1.单元位移 u(x, y)=a+a,x+a,y 2△ (a4+a0+a4)+(b4+b1+b4)x+(c+cl+C4 2△ 2△ Nu..tnu 其中N_1 (a,+bx+cy 2 同理v(x,y)=NV+N+Nkvk 整理后,得 (a, u, +a, u,+aruk) 2△ (b1+b,11+bk) 2△ 2△c4+c1+cklk) 其中a1=x1yk-xky (i→j>k->i) C k1.单元位移 a u a u a u b u b u b u x c u c u c u y u x y x y i i j j k k i i j j k k i i j j k k ( ) 2 1 ( ) 2 1 ( ) 2 1 ( , ) 1 2 3 + +  + + +  + + +  = = + + ( ) 2 1 ( ) 2 1 ( ) 2 1 3 2 1 i i j j k k i i j j k k i i j j k k c u c u c u b u b u b u a u a u a u + +  = + +  = + +  =    其中 整理后,得 i k j i j k i j k k j c x x b y y i j k i a x y x y = − = − → → → = − ( ) = Ni ui + N j u j + Nk uk 其中 ( ) ( , , ) 2 1 N a b x c y i j k i i + i + i  = 同理 i i j j k k v(x, y) = N v + N v + N v