Deformation measurements were made on a flat rock surface using 0.5000 m-long gauge lengths. The following observations were recorded:
0.5002 m along the datum line, 0.4999 m and 0.5001 m along lines 45° and 90° from the datum line, respectively. Determine the following.
a) Principal strains
b) Principal stresses
c) Principal angles Theta_1 and Theta_2
Take E = 60 GPa and v = 0.2.