Half-space response to trains moving along curved paths by 2.5D finite/infinite element approach

2021 ◽  
Vol 145 ◽  
pp. 106740
Author(s):  
Y.B. Yang ◽  
S.J. Liu ◽  
W. Chen ◽  
Q. Tan ◽  
Y.T. Wu
Keyword(s):  
Half Space ◽  
Infinite Element ◽  
Element Approach ◽  
Curved Paths ◽  
Space Response

Dynamic Response of Elastic Half-Space with Cavity Subjected to P and SV Waves by Finite/Infinite Element Approach

2015 ◽  
Vol 15 (07) ◽  
pp. 1540009 ◽  
Author(s):  
Y. B. Yang ◽  
Hsiao-Hui Hung ◽  
Kuan-Chung Lin ◽  
Kai-Wen Cheng
Keyword(s):  
Half Space ◽  
Elastic Half Space ◽  
Three Solutions ◽  
Element Mesh ◽  
Infinite Element ◽  
Infinite Elements ◽  
Element Approach ◽  
The Difference ◽  
P And Sv Waves ◽  
Incident Waves

The problem of a half-space with cavity under vertically incident waves was solved by many researchers using different approaches. However, substantially different solutions were obtained, partially due to the difference in the method of formulation, and partially due to the lack of complete identical data for use in analysis. In this paper, the finite/infinite element approach has been adopted to study the two-dimensional response of an elastic half-space containing a buried, unlined, infinitely long cylindrical of circular shape subjected to harmonic P and SV waves. First, the analysis procedure based on the finite and infinite elements is summarized. Second, considerations in preparing the finite element mesh to ensure the accuracy and convergence of the solution are presented. Next, the validity of the procedure of solution is verified for some intuitive, fundamental cases. Finally, the problems solved by previous researchers with identical or assumed data will be re-solved, along with discussions on the discrepancies existing among the three solutions. One feature with the finite/infinite element approach is that it is simple and straightforward, involving less assumptions and mathematical operations, whose reliability has been verified in solving various soil vibration problems. The fact that the present solutions are in close agreement to those by Luco and De Barros (1994) for all the cases studied indicates that the latter is the most reliable one among the existing theories.

scholarly journals 2.5D FINITE∕INFINITE ELEMENT APPROACH FOR SIMULATING TRAIN-INDUCED GROUND VIBRATIONS

2010 ◽  
Author(s):  
Y. B. Yang ◽  
H. H. Hung ◽  
J. C. Kao ◽  
Jane W. Z. Lu ◽  
Andrew Y. T. Leung ◽  
...  
Keyword(s):  
Ground Vibrations ◽  
Infinite Element ◽  
Element Approach

scholarly journals A COMPARISON OF TRANSIENT INFINITE ELEMENTS AND TRANSIENT KIRCHHOFF INTEGRAL METHODS FOR FAR FIELD ACOUSTIC ANALYSIS

2013 ◽  
Vol 21 (02) ◽  
pp. 1350006 ◽  
Author(s):  
TIMOTHY F. WALSH ◽  
ANDREA JONES ◽  
MANOJ BHARDWAJ ◽  
CLARK DOHRMANN ◽  
GARTH REESE ◽  
...  
Keyword(s):  
Acoustic Pressure ◽  
Acoustic Analysis ◽  
System Stability ◽  
Far Field ◽  
Element Analysis ◽  
Infinite Element ◽  
Infinite Elements ◽  
Integral Methods ◽  
Element Approach ◽  
Kirchhoff Integral

Finite element analysis of transient acoustic phenomena on unbounded exterior domains is very common in engineering analysis. In these problems there is a common need to compute the acoustic pressure at points outside of the acoustic mesh, since meshing to points of interest is impractical in many scenarios. In aeroacoustic calculations, for example, the acoustic pressure may be required at tens or hundreds of meters from the structure. In these cases, a method is needed for post-processing the acoustic results to compute the response at far-field points. In this paper, we compare two methods for computing far-field acoustic pressures, one derived directly from the infinite element solution, and the other from the transient version of the Kirchhoff integral. We show that the infinite element approach alleviates the large storage requirements that are typical of Kirchhoff integral and related procedures, and also does not suffer from loss of accuracy that is an inherent part of computing numerical derivatives in the Kirchhoff integral. In order to further speed up and streamline the process of computing the acoustic response at points outside of the mesh, we also address the nonlinear iterative procedure needed for locating parametric coordinates within the host infinite element of far-field points, the parallelization of the overall process, linear solver requirements, and system stability considerations.

The effect of a conductive half‐space on the transient electromagnetic response of a three‐dimensional body

Geophysics ◽  
1985 ◽  
Vol 50 (7) ◽  
pp. 1144-1162 ◽  
Author(s):  
William A. SanFilipo ◽  
Perry A. Eaton ◽  
Gerald W. Hohmann
Keyword(s):  
Half Space ◽  
Free Space ◽  
Eddy Currents ◽  
Three Dimensional ◽  
Vertical Component ◽  
The Body ◽  
Electromagnetic Response ◽  
Loop Current ◽  
Transient Electromagnetic ◽  
Space Response

The transient electromagnetic (TEM) response of a three‐dimensional (3-D) prism in a conductive half‐space is not always approximated well by three‐dimensional free‐space or two‐dimensional (2-D) conductive host models. The 3-D conductive host model is characterized by a complex interaction between inductive and current channeling effects. We numerically computed 3-D TEM responses using a time‐domain integral‐equation solution. Models consist of a vertical or horizontal prismatic conductor in conductive half‐space, energized by a rapid linear turn‐off of current in a rectangular loop. Current channeling, characterized by currents that flow through the body, is produced by charges which accumulate on the surface of the 3-D body and results in response profiles that can be much different in amplitude and shape than the corresponding response for the same body in free space, even after subtracting the half‐space response. Responses characterized by inductive (vortex) currents circulating within the body are similar to the response of the body in free space after subtracting the half‐space contribution. The difference between responses dominated by either channeled or vortex currents is subtle for vertical bodies but dramatic for horizontal bodies. Changing the conductivity of the host effects the relative importance of current channeling, the velocity and rate of decay of the primary (half‐space) electric field, and the build‐up of eddy currents in the body. As host conductivity increases, current channeling enhances the amplitude of the response of a vertical body and broadens the anomaly along the profile. For a horizontal body the shape of the anomaly is distorted from the free‐space anomaly by current channeling and is highly sensitive to the resistivity of the host. In the latter case, a 2-D response is similar to the 3-D response only if current channeling effects dominate over inductive effects. For models that are not greatly elongated, TEM responses are more sensitive to the conductivity of the body than galvanic (dc) responses, which saturate at a moderate resistivity contrast. Multicomponent data are preferable to vertical component data because in some cases the presence and location of the target are more easily resolved in the horizontal response and because the horizontal half‐space response decays more quickly than does the corresponding vertical response.

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