Author Contributions
Conceptualization, Y.T.; methodology, Z.Z. and Z.Y.; software, Z.Z., C.F. and Z.Y.; validation, Z.Z.; formal analysis, Z.Z., C.F. and Z.Y.; investigation, Z.Z.; resources, C.L.; data curation, Z.Z.; writing—original draft preparation, Z.Z.; writing—review and editing, Y.T. and C.L.; visualization, Z.Z. and Z.Y.; supervision, C.L.; project administration, C.L.; funding acquisition, Y.T. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Illustration of specimen preparation: the material preparation including (a) EMAA filament and (b) the prepreg, as well as (c) the preform preparation; (d) the manufacturing process.
Figure 1.
Illustration of specimen preparation: the material preparation including (a) EMAA filament and (b) the prepreg, as well as (c) the preform preparation; (d) the manufacturing process.
Figure 2.
The testing platform for conducting the LVI tests. (a) the testing platform used to carry out the LVI tests, (b) the anti-secondary impact device and (c) the support fixture.
Figure 2.
The testing platform for conducting the LVI tests. (a) the testing platform used to carry out the LVI tests, (b) the anti-secondary impact device and (c) the support fixture.
Figure 3.
Schematic illustration of the construction of the microscopic model: (a) fiber bundle, (b) RVE model.
Figure 3.
Schematic illustration of the construction of the microscopic model: (a) fiber bundle, (b) RVE model.
Figure 4.
Schematic illustration of local high-fidelity mesoscopic RVE model structure: (a) top view, (b) lateral side view.
Figure 4.
Schematic illustration of local high-fidelity mesoscopic RVE model structure: (a) top view, (b) lateral side view.
Figure 5.
Illustration of: (a) transformation of local high fidelity mesoscopic RVE model into ECPL model, (b) global mesoscopic ECPL model structure of real composite laminate.
Figure 5.
Illustration of: (a) transformation of local high fidelity mesoscopic RVE model into ECPL model, (b) global mesoscopic ECPL model structure of real composite laminate.
Figure 6.
Macroscopic model used for the LVI simulation of EWL.
Figure 6.
Macroscopic model used for the LVI simulation of EWL.
Figure 7.
Damage according to local high-fidelity mesoscopic models under different conditions: (a) X-direction tension, (b) X-direction compression, (c) Y-direction tension and (d) Y-direction compression.
Figure 7.
Damage according to local high-fidelity mesoscopic models under different conditions: (a) X-direction tension, (b) X-direction compression, (c) Y-direction tension and (d) Y-direction compression.
Figure 8.
The mechanical properties according to mesoscopic RVE models of unstitched and different stitched composites.
Figure 8.
The mechanical properties according to mesoscopic RVE models of unstitched and different stitched composites.
Figure 9.
Comparison of F-T and E-T curves between numerical and experimental results of LVI tests.
Figure 9.
Comparison of F-T and E-T curves between numerical and experimental results of LVI tests.
Figure 10.
Damage morphologies of EWL from top and bottom view.
Figure 10.
Damage morphologies of EWL from top and bottom view.
Figure 11.
Simulated damage morphologies of EWL, top and bottom view.
Figure 11.
Simulated damage morphologies of EWL, top and bottom view.
Figure 12.
(a) F-T and (b) E-T curves of EWL with 10 mm, 15 mm, and 20 mm stitch spacings in the 15 J impact energy case.
Figure 12.
(a) F-T and (b) E-T curves of EWL with 10 mm, 15 mm, and 20 mm stitch spacings in the 15 J impact energy case.
Figure 13.
The damage morphology of EWL with 10 mm, 15 mm, and 20 mm stitch spacings in the 15 J impact energy case.
Figure 13.
The damage morphology of EWL with 10 mm, 15 mm, and 20 mm stitch spacings in the 15 J impact energy case.
Figure 14.
Secondary impact F-T curves of EWL with different stitch spacings at 15 J energy: (a) 10 mm EWL unhealed experimental curve, and experimental and simulation curves of EWL after self-healing: (b) 10 mm, (c) 15 mm, (d) 20 mm.
Figure 14.
