scholarly journals Subsection Forward Modeling Method of Blasting Stress Wave Underground

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Bo Yan ◽  
Xinwu Zeng ◽  
Yuan Li
Keyword(s):  
Finite Element ◽  
Stress Wave ◽  
Source Region ◽  
Stress Waves ◽  
Nonlinear Finite Element ◽  
Stress Wave Propagation ◽  
Local Structures ◽  
Nonlinear Responses ◽  
Induced Stress ◽  
Material Nonlinear

The generation of stress waves induced by explosions underground is governed by material nonlinear responses of materials surrounding explosions and affected by source region mediums and local structures. A nonlinear finite element (NFE) method can simulate the generation efficiently. However, the calculation using the NFE to observational distances, where motions are elastic, is computationally challenging. In order to tackle this problem, we present a subsection numerical simulating method for forward modelling the generation and propagation of stress waves with a hybrid method coupling the NFE and a linear finite element (LFE). The subsection idea is developed based on previous works; calculating steps of the subsection method as well as techniques of passing motions from a source region to an elastic region are discussed. 3D numerical simulations of stress wave propagation in rock generated by decoupled explosion underground with two methods for comparison are carried out. The accuracy of the subsection method is demonstrated with simulated results. The demand of PC memory and the calculating time are investigated. The subsection method provides another approach for modeling and understanding the generation and propagation of explosion-induced stress waves, though, currently, studies are preliminary.

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.

Elasto-Viscoplastic Dispersive Waves in Silicon Wafers

2007 ◽  
Author(s):  
Li Liu ◽  
C. Steve Suh
Keyword(s):  
Stress Wave ◽  
High Temperatures ◽  
Nonlinear Function ◽  
Low Frequency ◽  
Propagation Model ◽  
Constitutive Law ◽  
Stress Wave Propagation ◽  
Thickness Variation ◽  
Low Frequencies ◽  
Induced Stress

This paper provides the required knowledge base for establishing Laser Induced Stress Wave Thermometry (LISWT) as a viable alternative to current infrared technologies for temperature measurement up to 1000°C with ±1°C resolution. A stress wave propagation model having a complex, temperature-dependent elasto-viscoplastic constitutive law is developed. Investigated results show that wave group velocity is a nonlinear function of temperature. Nonlinearity becomes more prominent at high temperatures and low frequencies. As such, for LISWT to achieve better thermal resolution at high temperatures, low frequency components of the induced stress wave should be exploited. The results also show that the influence of temperature on attenuation is relatively small. It is not recommended to use attenuation for resolving temperature variation as small as several degrees Celsius. In addition to temperature, geometry also is found to have an impact on wave dispersion and attenuation. The influence of thickness on wave velocity is significant, thus suggesting that for LISWT to achieve high temperature resolution, wafer thickness must be accurately calibrated in order to eliminate all possible errors introduced by thickness variation.

Research on Attenuation of Shock Induced Stress Wave in Multi-Layered Thin Cylindrical Rods

2018 ◽  
Vol 878 ◽  
pp. 35-40
Author(s):  
Fei Peng ◽  
Zhi Guang Yang ◽  
Li Peng Wang
Keyword(s):  
Stress Wave ◽  
Wave Attenuation ◽  
Impact Load ◽  
Layered Media ◽  
One Dimension ◽  
Stress Wave Propagation ◽  
Propagation Theory ◽  
Induced Stress ◽  
The One ◽  
Wave Induced

The attenuation of stress wave induced by impact load in multi-layered thin cylindrical rods has been investigated and analyzed. Firstly, based on stress wave propagation theory, the one dimension solution of the response of stress wave in three-layered media has been given. Secondly, a three-layered thin cylindrical rod has been established through FEM, and the propagation and attenuation of stress wave in it has been analyzed. The analytical and numerical results showed that the stress wave attenuation could be achieved by using multi-layered media.

