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# Copyright (c) 2005 Johan Jansson (johanjan@math.chalmers.se)
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# Licensed under the GNU LGPL Version 2.1
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# Modified by Anders Logg 2006-2007
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# Modified by Garth N. Wells 2008
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# Last changed: 2008-09-12
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# The bilinear form for classical linear elasticity (Navier).
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# Compile this form with FFC: ffc -l dolfin Elasticity.form.
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element = VectorElement("Lagrange", "tetrahedron", 1)
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v = TestFunction(element)
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u = TrialFunction(element)
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mu = Constant("tetrahedron")
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lmbda = Constant("tetrahedron")
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return 0.5*(grad(v) + transp(grad(v)))
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return 2*mult(mu, epsilon(v)) + mult(lmbda, mult(trace(epsilon(v)), Identity(len(v))))
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a = dot(epsilon(v), sigma(u))*dx