PI Consider situations in which 0 11 22-D011 (a1+02)≠0!! ∈ 0 (29) E (30) ∈ 2=E 002(1+) 5Plane stress Consider situations in which: σi3 = 0 (25) x1 x2 x3 Then: 1 � � �11 = σ11 − νσ22 (26) E 1 � � �22 = σ22 − νσ11 (27) E −ν � � �33 = σ11 + σ22 �= 0 !!! (28) E �23 = �13 = 0 (29) σ12 (1 + ν)σ12 �12 = = (30) 2G E In matrix form:      �11 1 1 −ν 0 σ11  �22  = −ν 1 0 σ22 (31) E 2�12 0 0 2(1 + ν) σ12 5