Thanks Chet...
realized my maths was terrible in those attachments... lol corrected my maths but that's just left me with a dead end. eughhhhh!
cant tell where you said i implied (σx+σy)=(σx'+σy') came from...?
i didnt have an equation for σy but...
if σx=-2τxy then τxy= σx/-2
if one of the principle stresses are 40Mpa, if we assume σx is 40Mpa then τxy= -20Mpa
so, knowing the angle and assuming τxy is 40Mpa, using mohrs circle and trig functions it just wasn't looking correct.
i then...
Homework Statement
DIAGRAM ATTACHED AT BOTTOM
Q. The following statements are true for an element in plane stress state. (this is 2D)
(1) one of the principle stresses is 40Mpa;
(2) σx= -2τxy; (the algebraic values)
(3) in x'oy' with θ=30°, the two normal stresses σx'=σy'
Determine...