Three Dimensional Hybrid Finite-Boundary Element Model for Eddy Current NDE

2005 ◽  
Author(s):  
S. Nath ◽  
W. Lord ◽  
T.J. Rudolphi
Keyword(s):  
Boundary Element ◽  
Eddy Current ◽  
Three Dimensional ◽  
Element Model ◽  
Finite Boundary ◽  
Eddy Current Nde

Modelling ground vibration from railways using wavenumber finite- and boundary-element methods

2005 ◽  
Vol 461 (2059) ◽  
pp. 2043-2070 ◽  
Author(s):  
X Sheng ◽  
C.J.C Jones ◽  
D.J Thompson
Keyword(s):  
Boundary Element ◽  
Singular Integrals ◽  
Moving Load ◽  
Three Dimensional ◽  
Ground Surface ◽  
Ground Vibration ◽  
Element Model ◽  
Boundary Element Methods ◽  
Element Discretization ◽  
Environmental Vibration

A mathematical model is presented for ground vibration induced by trains, which uses wavenumber finite- and boundary-element methods. The track, tunnel and ground are assumed homogeneous and infinitely long in the track direction ( x -direction). The models are formulated in terms of the wavenumber in the x -direction and discretization in the yz -plane. The effect of load motion in the x -direction is included. Compared with a conventional, three-dimensional finite- or boundary-element model, this is computationally faster and requires far less memory, even though calculations must be performed for a series of discrete wavenumbers. Thus it becomes practicable to carry out investigative study of train-induced ground vibration. The boundary-element implementation uses a variable transformation to solve the well-known problem of strongly singular integrals in the formulation. A ‘boundary truncation element’ greatly improves accuracy where the infinite surface of the ground is truncated in the boundary-element discretization. Predictions of vibration response on the ground surface due to a unit force applied at the track are performed for two railway tunnels. The results show a substantial difference in the environmental vibration that could be expected from the alternative designs. The effect of a moving load is demonstrated in a surface vibration example in which vibration propagates from an embankment into layered ground.

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