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Configuration and geometric parameters (mm) of specimens: tensile specimen (a) and compression specimen (b).
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Microvascular self-healing composite materials have significant potential for application and their mechanical properties need in-depth investigation. In this paper, the tensile and compressive properties of woven fabric carbon fiber-reinforced polymer (CFRP) laminates containing three-dimensional microvascular channels were investigated experiment...
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Citations
... Additionally, due to the complex manufacturing process of the novel T-joint [23], conducting parameter studies through experiments can incur high time and manufacturing costs. With the advancement of numerical simulation technologies, using validated finite element models for parameter analysis can reduce the number of experimental samples and significantly shorten the development cycle of engineering structures [6,[38][39][40][41][42]. Therefore, it is feasible to establish a bending finite element model for the novel T-joint, evaluate it through experiments, and subsequently conduct in-depth research on various parameters of the novel T-joint. ...
The composite bolted T-joint, consisting of internal laminate skeleton and external skin, presents substantial potential for replacing aluminum alloys as the primary load-carrying connection structure. However, its complex failure mechanisms and numerous design parameters pose challenges for engineering applications. To identify critical design parameters significantly impacting its bending performances, a validated finite element model of this T-joint under bending loads was established. Using uniform design and multiple linear regression methods, the significance of 15 design parameters related to machining, configuration, and resin properties on bending performances was systematically investigated and the effect mechanisms of certain parameters were discussed. The results show that parameters such as the base panel bolt hole radius (rB), corner radius (rC), the thickness of the upper surface skin (tU), base panel skeleton (tS_B), and lug skeleton (tS_L) have significant positive effects. Failure of the resin area between the skin and skeleton results in localized weak stress area in the skin, thereby reducing the overall load-carrying capacity of the joint. rB has an optimal value that balances bending performances and fastener weight. The final failure location of the joint is either in the base panel skeleton or lug skeleton, depending on the relative thickness of each. Additionally, when designing composite T-joints with multiple configuration components for primary load-carrying connections, it is advisable to place weak load-carrying positions away from the load-carrying core.
... When the material is damaged, the crack induces the rupture of the carrier and releases the repair agent, realizing the self-healing of material damage [7,8]. In various repair systems, the interconnected microvascular network carriers [9] can realize the supply and replacement of repair agents, and have the characteristics of multi-point and multi-time repair, becoming the main technical means of self-healing research [10,11]. However, in the self-healing design of anisotropic materials, it is difficult to solve the influence of embedded carriers on the mechanical properties of the structure, while ensuring the fluidity of repair agents and real-time repair. ...
Due to the anisotropic structure and mechanical properties of composite laminates, internal damage cracks can easily occur. In this study, orthotropic anisotropic glass-fiber-reinforced polymer composites were used as the repair object. Firstly, the anisotropic material was analyzed using the finite element method, the self-healing structural compliance, water head loss, and volume percentage of the microvascular network were taken as the objective functions, and the topology optimization of the microvascular network structure was carried out using non-dominated soring genetic algorithm II. Secondly, the self-healing material with a wall-less microvascular network was prepared via the vacuum-assisted resin transfer molding process and the embedded wire removal method. Finally, the light repair performance was tested using the three-point bending test. The results show that in the case of no intervention for light repair, the average maximum failure load of the self-healing structure after embedding the microvascular network can reach 94.06% of that before embedding; with the introduction of real-time light repair, the average maximum failure load of the self-healing structure with light repair was increased by 4.1% compared with the self-healing structure without light repair. Meanwhile, the second peak load of the light-repaired structure can reach 51.36% of the average maximum failure load, which is 28.56% higher than that of the non-light-repaired structure.
... After comparing the impact testing results with the damage evolution models that the authors had created, the authors concluded that the damage evolution models were highly accurate for the various failure modes that may occur in composites. Within high-speed collisions, the authors in [30] have identified three potential methods in which fiberreinforced laminates can absorb impact energy. Local fragmentation, linear momentum transfer, and tensile fiber breaking are the names given to these three techniques. ...
