格林函数: 将冲量定理法扩展到空间坐标 (x:)=。J=0)(x=500-)ddr 对两端固定的弦 G|x0=G|x=0 G -a'G=d(x-58(t-t 问题变成 =0 G.-aG=0 Gl=x0=0,G|x=(x-5) (x,t)= f(5,r)G(x,t2)d5. 0 l(G)=川v(,)f(F)l ou( v(F,) u(r av(r, olds格林函数： 将冲量定理法扩展到空间坐标 0 0 ( , ) ( , ) ( ) ( ) . t l f x t f x t d d           = = = − −   对两端固定的弦 2 ( ) ( ); G a G x t tt xx − = − −     0 0; G G x x l = = = = 0 0 0. G G t t t = = = = 2 0 G a G tt xx − = 0 0; G G x x l = = = = 0 0 0, ( ). G G x t t t = + = +   = = −   问题变成 0 0 ( , ) ( , ) ( , , ) . t l u x t f G x t d d        = = =   ] . ( , ) ( ) ( ) [ ( , ) ( ) ( , ) ( ) 0 0 0 0      −   − = − dS n v r r u r n u r v r r u r v r r f r dV T          