eas4240_exam2_2009
TRANSCRIPT
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EAS 4240 Aerospace Structural Composites Class ID: _______________
Spring 2009 Exam 2
Problem 1.1
Some of the assumptions made in deriving the classical lamination theory are:
Assumption Circle onea The plies used in fabricating the composite laminate should be as
thin as 0.005 in (0.125 mm)True False
b Thickness of any layer should be very small compared to the
laminate thickness (hk
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EAS 4240 Aerospace Structural Composites Class ID: _______________
Spring 2009 Exam 2
Problem 2: The through-the thickness distribution of the stress component xx in a two-layer laminate is shown below.
Each layer has a thickness of 2 mm. Determine the force resultantNxand moment resultantMx.
Layer 2
Layer 1
+300 MPa
+100 MPa
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EAS 4240 Aerospace Structural Composites Class ID: _______________
Spring 2009 Exam 2
Problem 3: A graphite/epoxy shaft in a pump is
subjected to a state of stress given by
0, 50, 000 MPax y xy T = = = where T
is the torque in N-m. The fiber orientation
is at 45o with respect to thex-axis.(a) Determine the maximum torque that can
be applied according to Tsai-Hill
Failure theory.
(b) If the pump is reversed, then the torque
is considered as negative and the
stresses will be reversed. What is themaximum torque that can be applied in
the reverse direction?
The strength properties of the composite in
MPa units are:
1 1 2
2 12
1500, 1200, 50
200, 100
T C T
C F
= = =
= =
x
y45o
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EAS 4240 Aerospace Structural Composites Class ID: _______________
Spring 2009 Exam 2
Problem 4: A composite lamina is underuniaxial tension as shown in the figure below.
Determine the maximum x that can be applied
before failure according to:(a) Maximum stress theory;
(b) Maximum strain theory.
Elastic constants in GPa units are:
1 2 12
12 21
200, 20, 10
0.25, 0.025
E E G
= = =
= =
Strength properties in MPa units are:
1 1 2
2 12
1500, 1200, 50
200, 100
T C T
C F
= = =
= =