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THE CHOICE BETWEEN TEXTILES AND TAPE LAMINATES
3-9
0
100
200
300
400
500
Unnotched
6.35 mm Hole
25.4 mm Hole
Tape Equivalent
Braid
Strength (MPa)
[0 /
±
45 ]
6k
15k
12% Axial
0
200
400
600
800
1000
1200
Unnotched
6.35 mm Hole
25.4 mm Hole
Tape Equivalent
Braid
Strength (MPa)
[0 /
±
45 ]
36k
15k
46% Axial
Figure 3-4. Comparison of unnotched and open hole tensile strengths for two triaxial
braids and equivalent tape laminates (from [3.7]).
Strength knockdowns for unnotched triaxial braids have also been estimated by
other means. Aligned axial tows in triaxial glass/urethane braided composites are found to
fail at about 70% of the strain to failure of unidirectional tape laminates, indicating a 30%
reduction in strength for the tows in the braided architecture [3.1]. This reduction is
consistent with Fig. 3-4.