The specific energy expressed by the components of strain E U71= 20+01-2 e+(2++E)+,V=+y=+y Where e=8.,t8. Therefore, we have the partial differentiation of specific energy by components of stress 少=eU 0U7 aU Y-r? aT 二X 99 The specific energy expressed by the components of strain: ( ) ( ) ( )      + + + + + + + − = 2 2 2 2 2 2 2 1 2 1 2 1 1 2 x y z yz z x xy e E U          Where x y z e =  +  +  Therefore, we have the partial differentiation of specific energy by components of stress z z y y x x U U U       =   =   =   1 1 1 , , xy xy z x z x yz yz U U U       =   =   =   1 1 1 ,