Strain Components for Problem 1  
scene 4 of 11
Here is Canvas object wihch demonstrate the problem.

Strain measurement with rosettes

Begin with the transformation equation for gage a to find εx:

ε a   =   ε x cos 2 θ a   +   ε y sin 2 θ a   +   γ xy sinθ a cosθ a

Gage a is aligned with the x-axis, making θa = 0°. Therefore:

cosθa = 1 and sinθa = 0

The strain transformation equation reduces to:

εa = εx     ∴εx = -215με