ISOLATION DESIGN AND SIMULATIONAL EXPERIMENT OF NANOMETER MICRO MOVEMENT TEST-BED

The relation of mass, stiffness and rate of damping is obtained by using the mechanical analysis of the obstructive vibration system of two dimensions for the design of the obstructive vibration system of more freedom and the micro vibration test bed. The result of stimulational experiment indicates that the isolation of vibration of this system is satisfactory. The design method of vibration can be used as the reference to ultra precision machine tool, super micro orientation machanism and so on.

Mitigation of micro vibration by viscous dampers

This study proposes a micro vibration mitigation system using viscous dampers to solve the problem of vibration in a high-tech building. Due to the operating frequency of the air conditioners and fundamental mode of the floors, a resonant phenomenon is occasionally experienced at the upper levels of the structure. Several strategies were considered, and viscous dampers combined with a suspension system were chosen to mitigate this annoying situation. A theoretical analysis was first executed to determine the optimal design value of the damper and the suspension spring. An efficient reduction in floor velocity of approximately 50 % was achieved by the proposed system. Practical verifications including a performance test of the micro-vibration-oriented dampers, the pragmatic application result, and a comparison in one-third octave spectrum was then carried out. The performance of the system was demonstrated by the data measured. It alleviated more trembling than was numerically expected. The energy absorbed by the viscous dampers is illustrated by the hysteresis loops and the one-third octave spectrum. It is found that with the proposed system, the vibration can be effectively captured by the viscous damper and converted to lower frequency-content tremors. The success of this project greatly supports the proposed standard two-stage analysis procedure for mitigating micro-vibration problems in practice. This research extends the use of viscous dampers to a new field.

Effects of Micro Vibration Therapy Nursing Care on Muscle Hardness and Skin Blood Flow: A Pre/Post Group Comparison Study

Purpose: The purpose of this study was to investigate the effects of Micro Vibrational therapy (MVT) on muscle stiffness and blood flow in the skin before and after Micro Vibrational therapy in healthy subjects in order to scientifically verify the effects of MVT. Methods: Micro Vibrational therapy is nurse care use in Japan. It was performed on the backs of 30 subjects (8 males and 22 females) in their 20 s to 50 s according to the eligibility criteria. The resting state before implementation was set as the baseline for the control group, and after 30 seconds of MVT was set as the intervention group. The effects of the MVT were statistically analyzed by these factors and subjective sensation by Visual Analog Scale. Results: The muscle hardness of the area where the MVT was applied for 30 seconds decreased to 29.54 (SD 5.04) after the application, compared to 30.45 (SD 5.05) before. A corresponding t-test showed a significant difference (p = 0.019). Skin blood flow increased from a median of 0.76 (variance 0.062) before to a median of 0.86 (variance 0.16) after the procedure. The Wilcoxon rank test showed a significant difference (p = 0.000). Circulatory response was confirmed by SBP, DBP, and HR. SBP of 108.6 mmHg (SD 14.8) before the study decreased to 105.7 mmHg (SD 15.0) after the study, and DBP of 65.6 mmHg (SD 11.1) before the study decreased to 62.7 mmHg (SD 11.8) after the study. HR decreased from 71.6 beats per minute (SD 10.3) before to 69.2 beats per minute (SD 11.7) after. There was a significant difference in all cardiovascular indices (p < 0.05). VAS (pain, stiffness, and fatigue) was significantly decreased after MVT (p < 0.05). Conclusion: Micro Vibrational therapy tended to decrease muscle hardness and increase skin blood flow even in the short time of 30 seconds. The results suggest that local vibration stimulation is not likely to cause a sudden increase in blood pressure or pulse rate fluctuation. These results suggest that hand vibration nursing care may be applicable to acute patients with unstable circulatory conditions.

Effects of Rubber Shock Absorber on the Flywheel Micro Vibration in the Satellite Imaging System

When a satellite is in orbit, its flywheel will generate micro vibration and affect the imaging quality of the camera. In order to reduce this effect, a rubber shock absorber is used, and a numerical model and an experimental setup are developed to investigate its effect on the micro vibration in the study. An integrated model is developed for the system, and a ray tracing method is used in the modeling. The spot coordinates and displacements of the image plane are obtained, and the modulate transfer function （MTF） of the system is calculated. A satellite including a rubber shock absorber is designed, and the experiments are carried out. Both simulation and experiments results show that the MTF increases almost 10 %, suggesting the rubber shock absorber is useful to decrease the flywheel vibration.

Micro injection of metallic glasses parts under ultrasonic vibration

This work investigates the evolution of structure and mechanical performance of metallic glasses（MGs）under a proposed rapid forming approach. Through the unique ultrasonic-assisted micro injection method, micro MGs parts with fine dimensional accuracy were successfully fabricated. The temperature during the micro injection is higher than the glass transition temperature and lower than the crystallization temperature. Differential scanning calorimeter curve and X-ray diffraction pattern show that the MGs micro parts keep the amorphous nature after the ultrasonic-assisted micro injection. Our results propose a novel route for the fast forming of MGs and have promising applications in the rapid fabrication of micro scale products and devices.

Bioinspired Scraper-File Type Frequency-Doubling Ultrasonic Exciter

In the natural world,leaf-cutting ants cause vibrations through their mutual scraping of file-scraper organs.In this study,we designed a Biomimetic Ultrasonic Exciter(BUE)that imitates leaf-cutting ants.The operating characteristics of the BUE were studied through experimental testing and finite element simulations.The results showed that the BUE could generate stable ultrasonic vibrations,and that the excitation frequency only needed to be half the Output Frequency(OF).This frequency-doubling phenomenon was conducive to achieving BUE miniaturization.To further explore the phenomenon of frequency-doubling vibration output,this study designed scrapers of five different sizes,conducted excitation and first-order natural frequency measurement tests,and the corresponding finite element simulations.It was found that each scraper could operate in frequency-doubling mode,but the operating frequency and natural mode frequencies did not correspond with one another.To further explicate experimental and simulation results,a two-degrees-of-freedom vibration model was developed.It was evident that the contact relationship between the dentate disc and scraper introduced strong nonlinear factors into the system,accounting for the frequency-doubling phenomenon and the difference between the BUE’s operating and mode frequencies.The BUE could be expected to facilitate the production of high-power micro-ultrasonic generators and has potential application value in the fields of mechanical processing,industrial production,and medical health.

Reducing the negative effects of flywheel disturbance on space camera image quality using the vibration isolation method

Although the performance of space cameras has largely improved, the micro vibration from flywheel disturbances still significantly affects the image quality of these cameras. This study adopted a passive isolation method to reduce the negative effect of flywheel disturbance on image quality. A metal-rubber shock absorber was designed and installed in a real satellite. A finite element model of an entire satellite was constructed, and a transient analysis was conducted afterward. The change in the modulate transfer function was detected using ray tracing and optical transfer function formulas. Experiments based on real products were performed to validate the influence of the metal-rubber shock absorber. The experimental results confirmed the simulation results by showing that the negative effects of flywheel dis- turbance on the image quality of space cameras can be diminished significantly using the vibration isolation method.