In this study, investigation of the high-Velocity Impact test on the curved glass fiber reinforced plastic (GFRP) composites using explicit dynamics analysis has been performed using FEM. Four types of energy were examined: internal energy, kinetic energy, contact energy, and hourglass energy. The investigation revealed that the most significant variation occurred in the internal energy, reaching a peak value of 1.0e-3. Deformation due to impacted forces was considered accordingly. Three forces were considered accordingly: 1,2,3 kn. Based on the numerical analysis, the maximum deformation was reached 76 mm. Von Mises stress due to the applied load was considered as well. The von Mises stresses using explicit dynamic tools in analysis software. Three loads were considered for the general inspections till 3 KN. The numerical results proved that the maximum stress reached 22 MPa. This substantial change is primarily due to the alterations in the material's morphology, indicating how the material's internal structure responded to the applied conditions. Kinetic energy, which relates to the motion of the material, and contact energy, which pertains to the interactions at the material's surfaces, were also analyzed. However, these energies did not exhibit as pronounced changes as the internal energy.
... The reason for the above results is that the film's exothermic peak temperature was relatively low at a lower heating rate. In this moment, a heat preservation temperature of 180 °C was more conducive to stimulating the film curing reaction and promoting the three-dimensional network structure to form quickly [36]. There is further indication that the temperature range of the curing exothermic peak needs time to activate the curing reaction and maintain polymer bond formation. ...
... The reason for the above results is that the film's exothermic peak temperature was relatively low at a lower heating rate. In this moment, a heat preservation temperature of 180 • C was more conducive to stimulating the film curing reaction and promoting the three-dimensional network structure to form quickly [36]. There is further indication that the temperature range of the curing exothermic peak needs time to activate the curing reaction and maintain polymer bond formation. ...
Due to their mechanical load-bearing and functional wave transmission, adhesively bonded joints of carbon fiber–quartz fiber composites have been widely used in the new generation of stealth aviation equipment. However, the curing defects, caused by deviations between the process environment and the setting parameters, directly affect the service performance of the joint during the curing cycle. Therefore, the thermophysical parameter evolution of adhesive films was analyzed via dynamic DSC (differential scanning calorimeter), isothermal DSC and TGA (thermal gravimetric analyzer) tests. The various prefabricating defects within the adhesive layer were used to systematically simulate the impacts of void defects on the tensile properties, and orthogonal tests were designed to clarify the effects of the curing process parameters on the joints’ bonding performance. The results demonstrate that the J-116 B adhesive film starts to cure at a temperature of 160 °C and gradually forms a three-dimensional mesh-bearing structure. Furthermore, a bonding interface between the J-116 B adhesive film and the components to be connected is generated. When the curing temperature exceeds 200 °C, both the adhesive film and the resin matrix thermally degrade the molecular structure. The adhesive strength weakens with an increasing defect area ratio and number, remaining more sensitive to triangle, edge and penetration defects. By affecting the molecular structure of the adhesive film, the curing temperature has a significant impact on the bonding properties; when the curing degree is ensured, the curing pressure directly impacts the adhesive’s performance by influencing the morphology, number and distribution of voids. Conversely, the heating rate and heat preservation time have minimal effects on the bonding performance.
This study investigates the enhancement of mechanical characteristics of hybrid polymer composites reinforced with palmyra palm leaflet (PPL) and coconut sheath leaf (CSL) fibers by integrating tamarind shell powder as a filler material. The composites were fabricated with varying ratios of PPL and CSL fibers, and their tensile strength, flexural strength, interlaminar shear strength (ILSS), impact strength, hardness, and water absorption were evaluated. The composite with 20% PPL and 10% CSL exhibited superior mechanical performance, achieving the highest tensile strength of 42 MPa, flexural strength of 94 MPa, ILSS of 7.52 MPa, and impact strength of 5.98 J. Hardness values peaked at 84 SD for the same composition. Moreover, the integration of tamarind shell powder significantly improved the mechanical properties compared to composites without filler, which showed lower values across all parameters. Water absorption tests revealed an increase in water uptake with filler incorporation, though within acceptable limits for practical applications. Scanning electron microscopy supported these results by revealing enhanced fiber-matrix bonding and better dispersion of the filler, resulting in fewer voids and defects. This research highlights the potential of bio-based fillers in optimizing the mechanical performance of hybrid composites for sustainable engineering applications.
