The problems for Section 2.9 involve the determination of principal strains and maximum sh...

The problems for Section 2.9 involve the determination of principal strains and maximum shear strain from measurements by strain rosettes.

Let the arm a of a delta rosette (Figure 2.20a) be directed along the positive x axis of axes (x, y). From measurements, ϵa = 2450 μ, ϵb = 1360 μ, and ϵc = −1310 μ. Determine the two principal surface strains, the direction of the principal axes, and the associated maximum shear strain ϵxy.

FIGURE 2.20 Rosette strain gages, Delta rosette, (a) Delta rosette.