au Jiideii I. not necessarily linear elastic Ciiklekde 11) Complementary strain energy and complementary strain energy density CA Figure 4: Complementary strain energy density 5˙ ˙ � � � � � � ∂U� �ij � �� � ∂�ij = σij �ij ???? ∂U� σij = ∂�ij � �ij 0 U = σijd�ij , not necessarily linear elastic Linear case: U = �ij 0 Cijkl�kld�ij = 1 Cijkl�kl�ij = 2 1 σij �ij (11) 2 Complementary strain energy and complementary strain energy density Figure 4: Complementary strain energy density V Uc = UcdV (12) � σij 0 Uc = �ijdσij (13) 5