scholarly journals Analysis of teacher’s ability in planning and implementing learning on vibration, wave and sound submaterials

2021 ◽  
Vol 1806 (1) ◽  
pp. 012132
Author(s):  
N A Azizah ◽  
S Sukarmin ◽  
M Masykuri
Keyword(s):  
Vibration Wave

scholarly journals Experimental Investigation of the Propagation and Attenuation Rule of Blasting Vibration Wave Parameters Based on the Damage Accumulation Effect

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Huaibao Chu ◽  
Xiaolin Yang ◽  
Shuanjie Li ◽  
Weimin Liang
Keyword(s):  
Frequency Band ◽  
Damage Accumulation ◽  
Low Frequency ◽  
Experimental Results ◽  
Vibration Velocity ◽  
Blasting Vibration ◽  
Main Frequency ◽  
Wave Parameters ◽  
Accumulation Effect ◽  
Vibration Wave

The propagation and attenuation rule of blasting vibration wave parameters is the most important foundation of blasting vibration prediction and control. In this work, we pay more attention to the influence of the damage accumulation effect on the propagation and attenuation rule of vibration wave parameters. A blasting damage accumulation experiment was carried out, the ultrasonic wave velocity of the specimens was measured, and the damage value was calculated during the experiment. The blasting vibration wave was monitored on the surface of the specimens, and its energy was calculated by using the sym8 wavelet basis function. The experimental results showed that with the increase in the number of blasts, the damage continues to increase; however, the vibration velocity and the main frequency decrease continuously, the unfocused vibration wave energy in the zone near to the blasting source is rapidly concentrated in the low-frequency band (frequency bands 1 to 3), and the energy is further concentrated in the low-frequency band in the intermediate zone and zone far from the blasting source. There is a distortion process in which the vibration velocity and the main frequency increase slightly and the energy of the blasting vibration wave converges to the high-frequency band (the 5th band) before the sudden unstable fracture failure of the specimens. The experimental results indicate that the prediction and evaluation of blasting vibration should consider the variation rule of blasting vibration wave parameters synthetically based on the cumulative damage effect, and it is not safe to use only one fixed vibration control standard for the whole blasting operation.

scholarly journals Study on the Transmission and Evolution Characteristics of Vibration Wave from Vibratory Roller to Filling Materials Based on the Field Test

2020 ◽  
Vol 10 (6) ◽  
pp. 2008
Author(s):  
Changwei Yang ◽  
Liang Zhang ◽  
Yixuan Han ◽  
Degou Cai ◽  
Shaowei Wei
Keyword(s):  
Frequency Domain ◽  
Fundamental Wave ◽  
Primary Wave ◽  
Compaction Process ◽  
Vibration Acceleration ◽  
Intelligent Compaction ◽  
Filling Materials ◽  
Evolution Characteristics ◽  
Attenuation Rate ◽  
Vibration Wave

Compaction quality of railroad subgrade relates directly to the stability and safety of train operation, and the core problem of the Intelligent Compaction of railroads is the transmission and evolution characteristics of vibration wave. Aiming at the shortages in exploring the transmission and evolution characteristics of the vibration signal, the typical subgrade compaction project of Jingxiong Intercity Railway Gu’an Station was selected to carry out the field prototypes tests, and the dynamic response from the vibratory roller to filling materials was monitored in the whole compaction process, and some efficient field tests data will be obtained. Based on this, the transmission and evolution characteristics of the vibration wave from the vibratory roller to filling materials in the compaction process are studied from the time domain, frequency domain, jointed time–frequency domain and energy domain by using one new signal analysis technology—Hilbert–Huang Transform. Some conclusions are shown as follows: first, the vibration acceleration peak gradually decreases with the increase of buried depth, and when the buried depth reaches 1.8 m, the vibration acceleration peak is closed to zero. At the same time, when the vibration wave propagates from the wheel to the surface of filling, the attenuation rate of acceleration gradually increases with the increase of rolling compaction times, while the attenuation rate of other layers in different buried depths gradually decreases. Second, the vibration wave contains fundamental wave and multiple harmonics, and the dominant frequency of the fundamental wave is nearly 21 Hz. With the increase of buried depth, the amplitude of fundamental, primary, secondary, until fifth harmonics decreases exponentially and the concrete functional relationship among different amplitudes of harmonics can be summarized as y = Ae−BX. Third, the vibration energy focuses on the fundamental wave and primary wave, which can increase with the increase of rolling compaction times, and when the rolling compaction time reaches five, their energy reaches maximum. However, when the filling reaches a dense situation, the energy of the primary wave gradually decreases. Therefore, the maximum rolling compaction time is five in the practical engineering applications, which will be helpful for optimizing the compaction quality control models and providing some support for the development of the Intelligent Compaction theory of railway subgrade.

