scholarly journals A Coupled Gas Flow-Mechanical Damage Model and Its Numerical Simulations on High Energy Gas Fracturing

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Yu Bai ◽  
Li Sun ◽  
Chenhui Wei
Keyword(s):  
Numerical Simulations ◽  
Stress Wave ◽  
Gas Flow ◽  
High Energy ◽  
Stress Wave Propagation ◽  
Crack Evolution ◽  
Element Analysis ◽  
Unconventional Gas ◽  
Radial Cracks ◽  
The Impact

High-energy gas fracturing (HEGF) and gas fracturing (GF) are considered to be efficient to enhance the permeability of unconventional gas reservoir. The existing models for HEGF mainly focus on the dynamic loading of stress wave or static loading of gas pressurization, rather than on the combined actions of them. Studies on the combination of HEGF and GF (HEGF+GF) are also few. In this paper, a damage-based stress wave propagation-static mechanical equilibrium-gas flow coupling model is established. Numerical model and determination of mesomechanical parameters in finite element analysis are described in detail. Numerical simulations on crack evolution under HEGF, GF, and HEGF+GF are carried out, and the impact of in situ stress conditions on crack evolution is discussed further. A total of 11 cracks with length of 2.3-4 m in HEGF, 4 main cracks with length of 6.5–8 m in GF, and 11 radial cracks with length of 2–11.5 m in HEGF+GF are produced. Many radial cracks around the borehole are formed in HEGF and extended further in GF. The crustal stress difference is disadvantageous for crack complexity. This study can provide a reference for the application of HEGF+GF in unconventional gas reservoirs.

Modeling of Impact Behavior of Lightweight Composites under Metallic Projectile

2011 ◽  
Vol 88-89 ◽  
pp. 214-218 ◽  
Author(s):  
Ali Asadi ◽  
Seyedali Ali Sadough
Keyword(s):  
Wave Propagation ◽  
Numerical Simulations ◽  
Stress Wave ◽  
Alumina Ceramic ◽  
Impact Behavior ◽  
Stress Wave Propagation ◽  
Classic Theory ◽  
Lightweight Composites ◽  
The Impact ◽  
Good Agreement

The purpose of this article is studying the behavior of lightweight composites under metallic projectile by stress wave and comparing the results with numerical simulations. The target includes external layer, Alumina ceramic layer and supportive layer. The impact velocity of the projectile is 500 m/s. In this article, two lightweight composite targets with polymeric supportive layer and metallic supportive layer are studied. The results of numerical simulations and classic theory of stress wave propagation are in good agreement. The effect of changing supportive layer material and time of stress wave propagation into layers by the results of modeling is also studied.

Impact Load Buffering Method Based on Stress Wave Attenuation Principle

2019 ◽  
Vol 11 (02) ◽  
pp. 1950019 ◽  
Author(s):  
Lin Gan ◽  
He Zhang ◽  
Cheng Zhou ◽  
Lin Liu
Keyword(s):  
Stress Wave ◽  
Wave Attenuation ◽  
Impact Load ◽  
Dynamics Simulation ◽  
Scanning System ◽  
Isolation Method ◽  
Element Analysis ◽  
System A ◽  
High Emission ◽  
The Impact

Rotating scanning motor is the important component of synchronous scanning laser fuze. High emission overload environment in the conventional ammunition has a serious impact on the reliability of the motor. Based on the theory that the buffer pad can attenuate the impact stress wave, a new motor buffering Isolation Method is proposed. The dynamical model of the new buffering isolation structure is established by ANSYS infinite element analysis software to do the nonlinear impact dynamics simulation of rotating scanning motor. The effectiveness of Buffering Isolation using different materials is comparatively analyzed. Finally, the Macht hammer impact experiment is done, the results show that in the experience of the 70,000[Formula: see text]g impact acceleration, the new buffering Isolation method can reduce the impact load about 15 times, which can effectively alleviate the plastic deformation of rotational scanning motor and improve the reliability of synchronization scanning system. A new method and theoretical basis of anti-high overload research for Laser Fuze is presented.

