ENERGYMETHOD Example 1 A semicircle rod as shown in the figure is lie in horizontal plane A vertical force P act at its point A. Determine the displacement of point A in vertical direction Solution: In energy method work done by external forces is equal to the strain energy (dEtermine internal forces P 0c N R B T M T Bending moment: Mr()=PRsin Torque: MN(O)=PR(-cosP)Solution：In energy method（work done by external forces is equal to the strain energy） ①Determine internal forces MT () = PRsin M () = PR(1−cos) N A Bending moment: Torque: Example 1 A semicircle rod as shown in the figure is lie in horizontal plane. A vertical force P act at its point A. Determine the displacement of point A in vertical direction. P R O Q MN MT A A P N B  T O