Research on curing kinetics of multiaxial warp‐knitted composites

Self Cite

In this paper, the creep behavior of triaxial warp‐knitted composites (TWKC) was investigated. The TWKC specimens were prepared by applying vacuum‐assisted resin infusion (VARI), and the three‐point bending creep experiments at different temperatures were carried out. The shift factor was calculated based on the activation energy method, and the creep curve at 25°C within 105s was obtained according to the time–temperature equivalence principle, the time–temperature equivalent model was established, and the model was verified by measuring the long‐term creep data with self‐made instrument. There is approximately agreement between the prediction result and experimental one, which is less than 10% within 105s. The results show that the model could be used to predict the creep behavior of TWKC. The viscoelastic properties of the specimen were analyzed based on dynamic mechanical analysis (DMA), and the creep behavior of TWKC was further analyzed by acoustic emission and digital image correlation damage analysis.Highlights The viscoelasticity of TWKC was analyzed based on dynamic mechanical analysis (DMA), and the activation energy was calculated. Based on the activation energy method, the time–temperature equivalent model was established to predict the creep behavior of TWKC. The creep behavior of TWKC were further analyzed by acoustic emission (AE) and digital image correlation (DIC) damage analysis.

Section: Introductionmentioning

confidence: 99%

Research and prediction of creep behavior of triaxial warp‐knitted composites by time–temperature equivalent principle

You,

Gao,

et al. 2023

Self Cite

Preparation and properties analysis of CTBN/CeO₂ co‐toughened epoxy resin composites

Liang,

Li,

Zhang

et al. 2024

In this paper, carboxyl‐terminated nitrile rubber (CTBN) and Nano cerium oxide (n‐CeO2) were used to toughen epoxy resin (EP), and the effects of toughening agents on the mechanical and thermal properties of EP were studied. Orthogonal experiments determined that the ideal toughener proportions are 20 wt% CTBN and 1 wt% n‐CeO2, under which the resin demonstrated superior mechanical characteristics. The combined application of CTBN and n‐CeO2 significantly enhanced the resin's mechanical properties, surpassing the effects of individual particle toughening. Compared with pure EP, the impact, flexural, and tensile strengths of the resin‐cured product synergistically toughened by CTBN and n‐CeO2 increased by 462%, 136%, and 110%, respectively, and the flexural and Young's moduli increased by 38% and 35%, respectively. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were used to characterize the cured resin. The results indicate that incorporating CTBN and n‐CeO2 reduces the reaction activation energy, thereby accelerating the curing reaction and facilitating its progression. The addition of nanoparticles enhances the maximum weight loss temperature of the cured resin, thereby improving its thermal stability. CTBN and n‐CeO2 particles create a uniform phase separation structure within the resin, enhancing its toughness and strength. Furthermore, the impact fracture mode of the cured resin transitions from brittle to tough fracture, demonstrating a significant toughening effect. This provides an effective method for the toughening modification of EP.Highlights The synergistic use of CTBN and n‐CeO2 enhances the toughness of EP. The incorporation of nanoparticles improves the thermal stability of the cured resin. The addition of CTBN and n‐CeO2 accelerates the curing reaction rate. The inclusion of toughening agents transforms the fracture mode of the cured resin from brittle to tough fracture.

Temperature effects on tensile and bending properties of carbon/Kevlar hybrid fiber sandwich composites

Chen,

Gao,

Chen

et al. 2024

In this paper, the mechanical properties of carbon/Kevlar hybrid fiber‐reinforced resin composites at different temperatures were studied. The hybrid composites were prepared by Vacuum Assisted Resin Infusion (VARI). The sandwich structure of reinforcement consists of Kevlar plain weave fiber as a surface layer and carbon fiber plain weave fabric as a core layer, while the matrix consists of a curing agent and epoxy resin. The bending and tensile properties of the composite specimens were tested at different temperatures using the in situ testing method, separately. The fracture morphology was analyzed using scanning electron microscopy (SEM) to understand the damage mechanism of the material properties at the micro‐scales. The results show that the sandwich composite material shows a positive hybrid effect. The carbon fibers increases effectively the strength and rigidity of the sample, while Kevlar fiber improves the toughness and brittle damage mode. The mechanical properties of hybrid composite laminates are strongly dependent on temperature. The tensile and bending properties of carbon/Kevlar hybrid composites decreased when the temperature increased from −30°C to 40°C. The effect of temperature on the bending properties was more pronounced for the carbon/Kevlar hybrid composites. This study consists of damage analysis and variation analysis of the mechanical behavior of carbon/Kevlar composite specimens, which will lay the foundation to provide basic data for the application of carbon/Kevlar hybrid composites.Highlights Advantages of carbon/Kevlar hybrid sandwiched structure on tensile and bending properties. Comprehensive mechanical property testing in multiple composite environments. Based on the hybrid effect and temperature effect, the damage mechanism of the sample was analyzed.