FEA Robustness Verification in the Modeling of 1-D Stress Wave Propagation for a Split Hopkinson Bar (SHB) Test

2012 ◽  
Author(s):  
Michael L. McCoy ◽  
Rasoul Moradi ◽  
Hamid M. Lankarani
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Stress Wave ◽  
Hopkinson Bar ◽  
Stress Wave Propagation ◽  
Fe Model ◽  
Strain Gages ◽  
Split Hopkinson Bar ◽  
Split Hopkinson ◽  
Impact Problems

Impact loading on mechanical structures and components produces stress conditions that are large in magnitude and fluctuate with time which are difficult for the engineer to assess for design. The Stress Wave Propagation (SWP) is a classical methodology to account for these large stress levels. Due to the highly mathematical approach of stress wave theory along with consideration of boundary conditions interactions in the struck solid, the stress wave propagation method generates closed solutions to impact problems that are only 1-D in nature [1, 2]. In engineering practice, most mechanical problems are more complex than 1-D and thus numerical methods need to be applied to provide engineering solutions. The Finite Element Method (FEM) is a numerical technique that is commonly used in static and dynamic loading conditions to provide engineering solution to complex geometry and loading. In this paper, the FEM is examined to determine if this methodology is robust enough to accurately represent Stress Wave Propagation in solid mediums by the capturing wave propagation velocities, boundary reflections and transmissions along with large transient stress magnitudes using simple 2-D axisymmetrical elements. The most complex 1-D problem and perhaps the most practical solved problem by the Stress Wave Propagation is the Split Hopkinson Bar (SHB) test. The purpose of this test is to determine the dynamic strength of materials. A finite element (FE) model of an as-built SHB test apparatus was developed. In the same function as the strain gages, two nodes were used to extract the strain time histories from the FE model of the apparatus bars. It was found that the pseudo-strain gages of the FEA compared well to the SWP theory. The pulse magnitudes of strains, strain rates and stress were found extremely similar and exhibited magnitudes within 4% between SWP and direct examination. This model replicating a dynamic impact event demonstrated that the FEA can be used to solve complex impact problems involving stress wave propagation with the use of simple 2-D axisymmetric elements reducing computation time.

Nonlinear Finite Element Analysis on the Steel Frame with Semi-Rigid Connection under Periodic Load

2011 ◽  
Vol 255-260 ◽  
pp. 614-618
Author(s):  
Lai Wang ◽  
Bo Shun Liu ◽  
Ning Yang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Nonlinear Finite Element Analysis ◽  
Steel Frame ◽  
Nonlinear Finite Element ◽  
Periodic Load ◽  
Element Analysis ◽  
Finite Element Software ◽  
Rigid Connection ◽  
Material Nonlinear

In this paper, nonlinear finite element analysis on the steel frame with top-seat angle and double web-angles semi-rigid connection were carried out with ANSYS finite element software. In the analysis, connective, geometrical and material nonlinear were considered. Compare analysis results with experimental results, the influence of semi-rigid connection’s flexibility on steel frame was studied and some references to the design of steel frame with semi-rigid connection were supplied.

Meshless Method Used in Wave Propagation in Anisotropic Material

2004 ◽  
Vol 261-263 ◽  
pp. 525-530
Author(s):  
Dong Yun Ge ◽  
Ming Wan Lu ◽  
Qiu Hai Lu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Composite Material ◽  
Wave Propagation ◽  
Radial Basis Functions ◽  
Stress Wave ◽  
Anisotropic Material ◽  
Meshless Method ◽  
Basis Functions ◽  
Stress Wave Propagation

The compactly supported radial basis functions (RBFs) is modified and used to the wave propagation in the anisotropic materials. An example to simulate the wave propagation in composite material is used in the paper to verify this method. In this example, stress wave propagation histories are obtained. The comparison between results by this method and by finite element method is also made. And the agreement with two results shows that this method can be used to simulate the wave propagation history in anisotropic material efficiently.

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.

The Micro-Mechanism of Vibration Cutting Stress Wave and the Analysis of Macro-Processing Effect

2009 ◽  
Vol 407-408 ◽  
pp. 632-635
Author(s):  
Jia Yao ◽  
Wei Lu ◽  
Chun Shan Liu
Keyword(s):  
Finite Element Method ◽  
Stress Intensity Factor ◽  
Wave Propagation ◽  
Stress Wave ◽  
Dynamic Stress ◽  
Dynamic Stress Intensity Factor ◽  
Shear Angle ◽  
Stress Waves ◽  
Stress Wave Propagation ◽  
Vibration Cutting

The specification of the vibration cutting loading is a decision factor for the generation of stress wave and the stress wave propagation has a significant impact on its micro-mechanism. Making the stress waves’ generation in the cutting area of vibration cutting for entry point, the analysis of internal inflection wave, inflection fracture and dynamic stress intensity factor has been carried out, the simulation of vibration cutting has also been done by finite element method, the essential of energy concentrated role, shear angle increment and cutting quality improvement has been explained.

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