Examination of low‐velocity impact and mechanical properties after impact of fiber‐reinforced prepreg composites

Carbon fiber‐reinforced polymer composites (CFRPs) are widely used in many fields because of their excellent mechanical properties; however, they are very sensitive to low velocity impact. A new‐type biomimetic structure, which has a “bricks‐and‐mortar” arrangement of nacre from mollusk shells, was designed and manufactured for enhancing the impact resistance of the CFRPs. The impact response and absorption of impact energy of this structure were also investigated. Impact damage forms of the biomimetic structure were analyzed based on the surface and internal morphologies. The results indicate that biomimetic structure can decrease the impact damage of the CFRPs. Two damage behaviors of the biomimetic structure were observed under relatively higher impact energy. The discontinuous structure reduces the damage using a smaller load for the first damage and a larger deformation for the second damage, which improves the impact resistance of the CFRPs. The discontinuous structure restrains longitudinal crack propagation to a certain extent, effectively reducing the damaged area of the CFRPs. Thus, the proposed structure can increase the strength retention rate of the material by about 5%. In addition, the compression after impact damage modes of CFRPs with three types of structure are summarized and classified originally.

Section: Resultsmentioning

confidence: 89%

Section: Damage Tolerance and Mode Of Discontinuous Laminatesmentioning

confidence: 77%

Exploration of impact response and damage mechanism of discontinuous CFRP laminates subjected to low velocity impact

Xiao

et al. 2023

“…The LVI test results indicated that impact energy mainly affects the damage failure of composites. 34 Figure 2A displays the impact force-time and energy absorption-time curves of a typical LVI. The velocity of the impactor is calculated using Equation (1), where V (t), V i , F(t), m, and g represent the velocity of the impactor at a time "t," initial velocity, stress at a time "t," the mass of the impactor, and gravitational acceleration, respectively.…”

Section: Performance Testingmentioning

confidence: 99%

Synergistic effect of the glass bead and continuous glass fibers on the low‐velocity impact resistance of nylon 6 matrix composites

Yang,

Wei,

Yin

et al. 2024

Glass fiber‐reinforced resin matrix composites have good mechanical and impact resistance properties, while with particle co‐reinforcement, a synergistic effect can further improve their performance. In this paper, continuous glass fiber‐reinforced nylon 6 (GF/PA6) and continuous glass fiber (GF) with glass beads (GBs) co‐reinforced nylon 6 (GB–GF/PA6) were prepared to investigate the co‐reinforcement mechanism and the synergistic effect of particle and fiber. A quantitative parameter of the residual impact force divided by the critical force Pr/Pcr, as the damage degree of the low‐velocity impact, is defined to evaluate the impact resistance of the composite. The results indicate that the damage of GB–GF/PA6 was lower than that of GF/PA6, and the synergistic effect reaches the most obvious at the GB addition of 10 wt%. Scanning electron microscope (SEM) and x‐ray computed tomography (XCT) images disclose that GB impedes the type II crack spread in the matrix and fiber/matrix interface. With the type II cracks reducing, the materials' resistance to delamination can be significantly enhanced. For the composite structure, in which 10 wt% GB and 60 wt% GF are introduced, the flexural strength, shear strength, and pendulum impact strength were tested with the maximum values of 379.4 MPa, 53.1 MPa, and 219.0 J/m2, respectively. This composite structure design, presenting a continuous GF and GBs co‐reinforce effect, offers a manufacturing process that is easily scalable to achieve excellent characteristics.

“…[1][2][3][4] For instance, low-velocity impact (LVI) is a major issue, and this type of damage can cause invisible damage to the material, such as matrix cracking, microcracking, and internal delamination. [5][6][7][8][9][10] In addition to affecting the structure's strength, durability, and stability, these defects are frequently difficult to detect and repair. Moreover, such inherent limitations lead to an increase in composite waste, which is certain to have a significant impact on the environment.…”

Section: Introductionmentioning

confidence: 99%

“…However, CFRP still has weaknesses, including poor interlayer toughness due to the lack of z ‐directional toughening and a unique laminated structure that is susceptible to out‐of‐plane loads 1–4 . For instance, low‐velocity impact (LVI) is a major issue, and this type of damage can cause invisible damage to the material, such as matrix cracking, microcracking, and internal delamination 5–10 . In addition to affecting the structure's strength, durability, and stability, these defects are frequently difficult to detect and repair.…”

Section: Introductionmentioning

confidence: 99%

Low‐velocity impact response and post‐impact assessment of self‐healing composites with different stacking configurations of core–shell nanofibers

Cai,

Gan,

Chen

et al. 2023

This work investigates the low‐velocity impact (LVI) and self‐healing behavior of carbon fiber composite laminates interlaced with electrospun polyacrylonitrile core–shell nanofibers (PAN@CFRP). The main goal is to investigate the influence of different stacking configurations of core–shell nanofibers on the impact resistance and self‐healing properties of composite laminates. To achieve the purpose, three different stacking configurations were designed and tested alongside virgin specimens. The damage mechanism and self‐healing of laminates following LVI were determined using ultrasonic C‐scan and cross‐sectional microscopy examinations. At an impact energy of 14.1 J, the flexural strength of the post‐healing PAN‐3@CFRP specimen reached 95.0% of the initial value, whereas at an impact energy of 21.8 J, severe impact damage was observed in the laminates with different configurations. Among the laminates, the PAN‐1@CFRP specimen had the highest flexural strength after healing, which reached 80.1% of its pre‐impact strength. As observed, the impact resistance and self‐healing capacity of composites could be significantly enhanced by optimizing the distribution configuration of core–shell nanofibers for various impact energies.Highlights The introduction of electrospun core–shell nanofibers has not significantly compromised the mechanical properties of the composites, but rather enhanced their toughness. The addition of core–shell nanofibers significantly enhances the impact resistance of the composites and imparts excellent self‐healing properties to the material. The flexural strength of impact‐damaged specimens with different stacking configurations can be restored up to 95% of the undamaged specimen after repair treatment. Significantly improved impact resistance and self‐healing ability of laminates by optimizing the distribution configuration of core–shell nanofibers between composite layers.