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

Next, consider the transformation equation for gage b:

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

Gage b makes an angle of 60° with the x-axis; therefore:

{cosθ}_{b} = 0.5

and

{sinθ}_{b} = 0.866

The strain transformation equation for gage b reduces to:

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

Since this equation has two unknowns (ε_y and γ_xy), it cannot be solved yet.