Study on the Scattering Effect of Micro-Scale Inhomogeneity to the Elastic Wave

2013 ◽  
Vol 807-809 ◽  
pp. 2228-2231
Author(s):  
Ning Yang ◽  
Xu Qian
Keyword(s):  
Random Media ◽  
Random Medium ◽  
Wave Length ◽  
Seismic Record ◽  
Obvious Effect ◽  
Von Karman ◽  
Scale Inhomogeneity ◽  
Von Kármán ◽  
Dielectric Objects ◽  
The Impact

Some research on the wave propagation in random medium with Von Karman correlation has been developed in this paper. It focuses on the seismic record of circular disturbance in random medium with Von Karman autocorrelation function. Six different kinds of random medium become the background of the dielectric object. The study of the impact to the responds of the dielectric objects can be measured by applying the FDTD to random background medium model. The numerical results show that the random media make the most obvious effect when the scale of imhomogeneity is close to the wave length.

Constructing Von Karman Random Media Model with Power Spectrum Method

2014 ◽  
Vol 536-537 ◽  
pp. 911-914
Author(s):  
Ning Yang ◽  
Xu Qian
Keyword(s):  
Power Spectrum ◽  
Frequency Domain ◽  
Random Media ◽  
Correlation Lengths ◽  
Spectrum Method ◽  
Inverse Fourier Transformation ◽  
Von Karman ◽  
Auto Correlation Function ◽  
Power Spectrum Method ◽  
Von Kármán

In this paper, Von Karman random media is constructed with power spectrum method. The random media with Von Karman autocorrelation cannot be constructed in time domain but in frequency domain. So power spectrum method is utilized to solve the problem. The spectrum of random function is generated in frequency domain with random field and auto-correlation function. With inverse Fourier transformation, the Von Karman random media model is constructed. With different correlation lengths, six group of Von Karman random media are constructed.

Rigid-Body Water–Surface Impact Dynamics: Experiment and Semianalytical Approximation

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Ravi Challa ◽  
Solomon C. Yim ◽  
V. G. Idichandy ◽  
C. P. Vendhan
Keyword(s):  
Rigid Body ◽  
Closed Form ◽  
Experimental Results ◽  
Scale Model ◽  
Water Impact ◽  
Equivalent Radius ◽  
Closed Form Solutions ◽  
Von Karman ◽  
Von Kármán ◽  
The Impact

An experimental study of the dynamics of a generic rigid body during water impact and an equivalent-radius approximate analytical procedure is developed and calibrated in this study. The experimental tests in a wave basin covered a range of drop heights using a 1/6th-scale model of a practical water-landing object prototype for two drop mechanisms to determine the water impact and contact effects. The first mechanism involved a rope and pulley arrangement, while the second mechanism employed an electromagnetic release to drop the rigid body. Hydrodynamic parameters including peak acceleration and touchdown pressure were measured and the maximum impact/contact force was estimated for various entry speeds (corresponding to various drop heights) and weights of the rigid body. Results from the tests show that the impact acceleration and touchdown pressure increases approximately linearly with increasing drop height and the data provides conditions that keep impact accelerations under specified limits for the rigid-body prototype. The experimentally measured maximum accelerations were compared with classical von Karman and Wagner approximate closed-form solutions. In this study, an improved approximate solution procedure using an equivalent radius concept integrating experimental results with the von Karman and Wagner closed-form solutions is proposed and developed in detail. The resulting semianalytical estimates are calibrated against experimental results and found to provide close matching.

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