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Boundary Element Method. OUTLINE. Motivation. Laplace`s equation with boundary conditions Essential Dirichlet type Natural Neumann type. Method of Weighted Residuals. Green`s Theorem. Classification of Approximate Methods. Original statement Weak statement Inverse statement.
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Boundary Element Method OUTLINE
Motivation Laplace`s equation with boundary conditions EssentialDirichlet type NaturalNeumann type
Method of Weighted Residuals Green`s Theorem
Classification of Approximate Methods • Original statement • Weak statement • Inverse statement
Original statement Basis functions for u and w are different Basis functions for u and w are the same Finite differences Method of moments General weighted residual Original Galerkin Weak formulation General weak weighted residual formulations Finite element Galerkin techniques Inverse statement Boundary integral Trefftz method
BEM formulation whereu* is the fundamental solution Note:
Boundary integral equation Fundamental solution for Laplace`s equation
Discretization Nodes Element
Matrix form Note: matrixAis nonsymmetric
2D-Interpolation Functions • Linear element • Bilinear element • Quadratic element • Cubic element
Elastostatics Betti`s theorem Field equations Boundary conditions Lame`s equation
Fundamental solution Lame`s equation 2D-Kelvin`s solution displacement traction stress
Somiglian`s formulation On boundary For internal points displacement stress
Discretization FEM BEM
BEM elastoplasticity-initial strain problem Governing equations Equation used in iterative procedure where Note: vectors store elastic solution matrices are evaluated only once
Other problems 2D, 3D, axisymmetric Plate bending Diffusion • Linear • Nonlinear - Time discretization – time independent fundamental solution – time dependent fundamental solution Heat transfer Coupled heat and vapor transfer Consolidation