XZ 面 Z FBVF M(F)=0 X FA FBH F=0 T d282.5 M 2 3×1284.8N·mm =181481N·mmxz面: x z MT FAH FBH FBV FAV FT Fr ( ) 0 M F A = 0 2 T t d M F − = 282.5 1284.8 2 2 T t d M F N mm = =   =  181481N mm