This section contains the engineering properties of aluminum alloy sheet laminates. These products consist of thin high-strength aluminum alloy sheets alternating with fiber layers impregnated with adhesive. These sheet laminates provide a very efficient structure for certain applications and exhibit excellent fatigue resistance.
Tensile and compressive properties for the aluminum alloy sheet laminates were determined using test specimens similar to those used for testing conventional aluminum alloy sheet with one exception. The Iosipescu shear specimen was the most appropriate configuration for the determination of shear strength. Shear yield strength and shear ultimate strength were determined using the Iosipescu test procedure. Shear yield strength was determined at 0.2% offset from load-deformation curves. Bearing tests were conducted according to ASTM E 238, which is applicable to conventional aluminum alloy products. Bearing specimens exhibited several different types of failure and bearing strength was influenced by failure mode. Consequently, a more suitable bearing test procedure for aramid fiber reinforced aluminum alloy sheet laminates is currently being developed. However, the design values for bearing strength determined according to ASTM E 238 are conservative and are considered suitable for design. These sheet laminates exhibit low elongation as measured by the tensile test. Consequently, a more realistic measure of ductility is total strain at failure, εt, defined as the measure of strain determined from the tensile load-deformation curve at specimen failure. This measurement includes both elastic and plastic strains. The minimum total strain at failure value from the material specification will be presented in the room temperature design allowable table. These sheet laminates are generally anisotropic. Therefore, design values for each grain orientation of the aluminum alloy sheet will be presented for all mechanical properties, except Fsu and Fsy. The longitudinal direction is parallel to the rolling direction of the aluminum alloy sheet or length of sheet laminate, while the long transverse direction is 90° to the longitudinal direction or parallel to the width of the sheet laminate. The design values for Fcy, Fsy, Fsu, Fbry, and Fbru were derived conventionally in accordance with the guidelines.
This product consists of thin 2024-T3 sheets alternating with aramid fiber layers embedded in a special resin. Nominal thickness of aluminum sheet is 0.012 inch with a prepreg nominal thickness of 0.0085 inch. The primary advantage of this product is the significant improvement in fatigue and fatigue crack growth properties compared to conventional aluminum alloy structures. The product also has good damping capacity and resistance to impact. Compared to 7475-T761 aramid fiber-reinforced sheet laminate, this product has better formability and damage tolerance characteristics.
Manufacturing Considerations — This product can be fabricated by conventional metal practices for machining, sawing, drilling, joining with fasteners and can be inspected by conventional procedures.
Environmental Considerations — This product has good corrosion resistance. The maximum service temperature is 200°F.
Specification and Properties — A material specification is presented in Table 7.5.1.0(a). Room-temperature mechanical properties are presented in Table 7.5.1.0(b).
| Specification | Form |
|---|---|
| AMS 4254 | Sheet laminate |
| Specification | AMS 4254 | |||
|---|---|---|---|---|
| Form | Aramid fiber reinforced sheet laminate | |||
| Laminate lay-up | 2/1 | 3/2 | 4/3 | 5/4 |
| Nominal thickness, in. | 0.032 | 0.053 | 0.074 | 0.094 |
| Basis | S | S | S | S |
| Mechanical Properties: | ||||
| Ftu, ksi: | ||||
| L | 90 | 96 | 101 | 101 |
| LT | 48 | 44 | 43 | 42 |
| Fty, ksi: | ||||
| L | 48 | 49 | 49 | 49 |
| LT | 33 | 30 | 30 | 30 |
| Fcy, ksi: | ||||
| L | 35 | 35 | 34 | 33 |
| LT | 33 | 30 | 30 | 30 |
| Fsua, ksi | b | b | b | b |
| Fsya, ksi | 16 | 15 | 14 | 14 |
| Fbruc, ksi: | ||||
| L (e/D = 1.5) | 78 | 73 | 73 | 68 |
| LT (e/D = 1.5) | 89 | 84 | 80 | 75 |
| L (e/D = 2.0) | 93 | 86 | 83 | 77 |
| LT (e/D = 2.0) | 95 | 89 | 81 | 76 |
| Fbryc, ksi: | ||||
| L (e/D = 1.5) | 53 | 52 | 51 | 50 |
| LT (e/D = 1.5) | 56 | 52 | 52 | 52 |
| L (e/D = 2.0) | 63 | 63 | 61 | 59 |
| LT (e/D = 2.0) | 66 | 61 | 61 | 60 |
| εtd, percent: | ||||
| L | 2 | 2 | 2 | 2 |
| LT | 12 | 12 | 12 | 14 |
| E, 103 ksi: | ||||
| L | 9.9 | 9.9 | 9.7 | 9.6 |
| LT | 8.1 | 7.5 | 7.1 | 7.0 |
| Ec, 103 ksi: | ||||
| L | 9.5 | 9.4 | 9.3 | 9.1 |
| LT | 8.0 | 7.5 | 7.2 | 7.0 |
| G, 103 ksi: | ||||
| L | 2.7 | 2.5 | 2.4 | 2.2 |
| LT | 2.6 | 2.4 | 2.4 | 2.2 |
| μ: | ||||
| L | 0.33 | 0.34 | 0.34 | 0.32 |
| LT | 0.29 | 0.27 | 0.26 | 0.25 |
| Physical Properties: | ||||
| ω, lb/in.3 | 0.086 | 0.084 | 0.082 | 0.081 |
| C, K, and α | ··· | ··· | ··· | ··· |
| a Shear values determined from data obtained using Iosipescu shear specimens. | ||||
| b Shear ultimate strengths not determinable due to excessive deflection of specimen. | ||||
| c Bearing values are “dry pin” values per Section 1.4.7.1 determined in accordance with ASTM E238. | ||||
| d Total (elastic plus plastic) strain at failure determined from stress-strain curve. | ||||
Typical tensile and compressive stress-strain and tangent-modulus curves are shown in Figures 7.5.1.1.6(a) through (l).
