vibration velocity
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Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 492
Author(s):  
Karlo Petrović ◽  
Antonio Petošić ◽  
Tomislav Župan

In this work, the vibrations on the surfaces of the tank wall, stiffeners, and the cover of a 5 MVA transformer experimental model were measured during open-circuit and short-circuit transformer tests. Vibration measurements of a transformer tank side were conducted at discrete points using two different voltage sources in no-load test. Using interpolation functions, the RMS values of acceleration and vibration velocity are visualized and compared for each considered measurement configuration (no-load and load tests and two different excitation sources). Significant differences in mode shapes and amplitudes of vibrations at different frequencies are observed. The maximum RMS values of acceleration, velocity and displacement in the open-circuit test are 0.36 m/s2, 0.31 mm/s, and 0.42 µm, respectively. The maximum values in short-circuit test are 0.74 m/s2, 1.14 mm/s, and 1.8 µm, respectively. In the short-circuit test, the frequency component of 100 Hz is dominant. In the open-circuit test, the first few 100 Hz harmonics are significant (100 Hz, 200 Hz, and 300 Hz). In addition to the visualization of RMS values during the open-circuit and short-circuit tests, animations of the vibrations are created. Fourier analysis and phase comparison between frequency components are also used to show vibration animations at dominant frequencies in the spectrum (100 Hz harmonics). The visualization of the vibrations at the tank wall surfaces is transferred into 3D space in such a way that all 15 surfaces are mapped to the spatial coordinates of the surfaces so that a 3D model of the acceleration, vibration velocity, and displacement of the transformer tank is shown.


2022 ◽  
Vol 2022 ◽  
pp. 1-13
Author(s):  
Wei He ◽  
Suxia Zhang

In this study, the stability parameter range of a tethered quadrotor unmanned aerial vehicle (UAV) under the action of the transient wind field is numerically analyzed, which can provide a theoretical basis for the design and application of such systems. Three factors affecting the stability of tethered UAV system are determined, namely, cable tension, cable elongation, and UAV vibration velocity, and the corresponding judgment criteria are obtained. Specifically, the priority of the three criteria sequentially decreases. According to these criteria, the stability parameter range of the tethered UAV is examined under the cable parameters such as length, diameter, and elastic modulus and the environmental parameters such as the amplitude and period of the wind field. The results show that for designing the tethered UAV structure, by reducing the length of the tethered cable and increasing its diameter and elastic modulus, the working stability of tethered UAV system can be improved.


Author(s):  
Farhad Forouharmajd ◽  
Shiva Soury ◽  
Mehran Mokhtari ◽  
Zahra Mohammadi

Background and purpose: Vibration caused by ventilation systems in buildings is one of the harmful physical factors that can cause harm to residents. Therefore, measuring and controlling vibration is important. Materials and Methods: In the first step of the study, the vibration accelerometer was placed on the base of a fan where the vibrations were sent toward the duct wall. A vibration assessment of the building was conducted in the other steps to compare with guidelines. In the next step, isolation method was used to control vibration. By placing the isolator on the duct wall, the accelerometer was located on the body of the duct wall and the value of vibration was measured in a millimeter per second. All stages of the experiment were performed in the Faculty of Health of Isfahan University of Medical Sciences in 2018. Results: The maximum vibration velocity reduction in the building was related to the frequency of 68 Hz, which reached 33 mm/s after isolation. In addition, the fan vibration at 485 Hz was equal to 2.1 m /s, which decreased to 2 mm /s after isolation. Conclusion: Comparison of vibration after fan isolation with standard showed that this method has been effective in reducing the fan vibration resulting in the vibration to reach below the standard.


2022 ◽  
Vol 2148 (1) ◽  
pp. 012023
Author(s):  
Wu Ye ◽  
Yong Lu ◽  
Lingzhi Xi ◽  
Qiang Zhang ◽  
Shaobin Hu

Abstract Rock breaking technology based on dry ice and energy-gathered agent has been developed and successfully applied in trench excavation for construction of oil pipeline. The vibration velocity waveform induced by this technology was monitored in site test to determine the attenuation law of vibration velocity with hypocentral distance. The results show that this rock breaking technology is effective method of trench excavation. It does not excessively damage the adjacent rock mass, ensuring the integrity of ditch walls. The vibration velocity induced by this technology is decay with the increase of hypocentral distance. At the hypocentral distance of 10m, the vibration velocity reduces to less than 20mm/s, which meets the requirements of the safety standard of blasting vibration in general buildings engineering. The results of this experiment have an important guiding effect on the field engineering practice and application of rock breaking technology based on dry ice and energy-gathered agent.


