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(a) Determine the strains using Young's modulus of 100 GPa and Poisson's ratio of 0.25.

(b) Compute the strain energy density using these stresses and strains.

(c) Calculate the principal stresses.

(d) Calculate the principal strains from the strains calculated in (a).

(e) Show that the principal stresses and principal strains satisfy the constitutive relations.

(f) Calculate the strain energy density using the principal stresses and strains.