Figure 7.5.1.1.6(a). Typical tensile stress-strain curves for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.032 in.; layup: 2/1; Ramberg-Osgood n (LT - tension) = 12.
Figure 7.5.1.1.6(b). Typical tensile stress-strain curves for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.053 in.; layup: 3/2; Ramberg-Osgood n (LT - tension) = 9.9.
Figure 7.5.1.1.6(c). Typical tensile stress-strain curves for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.074 in.; layup: 4/3; Ramberg-Osgood n (LT - tension) = 11.
Figure 7.5.1.1.6(d). Typical tensile stress-strain curves for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.094 in.; layup: 5/4; Ramberg-Osgood n (LT - tension) = 12.
Figure 7.5.1.1.6(e). Typical compressive stress-strain and compressive tangent-modulus curves for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.032 in.; layup: 2/1; Ramberg-Osgood n (L - comp.) = 13, n (LT - comp.) = 12.
Figure 7.5.1.1.6(f). Typical compressive stress-strain and compressive tangent-modulus curves for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.053 in.; layup: 3/2; Ramberg-Osgood n (L - comp.) = 13, n (LT - comp.) = 13.
Figure 7.5.1.1.6(g). Typical compressive stress-strain and compressive tangent-modulus curves for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.074 in.; layup: 4/3; Ramberg-Osgood n (L - comp.) = 12, n (LT - comp.) = 12.
Figure 7.5.1.1.6(h). Typical compressive stress-strain and compressive tangent-modulus curves for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.094 in.; layup: 5/4; Ramberg-Osgood n (L - comp.) = 12, n (LT - comp.) = 12.
Figure 7.5.1.1.6(i). Typical tensile stress-strain curves (full range) for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.032 in.; layup: 2/1.
Figure 7.5.1.1.6(j). Typical tensile stress-strain curves (full range) for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.053 in.; layup: 3/2.
Figure 7.5.1.1.6(k). Typical tensile stress-strain curves (full range) for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.074 in.; layup: 4/3.
Figure 7.5.1.1.6(l). Typical tensile stress-strain curves (full range) for 2024-T3 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.094 in.; layup: 5/4.
This product consists of thin 7475-T761 sheets alternating with aramid fiber layers embedded in a special resin. Nominal thickness of aluminum sheet is 0.012 inch with a prepreg nominal thickness of 0.0085 inch. The primary advantage of this product is the significant improvement in fatigue and fatigue crack growth properties compared to conventional aluminum alloy structures. The product also has good damping capacity and resistance to impact.
Manufacturing Considerations — This product can be fabricated by conventional metal practices for machining, sawing, drilling, joining with fasteners and can be inspected by conventional procedures.
Environmental Considerations — This product has good corrosion resistance. The maximum service temperature is 200°F.
Specifications and Properties — A material specification is presented in Table 7.5.2.0(a). Room-temperature mechanical properties are presented in Table 7.5.2.0(b).