Investigation of Stress Wave Propagation in Brain Tissues Through the Use of Finite Element Method

2010 ◽  
Author(s):  
Biaobiao Zhang ◽  
W. Steve Shepard ◽  
Candace L. Floyd
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Brain Injury ◽  
Stress Wave ◽  
Brain Research ◽  
Complex Structure ◽  
Stress Wave Propagation ◽  
Wave Loads ◽  
The Impact ◽  
The Brain

Because axons serve as the conduit for signal transmission within the brain, research related to axon damage during brain injury has received much attention in recent years. Although myelinated axons appear as a uniform white matter, the complex structure of axons has not been thoroughly considered in the study of fundamental structural injury mechanisms. Most axons are surrounded by an insulating sheath of myelin. Furthermore, hollow tube-like microtubules provide a form of structural support as well as a means for transport within the axon. In this work, the effects of microtubule and its surrounding protein mediums inside the axon structure are considered in order to obtain a better understanding of wave propagation within the axon in an attempt to make progress in this area of brain injury modeling. By examining axial wave propagation using a simplified finite element model to represent microtubule and its surrounding proteins assembly, the impact caused by stress wave loads within the brain axon structure can be better understood. Through conducting a transient analysis as the wave propagates, some important characteristics relative to brain tissue injuries are studied.

Wave Propagation in an Elastic Rod Exhibiting Internal Coulomb Friction, Considered as a Model for a Ring Spring

1956 ◽  
Vol 23 (3) ◽  
pp. 367-372
Author(s):  
E. H. Lee ◽  
A. J. Wang
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Coulomb Friction ◽  
Stress Wave Propagation ◽  
Infinite Length ◽  
Input Energy ◽  
Elastic Rod ◽  
Total Input ◽  
Conical Bearing ◽  
The Impact

Abstract The problem of stress-wave propagation in a ring spring is considered. A ring spring consists of rings placed normal to the spring axis with alternate internal and external conical bearing surfaces. The friction between these surfaces causes a loading-unloading relation which is strongly irreversible, leading to marked energy absorption for oscillatory stressing. The attenuation of a pulse of stress is analyzed in detail as it is propagated down a spring of infinite length. The influence of certain spring characteristics is evaluated. Concentration of the absorption of the total input energy is found in the region of the impact end of the spring, and particular examples are presented.

Experimental investigation of stress wave propagation in standing trees

Holzforschung ◽  
2011 ◽  
Vol 65 (5) ◽  
Author(s):  
Houjiang Zhang ◽  
Xiping Wang ◽  
Juan Su
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Wave Energy ◽  
Structural Defects ◽  
Stress Wave Propagation ◽  
Tree Trunk ◽  
Wave Fronts ◽  
Contour Maps ◽  
Standing Trees ◽  
The Impact

Abstract The objective of this study was to investigate how a stress wave travels in a standing tree as it is introduced into the tree trunk through a mechanical impact. A series of stress wave time-of-flight (TOF) data were obtained from three freshly-cut red pine (Pinus resinosa Ait.) logs by means of a two-probe stress wave timer. Two-dimensional (2D) and three-dimensional (3D) stress wave contour maps were constructed based on the experimental data using a commercial software. These stress wave contour maps represent the wave fronts in a time sequence, illustrating the flow of stress wave energy within a log. The analysis of TOF data and wave fronts indicates that stress wave propagation in standing trees is affected by tree diameter, travel distance, and internal wood conditions (wood properties and structural defects). When a stress wave is introduced into a tree trunk from a point source, it initially propagates in the impact direction as a 3D wave. Then the flow of the stress wave energy gradually changes towards the longitudinal directions. As the diameter-to-distance ratio reaches 0.1 or below, the wave begins to travel as a quasi 1D wave.

Containment and Arrest of Blade Shedding in Gas Turbine Engines Using Novel Dual-Ring Design

2021 ◽  
Author(s):  
Prayers Roy ◽  
Shaker A. Meguid
Keyword(s):  
Energy Absorption ◽  
Impact Damage ◽  
Impact Resistance ◽  
High Energy ◽  
Element Analysis ◽  
Single Ring ◽  
High Energy Absorption ◽  
Interfacial Gap ◽  
The Impact ◽  
Dual Ring

