A [0/+60/-60]s laminate with the ply properties listed in the table below is to be subjected to a

temperature change from its initial temperature of 75°F. This temperature change can be expressed

as a linear temperature change through the thickness of the laminate, with the temperature at the top

of the six-ply laminate set at 225°F and the temperature at the bottom of the six-ply laminate set to

-75°F.

Therefore, for the temperature distribution defined by the equation AT(2) = AT+T'z,

with ATh2=225°F - 75°F = 150°F and AT-2=-75°F-75°F=-150°F,

AT. =(AT1/2+AT-1/2)/2= [150+(-150)]/2=0°F and

T'=(AT12-AT-1/2)/h=(150-(-150))/6(0.0052) = 9,615.4°F/inch

we obtain the distribution expression

a) Determine the stresses in the lamina coordinate system at both the top and bottom in each of

the 0°, +60° and -60° plies.

b) Given the lamina strengths in the table below, determine if the laminate subjected to this

temperature change distribution could be expected to survive with no excessive lamina

stresses and therefore with no damage to the laminate.

c) Assuming the same initial stress-free temperature of 75°F and by subjecting this same

[0/+60/-60]s laminate separately to (i) a uniform temperature of 225°F and (ii) a uniform

temperature of -75°F, answer the question "Is the through thickness temperature gradient

more stressing on the laminate than either the uniform through thickness temperature of

225°F or the uniform through thickness temperature of -75°F?"

Property

E₁

E₂

G12

V12

α₁ (-200°F to 200°F)

α₂ (-200°F to 200°F)

01

0

AT(2) AT+T'z = 9,615.4°F/inch*z

TL

cu

OL

σχετι

Ply thickness

Lamina Value

25 x 10º psi

1.7 x 106 psi

1.3 x 10º psi

0.3

-0.3 x 10 in/in/°F

19.5 x 10 in/in/°F

110 x 10³ psi

4.0 x 10³ psi

9.0 x 10³ psi

110 x 10³ psi

20 x 10³ psi

0.0052 inch