| Specification | Form |
|---|---|
| AMS 4302 | Sheet laminate |
| Specification | AMS 4302 | |||
|---|---|---|---|---|
| Form | Aramid fiber reinforced sheet laminate | |||
| Laminate lay-up | 2/1 | 3/2 | 4/3 | 5/4 |
| Nominal thickness, in. | 0.032 | 0.053 | 0.074 | 0.094 |
| Basis | S | S | S | S |
| Mechanical Properties: | ||||
| Ftu, ksi: | ||||
| L | 103 | 111 | 114 | 116 |
| LT | 56 | 51 | 50 | 48 |
| Fty, ksi: | ||||
| L | 76 | 82 | 82 | 84 |
| LT | 48 | 43 | 42 | 40 |
| Fcy, ksi: | ||||
| L | 46 | 46 | 44 | 44 |
| LT | 51 | 48 | 47 | 45 |
| Fsua, ksi | 35 | 33 | 33 | 32 |
| Fsya, ksi | 24 | 23 | 22 | 21 |
| Fbrub, ksi: | ||||
| L (e/D = 1.5) | 91 | 83 | 84 | 82 |
| LT (e/D = 1.5) | 96 | 85 | 86 | 80 |
| L (e/D = 2.0) | 104 | 87 | 88 | 84 |
| LT (e/D = 2.0) | 108 | 88 | 86 | 80 |
| Fbryb, ksi: | ||||
| L (e/D = 1.5) | 73 | 70 | 66 | 69 |
| LT (e/D = 1.5) | 76 | 69 | 69 | 67 |
| L (e/D = 2.0) | 83 | 81 | 77 | 79 |
| LT (e/D = 2.0) | 84 | 76 | 75 | 72 |
| etc, percent: | ||||
| L | 1.5 | 1.8 | 1.7 | 1.8 |
| LT | 6.1 | 6.4 | 6.3 | 6.6 |
| E, 103 ksi: | ||||
| L | 9.8 | 9.9 | 10.0 | 9.8 |
| LT | 7.7 | 7.1 | 6.7 | 6.7 |
| Ec, 103 ksi: | ||||
| L | 9.6 | 9.6 | 9.6 | 9.7 |
| LT | 7.8 | 7.3 | 7.0 | 6.9 |
| G, 103 ksi: | ||||
| L | 2.8 | 2.6 | 2.3 | 2.3 |
| LT | 2.6 | 2.4 | 2.3 | 2.3 |
| μ: | ||||
| L | 0.35 | 0.35 | 0.35 | 0.35 |
| LT | 0.25 | 0.25 | 0.25 | 0.25 |
| Physical Properties: | ||||
| ω, lb/in.3 | 0.085 | 0.083 | 0.082 | 0.081 |
| C, K, and α | ··· | ··· | ··· | ··· |
| a Shear values determined from data obtained using Iosipescu shear specimens. | ||||
| b Bearing values are “dry pin” values per Section 1.4.7.1 determined in accordance with ASTM E 238. | ||||
| c Total (elastic plus plastic) strain at failure determined from stress-strain curve. Values are minimum but not included in AMS 4302. | ||||
Tensile and compressive stress-strain and tangent modulus curves are shown in Figures 7.5.2.1.6(a) through (f). Full-range tensile stress-strain curves are presented in Figures 7.5.2.1.6(g) through (j).
Figure 7.5.2.1.6(a). Typical tensile stress-strain curves for 7475-T761 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.032 in.; layup: 2/1; Ramberg-Osgood n (L - tension) = 6.4, n (LT - tension) = 6.1.
Figure 7.5.2.1.6(b). Typical tensile stress-strain curves for 7475-T761 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.053 in.; layup: 3/2; Ramberg-Osgood n (L - tension) = 5.2, n (LT - tension) = 5.8.
Figure 7.5.2.1.6(c). Typical tensile stress-strain curves for 7475-T761 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.074 in., layup: 4/3, and thickness: 0.094 in., layup: 5/4; Ramberg-Osgood n (L - tension, 0.074 in.) = 5.5, n (LT - tension, 0.074 in.) = 7.5, n (L - tension, 0.094 in.) = 5.7, n (LT - tension, 0.094 in.) = 6.4.
Figure 7.5.2.1.6(d). Typical compressive stress-strain and compressive tangent-modulus curves for 7475-T761 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.032 in.; layup: 2/1; Ramberg-Osgood n (L - comp.) = 6.7, n (LT - comp.) = 13.
Figure 7.5.2.1.6(e). Typical compressive stress-strain and compressive tangent-modulus curves for 7475-T761 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.053 in.; layup: 3/2; Ramberg-Osgood n (L - comp.) = 6.2, n (LT - comp.) = 14.
Figure 7.5.2.1.6(f). Typical compressive stress-strain and compressive tangent-modulus curves for 7475-T761 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.074 in., layup: 4/3, and thickness: 0.094 in., layup: 5/4; Ramberg-Osgood n (L - comp., 0.074 in.) = 5.3, n (LT - comp., 0.074 in.) = 15, n (L - comp., 0.094 in.) = 5.8, n (LT - comp., 0.094 in.) = 14.
Figure 7.5.2.1.6(g). Typical tensile stress-strain curves (full range) for 7475-T761 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.032 in.; layup: 2/1.
Figure 7.5.2.1.6(h). Typical tensile stress-strain curves (full range) for 7475-T761 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.053 in.; layup: 3/2.
Figure 7.5.2.1.6(i). Typical tensile stress-strain curves (full range) for 7475-T761 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.074 in.; layup: 4/3.
Figure 7.5.2.1.6(j). Typical tensile stress-strain curves (full range) for 7475-T761 aluminum alloy, aramid fiber-reinforced, sheet laminate. Thickness: 0.094 in.; layup: 5/4.