Abstract In this paper, we examine the energy absorption and containment capabilities of a newly proposed dual-ring design accounting for interactions between a released blade and fully bladed fan disk using 3D finite element analysis. The components of this dual-ring design are strategically selected to ensure high energy absorption and high impact resistance, thus leading to reduced damage of the disk and increased safety. Three containment ring designs are examined: (i) conventional single-ring design composed of one of titanium, aluminum or Kevlar, (ii) a newly proposed aluminium-Kevlar dual-ring arrangement, and (iii) dual-ring arrangement with an interfacial gap between them to arrest and contain the released blade and ensure free passage of the trailing blades. The results of our numerical simulations indicate that although the single-ring design resists penetration and contains the released blade within the confines of the disk, it does not remove the released blade from the path of the trailing blades leading to severe damage to the fan disk. On the contrary, our new dual-ring design, which contains an interfacial gap, has potential to successfully arrest the released blade within the confines of the ring and out of the path of the trailing blades. This design significantly can reduce the impact damage to the fan disk and reduces kinetic energy of the released blade to near zero in less than half a rotation of the fan disk.

The Buckling Mechanism of Square Tube Subjected to the Impact of a Mass

2014 ◽  
Vol 624 ◽  
pp. 267-271
Author(s):  
Zhu Hua Tan ◽  
Bo Zhang ◽  
Peng Cheng Zhai
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Numerical Methods ◽  
Stress Wave ◽  
Significant Influence ◽  
Strain Localization ◽  
Stress Wave Propagation ◽  
Low Velocity ◽  
Buckling Modes ◽  
The Impact

The dynamic response of the square tube subjected to the impact of a mass was investigated by using experimental and numerical methods. The square tube was impacted by a mass at the velocity ranging from 5.09 m/s to 12.78 m/s, and different progressive buckling modes were obtained. The numerical simulation was also carried out to analyze the buckling mechanism of the square tube. The results show that there is obvious stress wave propagation and strain localization in the tube, which has a significant influence on the buckling mechanism of the tube. The stress wave and inertia of the mass play different roles at various impact velocities. And buckling mechanism at low velocity is mainly caused by stress wave, whereas the buckling mechanism at high velocity is resulted from the inertial of the mass.

THE REDUCTION OF STRESS WAVE PROPAGATION THROUGH POROUS MATERIALS

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1215-1220
Author(s):  
SOTO AKI KIDA ◽  
KEITA FUKUSHIMA ◽  
MASAYA MATSUMOTO
Keyword(s):  
Porous Medium ◽  
Porous Materials ◽  
Stress Wave ◽  
Acrylic Resin ◽  
Wave Theory ◽  
Stress Waves ◽  
Stress Wave Propagation ◽  
Impact Stress ◽  
The Impact ◽  
Impact Stress Wave

Impact stress wave propagating through porous materials is investigated in order to examine the ability of the shock absorbing effect. The specimens are modeled as the porous medium with different porous diameters made of the acrylic resin plate. When these models are impacted with different impact velocities, the impact stress waves propagating before and after the porous parts are measured using the strain gages in the experiments. As the reduction effect of the impact stress wave propagating in the porous medium, we pay attention to the maximum stresses and the duration times from the histories of the impact stress waves. One-dimensional wave theory and dynamic element method simulated this model are applied in order to explain these phenomena.

scholarly journals Measurement of Stress Waves Propagation in Percussive Drilling

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3677
Author(s):  
Diego Scaccabarozzi ◽  
Bortolino Saggin
Keyword(s):  
Stress Wave ◽  
Axial Stress ◽  
Element Model ◽  
Stress Waves ◽  
Stress Wave Propagation ◽  
Drill Bit ◽  
Torsional Vibrations ◽  
Flexural Stress ◽  
Percussive Drilling ◽  
The Impact

This work describes the results of a test campaign aimed to measure the propagation of longitudinal, torsional, and flexural stress waves on a drill bit during percussive rock drilling. Although the stress wave propagation during percussive drilling has been extensively modeled and studied in the literature, its experimental characterization is poorly documented and generally limited to the detection of the longitudinal stress waves. The activity was performed under continuous drilling while varying three parameters, the type of concrete, the operator feeding force, and the drilling hammer rotational speed. It was found that axial stress wave frequencies and spectral amplitudes depend on the investigated parameters. Moreover, a relevant coupling between axial and torsional vibrations was evidenced, while negligible contribution was found from the bending modes. A finite element model of the drill bit and percussive element was developed to simulate the impact and the coupling between axial and torsional vibrations. A strong correlation was found between computed and measured axial stress spectra, but additional studies are required to achieve a satisfactory agreement between the measured and the simulated torque vibrations.

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