To enhance the quality and mechanical performance of a carbon fiber–reinforced polymer (CFRP) workpiece, this paper prepares a polyacrylonitrile (PAN)-based carbon fiber–reinforced thermosetting polymer (CFRTP) laminated board through compression molding, and carries out orthogonal tests and single-factor tests to disclose the effects of different process parameters (i.e., compression temperature, compression pressure, pressure-holding time, and cooling rate) on the mechanical performance of the CFRTP workpieces. Moreover, the process parameters of compression molding were optimized based on the test results. The research results show that: The process parameters of compression molding can be ranked as compression temperature, pressure-holding time, compression pressure, cooling rate, and mold-opening temperature, in descending order of the impact on the mechanical property of the CFRTP; the optimal process parameters for compression molding include a compression temperature of 150 °C, a pressure-holding time of 20 min, a compression pressure of 50 T, a cooling rate of 3.5 °C/min, and a mold-opening temperature of 80 °C. Under this parameter combination, the tensile strength, bending strength, and the interlaminar shear strength (ILSS) of the samples were, respectively, 785.28, 680.36, and 66.15 MPa.

The progressive damage behavior and failure mechanism of molded carbon fiber reinforced composite laminates under tensile and three-point bending loads were studied. The mechanical properties and failure mechanism of composite laminates were studied by theoretical analysis, numerical simulation and experimental characterization. The results show that the tensile failure mode of molded carbon fiber reinforced composite laminates presents the phenomenon of resin matrix cross-section fracture, fiber fracture and fiber pull-out. Under three-point bending load, the main failure modes of molded carbon fiber reinforced composite laminates are matrix crack, interlayer separation and fiber fracture. Based on the progressive energy dissipation theory and the incremental method, the FEA-VUMAT model is established, which can accurately predict the tensile, three-point bending response and failure mechanism. The predicted load–displacement curves and load disturbance curves of the model are in good agreement with the experimental results. The prediction accuracy of the maximum tensile load, flexural modulus and flexural strength is 97%, 96% and 93%, respectively, which verifies the validity of the model.

In order to enhance the quality and mechanical properties of 3D printing carbon fiber reinforced composite (CFRP) workpiece, this paper prepares 3D printing CFRP laminates by proposing a layered coherent composite scanning path, and carries out orthogonal tests and single factor tests to disclose the effects of different process parameters (i.e., layer thickness, first layer thickness, nozzle temperature and printing speed) on the mechanical performance of the CFRP workpieces. Moreover, The grey relation analysis method is used to analyze the multi-objective parameters of the orthogonal tests results and the process parameters of 3D printing CFRP are optimized based on the tests results. The research results show that the process parameters of 3D printed CFRP can be ranked as delamination thickness, nozzle temperature, first layer thickness and printing speed, in descending order of the impact on the mechanical property of the CFRP laminates. the optimal process parameters for 3D printing include a layer thickness of 0.25 mm, a first layer thickness e of 0.2 mm, a nozzle temperature of 180°C, and printing speed of 45 mm/s. Under this parameter combination, the tensile strength, bending strength, and the interlaminar shear strength (ILSS) of the samples are 52.77 MPa, 276.63 MPa and 38.56 Mpa respectively, and the grey correlation degree increased to 0.845.

Carbon Fiber Reinforced Polymer (CFRP) laminates habitually experience either tensile or compressive prestressing loads and are simultaneously susceptible to external low-velocity impacts in genuine operating scenarios. The current study establishes a meticulous model to elucidate the low-speed impact behavior of prestressed CFRP laminates, substantiated by finite element simulations. Initial validation of the model is accomplished by comparing simulated low-velocity impact scenarios without prestress against experimental data. Subsequently, the validated model is employed to simulate the low-velocity impact process under varying impact velocities and under both tensile and compressive prestress loads. It is demonstratively shown that tensile prestressing accentuates the extent of damage incurred by the laminate, a phenomenon that amplifies concomitantly with increasing impact speed. In contrast, compressive prestress is found to mitigate the laminate damage to a particular degree, albeit this mitigative effect is observed to diminish with escalating impact velocities. The findings derived from the investigation furnish pivotal data concerning the impact resilience of composite materials under practical working conditions and yield substantial engineering applicability for optimizing the design of related structures.

The carbon-fiber-reinforced polymer (CFRP) is a mainstream material for lightweight products from the end of the 20th century to the present day. Its compression molding process has obvious advantages in mass production. This paper attempts to establish the constitutive models of compression molding of the CFRP materials and study their mechanism. Based on anisotropic linear elastic mechanics, viscoelastic mechanics, and thermodynamics, as well as the Maxwell viscoelastic constitutive model, we first establish the constitutive model of thermorheologically simple CFRP materials (TSMs). Then, considering the influence of temperature on the initial stiffness and equilibrium stiffness, the concept of temperature stiffness coefficient is introduced, and the Cartier coordinate system is converted into a cylindrical coordinate system, thereby establishing the constitutive model of thermorheologically complex materials (TCMs) using the tensor form. Finally, by comparing to the structure of the Zocher model, the two constitutive models established in this study are verified. The research findings have important theoretical research significance for studying the compression molding mechanism of carbon fiber and further improving the quality of product molding.