Construction of the Health Monitoring System of a Machine Structure

2009 ◽  
Author(s):  
Masanori Shintani ◽  
Keita Masaki
Keyword(s):  
Monitoring System ◽  
Health Monitoring ◽  
Normal Vibration ◽  
Wigner Distribution ◽  
Random Noise ◽  
Unsteady State ◽  
High Frequency Region ◽  
Health Monitoring System ◽  
Time Frequency ◽  
Vibration Wave

When big power like an earthquake acts at the place that the machine is normally operating, abnormalities may occur to a machine. If the machine is operated without finding abnormally, danger may attain to mechanical fatal damage and a mechanical work pursuer. Therefore, detecting in the situation where mechanical abnormalities are operated is very important as a health monitoring system. In this research, the system that takes in the vibration wave on the rotation part of the machine currently rotated is constructed. A vibration wave is analyzed using time-frequency analysis (STFT, the Wigner distribution, wave let analysis) From the result, the system by which normal vibration and abnormal vibration are evaluated is constructed from random noise. As a result of comparing normal vibration with abnormal vibration, the peak may have occurred in the high frequency region. It turned out that the analysis result of an unsteady state has a peak 2000Hz–3000Hz of frequency domains, and 4000Hz–5000Hz also in STFT and Wigner distribution. I think that this becomes the important tool which distinguishes the stationary state and unsteady state in health monitoring.

Local Triads of Sensors to Mine Collocated Acceleration for Structural Health Monitoring of an Aluminum Beam With Bolted Joints

2014 ◽  
Author(s):  
Ioannis T. Georgiou
Keyword(s):  
Aluminum Alloy ◽  
Research Effort ◽  
Complex Structure ◽  
Three Dimensional ◽  
Local Area ◽  
Bolted Joints ◽  
Critical Area ◽  
Local Areas ◽  
Vibration Wave ◽  
Aluminum Beam

Several aerospace, space, and naval platforms process a core structural system assembled wholly or partially by aluminum alloy elementary structures, such as beams, plates, and cylinders, among others. Aluminum alloys are preferred due to light weight and corrosion resistance. The formed complex aluminum alloy structure is characterized by a number of joints where different structural elements are joined together. Areas with joints are prone to damage. Some joints are made by bolts for assembly and reassembly purposes. A loose bolt can be considered as a man-induced damage in the whole complex structure. This damage can result in a catastrophic failure. The vibration and elastic wave propagation-based monitoring of a critical area bearing bolt joints can offer a reliable monitoring. In this work, we present a basic experimental research effort. We consider an aluminum alloy beam composed of two sunbeams joined by means of two bolts. The bolts are healthy in the sense that they are tight to the level of design recommended force. We use three mono-axial sensors in three dimensional arrangement and mine vibration-wave data in the form of collocated signals. These signals are analyzed by means of the proper orthogonal decomposition transform. The local tri-axial arrangement of mono-axial sensors is used to collect collocated acceleration signals in two local areas. One of the local areas contains the bolted joints. The other local area contains the free end of the structure. This is not considered as a critical area but a boundary accessible area. The POD modal structures of collocated vibration signals are quite different. The behavior is compared to that of structure without bolted joints.

Vibration wave detecting method and vibration wave detector

2002 ◽  
Vol 111 (3) ◽  
pp. 1151
Author(s):  
Muneo Harada ◽  
Naoki Ikeuchi
Keyword(s):  
Wave Detector ◽  
Vibration Wave ◽  
Detecting Method

Electro-mechanical energy converter and vibration wave driving

2010 ◽  
Vol 127 (6) ◽  
pp. 3861
Author(s):  
Kiyoshi Nitto
Keyword(s):  
Mechanical Energy ◽  
Energy Converter ◽  
Vibration Wave

Adaptive control of vibration wave propagation in cylindrical shells using SMA wall joint

2004 ◽  
Vol 278 (1-2) ◽  
pp. 307-326 ◽  
Author(s):  
M.B. Xu ◽  
G. Song
Keyword(s):  
Wave Propagation ◽  
Adaptive Control ◽  
Cylindrical Shells ◽  
Vibration Wave

Study on the Method of Multi-Rope Hoist Rope Tension Imbalance Fault Monitoring and Diagnosis

2010 ◽  
Vol 139-141 ◽  
pp. 2591-2594 ◽  
Author(s):  
Shao Jin Wang ◽  
Zhao Jian Yang ◽  
Fan Du
Keyword(s):  
Fault Diagnosis ◽  
Measurement Data ◽  
Wire Rope ◽  
Test Method ◽  
Wave Method ◽  
New Methods ◽  
Fault Monitoring ◽  
Vibration Wave ◽  
Mechanical Dynamics ◽  
Mine Hoist

In order to solve the problem that the tension measurement data of mine hoist wire-rope is inaccurate and the method of fault diagnosis of multi-rope hoist rope tension imbalance is non-standard, the systematic study of monitoring, forecasting and fault diagnosis of rope tension imbalance was made by using the principles of vibration wave method in mechanical dynamics. A set of new methods about monitoring, forecasting and fault diagnosis were developed, which the test method of hoist wire-rope tension based on inhomogeneous chord vibration and the methods for fault diagnosis of steel rope unbalance tension were described deeply. The vibration wave method was also used in these methods. The field test indicated that these methods were simple to operate and had higher accuracy and reliability.

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