scholarly journals TECHNOLOGICAL FIXTURES FOR MACHINING LARGE-SIZED THIN-WALLED SHELLS OF COMPLEX PROFILE

2021 ◽  
pp. 28-41
Author(s):  
Svitlana Oliinyk ◽  
Lydmila Kalafatova
Keyword(s):  
Dynamic Stability ◽  
Frequency Spectrum ◽  
Dynamic Characteristics ◽  
Technological System ◽  
Complex Profile ◽  
Study Results ◽  
Thin Walled ◽  
Grinding System

The paper analyzes the structure of technological fixtures for the positioning and fixing of large-sized thin-walled pyroceram shells as a factor affecting the dynamic characteristics of the grinding system. The solution to the problem of ensuring the dynamic stability of the «mandrel-workpiece» subsystem is necessary to increase the efficiency of shell machining in present conditions. Studying the vibrations frequency spectrum of the technological system during grinding has made it possible to determine their sources. The magnitude and frequency of vibrations depend on the mandrel structure - the clamping fixture. The study results are the requirements for a new mandrel structure, considering the dynamic stability of the technological system.

scholarly journals Monitoring and Analysis of Dynamic Characteristics of Super High-rise Buildings using GB-RAR: A Case Study of the WGC under Construction, China

2020 ◽  
Vol 10 (3) ◽  
pp. 808 ◽  
Author(s):  
Lv Zhou ◽  
Jiming Guo ◽  
Xuelin Wen ◽  
Jun Ma ◽  
Fei Yang ◽  
...  
Keyword(s):  
Wavelet Analysis ◽  
Dynamic Characteristics ◽  
Horizontal Displacement ◽  
Dynamic Monitoring ◽  
High Rise ◽  
The North ◽  
Study Results ◽  
Under Construction ◽  
East West

Accurate dynamic characteristics of super high-rise buildings serve as a guide in their construction and operation. Ground-based real aperture radar (GB-RAR) techniques have been applied in monitoring and analyzing the dynamic characteristics of different buildings, but only few studies have utilized them to derive the dynamic characteristics of super high-rise buildings, especially those higher than 400 m and under construction. In this study, we proposed a set of technical methods for monitoring and analyzing the dynamic characteristics of super high-rise buildings based on GB-RAR and wavelet analysis. A case study was conducted on the monitoring and analysis of the dynamic characteristics of the Wuhan Greenland Center (WGC) under construction (5–7 July 2017) with a 636 m design height. Displacement time series was accurately derived through GB-RAR and wavelet analysis, and the accuracy reached the submillimeter level. The maximum horizontal displacement amplitudes at the top of the building in the north–south and east–west directions were 18.84 and 15.94 mm, respectively. The roof displacement trajectory of the WGC was clearly identified. A certain negative correlation between the temperature and displacement changes at the roof of the building was identified. Study results demonstrate that the proposed method is effective for the dynamic monitoring and analysis of super high-rise buildings with noninvasive and nondestructive characteristics.

scholarly journals COMPARISON OF DYNAMIC STABILITY DURING WALKING AND RUNNING ON NONMOTORIZED CURVED TREADMILL ACCORDING TO CURVATURE RADIUS

2017 ◽  
Vol 17 (08) ◽  
pp. 1750105
Author(s):  
SAYUP KIM ◽  
JONGRYUN ROH ◽  
JOONHO HYEONG ◽  
YOUNGHO KIM
Keyword(s):  
Dynamic Stability ◽  
Repeated Measures ◽  
The Elderly ◽  
Curvature Radius ◽  
Adult Men ◽  
High Speeds ◽  
Slow Walking ◽  
Study Results ◽  
The Stability ◽  
Post Hoc

It is generally believed that running on a curved surface is more unstable than running on a flat surface. In this study, the dynamic stability of locomotion on a nonmotorized curved treadmill (NMCT) with three curvature radii was compared with that on a motorized flat treadmill. Sixteen healthy adult men maintained four different self-paced speeds: slow walking, fast walking, jogging, and running. Significant differences were statistically verified using two-way repeated-measures analysis of variance (ANOVA) according to the curvature radii and speeds, and the interaction effects were confirmed. Furthermore, to understand the significant differences between the speed and curvature radius, post hoc analyses were performed using one-way ANOVA. Except for the step width, the other parameters showed differences and correlation effects between the curvature radius and speed. As the curvature radius decreased, the stability decreased at slow speeds (slow walking) but increased at fast speeds (running). However, as the curvature radius increased, the stability increased at slow speeds (slow walking) but decreased at high speeds (running). The study results will help in suggesting the appropriate curvature radius for different user types such as athletes, the elderly, and people who require rehabilitation and will serve as preliminary data for designing the curvature radii of NMCTs.

Investigation of Static and Dynamic Characteristics of Complex Thin-Walled Shell Structure with Cracks

2016 ◽  
Vol 48 (3) ◽  
pp. 401-410
Author(s):  
O. O. Luk’yanchenko ◽  
O. V. Kostina ◽  
N. I. Bouraou ◽  
O. V. Kuz’ko
Keyword(s):  
Dynamic Characteristics ◽  
Shell Structure ◽  
Static And Dynamic Characteristics ◽  
Thin Walled
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