An equivalent simulation method for whole time-history blasting vibration

2012 ◽  
pp. 493-502
Keyword(s):  
Time History ◽  
Simulation Method ◽  
Blasting Vibration

Dynamic Response Analysis of Butt Joint of HTS-A Steel Considering Welding Residual Stresses

2013 ◽  
Vol 423-426 ◽  
pp. 944-950
Author(s):  
Wei Shen ◽  
Ren Jun Yan ◽  
Lin Xu ◽  
Kai Qin ◽  
Xin Yu Zhang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Dynamic Response ◽  
Hot Spot ◽  
Time History ◽  
High Strength ◽  
Simulation Method ◽  
Butt Joint ◽  
Welding Residual Stress ◽  
Response Analysis ◽  
Hull Structure

This paper uses both numerical simulation method and experimental research method to study on welding residual stress of high-strength steel of the cone-cylinder hull. Welding is often accompanied by a larger welding residual stress, which directly affects the safety and service life of the hull structure. In order to obtain the distribution of the welding residual stress, the welding procedure was developed by its parameter language by using FE analysis software in this paper. Then the welding residual stress of hot spot region was measured through X-ray nondestructive testing method, and compared it with simulation results. Finally, considering the residual stress as the initial stress, this paper analyzed dynamic response process of the welding structure under combined actions of the welding residual stress and multiaxial loads, which could more accurately determine the stress of welding structure and the location of fatigue risk point. According to the amplitude of damage parameters and strain time-history curve, we can estimate the fatigue life of structure by selecting the corresponding damage models.

CFD Modelling for Gas-Liquid and Liquid-Liquid Taylor Flows in the Entrance Region of Microchannels

2021 ◽  
Author(s):  
Amin Etminan ◽  
Yuri S. Muzychka ◽  
Kevin Pope
Keyword(s):  
Liquid Flow ◽  
Continuous Flow ◽  
Velocity Ratio ◽  
Time History ◽  
Simulation Method ◽  
Cfd Modelling ◽  
Cross Sectional ◽  
Systematic Analysis ◽  
Gas Liquid Flow ◽  
The Moment

Abstract This paper presents a CFD-based simulation method for air/water and water/dodecane Taylor flows through an axisymmetric microchannel with a circular cross-sectional area. A systematic analysis is conducted by exploring the effects of different superficial velocities and apparent viscosities on the hydrodynamics of a slug flow regime. A concentric junction is employed to make bubbles of air in a continuous flow of water and slugs of water in a continuous flow of dodecane oil. A time-history study is conducted to predict the air-bubble and water-slug evolution processes, in particular at the moment of slug breakup. The results show that the larger apparent viscosity ratio of phases involved in the liquid-liquid flow generates a more stable interface. However, the liquid slug length is less and film thickness is slightly larger in liquid-liquid compared to gas-liquid flow. Furthermore, variations in gas and liquid holdups are correlated by the superficial velocity ratio. The numerical analysis developed in this paper is in good agreement with the correlations and data in the literature.

scholarly journals Study on Seismic Behaviors of the Pagoda in Songyue Temple

2020 ◽  
Vol 213 ◽  
pp. 02023
Author(s):  
Shaochun Ma ◽  
Lianghui Li ◽  
Peng Bao
Keyword(s):  
Weak Link ◽  
Dynamic Properties ◽  
Time History ◽  
Simulation Method ◽  
Equivalent Model ◽  
Natural Vibration Frequency ◽  
Natural Period ◽  
Related Data ◽  
Earthquake Force ◽  
Seismic Behaviors

The dynamic properties and anti-earthquake behaviors of Pagoda in Songyue Temple was studied by numerical simulation method. Firstly, based on the its contexture, the equivalent model reflecting the force transfer mechanism is established. Secondly, by analyzing the dynamic characteristics of the computational model, the vibration modes, natural vibration frequency and natural period of vibration are measured. The correctness of the model verified by comparing the theoretical calculation results and the simulation results. Lastly, the seismic behaviors of the Pagoda in Songyue Temple was evaluated according to the elastic spectrum analysis and time-history analysis results and related data. The results show that: the stiffness is uniformly distributed and the seismic performance is good enough. Under the action of earthquake force, it is easy to produce tension rupture and the tacha, the pagoda body without section change, as weak link of the structure, need to focus on.

