scholarly journals Numerical Study on the Elastic Deformation and the Stress Field of Brittle Rocks under Harmonic Dynamic Load

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 851
Author(s):  
Siqi Li ◽  
Shenglei Tian ◽  
Wei Li ◽  
Xin Ling ◽  
Marcin Kapitaniak ◽  
...  
Keyword(s):  
Stress Field ◽  
Numerical Simulations ◽  
Elastic Deformation ◽  
Fatigue Damage ◽  
Dynamic Load ◽  
Static Load ◽  
Numerical Study ◽  
Rock Fracture ◽  
Dynamic Loads ◽  
Brittle Rocks

In order to study the deformation displacement and the stress field of brittle rocks under harmonic dynamic loading, a series of systematic numerical simulations are conducted in this paper. A 3D uniaxial compression simulation is carried out to calibrate and determine the property parameters of sandstone and a model of the cylindrical indenter intruding the rock is proposed to analyze the process of elastic deformation. Four main parameters are taken into account, namely the position on the rock, the frequency and the amplitude of dynamic load, the type of indenter and the loading conditions (static and static-dynamic). Based on the analysis undertaken, it can be concluded that both of the deformation displacement and stress field of the rock change in a harmonic manner under the static-dynamic loads. The frequency and the amplitude of harmonic dynamic load determine the period and the magnitude of the rock response, respectively. In addition, the existence of harmonic dynamic load can aggravate the fatigue damage of the rock and allow a reduction in static load. Our investigations confirm that the static-dynamic loads are more conducive to rock fracture than static load.

The Specific Characteristics of Shock and Blast Impacts on Construction Sites

2021 ◽  
pp. 81-88
Author(s):  
A.A. Komarov ◽  
Keyword(s):  
Dynamic Load ◽  
Static Load ◽  
Dynamic Loads ◽  
Potential Hazard ◽  
Construction Sites ◽  
Static Loads ◽  
Equivalent Static Loads ◽  
Plane Crash ◽  
Nuclear Plants ◽  
The Impact

The practices of hazardous and unique facilities’ construction imply that specific attention is paid to the issues of safety. Threats associated with crash impacts caused by moving cars or planes are considered. To ensure safety of these construction sites it is required to know the potential dynamic loads and their destructive capacity. This article considers the methodology of reducing dynamic loads associated with impacts caused by moving collapsing solids and blast loads to equivalent static loads. It is demonstrated that practically used methods of reduction of dynamic loads to static loads are based in schematization only of the positive phase of a dynamic load in a triangle forms are not always correct and true. The historical roots of this approach which is not correct nowadays are shown; such approach considered a detonation explosion as a source of dynamic load, including TNT and even a nuclear weapon. Application of the existing practices of reduction of dynamic load to static load for accidental explosions in the atmosphere that occur in deflagration mode with a significant vacuumization phase may cause crucial distortion of predicted loads for the construction sites. This circumstance may become a matter of specific importance at calculations of potential hazard of impacts and explosions in unique units — for instance, in the nuclear plants. The article considers a situation with a plane crash, the building structure load parameters generated at the impact caused by a plane impact and the following deflagration explosion of fuel vapors are determined.

scholarly journals Numerical Analysis of Roadway Rock-Burst Hazard Under Superposed Dynamic and Static Loads

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3761 ◽  
Author(s):  
Kong ◽  
Jiang ◽  
Jiang ◽  
Wu ◽  
Chen ◽  
...  
Keyword(s):  
Energy Density ◽  
Rock Burst ◽  
Elastic Energy ◽  
Dynamic Load ◽  
Static Loading ◽  
Static Load ◽  
Dynamic Loads ◽  
Loading Conditions ◽  
Static Loads ◽  
Elastic Energy Density

Microseismic events commonly occur during the excavation of long wall panels and often cause rock-burst accidents when the roadway is influenced by dynamic loads. In this paper, the Fast Lagrangian Analysis of Continua in 3-Dimensions (FLAC3D) software is used to study the deformation and rock-burst potential of roadways under different dynamic and static loads. The results show that the larger the dynamic load is, the greater the increase in the deformation of the roadway under the same static loading conditions. A roadway under a high static load is more susceptible to deformation and instability when affected by dynamic loads. Under different static loading conditions, the dynamic responses of the roadway abutment stress distribution are different. When the roadway is shallow buried and the dynamic load is small, the stress and elastic energy density of the coal body in the area of the peak abutment stress after the dynamic load are greater than the static calculations. The dynamic load provides energy storage for the coal body in the area of the peak abutment stress. When the roadway is deep, a small dynamic load can still cause the stress in the coal body and the elastic energy density to decrease in the area of the peak abutment stress, and a rock-burst is more likely to occur in a deep mine roadway with a combination of a high static load and a weak dynamic load. When the dynamic load is large, the peak abutment stress decreases greatly after the dynamic loading, and under the same dynamic loading conditions, the greater the depth the roadway is, the greater the elastic energy released by the dynamic load. Control measures are discussed for different dynamic and static load sources of rock-burst accidents. The results provide a reference for the control of rock-burst disasters under dynamic loads.