2022 ◽  
Vol 2160 (1) ◽  
pp. 012077
Author(s):  
Yanlong Ren ◽  
Xuanli Yang ◽  
Chang Li ◽  
Mingzhe Lü ◽  
Jinzhao Zhuang

Abstract The blasting tunneling construction method is often used in the underground engineering projects such as tunnels, coal mines roadway, chambers and so on, rock bolt and shotcrete support is used. Although the blasting construction method has many advantages, but also will be accompanied by adverse effects. Blasting vibration of blasting construction not only to the surrounding environment, building (structure) and other adverse effects, but also on the support of the underground project itself has a negative impact. In order to discuss the impact of blasting vibration on shotcrete and rock bolt support in the process of blasting tunneling of roadway, a certain amount of explosives is detonated in the hole of the working face, the finite element software ANSYS/LS-DYNA was used to establish the numerical calculation model, through time history analysis calculation, the distribution law of the vibration velocity on the shotcrete surface along the section and the variation law of the longitudinal tension and compression stress of the rock bolt are obtained. The results show that the blasting vibration produced by blasting tunneling has a great influence on the shotcrete at the shoulder, but little influence on the axial force of the rock bolt.


Author(s):  
S. G. Zubairov ◽  
◽  
R. R. Yakhin ◽  
A. N Zotov ◽  
T. I. Salikhov ◽  
...  

The article describes a way to combat fatigue effects in the details of connecting modules of an electric driven centrifugal pump unit for oil production. A constructive solution for implementing the method in relation to complex downhole conditions in the form of a multifunctional damper using a differential piston to transfer it from the transport position when lowering into the well into the working one is shown. For a full-size damper, experimental studies of its vibration- isolating characteristics have been carried out when used in the form of substrates for supporting arms of elastomers of various densities and compositions. The preferred characteristics of elastomers and their ranking for various frequencies of forced vibrations are determined. Keywords: module, connection parts; electrically driven centrifugal pump unit; electrocentrifugal pumping unit; differential piston; damper; sbstrate; vibration velocity.


2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Jianxin Yu ◽  
Zhibin Zhou ◽  
Xin Zhang ◽  
Xiaolin Yang ◽  
Jinxing Wang ◽  
...  

The vibration caused by the tunnel blasting and excavation will harm the surrounding rock and lining structure of the adjacent existing tunnels. This paper takes a two-lane large-span highway tunnel as the research object, conducts on-site monitoring tests on the impact of vibration caused by the blasting and excavation of new tunnels on the existing tunnels under different blasting schemes, and analyses in detail the three-dimension vibration velocity by different excavation footages. From the vibration speed, it is concluded that the influence of the existing tunnel of the newly built tunnel blasting team is affected by various factors, such as distance, free surface, charge, and blasthole distribution. With different blasting schemes, the greater the amount of charge, the greater the vibration caused by blasting. Existing tunnels correspond to the front of the tunnel, and the axial and radial vibration peaks are greater than the vertical. Although the cut segment uses a less amount of explosive and has a less blasthole layout, there is only one free surface. Because of the clamping of the rock, it is compared with the other two segments. The vibration caused is the largest. Although the peripheral holes are filled with a large amount of explosive, the arrangement of the blast holes is relatively scattered and there are many free surfaces. Hence, the vibration caused is the smallest. Corresponding to the back of the tunnel face, since there is no rock clamp, the vibration caused by the cut segment is the smallest, and the vibration caused by the peripheral segment and the floor segment is relatively large. The vibration caused by the front explosion side is significantly greater than the vibration caused by the back explosion side. The vibration velocity caused by the unit charge of 1.5 m footage is greater than that of the 3.0 m footage. The vibration velocity caused by the unit charge of the cut segment is the largest, and the vibration velocity caused by the peripheral segment and the floor segment is smaller. The research results provide a reference for the blasting control of similar engineering construction.