HHT-BASED SIMULATION OF UNIFORM HAZARD GROUND MOTIONS

2009 ◽  
Vol 01 (01) ◽  
pp. 71-87 ◽  
Author(s):  
Y. K. WEN ◽  
PING GU
Keyword(s):  
Los Angeles ◽  
Ground Motions ◽  
Time History ◽  
Simulation Method ◽  
Nonlinear Time History Analysis ◽  
Rupture Directivity ◽  
Regional Seismicity ◽  
Hilbert Huang Transform ◽  
History Analysis ◽  
Nonlinear Time History

Hilbert–Huang Transform (HHT) is a new analysis method for nonstationary and nonlinear signals. A simulation method based on HHT is used to generate uniform hazard ground motions, which are often needed for nonlinear time history analysis for structures in high-seismic zones. The HHT-based simulation method can reproduce the amplitude and frequency content change with time for nonstationary random processes, thus is very suitable for the simulation of earthquake ground motions, especially the near-fault ground motions with long-period pulses. Monte-Carlo method and historical earthquake records are used for the generation of a large pool of ground motions, from which the uniform hazard ground motions are selected. The regional seismicity and rupture directivity are considered. An example is given of a site near Los Angeles City Hall. The advantages and difficulties of the proposed method are also discussed.

Dynamic Analysis of Tunnel Blasting Excavation Effect on Overpass

2014 ◽  
Vol 971-973 ◽  
pp. 992-996
Author(s):  
Chun Lei Xin ◽  
Bo Gao
Keyword(s):  
Three Dimensional ◽  
Simulation Method ◽  
Vertical Vibration ◽  
Vibration Velocity ◽  
Blasting Vibration ◽  
Strong Constraint ◽  
Protection Measures ◽  
Blasting Excavation ◽  
Tunnel Blasting ◽  
Complicated Conditions

Although drilling and blasting method is widely used to excavate tunnel structures, it has great effect on adjacent ground structures. In order to find out the influence sphere and features of this construction method on overpass, three-dimensional numerical simulation method was used to analyze the displacement, stress and blasting vibration velocity of overpass. The results show that: (1) Drilling and blasting excavation method can cause differential settlement of stratum and overpass which is above the crown of tunnel. (2) The strong constraint structures of overpass are obviously affected by blasting vibration than other parts. (3) It should be taken extra protection measures at connection points between piers and decks as well as connection points between piers and stratum. (4) Horizontal vibration velocity caused by blasting excavation is lower than vertical vibration velocity. To control the vertical blasting vibration velocity is the essential to control the security of tunnel structure and upper structures. The above results certainly contribute to construct tunnel structures by using drilling and blasting excavation under complicated conditions.

scholarly journals Prediction of Blasting Vibration Velocity of Layered Rock Mass under Multihole Cut Blasting

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jie Zhu ◽  
Haixia Wei ◽  
Xiaolin Yang ◽  
Huaibao Chu
Keyword(s):  
Differential Equation ◽  
Rock Mass ◽  
Prediction Accuracy ◽  
Time History ◽  
Vibration Velocity ◽  
Blasting Vibration ◽  
Underground Engineering ◽  
Layered Rock ◽  
Propagation Law ◽  
Layered Rock Mass

In the blasting construction of underground engineering in layered rock mass, the mechanism of cut blasting and the propagation law of blasting vibration waves are very complex. In this paper, a new method for predicting the blasting vibration velocity of layered rock mass under multihole cut blasting is proposed. The key steps include determining the equivalent elastic boundary and load, establishing the multidegree freedom model of blasting vibration and its motion differential equation, and solving the motion differential equation by time-history analysis method. Two multihole cut blasting tests of different schemes were carried out in the construction site of layered rock mass, and the measured results of blasting vibration waves were obtained. By comparing the time-history curves of the predicted and measured blasting vibration velocity, it can be seen that the time-history curves predicted by the proposed method can reflect the characteristics and attenuation law of blasting vibration waves, and the predicted waveforms are similar to the measured waveforms. By using the proposed method, the prediction accuracy for the peak velocity of blasting vibration in the two tests is 93% and 94%, respectively, and the prediction accuracy for the dominant frequency of blasting vibration in the two tests is 86% and 94%, respectively. The prediction accuracy of the main characteristic parameters of blasting vibration waves is high. So it can be proved that the prediction method proposed in this paper is feasible in effectiveness and accuracy, which can provide important theoretical guidance for the optimization of blasting design and the control of blasting vibration in underground engineering in layered rock mass.

