1 CST ELEMENT STIFFNESS MATRIX • Strain energy – Element Stiffness Matrix: – Different from the truss and beam elements, transformation matrix [T] is not required in the two-dimensional element because [k] is constructed in the global coordinates. • The strain energy of the entire solid is simply the sum of the element strain energies assembly (e) T (e) A (e) T T (e) 63 33 36 A (e) T (e) (e) 66 h U {} [ ]{}dA 2 h { } [] [] [] dA { } 2 1 { }[ ] { } 2 C q B C B q q k q (e) T [ ] hA[ ][ ][ ] k B C B NE NE (e) (e) T (e) (e) e1 e1 1 U U { }[ ]{ } 2 q k q T s s s 1 U { }[ ]{ } 2 Q K Q