Problem on unidirectional carbon-epoxy prepreg

Question

Solve the following problem:

Use the material properties described in Problem 1 and Example  to verify that the experimental values of strain to failure (listed below) are higher than those computed assuming linear elastic behavior (Equ.). Comment your findings

Problem:

The following data has been obtained experimentally for a composite based on an unidirectional carbon-epoxy prepreg (MR50 carbon fiber at 63% by volume in LTM25 epoxy). Determine if the restrictions on elastic constants are satisfied.

E₁ = 156.403 Gpa, E₂ = 7.786 GPa

v₁₂ = 0.352,  v₂₁ = 0.016

G₁₂ = 3.762 GPa

Equ. :

E_1t = F_1t/E₁    E_1c = F_1c/E₁

E_2t = F_2t/E₂    E_2c = F_2c/E₂

γ_4u = F₄/G₂₃    γ_5u = F₅/G₁₃     γ_6u = F₆/G₁₂