Dynamic Simulation Technique for Prediction of Stress on Element of Metal Pushing V-Belt Under CVT Operation

2006 ◽  
Author(s):  
Toshihiro Saito
Keyword(s):  
Stress Distribution ◽  
Dynamic Behavior ◽  
Large Scale ◽  
Time History ◽  
Dynamic Strength ◽  
Simulation Method ◽  
Scale Model ◽  
Individual Element ◽  
High Rotational Speed ◽  
Simultaneous Prediction

A simulation method enabling simultaneous prediction of dynamic behavior and stress distribution on an individual element has been developed for durability evaluation of dynamic strength of metal pushing V-belts. The finite-element-method that enables contact analyses in time history with large-scale model was adopted to reproduce the dynamic behavior of the V-belt in high rotational speed range of CVT. This paper focuses on the element strength in actual CVT operation, and also discusses modifications made to the previously reported simulation method to enable the prediction of detailed stress. A new technique named inertia-relief is introduced, which does not require the application of constraint conditions when calculating the detailed stress on element in respectively. This results in allowing the stress distribution on any element to be found at any position on the trajectory of the V-belt and the elastic deformation of the element to be identified. Using this technique, it has been found that the stress on the necks of elements at the entrance and exit of the pulleys affects the dynamic strength of the V-belt. Furthermore, a method of evaluating this stress was also determined. In addition, consideration was given to the effect of the elements tail side concave shape on the dynamic strength of the V-belt.

scholarly journals Blasting Vibration Generated by Breaking-Blasting Large Barriers with EBBLB

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Wang Zhen-xiong ◽  
Gu Wen-bin ◽  
Liang Ting ◽  
Liu Jian-qing ◽  
Xu Jing-lin ◽  
...  
Keyword(s):  
Seismic Waves ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Time History ◽  
Ground Vibration ◽  
Blasting Vibration ◽  
Human Beings ◽  
Hilbert Huang Transform ◽  
Energy Information ◽  
Center Time

Equipment for breaking and blasting large barriers (EBBLB) is new break-blast equipment, which inevitably induces ground vibration and may cause substantial damage to rock mass and nearby structures as well as human beings. The ground vibration induced by break-blast is one of the inevitable outcomes. By monitoring vibration at measuring points at different distances from blasting center, time history curve of vibrating velocity can be obtained; it can be drawn that blasting seismic waves are generated mainly from the explosion of the precharge. Furthermore, different approaches have been adopted to fit relationship between particle peak velocity (PPV) and distance from blasting center, comparative analysis of which provides the most appropriate relation expression to predict attenuation of PPV of vibration with distance from blasting center. The relation between vibration frequency and distance from blasting center is obtained by Fourier transform. And the research decomposes vibrating signals in vertical direction of different distances from blasting center with Hilbert-Huang Transform (HHT), extracting information of empirical mode components of blasting vibration signals; thus vibrating signals are contracted by spectrum information and energy information, three-dimensional energy, and energy attenuation of vibration with different distances from blasting center. The study can predict ground vibration generated by EBBLB and assess its damaging effects of blasting vibration for security and protection.

scholarly journals Simulation of Structure Dynamic Stress under Multi-load Condition in Resonance State

2018 ◽  
Vol 165 ◽  
pp. 10001
Author(s):  
Fansong Li ◽  
Pingbo Wu ◽  
Chaotao Liu
Keyword(s):  
Frequency Domain ◽  
External Load ◽  
Dynamic Stress ◽  
Load Condition ◽  
Time History ◽  
Resonance State ◽  
Simulation Method ◽  
Phase Information ◽  
Spectrum Density ◽  
Stress Simulation

Some metro vehicle lifeguard structure cracking emerged during operation, and the reason is due to resonance. In order to simulate the dynamic stress accurately in resonance state, the formula for calculating the dynamic stress under multi-load condition was deduced based on structural dynamics mechanics. During the dynamic stress simulation, firstly, the frequency response function (FRF) of each external load was calculated, which including the phase information. Then, the method was based on Fast Fourier Transform (FFT) to get the frequency domain with real and imaginary part of each external load rather than power spectrum density (PSD) calculation, avoiding loss of the phase information due to PSD method. Finally, the dynamic stress frequency domain data could be calculated by FFT results and FRFs. Based on above, the dynamic stress time history could be acquired by Inverse FFT (IFFT) of stress frequency domain data, and the stress simulation method was verified by the line test result. Compared with the conventional stress PSD calculation method, the method in this paper can retain the phase information of the each external load. Meanwhile, the conventional stress simulation method based on PSD could not get satisfactory result.

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