单项选择题
如图所示应力状态,斜边为自由表面(应力为零),则该点的三个主应力为:()。
A.80MPa,0,-20MPaB.20MPa,0,-80MPaC.0,-20MPa,-80MPaD.0,0,-80MPa
A.20MPaB.40MPaC.60MPaD.80MPa
A.0,-26.6MPa,-83.4MPaB.26.6MPa,0,-83.4MPaC.83.4MPa,0,-26.6MPaD.83.4MPa,-26.6MPa,0