Search

Although the carbon fiber reinforced composite material has high specific strength and stiffness, design-versatility, anti-corrosion and other excellent features, but the impact resistance of composite structures is poor. Therefore, the composite laminates low-speed damage analysis has important significance. Based on a three-dimensional analysis theory of cumulative damage, using the commercial finite element analysis software ABAQUS to establish laminates subjected to low velocity impact finite element model. according to the numerical results and the consistency of the test results, shows that the used model of the article is reasonable and accurate, and the numerical simulation method is verified to be feasible. Finally, through the numerical simulation of process of laminated plates low speed impact damage, the damage characteristics and damage mechanism of the laminates at different times are analyzed, and the forming reasons and expanding rules of the main damage forms of fiber damage and matrix damage are revealed.

This study explores the effect of different graphene contents on the mechanical behaviour, tensile and flexural properties, and the electrochemical performance of cross-layered glass-reinforced aluminium (GLARE) laminates. Results show that the mechanical properties of GLARE with different graphene contents are similar but not identical. The mass fraction of graphene (0 wt.%–1.0 wt.%) is calculated from the total mass of adhesive. As the graphene content increases (0 wt.%–1.0 wt.%), flexural strength peaks in the presence of 0.5 wt.% graphene, but tensile strength continues to increase. When the graphene mass ratio is 1.0 wt.%, the maximum tensile strength is 245.45 MPa. When the graphene mass ratio is 0.5 wt.%, interlaminar shear strength and flexural strength are 19.06 and 260.22 MPa, respectively, which correspond to different span–thickness ratios of 8/1 and 32/1. This graphene mass ratio indicates the best three-point flexural performance of graphene-reinforced GLARE. This study further explains the enhancement mechanism through fracture surface observation. Graphene with a mass ratio of 0.5 wt.% maximises the flexural strength whilst maintaining a strong GLARE electrochemical performance. At scanning speeds of 40, 80, and 100 mV/s, the specific capacitance values are 1.76, 2.47, and 2.88 F/g, respectively. According to quantum tunnelling theory, graphene can form a conductive network when it is dispersed in a resin matrix. This theory reveals the reason why 0.5 wt.% graphene platelet-modified GLARE has good electrochemical properties. [ABSTRACT FROM AUTHOR]

Interlaminar fracture failure is the dominant factor restricting the development and application of fiber metal laminates (FMLs). In the current work, the primary purpose is an assessment of the effect of the hybrid combination of graphenes (GNPs) and multiwalled carbon nanotubes (MWCNTs) on the interlaminar performance of FMLs. The effect of different ratios (GNPs: MWCNTs = 1:1, 3:7, 7:3) of hybrid carbon nano‐fillers on the mode I and mode II interlaminar fracture strain energy release rates (GΙC and GΙΙC) of FMLs containing GNPs and MWCNTs hybrid modified epoxy matrices are studied via double cantilever beam and end notched flexure tests. Results indicate that different ratios of GNPs and MWCNTs have different effects on the mode I and mode II interlaminar fracture performance of the samples. Compared with that of the baseline material, the GΙC of hybrid modified FMLs with GNPs: MWCNTs = 7:3 is increased by 344%. By contrast, the GΙΙC of hybrid modified FMLs with GNPs: MWCNTs = 3:7 is increased by 82.9% relative to the baseline value. Scanning electron microscopy of the fracture surface reveals the synergistic toughening mechanism of the two hybrids. [ABSTRACT FROM AUTHOR]

Outstanding mechanical properties and high thermal conductivity epoxy composites are being developed and are becoming urgent in the electronic and aerospace industries. Boron nitride nanosheet (BN), a nanomaterial with high thermal conductivity, and its epoxy composite adhesive have high thermal conductivity. However, due to its characteristics, the mechanical properties of BN/epoxy will decrease when more BN is added. Therefore, this study graphene platelet and carbon nanotube are selected and packed epoxy/BN composite adhesives to develop adhesives with excellent mechanical properties and thermal conductivity at the same time. In this study, an enhancement effect between a graphene platelet (GnP) and a carbon nanotube (CNT) within an epoxy/BN composite is reported. In the three-phase composite adhesive, the 2 D graphene platelets and 1D carbon nanotubes form a global bearing force network, and the boron nitride nanosheets provide high heat conduction inside the epoxy. They both complement each other in developing thermal conductive and high mechanical energy epoxy composite adhesives. At filler ranging from 0 to 1.0 wt%, epoxy/BN-CNT can improve the fracture toughness (K1c), critical stress-energy release rate (G1c) and Young's modulus of pure epoxy, are 89, 484, and 67% compared to 52, 286, and 42% in epoxy/BN-GnP composites, respectively. When adding 5.0 wt% of BN-CNT, the epoxy composites' thermal conductivity is up to 0.8 W/m%K, 400% higher than pure epoxy. This article also tested the electrical conductivity of epoxy/BN-CNT and epoxy/BN-GnP composites and found that the electrical conductivity was increased by 12 and 10 orders of magnitude, respectively, and it could be used as an antistatic material. Investigating the enhanced mechanism of epoxy/BN/CNT and epoxy/BN/GnP composites by scanning electron microscopy analysis. Lap shear strength tests on epoxy composite adhesives confirm the reinforcement effect of GnP and CNT of epoxy/BN composites. [ABSTRACT FROM AUTHOR]

