Compute the middle-surface strains

Question

Solve the following problem:

Compute the stresses σ_x and σ₁ in the 45° and in the -45° laminae right next to the interface based on the strains computed in Problem 1 using (6.24). Discuss the results.

Problem 1: Compute the strains ?_x, ?_y, and γ_xy at the interface between the 45? and -45? laminae above the middle surface by using the results of case (b) of Problem 2 and (6.23).

Problem 2: Consider a [+45/ - 45]S laminate with the material properties of Problem 3. Compute the middle-surface strains ?⁰_x, ?⁰_y, γ⁰_xy, and the curvatures κ_x, κ_y, κ_xy for the following load cases

(a) N_x = 1000 N/m; all remaining components are equal to zero

(b) M_xy = 1 Nm/m; all remaining components are equal to zero

(c) Comment on the coupling effects observed.

Problem 3: Consider a [0/90]S laminate made out of Kevlar 49-epoxy (see Table ), each lamina 1.0 mm thick. Compute the stresses in material coordinates when N_x = 1 N/m.