2021 ◽  
Vol 12 (1) ◽  
pp. 12
Author(s):  
Fan Chen ◽  
Gengsheng He ◽  
Shun Dong ◽  
Shunjun Zhao ◽  
Lin Shi ◽  
...  

The vibration produced by blasting excavation in urban underground engineering has a significant influence on the surrounding environment, and the strength of vibration intensity involves many influencing factors. In order to predict the space-time effects of blasting vibration more accurately, an automatic intelligent monitoring system is constructed based on the rough set fuzzy neural network blasting vibration characteristic parameter prediction model and the network blasting vibrator (TC-6850). By setting up the regional monitoring network of monitoring points, the obtained monitoring data are analyzed. An artificial intelligence model is used to predict the influence of stratum condition, excavation hole, and high-rise building on blasting vibration velocity and frequency propagation. The results show that the artificial intelligence prediction model based on a rough set fuzzy neural network can accurately reflect the formation attenuation effect, hollow effect, and building amplification effect of blasting vibration by effectively fuzzing and standardizing the influencing factors. The propagation of blasting vibration in a soil–rock composite stratum is closely related to the surrounding rock conditions with a noticeable elastic modulus effect. The hollow effect is regional, which has a significant influence on the surrounding ground and buildings. Besides, the blasting vibration of the excavated area is stronger than that of the unexcavated area. The propagation of blasting vibration on high-rise buildings was complicated, of which the peak vibration velocity is maximum at the lower level of the building and decreased with the rise of the floor gradually. The whip sheath effect appears at the top floor, which is related to the blasting vibration frequency and the building’s natural vibration frequency.


2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Chengyu Xie ◽  
Jie Cao ◽  
Dongping Shi

The fruit fly optimization algorithm-general regression neural network (FOA-GRNN) coupled model and the Finite Element Method-Smoothed Particle Hydrodynamics (FEM-SPH) numerical calculation method are comprehensively used. The control problem of blasting vibration in the process of mining hidden resources under complex environmental conditions has been studied. Taking a lead-zinc mine as the engineering background, the development of hidden resources in the collapse area due to unreasonable mining was studied. Based on the establishment of the first mining stope and its mining method in this area, biosimulation and generalized neural networks were introduced to solve this problem, the coupling of blasting parameters was analyzed, and the 3D nonlinear dynamic coupling model was constructed for numerical simulation. The results show that the blasting parameters of deep-hole mining were optimized, including the values of six output quantities: hole distance, row spacing, side hole distance, explosive unit consumption, minimum resistance line, and interval ratio (the Root Mean Squared Error value is only 0.051). The error between the network optimization parameters and the empirically obtained values was controlled to within 0.05; five possible edge-hole charge structures were designed (the interval ratio is 0.696), and the vibration velocity peak and pressure peak variations with time after detonation are reflected by the simulation results. The dynamic evolution law of the rock mass velocity vector and the damage of the rock damage was revealed. According to the analysis in this paper, the smallest and optimal edge-hole charge structure of the surrounding rock was obtained.


2021 ◽  
Vol 2130 (1) ◽  
pp. 012005
Author(s):  
K Pietrykowski ◽  
M Biały

Abstract One of the characteristic features of piston engines are vibrations caused by the pistons moving in the cylinders. During the engine design process, it is necessary to determine the level of vibration that can occur in the engine. This is especially important for aircraft engines. Due to the minimization of the weight of the aircraft, it is necessary to limit the factors that may cause damage to the structure. One of these factors is engine vibration, which can cause resonance and, consequently, a dangerous stress concentration. Long-term action of variable loads may also lead to the formation of fatigue cracks. The article presents the results of a multibody analysis of an opposed-piston diesel engine. It is a two-stroke three-cylinder aircraft engine. The engine has two crankshafts and six pistons that run opposite each other, but the rotation of the shafts is shifted in phase 14°. Engine vibration will also be caused by crankshafts which, to reduce weight, are not equipped with counterweights. The calculation results are presented in the form of time courses of forces and displacements on the engine supports and FFT analysis of the vibration velocity. The results show that the maximum vibration velocity is 7 mm/s and occurs at a frequency of 140 Hz, which corresponds to twice the rotational speed of the crankshafts. The results obtained from the tests allow for the selection of the flexible elements used in the real prototype engine supports.


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