F-广义力(generalized force) 包括力和力偶(include force and couple) B 6广义位移 (generalized displacement) 包括线位移和角位移 (include normal displacement &angular displacement) 10 10 F--广义力 （generalized force) 包括力和力偶(include force and couple) δ--广义位移 (generalized displacement) 包括线位移和角位移 (include normal displacement &angular displacement)  1  2  3 B ' C ' U Fδ 21 = F3 B CF2 A F1