MecMovies 4.0 : M13.5: Strain Measurement with Rosettes

scene 8 of 11

ε_a = +800 με

ε_b = -200 με

ε_c = +625 με

Consider the transformation equation for gage c:

ε_{c} = ε_{x} \cos^{2} θ_{c} + ε_{y} \sin^{2} θ_{c} + γ_{xy} {sinθ}_{c} {cosθ}_{c}

Gage c makes an angle of 120° with the x-axis; therefore:

{cosθ}_{c} = - 0.5

and

{sinθ}_{c} = 0.866

The strain transformation equation for gage c reduces to:

+ 625 με = (800 με) (0.25) + ε_{y} (0.75) - γ_{xy} (0.433)

We now have two equations in terms of the unknowns ε_y and γ_xy. These equations can be solved simultaneously.