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1. 2. Stephen Tsai. 3. A lamina is a single layer of matrix reinforced with fibers (tows). Lamina 1X. 12 Ply Layup10X. A laminate is a combination of lamina of the same or different materials and/or orientation. 4.
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A lamina is a single layer of matrix reinforced with fibers (tows). Lamina 1X 12 Ply Layup10X A laminate is a combination of lamina of the same or different materials and/or orientation. 4
Fiber patterns and/or plies orientation(s) can be selected to suit the direction of loading. directional fibers for directional loading shear directional truss transverse 5
When loaded in the direction of the fibers, composites have approximately three times the specific strength and stiffness of metals. Metals Composites Metals Composites Metals Composites Composites Metals Composites Metals Composites Metals 6
Composites are lighter than metals - but extra plies may be required to enhance transverse and/or shear strength. 7
Composites have a higher static strength than metals. 0o/+45o/90o Tensile Strength PURE UNI SpecificTensile Strength 8
Notched fatigue strength of composites is higher than for metals. notched KT=3.0 open hole (quasi-isotropic) (isotropic) 9
Composites are less notch sensitive in fatigue than metals. un-notched notched KT=1.0 open hole KT=3.0 Static Static Static Net Area Tensile Strength - ksi Static Fatigue Fatigue Fatigue Fatigue Aluminum Gr/Ep Gr/Ep Aluminum 10
Composite strength is more sensitive to impact than for metals. Metals - No Effect Compression Strength (strain) After Impact (in./in.) Hail Small Tools 11
Composites and metals have comparable fracture strength. All +45o Quasi-Isotropic 12
Composite (matrix) strength is degraded by elevated temperature and/or moisture content. 400 200 0 300 100 13
The “Achilles Heel” of composites is the matrix. Transverse Strength - ksi 14
Graphite Fiber Composites are poor conductors of heat. 15
Composites expand less than metals - tool design can be critical. Graphite Epoxy Typical Range 16
Poisson’s ratio is highly dependent on lamina form and laminate buildup. 17