Stiffness of Magnetic Bearings Subjected to Combined Static and Dynamic Loads

1992 ◽  
Vol 114 (4) ◽  
pp. 785-789 ◽  
Author(s):  
D. K. Rao ◽  
G. V. Brown ◽  
P. Lewis ◽  
J. Hurley
Keyword(s):  
Dynamic Load ◽  
Static Load ◽  
Dynamic Stiffness ◽  
Load Ratio ◽  
Magnetic Bearing ◽  
Dynamic Loads ◽  
Approximate Design ◽  
Critical Gap ◽  
Gap Fraction ◽  
Static And Dynamic Loads

This paper investigates the stiffness of a magnetic bearing that is subjected to the combined action of static and dynamic loads. Since their sum cannot exceed the saturation load, a large static load will imply that the bearing can carry only a small dynamic load. This smaller dynamic load together with the practical vibration amplitude define a practical upper bound to the dynamic stiffness. This paper also presents approximate design formulas and curves for this stiffness capacity as a function of the ratio of dynamic and static loads. In addition, it indicates that vibrations larger than a certain gap fraction can destabilize the magnetic bearing. This gap fraction, called the critical gap fraction, depends on the dynamic and static load ratio. For example, if the dynamic load is half of the static load, the use of more than 25 percent of gap can destabilize the bearing.

scholarly journals New studies on network frequency responses considering dynamic loads

2019 ◽  
Vol 8 (3) ◽  
pp. 209
Author(s):  
L. T. M. Trang ◽  
H. Nouri
Keyword(s):  
Dynamic Load ◽  
Pid Controller ◽  
Static Load ◽  
Frequency Control ◽  
Dynamic Loads ◽  
Control Technique ◽  
Transmission Network ◽  
Frequency Oscillation ◽  
Static Loads ◽  
Frequency Responses

<p>The dynamic model construction of transmission network components that include generator buses, load buses and power branches, within MATLABSimulink environment is presented. The degree of frequency deviation of buses when the power of motor loads and static loads vary, is studied. Furthermore, the influence of motor loads with different inertia constants are considered in the control technique of load frequency using a PID controller. The results show that the frequency oscillation of the dynamic load is greater than the frequency oscillation of static load. Also the speed of frequency control of the dynamic load is greater than the speed of the frequency control of the static load and the inertia constants of the dynamic load has significant influence on the frequency control characteristics.</p>

scholarly journals IMPACT OF INTERLAMINAR ELLIPTICAL DEFECTS UPON BEHAVIOR OF RECTANGULAR CARBON PLASTIC PLATE AT STATIC AND DYNAMIC LOADS

2020 ◽  
Vol 2020 (12) ◽  
pp. 19-30
Author(s):  
Aleksandr Medvedskiy ◽  
Mihail Martirosov ◽  
Anton Homchenko ◽  
Darina Dedova
Keyword(s):  
Rectangular Plate ◽  
Dynamic Load ◽  
Static Load ◽  
Dynamic Loads ◽  
Carbon Plastic ◽  
Plastic Plate ◽  
Investigation Methods ◽  
Static And Dynamic Loads ◽  
The Impact ◽  
Distribution Of Stresses

The purpose of this work is to investigate the impact of the inner defects of elliptical stratification type upon behavior of the rectangular carbon plastic plate at the impact of static and dynamic loads. The investigation methods: the problem is solved in a numerical way with the aid of a finite ele-ment method (FEM) in the LS-DYNA software com-plex (Livermore Software Technology Corp.). The investigation results: the distribution of stresses in plate layers under the impact of static and dynamic loads is obtained. The distribution of destruc-tion indices with the use of different destruction criteria for unidirectional composites (on the basis of carbon band) is defined. Conclusions: the impact of defects of the type of specified shape stratification, dimensions, amount and places of location with regard to the plate under consideration under the action of compressive static load does not practically tell. Under the action of the compressive dynamic load there is observed a noticeable impact of inner defects upon rectangular plate behavior.

