多层圆筒壁 与多层平壁同理可得 11-I b2 442 aSmi nsm2 AS I2 Q 2nL(1-t4) In +-In O 或Q=4 I(t-t,D) ∑R >hni+L3、 多层圆筒壁 与多层平壁同理可得 或 3 4 2 3 3 1 2 2 1 1 4 3 3 3 2 2 2 1 1 1 1 4 1 2 3 1 4 ln 1 ln 1 ln 1 2 ( ) r r r r r r L t t S b S b S b t t R R R t t Q m m m        + + − = + + − = + + − =   = + + = + = + − = − = − = n i i i i n n i i mi n n i i n r r L t t S b t t R t t Q 1 1 1 1 1 1 1 1 1 1 ln 1 2 ( )    z, t O r 1 t 2 t 1 r 2 r L 3 t 4 t 3 r 4 r 1 2 3 Q