材料力学中 如何证明个相同性材料的三个弹性常数之间的关系:G=E/2(1...答:0.5*gammant=epsilonnt=epsilonxx * cos(n,x)*cos(t,x)+epsilonxy * cos(n,y)*cos(t,y)=sigmax/E*(1+Nu)* cos(n,x)*cos(t,x)G=taunt/gammant=[sigmaxx * cos(n,x)* cos(t,x)]/[sigmax/E*(1+Nu)* cos(n,x)*cos(t,x)]=E/2(1+NU)即:G=E/2(1+NU)...