scholarly journals Experimental and Numerical Study of Fatigue Damage Assessment under Combined High and Low Cycle Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Chaoshuai Han ◽  
Xianqiang Qu ◽  
Yongliang Ma ◽  
Dexin Shi
Keyword(s):  
Fatigue Life ◽  
Numerical Simulations ◽  
Fatigue Damage ◽  
Damage Assessment ◽  
Numerical Study ◽  
Engineering Application ◽  
Design Tool ◽  
Combined Loading ◽  
Type Specimens ◽  
Cycle Loading

This paper studies fatigue damage under combined high and low cycle loading. The interaction of two types of loading will greatly reduce fatigue life of structures. Existing methods usually neglect the minor high cycle loading, which obviously underestimates the total fatigue damage. To solve this problem, four methods are proposed and extended for the case of combined loading. Numerical simulations based on the superposition of two sine waves are performed. Experiments are carried out using “DH36” smooth round-type specimens. Damage predictions results by four methods are compared to the experimental results. It is concluded that some methods give satisfactory fatigue damage estimations and can be regarded as a safe design tool in engineering application.

Using Ansys for Design and Numerical Study of a Specific Fixed Wing UAV

2018 ◽  
Vol 55 (4) ◽  
pp. 652-657 ◽  
Author(s):  
Gabriel Murariu ◽  
Razvan Adrian Mahu ◽  
Adrian Gabriel Murariu ◽  
Mihai Daniel Dragu ◽  
Lucian P. Georgescu ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Unmanned Aerial Vehicle ◽  
Numerical Study ◽  
Flight Time ◽  
Cluster System ◽  
Numerical Results ◽  
Operational Performance ◽  
Gliding Flight ◽  
Aerial Vehicle ◽  
Constant Altitude

This article presents the design of a specific unmanned aerial vehicle UAV prototype own building. Our UAV is a flying wing type and is able to take off with a little boost. This system happily combines some major advantages taken from planes namely the ability to fly horizontal, at a constant altitude and of course, the great advantage of a long flight-time. The aerodynamic models presented in this paper are optimized to improve the operational performance of this aerial vehicle, especially in terms of stability and the possibility of a long gliding flight-time. Both aspects are very important for the increasing of the goals� efficiency and for the getting work jobs. The presented simulations were obtained using ANSYS 13 installed on our university� cluster system. In a next step the numerical results will be compared with those during experimental flights. This paper presents the main results obtained from numerical simulations and the obtained magnitudes of the main flight coefficients.

scholarly journals Thermoelastic analysis of FGM hollow cylinder for variable parameters and temperature distributions using FEM

2020 ◽  
Vol 9 (1) ◽  
pp. 256-264
Author(s):  
Dinkar Sharma ◽  
Ramandeep Kaur
Keyword(s):  
Stress Field ◽  
Hollow Cylinder ◽  
Numerical Study ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Functionally Graded ◽  
Gradient Index ◽  
Variable Parameters ◽  
Graded Material ◽  
Governing Differential Equation

AbstractThis paper presents, numerical study of stress field in functionally graded material (FGM) hollow cylinder by using finite element method (FEM). The FGM cylinder is subjected to internal pressure and uniform heat generation. Thermoelastic material properties of FGM cylinder are assumed to vary along radius of cylinder as an exponential function of radius. The governing differential equation is solved numerically by FEM for isotropic and anistropic hollow cylinder. Additionally, the effect of material gradient index (β) on normalized radial stresses, normalized circumferential stress and normalized axial stress are evaluated and shown graphically. The behaviour of stress versus normalized radius of cylinder is plotted for different values of Poisson’s ratio and temperature. The graphical results shown that stress field in FGM cylinder is influenced by some of above mentioned parameters.

Comparing Shock, Random and Sine Vibration Loads of the Electronic Equipment

2005 ◽  
Author(s):  
Frank Fan Wang
Keyword(s):  
Dynamic Load ◽  
Random Vibration ◽  
Sine Wave ◽  
Electronic Equipment ◽  
Dynamic Loads ◽  
Peak Acceleration ◽  
Maximum Acceleration ◽  
Dynamic Excitations ◽  
Dynamic Damage ◽  
Resonant Point

It is a challenge to correlate different dynamic loads. Often, attempts are made to compare the peak acceleration of sine wave to the root mean square (RMS) acceleration of random vibration and shock. However, peak sine acceleration is the maximum acceleration at one frequency. Random RMS is the square root of the area under a spectral density curve. These are not equivalent. This paper is to discuss a mathematical method to compare different kinds of dynamic damage at the resonant point of the related electronic equipment. The electronic equipment will vibrate at its resonance point when there are dynamic excitations. The alternative excitation at the resonant frequency causes the most damage. This paper uses this theory to develop a method to correlate different dynamic load conditions for electronic equipment. The theory is that if one kind of dynamic load causes the same levels of damaging effects as the other, the levels of vibration can then be related.

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