Boundary Element Approach (boundary + element_approach)

Distribution by Scientific Domains
Engineering80%

Selected Abstracts

In Situ SEM Observation and Analysis of Martensitic Transformation During Short Fatigue Crack Propagation in Metastable Austenitic Steel,

ADVANCED ENGINEERING MATERIALS, Issue 4 2010
Ulrich Krupp
Abstract High cycle fatigue (HCF) life of metastable austenitic steels is governed by the ability of the parent austenite phase to transform into ,, martensite via metastable , martensite. The mechanism of this strain-induced transformation is closely related to the grain size, the crystallographic orientation distribution, as well as to amplitude, and cyclic accumulation of plastic strain. Aim of the present study is to identify and to quantitatively describe the basic principles of strain-induced martensite formation by means of in situ cyclic deformation experiments in a scanning electron microscope (SEM) in combination with electron back-scattered diffraction (EBSD) and numerical modeling using a boundary element approach. It was shown that during HCF loading martensite formation is inhomogeneous and not directly linked with crack initiation. Only when the fatigue crack propagates by operating multiple slip systems, the cyclic plastic zone exhibits martensitic transformation. [source]

Seismic response of slopes subjected to incident SV wave by an improved boundary element approach

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 10 2007
Behrouz Gatmiri
Abstract In this paper, an improved boundary element approach for 2D elastodynamics in time-domain is presented. This approach consists in the truncation of time integrations, based on the rapid decrease of the fundamental solutions with time. It is shown that an important reduction of the computation time as well as the storage requirement can be achieved. Moreover, for half-plane problems, the size of boundary element (BE) meshes and the computation time can be significantly reduced. The proposed approach is used to study the seismic response of slopes subjected to incident SV waves. It is found that large amplifications take place on the upper surface close to the slope, while attenuations are produced on the lower surface. The results also show that surface motions become very complex when the incident wavelength is comparable with the size of the slope or when the slope is steep. Copyright © 2006 John Wiley & Sons, Ltd. [source]

A Lagrangian boundary element approach to transient three-dimensional free surface flow in thin cavities

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2001
Jie Zhang
Abstract The lubrication theory is extended for transient free-surface flow of a viscous fluid inside a three-dimensional thin cavity. The problem is closely related to the filling stage during the injection molding process. The pressure, which in this case is governed by the Laplace's equation, is determined using the boundary element method. A fully Lagrangian approach is implemented for the tracking of the evolving free surface. The domain of computation is the projection of the physical domain onto the (x,,y) plane. This approach is valid for simple and complex cavities as illustrated for the cases of a flat plate and a curved plate. It is found that the flow behavior is strongly influenced by the shape of the initial fluid domain, the shape of the cavity, and inlet flow pressure. Copyright © 2001 John Wiley & Sons, Ltd. [source]

A variational approach to boundary elements,two dimensional Helmholtz problems

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 6 2003
Y. Kagawa
Abstract The boundary element method is a discretized version of the boundary integral equation method. The variational formulation is presented for the boundary element approach to Helmholtz problems. The numerical calculation of the eigenvalues in association with hollow waveguides demonstrates that the variational approach provides the upper and lower bounds of the eigenvalues. The drawback of the discretized system equation must be solved by a trial and error approach, which is shown to be removed by the introduction of the dual reciprocity method. Copyright © 2003 John Wiley & Sons, Ltd. [source]