| Fiber metal laminates(FMLs) are engineered materials composed of thin structural sheet metal plies alternately bonded to plies of fiber-reinforced polymer and have received an increasing amount of attention in the aircraft industry due to their light weight, outstanding fatigue resistance, ease of manufacture and repair. FMLs as a new type of composite material,constituted by a variety of components, changing the type of each component, volume fraction, and so will the layout of the laminate structure impact the performance of laminates.FMLs have a strong designing in order to design a high performance laminates he factors affecting the performance of the laminate are required to explore.This work used the finite element method and experimental method to research the influence of the layout of fiber layers, the type and volume fraction of each component on the tensile properties flexural properties, as well as residual stress of FMLs. the basic conclusions are shown as follows:(1) Layout of fiber layers: Unidirectional fiber reinforced metal laminates test results showed that with the layout of fiber angle increase(between 0°to 45°) the elastic modulus,yield strength, tangent modulus and the average residual stress were decrease, however the maximum residual stress was increase. Finite element simulation results showed that in FMLs3/2 0.2-0.5 S-Un laminates series, the maximum elastic modulus of 68.25 Gpa, the maximum yield strength of 330.59 Mpa, the corresponding grades was FMLs 3/2 0.5 0/0 S-Un; the maximum tangent modulus of 16.57 GPa, the corresponding grades was FMLs 3/2 0.2 0/0S-Un. Laboratory prepared a series of unidirectional fiber reinforced metal laminates namely FMLs 3/2 0.3 S-Un, and tensile properties have the same variation with FEM, the maximum elastic modulus of 29.65 GPa, the maximum yield strength of 272.62 MPa, the maximum tangent modulus of 8.45 GPa, the maximum yield strength of 679.10 MPa, the corresponding grades was FMLs 3/2 0.3 0/0 S-Un. The bending performance test results showed that with the increase of the angle of the layout of fiber laminate flexural modulus and flexural strengthdecreased, the maximum bending deflection gradually increased, the maximum flexural modulus of 69.78 GPa, the maximum flexural strength of 1056.11 MPa, the corresponding grades was FMLs 3/2 0.3 0/0 S-Un; the maximum bending deflection of 31.06 mm, the corresponding grades was FMLs 3/2 0.3 45/-45 S-Un. In order to simplify the process for preparing laminates, the twill fiber cloth were used in FMLs, the results showed that 0° and90° direction performance closely. In 0° direction, the elastic modulus of 20.12 GPa, yield strength of 245.58 MPa, tensile strength of 540 Mpa were maximum, in 45° direction laminates’ s elastic modulus of 29.00 GPa and intensity of 316.30 MPa were poor, however its elongation of 10.90% and the maximum bending deflection of 33.99 mm were both maximum.(2) The volume fraction of the components: the results showed that with the metal volume fraction increase(decrease in volume fraction fiber layer), the elastic modulus, yield strength and the average residual stress gradually increased, tangent modulus and the maximum residual stress decreased. Laboratory prepared FMLs 3/2 0/90 0.3-0.4 S-Un unidirectional laminates, tensile results showed that the maximum elastic modulus of18.42 GPa, the corresponding grades was FMLs 3/2 0/90 0.4/0.4/0.4 S-Un; the maximum yield strength of 470.22 MPa, the corresponding grades was FMLs 3/2 0/90 0.4/0.3/0.4 S-Un;the maximum tensile strength of 470.22 MPa, the maximum tangent modulus of 4.63 GPa,the corresponding grades was FMLs 3/2 0/90 0.3/0.3/0.3 S-Un. While FMLs 3/2 0.3-0.4 S-Tw has the same law. The maximum elastic modulus of 22.13 GPa, the maximum yield strength of 298.56 MPa, the corresponding grades was FMLs 3/2 0.4/0.4/0.4 S-Tw; the maximum tensile strength of 540.90 MPa, the maximum tangent modulus of 5.96 GPa, the corresponding grades was FMLs 3/2 0.3/0.3/0.3 S-Tw. Experimental results showed that the bending properties of laminates under external addition content of each component laminate adhesive strength was also affected, the tensile strength of the laminate bond strength would affect the laminate, flexural strength, flexural modulus and maximum bending deflection.(3) Species composition: Adding titanium and carbon fiber layers could greatly improve the mechanical properties, the elastic modulus, yield strength and the average residual stress of FMLs 3/2 Al/Ti/Al 0.2-X-0.2 gradually increased with the volume fraction of titaniumincreasing, the tangent modulus was just the opposite and the maximum residual stress decreased and then increased, and its position shifted from the middle of the titanium layer to both sides of aluminum layer. FEM showed that the maximum elastic modulus of 83.39 GPa,the maximum yield strength of 290.29 MPa, the corresponding grades was FMLs 3/2 Al/Ti/Al0.2/0.5/0.2 S-Un; the maximum tangent modulus of 10.50 GPa, the corresponding grades was FMLs 3/2 Al-Ti-Al 0.2/0.2/0.2 S-Un. Experimental prepared FMLs 3/2 0.3 E-Tw,FMLs 3/20.3 S-Tw,FMLs 3/2 0.3 B1-Tw,FMLs 3/2 0.3 C-Tw series laminates, the test results showed that the maximum elastic modulus of 37.80 GPa, the maximum tangent modulus of 13.32 GPa,the maximum tensile strength of 556.56 MPa, the corresponding grades was FMLs 3/2 0.3C-Tw. The maximum flexural modulus of 51.42 GPa, the corresponding grades was FMLs 3/20.3 E-Tw; the maximum flexural strength of 991.51 MPa, the corresponding grades was FMLs3/2 0.3 B1-Tw, the maximum elongation of 6.68%, the maximum bending deflection of17.15 mm, the corresponding grades was FMLs 3/2 0.3 S-Tw.(4) Mixed multilayered Plate: Carbon fiber reinforced metal laminates have excellent mechanical properties, but it is expensive and the elongation is poor, laboratory using a variety of fiber cloth mixed-layer laminate of different types of fiber woven fabric mixed layer, mixing different types of fiber cloth layers, different the areal density fiber cloth mixed layer, etc. The results showed that the same type of mixing layers of woven panels and surface density close to the cloth layers of mixed plate had high bonding strength between layers and excellent performance. Wherein the carbon fiber and glass fiber twill denim mixed layer plate had high bonding strength, excellent mechanical properties, carbon fiber metal laminates relatively improved elongation and improved loaded easy to layer defects. The maximum elastic modulus of 28.63 GPa, the maximum tangent modulus of 12.55 GPa, the corresponding grades was S0/C/S90-3/2-0.3; the maximum tensile strength of 492.27 MP, the corresponding grades was S/C/S-3/2-0.3; the maximum elongation of 4.54%, the corresponding grades was B1/C/B1-3/2-0.3; the maximum flexural modulus of 60.89 GPa, the corresponding grades was B1/C/B1-3/2-0.3; the maximum bending deflection of 9.37 mm, the corresponding grades was E/C/E-3/2-0.3.Based on the above research results and laws can provide reference for the future designof composite laminates, according to the actual needs of production performance of layer board to select suitable material preparation of the corresponding fiber metal layer, can save production time and reduce the production cost. |
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