amplitude of the vibration of the bed by producing the impulse. Based on the result of analysis, the vibration is finally controlled by modifying the structure of the shaft. After optimization, the amplitude of the vibration of the bed of reduces significantly to 0.046um, which was 0.056um before. In addition the eccentricity of the spindle is decrease by 0.1um.

Abstract: The trend of the measured signal can not only reflect the influence of the external environment, and also reflect the performance of the machine itself mutations. Therefore, removing and extracting tendency item is the necessary link in signal pretreatment.In order to eliminate endpoint effect and modal aliasing phenomenon in EMD and EEMD, based on EEMD,improved EEMD is put forward and the improved EEMD in the application of the signal trend analysis is researched in this paper.In the measured signals to join in a ramp signals,With the improved EEMD decomposition extracted residual items,and the residual items with the original slope signal similarity analysis,the similarity is 0.975.compared to EMD extracted residual items similarity 0.898, EEMD extracted residual items similarity 0.961,the improved EEMD extracted residual item can more accurately reflect the trend of signal.

Abstract: In order to anlyse the compaction process of vibrating roller more accurately, this paper built a new 6-DOF Vibration system dynamic model under the coupling operating condition of intellectual vibratory roller considering the qualities of soilmass and applied the new model on a type of intellectual vibratory roller’ dynamic analysis. On that basis, we optimized the design parameter of this vibratory, and found out the optimum working parameters. It would realize the effective control of intellectual vibratory roller in the process of compaction, advance the density and compaction efficiency in compacting process, and improve comfortabilityg of the complete machine. At the same time, it also provided an effective numerical basis for the optimization design of vibratory roller.

Abstract: The relationship between stress and crack growth was studied. Applying the software ANSYS, the method of calculating stress intensity factor of composite mode cracks was built. At the same time, the stress intensity factor of mode I crack was calculated and the influence of crack size and loading on the stress intensity factor was studied. The results show that the results of ANSYS are almost the same to analytic results, which proves that the method is feasible. When the crack is quite big or quite small, the result of ANSYS’ error is comparatively obvious, which is due to the problem of the refinement of meshing. When the crack is too big, the dense of meshing is inadequate.

Abstract: One of the important problems in developing the railgun is design of the rail and the related elements. The evaluation of the loads on rails is an important task. On operation, the armature runs at an acceleration. The acceleration load can cause more complicated dynamic responses of the railgun. Here, the equations for the forced responses of the rail on acceleration load are developed. Using these equations, the dynamic displacement responses of the rail to the running electromagnetic force for various accelerations are investigated. The results show that the maximum dynamic displacement peak of the rail and its position depends on the acceleration of the running armature. The larger is the acceleration, the more obvious is the increase of the dynamic displacements under condition that the armature velocity is above the critical velocity. The results are useful for design and application of the railgun system.

Abstract: This paper analysises and evaluates vibration situation and gives the general procedure for vibration analysis of pumps units, which contain determination of each evaluation matter-element and comprehensive evaluation method based on matter-element. Evaluation matter-element is established by evaluation system of pumps vibration, aimed at a particular example. The factors affecting the vibration of the pump unit has three major factors of the mechanical, hydraulic, electrical, sub-factors of the three factors. According to the characteristics of the pump unit vibration and the current technical condition, the vibration is divided into five levels: most serious, more serious, normal, minor, and slight. The evaluation weight matter-element are established by using AHP, weight are determined by using the combination of AHP and entropy, finally comprehensive evaluation of pumps vibration performance is practiced. Thus, this evaluation is feasible and useful.

Abstract: In connection with the nonlinear dynamic characteristics shown from the performance of fault rotating mechanical system, the authors propose the analysis method of Lyapunov dimension and exponent energy Spectrum to the signal feature of mechanical fault. Using theory of phase space reconstruction, simulating fault signal of rotating machine is reconstructed. In order to reconstruct the phase space which can be adequately reflect the movement characteristics of the system, the time delay and embedding dimension are discussed emphatically, on this basis, calculated the Lyapunov dimension and exponential energy spectrum. From the analysis and calculation on simulation of different fault signals, it shows that under different rotating machinery fault conditions, its Lyapunov dimension and exponential energy are significantly different, which verifies that this two nonlinear feature quantities is effective parameters for fault information