Studies in Composites
Homework 3
1.- A unidirectional fiber reinforced lamina has the following reduced stiffness matrix (in psi)
| 30e6
1e6 0 |
Q = | 1e6
30e6 0 |
| 0
0
1e6 |
Calculate the A, B and D matrices for a two ply laminate of this material assuming that the bottom
lamina is a 0.2 in thick and oriented at 0o while the top layer is 0. 1in thick and is oriented 45 o.
2.- Consider a two ply laminate formed by stacking a 1 in thick steel plate (E = 29e6 psi, ν = 0.28) on top
of a 1 in thick Aluminum plate (E = 10e6 psi, ν = 0.33). Calculate the A, B and D matrices for this
laminate.
3.- Consider a three ply laminate built of the same material in Problem 1 but with the stacking sequence
[+45/0/+45]. Let the top and bottom lamina be 0.1 in thick each and the middle lamina 0.2 in thick.
Calculate the A, B and D matrices for this laminate.
4.- Consider 8-ply ply laminates built of the same material in Problem 1 with all lamina 0.4 in thick.
Calculate the A, B and D matrices for the following laminates:
a) All 8 lamina at +45 o
b) [+45/+45/-45/-45/-45/-45/+45/+45]
c) [+45/-45/+45/-45]S