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Overview. Periodically distributed. 2-D elasticity problem. Overview. Periodically distributed. 2-D elasticity problem. Something else…. Overview. Periodic material (everywhere). One-dimensional problem. Chronological order. Something else….
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Overview Periodically distributed 2-D elasticity problem
Overview Periodically distributed 2-D elasticity problem Something else…
Overview Periodic material (everywhere) One-dimensional problem Chronological order Something else… Periodic with period Periodic with period One-dimensional problem Leave for later (latest slides)… Periodically distributed 2-D elasticity problem Something else…
One-dimensional problem - classical example - Coefficients
One-dimensionalproblem Exact solution ( )
One-dimensional problem Exact solution FEM approx. (h = 0.2)
One-dimensionalproblem Exact solution FEM approx. (h= 0.05)
One-dimensionalproblem Conclusion: Step size h must be taken smaller than !!! Exact solution FEM approx. (h= 0.01)
Homogenisation Multiple scale method – ansatz:
Homogenisation Can be shown… average of (in a certain sense)
Homogenisation Complicated to solve… approximation for average of (in a certain sense) Easy to solve…
Homogenisation Homogenised solution : Captures essential behaviour of but loses oscillations…
Homogenisation Approximate by Recover the oscillations… + Boundary corrector Cell Problem
Homogenisation Approximate by (C= boundary Corrector) Error
Removesimplification... Simplifications: Periodic material (everywhere) One-dimensional problem 0 0.1 1
Domain decomposition 0 0.1 1 Iterative scheme (Schwarz) 0.15 0 0.1 0.1 1
Domain decomposition 0 0.1 1 Iterative scheme (Schwarz) 0.15 ? ? 0 0.1 0.1 1
Domain decomposition ? ? Initial guess 0 0.1 1
Domain decomposition Initial guess Periodic with period 0 0.1 1 Homogenised solution
Domain decomposition Approximation for k=1 Error k=1
Domain decomposition Approximation for k=2 Error k=1 k=2
Domain decomposition Approximation for k=3 Error k=1 k=2 k=3
Hybrid approach 0 0.1 1 Iterative scheme (Schwarz) 0.15 Aproximate with homogenisation 0 0.1 0.1 1
Hybrid approach – stopping criterion Error reduction in the Schwarz scheme
Hybrid approach – stopping criterion Error reduction in the Hybrid scheme Error reduction in the Schwarz scheme
Hybrid approach – stopping criterion Error reduction in the Hybrid scheme
Hybrid approach – stopping criterion Error reduction in the Hybrid scheme Error reduction…
Hybrid approach – stopping criterion Error reduction in the Hybrid scheme (after a few iterations…) smaller…
Hybrid approach – stopping criterion Error reduction in the Hybrid scheme (after a few iterations…) No error reduction…
Hybrid approach – stopping criterion Error reduction in the Hybrid scheme (after a few iterations…) Stopping criterion:
Hybrid approach Error
Linear elasticity Young’s modulus Poisson’s ratio Young’s modulus Poisson’s ratio
Linear elasticity Young’s modulus Poisson’s ratio
Homogenisation Linear elasticity Periodic Periodic Schwarz
Homogenisation Young’s modulus Poisson’s ratio 0.5 Young’s modulus Poisson’s ratio -0.5 0.5
Homogenisation Exactsolution (horizontal component) Homogenised corrected solution Homogenised solution
Homogenisation Error Exactsolution (horizontal component)
Hybrid approach Young’s modulus Poisson’s ratio Young’s modulus Poisson’s ratio Young’s modulus Poisson’s ratio
Hybrid approach Horizontal component of the exact solution Vertical component of the exact solution Initial guess: disregard inclusions…
Hybrid approach Horizontal component of the initial guess Vertical component of the initial guess
Hybrid approach Horizontal component of the corrected Vertical component of the correctedhomogenised function homogenised function
Extra: Homogenisation Solvability condition for :