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THE CHOICE BETWEEN TEXTILES AND TAPE LAMINATES
3-5
Table 3.1 Braid and Equivalent Tape Laminate Specifications for Fig. 3-1
Braid Braid Designation Equivalent Laminate
1
[0
36K
,±45
15K
] 46% Axial [(45/0/-45/0)
2
/45/0/-45]
S
2
[0
30K
,±70
6K
] 46% Axial [(70/0/-70/0)
2
/70/0/-70]
S
3
[0
75K
,±70
15K
] 46% Axial [(70/0/-70/0)
2
/70/0/-70]
S
4
[0
6K
,±45
15K
] 12% Axial [(±45)
2
/0/(±45)
3
/0/(±45)
3
/0/(±45)
2
]
T
0
10
20
30
40
50
60
70
80
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
Tape Laminate
Braid
Modulus (GPa)
Braid No.
Long.
Tension
Transverse
Tension
Long.
Compression
Transverse
Compression
Figure 3-1. The Moduli of 2D Braids and Equivalent Tape Laminates
3.4 In-Plane Strength
Unnotched tensile and compressive strength are usually lower in quasi-laminar
textiles than in equivalent tape laminates. Part of the reason for this is the tow architecture
in textiles, which imparts waviness to tows and generates off-axis local stresses; and part is
due to damage sustained by fibers in the rigors of textile manufacture.
The role of waviness in the compressive failure of polymer matrix composites is
well established. Compressive failure when loads are aligned with one set of tows occurs
via kink band formation (see Sect. 4). The critical load for kinking falls in inverse