Consider the matrix of elastic constants for a composite consisting of an elastically soft matrix reinforced by a 90? cross-ply of stiff ?bers. The general form of the matrix of elastic constants is
|
s11
|
s12
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s13
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0
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0
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0
|
|
s12
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s11
|
s13
|
0
|
0
|
0
|
|
s13
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s13
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s33
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0
|
0
|
0
|
|
0
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0
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0
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s44
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0
|
0
|
|
0
|
0
|
0
|
0
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s44
|
0
|
|
0
|
0
|
0
|
0
|
0
|
s66
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Young's modulus for the composite when loaded parallel to one of the sets of ?bers is 100 GPa, so s11 = 10 × 10-12 Pa-1. Of the following values, which is most likely for s12? for s66?
A. 10 × 10-10 Pa-1.
B. 30 × 10-12 Pa-1.
C. 10 × 10-12 Pa-1.
D. 3 × 10-12 Pa-1.
E. 100 × 10-12 Pa-1.
F. -10 × 10-10 Pa-1.
G. -30 × 10-12 Pa-1.
H. -10 × 10-12 Pa-1.
I. -3 × 10-12 Pa-1.
J. -100 × 10-12 Pa-1.