The influence of internal structure on wave propagation in elastic beams under impact loading

2000 ◽  
Vol 10 (PR9) ◽  
pp. Pr9-475-Pr9-480
Author(s):  
E. I. Prockuratova ◽  
C. Gearhar
Keyword(s):  
Wave Propagation ◽  
Internal Structure ◽  
Impact Loading ◽  
Elastic Beams

Speed of stress wave propagation in lung

1986 ◽  
Vol 61 (2) ◽  
pp. 701-705 ◽  
Author(s):  
R. T. Yen ◽  
Y. C. Fung ◽  
H. H. Ho ◽  
G. Butterman
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Impact Loading ◽  
Wave Speed ◽  
Dynamic Pressure ◽  
Transpulmonary Pressure ◽  
Lung Parenchyma ◽  
Surface Velocity ◽  
Stress Wave Propagation ◽  
Rabbit Lung

The speed of stress waves in the lung parenchyma was investigated to understand why, among all internal organs, the lung is the most easily injured when an animal is subjected to an impact loading. The speed of the sound is much less in the lung than that in other organs. To analyze the dynamic response of the lung to impact loading, it is necessary to know the speed of internal wave propagation. Excised lungs of the rabbit and the goat were impacted with water jet at dynamic pressure in the range of 7–35 kPa (1–5 psi) and surface velocity of 1–15 m/s. The stress wave was measured by pressure transducer. The distance between the point of impact and the sensor at another point on the far side of the lung and the transit time of the stress wave were measured. The wave speed in the goat lung was found to vary from 31.4 to 64.7 m/s when the transpulmonary pressure Pa-Ppl was varied from 0 to 20 cmH2O where Pa represents airway pressure and Ppl represents pleural pressure. In rabbit lung the wave speed varied from 16.5 to 36.9 m/s when Pa-Ppl was varied from 0 to 16 cmH2O. Using measured values of the bulk modulus, shear modulus, and density of the parenchyma, reasonable agreement between theoretical and experimental wave speeds were obtained.

Plate bending wave propagation behavior under metal sphere impact loading

2018 ◽  
Vol 32 (3) ◽  
pp. 1117-1124 ◽  
Author(s):  
Seong-In Moon ◽  
To Kang ◽  
Jung-Seok Seo ◽  
Jeong-Han Lee ◽  
Soon-Woo Han ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Impact Loading ◽  
Plate Bending ◽  
Metal Sphere ◽  
Propagation Behavior ◽  
Bending Wave

Frequency-domain simulation of logging-while-drilling borehole sonic waveforms

Geophysics ◽  
2014 ◽  
Vol 79 (2) ◽  
pp. D99-D113 ◽  
Author(s):  
Paweł J. Matuszyk ◽  
Carlos Torres-Verdín
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Frequency Domain ◽  
Internal Structure ◽  
Adaptive Finite Element Method ◽  
Computational Domain ◽  
Mechanical Filter ◽  
Logging While Drilling ◽  
Sonic Logging

Numerical simulation of sonic logging-while-drilling (LWD) borehole measurements is challenging because of significant wave propagation effects due to the massive drilling collar occupying a large portion of the borehole. In addition, the internal structure of the LWD tool can have a significant impact on the measured dispersions of Stoneley and quadrupole modes. The collar is typically constructed with a set of inner periodic grooves, which act as a mechanical filter to attenuate undesirable collar modes. Reliable numerical simulation and interpretation of LWD sonic waveforms requires that all features and dimensions of the drilling collar be included in the simulation model. Furthermore, the presence of the drilling collar can prompt numerical instabilities due to backward propagating modes in the perfectly matched layer (PML) commonly used to truncate the computational domain. This problem can be circumvented with the implementation of artificial viscoelastic attenuation in the collar whenever the simulations are intended to reproduce only wave propagation within the surrounding rock formations. In addition, reliable modeling of borehole wave propagation in the presence of high contrasts in material properties and the internal structure of the LWD collar requires a numerical method capable of accurately and stably resolving all spectral scales present in the model. We implemented an automatic [Formula: see text]-adaptive finite-element method in the frequency domain combined with a PML technique to simulate LWD sonic logging measurements. Examples of the application verified the accuracy and reliability of the simulated borehole and formation propagation modes in the presence of casing and internal structures in the LWD collar. The presence of steel casing and quality of casing/formation bond significantly influence the propagation modes excited in a borehole. However, it is still possible to estimate the formation shear slowness using monopole and quadrupole sources regardless of the quality of cement bond in fast formations. Assessment of the formation compressional slowness was significantly impeded by the strong pipe mode. Estimation of formation shear slowness in slow formations is practically impossible due to the presence of casing and a strong annulus mode when the quality of casing bond is poor.

Simulation on Shock Wave Propagation in Metallic Foams Subjected to Impact Loading

2012 ◽  
Vol 226-228 ◽  
pp. 536-540
Author(s):  
Yi Fen Zhang
Keyword(s):  
Wave Propagation ◽  
Impact Loading ◽  
Plastic Material ◽  
Progressive Collapse ◽  
Peak Stress ◽  
Metal Foams ◽  
Pulse Loading ◽  
Valuable Insight ◽  
Metallic Foams ◽  
Compressive Wave

A discretization elastic-plastic material model was used for simulating the shock waves transmission within metallic foams. The density heterogeneity of metallic foams was considered. Several types of aluminum foams are studied on the transmission of displacement and stresses wave under impact loading. The results reveal the characteristics of compressive wave propagation within the metal foams. Under low impact pulses, considerable energy is dissipated during the progressive collapse of foam cells, and then reduces the crush of the objects. When the pulse is high sufficiently, on the fixed end of foam, stress enhancement may take place, where high peak stresses usually occur. The magnitude of the peak stress depends on the relative density of foams, the pulse loading intensity, the pulse loading duration as well as the density homogeneity of foam materials. This research offers valuable insight into the reliability of the metal foams used as vehicles and protective structure.

Elastic wave propagation in non-uniform rational B-spline rods under mechanical impact loading using an isogeometrical approach

2018 ◽  
Vol 233 (5) ◽  
pp. 1721-1733 ◽  
Author(s):  
Ahmad Yavari ◽  
Mohammad Hossein Abolbashari
Keyword(s):  
Wave Propagation ◽  
Elastic Wave ◽  
Impact Loading ◽  
Propagation Speed ◽  
Cross Sectional Area ◽  
Material Distribution ◽  
Sectional Area ◽  
Cross Sectional ◽  
B Spline ◽  
Radial Inertia

One-dimensional elastic wave propagation under quadratic impact loading in a rod with a variable cross section and material distribution is the subject of this study. The material distribution of the problem under investigation as well as the variations of the geometry was elucidated with non-uniform rational B-spline (NURBS). The problem was analyzed employing the isogeometric approach in order to ensure precise modeling of the geometry. The effects of impact loading, cross sectional area, material distribution, and radial inertia on elastic waves were examined in this study. In addition, propagation, reflections, and propagation speed along the axis were investigated. It was observed that the speed was not constant along the axial direction. Also, the cross sectional area had more effect on the amplitude of the elastic wave than the radial inertia. Furthermore, it was concluded that the material distribution and radial inertia may influence the wave propagation speed.

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