§26虚功方程、结构势能表达式 外力虚功 oW=」J{poh+J,Fyo{al 微元体上外力在虚变形位移上作的虚功 dy dw =o dy S8 dx +o,dx. SE, dy+ dx z,dx.c小y+z·Bx r dx o dE dA+o,,dA+Irda δ{=}{o}l4 sW,=SOpa 虚功方程: SW=Sw. Sa dx ∫@pyb{L+ LFS(d ]dA=Jllk y +B Bdx  x  y dy y y y   +   yx  xy  dy y xy xy   +   dx x yx yx   +   dx x x x   +   dy X Y §2.6 虚功方程、结构势能 表达式 外力虚功           =  + A T L T We  d dL F  d dA     dA T =    dx dx  x dWi = x dy   x dx + y dx   y dy + 微元体上外力在虚变形位移上作的虚功 dy dy  y     xy = +   xydx dy + yxdy  dx = x   x dA+ y   y dA+ xy  xydA W    dA A T i   =      ddL F ddA    dA T A A T L T           + = 虚功方程: We = Wi