Secondary impact F-T curves of EWL with different stitch spacings at 15 J energy: (a) 10 mm EWL unhealed experimental curve, and experimental and simulation curves of EWL after self-healing: (b) 10 mm, (c) 15 mm, (d) 20 mm.
Figure 15.
Cross-section of specimens before and after self-healing: (a) crack caused by impact, (b) EMAA flow to the area of damage, (c) schematic illustration of the healing mechanism.
Figure 15.
Cross-section of specimens before and after self-healing: (a) crack caused by impact, (b) EMAA flow to the area of damage, (c) schematic illustration of the healing mechanism.
Table 1.
Mechanical parameters of carbon fiber and epoxy resin. Superscripts f and m represent fiber and matrix, respectively.
Table 1.
Mechanical parameters of carbon fiber and epoxy resin. Superscripts f and m represent fiber and matrix, respectively.
Carbon Fiber T300/3K | Epoxy Resin 7901 |
---|
/GPa | 230 | /GPa | 3.5 |
/GPa | 40 | /GPa | 1.3 |
/GPa | 24 | | 0.35 |
/GPa | 14.3 | /MPa | 112 |
| 0.26 | /MPa | 241 |
| 0.44 | /MPa | 89.6 |
/MPa | 3258 | /(N/mm2) | 1 |
/MPa | 2470 | | |
/(N/mm2) | 12.5 | | |
Table 2.
Equivalent properties of the microscale RVE model. Superscript y represents fiber-bundle yarn.
Table 2.
Equivalent properties of the microscale RVE model. Superscript y represents fiber-bundle yarn.
Elastic Properties | Damage Properties |
---|
/GPa | 184.77 | /MPa | 2890 |
/GPa | 19.17 | /MPa | 2059 |
/GPa | 8.46 | /MPa | 92 |
/GPa | 14.3 | /MPa | 185 |
| 0.27 | /MPa | 107 |
| 0.42 | /MPa | 59 |
Table 3.
Geometric parameters of local mesoscopic RVE model.
Table 3.
Geometric parameters of local mesoscopic RVE model.
Parameter | l | h | D | b | a | w | t |
---|
Value/mm | 4 | 0.25 | 1.2 | 1.2 | 0.4 | 1.62 | 0.11 |
Table 4.
Equivalent mechanical parameters for 0°and 90° monolayers in ECPL modeling.
Table 4.
Equivalent mechanical parameters for 0°and 90° monolayers in ECPL modeling.
Parameter | 0° Monolayer | 90° Monolayer |
---|
Young’s modulus, E11/GPa | 70,075 | 67,840 |
Young’s modulus, E22, E33/GPa | 13,299 | 13,405 |
Shear modulus, G12, G13/GPa | 1440 | 1632 |
Shear modulus, G23/GPa | 2325 | 2148 |
Poisson’s ratio, υ12, υ13 | 0.13 | 0.13 |
Poisson’s ratio, υ23 | 0.43 | 0.4 |
Tensile strength, XT/MPa | 705 | 658 |
Compressive strength, XC/MPa | 675 | 587 |
Tensile strength, YT/MPa | 182 | 172 |
Compressive strength, YC/MPa | 76.2 | 92.4 |
Shear strength, S12, S13/MPa | 30 | 36 |
Shear strength, S23/MPa | 87 | 83 |
Table 5.
Mechanical property parameters of EAA and EMAA.
Table 5.
Mechanical property parameters of EAA and EMAA.
Parameter | EAA | EMAA |
---|
Tensile modulus, E/MPa | 33.1 | 22.3 |
Tensile strength, X/MPa | 18.6 | 16 |
Poisson’s ratio, υ | 0.4 | 0.42 |
Density, ρ/(g/cm3) | 0.91 | 0.90 |
Table 6.
The impact peak force and healing efficiency after healing.
Table 6.
The impact peak force and healing efficiency after healing.
Energy/J | Peak Force/N | Healing Efficiency |
---|
15 | Unhealed | 2814 | / |
10 mm | 3551 | 98.28% |
15 mm | 3447 | 97.26% |
20 mm | 3268 | 94.67% |