3D打印连续碳纤维增强复合材料与结构的力学性能和破坏机理研究

Due to their superior mechanical properties, the potential of the continuous carbon fiber reinforced composites (CCFRC) manufactured by a new 3D printing technique in the areas of high-end manufacturing, aeronautic and astronautic engineering is promising. However, the experimental results show that the stiffness and strength of the composites do not satisfy the rule of mixture in the classical theories of composite mechanics and currently no model can correctly predict the strength of the composites. In this proposed project, a meso-scale model of the composites is created based on the particular meso-structure of the composites. A set of experiments are carefully designed to obtain the parameters of this meso-scale model. The model is then utilized to simulate the progressive damage process of the composites reinforced with straight fibers. The simulation results are compared with the experimental results to obtain the constitutive model and the failure criteria of the composites. The mulit-scale analysis is performed to investigate comprehensively the effect of the curved fiber reinforcement on the mechanical behavior of the composites by experimental study, theoretical analysis and numerical simulations. Macro-scale computational tool is established to predict the mechanical responses and failure mechanism of general 3D printed CCFRC structures. The research will not only promote the design optimization and applications of CCFRC structures in industry, but also pave the way for the evolution of the related 3D printing techniques.

新型3D打印技术制备的连续碳纤维增强复合材料因其优异的力学性能而在航空航天、高端制造业等领域具有非常好的应用前景，但实验结果表明该复合材料的强度和刚度不满足经典复合材料力学理论的混合定律，迄今没有模型能正确预测其力学性能。本项目计划根据该复合材料的介观结构特点构建其介观模型，设计实验标定模型参数，模拟直纤维增强复合材料在各种受力条件下的渐进损伤力学行为，与宏观实验结果对比，得到宏观尺度的本构模型和破坏准则。通过实验观测、数值模拟和理论建模等手段从微观、介观和宏观尺度研究弯曲纤维对复合材料力学性能的影响，建立弯曲纤维增强复合材料的宏观计算模型。所建立的模型可预测3D打印连续碳纤维增强复合材料结构的受力变形和损伤破坏，为改进连续纤维增强复合材料的3D打印工艺、优化该复合材料结构的设计和促进其在航空航天、机械制造等领域的应用提供理论基础。

新型3D打印技术制备的连续碳纤维增强复合材料因其优异的力学性能而在航空航天、高端制造业等领域具有非常好的应用前景，但该复合材料的强度和刚度是否满足经典复合材料力学理论的混合定律，颇有争议。本项目根据该复合材料的结构特点，从多尺度角度出发，采用单轴拉伸实验测试得到微观尺度下3D打印原材料Onyx丝束与CF丝束的力学参数，采用单轴拉伸、单轴压缩、面内剪切实验测试得到介观尺度下3D打印试件的力学参数，基于这些模型参数，模拟预测直纤维增强复合材料的力学性能，并与宏观实验对比，得到描述该复合材料力学性能的本构模型和破坏准则。采用实验与数值模拟相结合的手段，研究了弯曲路径纤维对复合材料力学性能的影响。研究发现：经典混合定律可用于预测该复合材料的强度和刚度性能，前提是采用正确的材料组分参数，并合理考虑试件的打印路径。本项目所建立的模型可预测3D打印连续碳纤维增强复合材料结构的受力变形和损伤破坏，为改进连续纤维增强复合材料的3D打印工艺、优化该复合材料结构的设计和促进其在航空航天、机械制造等领域的应用提供理论基础。