The impact of solid–fluid interaction on transient stress wave propagation due to Acoustic Emissions in multi-layer plate structures

2014 ◽  
Vol 117 ◽  
pp. 411-422 ◽  
Author(s):  
Brian Burks ◽  
M.A. Hamstad
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Acoustic Emissions ◽  
Stress Wave Propagation ◽  
Plate Structures ◽  
Transient Stress ◽  
The Impact ◽  
Fluid Interaction

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.

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.

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.

scholarly journals Simulation of mTBI Utilizing White Matter Properties from MRE

2020 ◽  
Author(s):  
Amit Madhukar ◽  
Martin Ostoja-Starzewski
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
White Matter ◽  
Stress Wave ◽  
Peak Pressure ◽  
Material Model ◽  
Stress Wave Propagation ◽  
Head Model ◽  
Transient Stress ◽  
High Resolution Mri

We extend our high-resolution MRI-based Finite Element (FE) head model, previously presented and validated in [1–3], by considering the heterogeneities of the white matter structures captured through the use of Magnetic Resonance Elastography (MRE). This approach imparts more sophistication to our numerical model and yields results that more closely match experimental results. It is found that the peak pressure more closely matches the experiments as compared to the heterogeneous case. Qualitatively, we find differences in stress wave propagation near the corpus callosum and the corona radiata, which are stiffer on average than the global white matter. We are able to study the effects of these stiff structures on transient stress wave propagation within the cerebrum, something that cannot be done with a homogenized material model.

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