如图所示单元体中,ab斜面上的正应力σ(来学网)应为:
  • A.
    (来学网)(50-20)/2+[(50+20)/2]cos(-60°)-30sin(-60°)
  • B.
    (来学网)(50+20)/2+[(50-20)/2]sin(60°)-30cos(60°)
  • C.
    (来学网)(50+20)/2+[(50-20)/2]cos(-60°)+30sin(-60°)
  • D.
    (来学网)(50-20)/2+[(50+20)/2]cos(-60°)+30sin(-60°)
材料力学