In the electronics and aerospace industries, epoxy resins are generally regarded as economical and efficient adhesives and have a high status. However, epoxy resins are highly crosslinked polymers and are very brittle adhesives where they are prone to fast crack propagation under dynamic loads. Therefore, it is very necessary to enhance the toughness of epoxy resin adhesives. Nano-rubber has been proved to be an important toughening agent for epoxy resin, which can significantly improve the fracture toughness of epoxy resin. However, increasing the toughness of epoxy resin by adding nanomaterials is often accompanied by decreasing the strength and stiffness of resin. Therefore, in this work, rigid nano-silica particles were added to improve the rigidity and tensile strength reduction caused by the addition of rubber particles. And further increase the toughness of the epoxy resin to obtain an epoxy adhesive with balanced stiffness-toughness. As a result, it can be found that the addition of silica particles can significantly improve the decrease in stiffness caused by the addition of rubber particles. For example, Young's modulus and tensile strength are increased by 28%, and 23%, respectively, with 4% silica is added based on rubber particles. Through the single lap shear experiment, it is found that the shear strength of the epoxy/RnP/silica composite adhesive has increased, which further proves that the addition of nano-silica particles can increase the stiffness of the epoxy composite. The dynamic mechanical analysis experiment found that after adding nano-silica particles, the storage modulus of epoxy composites increased, which also shows that adding nano-silica particles can improve the stiffness of epoxy composites. Scanning electron microscopy analysis was performed to study the reinforcement mechanism of epoxy/RnP/silica composite materials. The thermal stability of epoxy composites was characterized by Dynamic mechanical analysis and thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

Graphene platelets (electrically conductive 2D filler) and rubber nanoparticles (0D soft filler) can work together to develop electrically conductive and toughened epoxy composite adhesives. In this study, complementing effect between graphene platelets (GnPs) and rubber nanoparticles (RnPs) within an epoxy matrix is reported. In the 3‐phase composite adhesive, the 2D graphene platelets form global conductive network and rubber nanoparticles provide a viscoelastic phase inside the epoxy, both complementing each other to develop electrically conductive and toughened epoxy composite adhesives. Fracture toughness (K1c) and critical strain energy release rate (G1c) of the epoxy were augmented by 422% and 872%, respectively by adding 1 wt% RnPs and it recorded electrical percolation threshold at 0.78 vol% GnP. Also, the Young's modulus and strength of epoxy/1 wt% RnP composite were promoted from 1.57 to 2.32 GPa when 1 wt% GnP is added. Scanning electron microscopy analysis was conducted to investigate the toughening mechanism of epoxy/RnP/GnP and epoxy/GnP composites. Lap shear strength tests on epoxy composite adhesives confirm the reinforcement effect of GnPs and toughness effect of RnPs. [ABSTRACT FROM AUTHOR]

This work investigated the effect of graphene nanoplatelets (GNPs) on the water absorption and impact resistance of fibre-reinforced metal laminates (FMLs) under hygrothermal and salt spray environments. Containing GNPs of 0.1, 0.3, 0.5 and 1.0 wt%, the resulting nanocomposite FMLs were investigated for 28 days of aging in the environments. The salt-spray environment was found to pose a more serious effect on FMLs than the hygrothermal environment. The addition of GNPs at 0.3 wt% effectively reduced the water absorption of FMLs by 57.6% whilst improving their impact resistance by 150.6% in comparison with pure FML in the case of treatment by the salt-spray environment. The water absorption reduction is caused by GNPs creating a tortuous path for diffusion of water molecules and restricting the intermolecular motion of the epoxy molecules. The impact resistance improvement can be attributed to GNPs improving the modulus and crack-resistance of the epoxy matrix and thus the interfacial bonding of FMLs. [ABSTRACT FROM AUTHOR]