单项选择题
如图所示单元体,分别按第三强度理论及第四强度理论求得的应力为()。
A.σr3=30MPa,σr4=128MPa B.σr3=110MPa,σr4=128MPa C.σr3=140MPa,σr4=128MPa D.σr3=140MPa,σr4=108MPa
A.cosy+2yex+2xln2,xsiny-ex B.cosy-2yex-2xln2,xsiny+2ex C.cosy-2yex+2xln2,-xsiny-2ex D.siny-2yex+2xln2,cosy-2ex
A.A B.B C.C D.D