碳纤维增强聚丙烯复合材料管件“成形-弯曲”耦合数值模型

"Forming-bending" coupling numerical model for the carbon fiber reinforced polypropylene composite tube

当前复合材料车身零部件在研发过程中依然面临着制造工艺与结构性能孤立分析的难题,开发平纹织物纤维增强热塑性复合材料(WFRTPs)的“成形-性能”耦合数值模型,对于促进WFRTPs在新能源汽车领域的产业化应用意义重大。本文通过热模压工艺制备了两种不同纤维夹角的碳纤维增强聚丙烯(CF/PP)薄壁管件,并对CF/PP预浸料和CF/PP层合板进行了准静态偏轴拉伸实验,对CF/PP管件进行了准静态弯曲测试,实验结果表明,由成形工艺引发的织物纤维夹角增加将导致CF/PP层合板剪切强度降低和失效应变增加,进一步造成CF/PP管件在弯曲工况下峰值载荷减小和失效位移增加。开发了CF/PP预浸料的次弹性成形本构模型、层合板的渐进损伤弯曲本构模型以及管件的“成形-弯曲”耦合本构模型并验证了上述本构模型的准确性,仿真结果表明,在压边力约束下制备的非正交CF/PP管件的剪切塑性应变比无压边力制备的正交试样高69%,纤维夹角的增加将显著增加CF/PP材料的塑性剪切应变,进而导致非正交CF/PP管件的弯曲失效位移显著增加。

Currently,composite automotive body components still face the challenge of isolated analysis of manufacturing process and structural performance in the research and development process,developing the"forming-performance"coupling model for woven fabric reinforced thermoplastics(WFRTPs)shows great significances to promote the industrial application of WFRTPs in the field of new energy vehicles.In this study,using the carbon fiber reinforced polypropylene(CF/PP)prepregs as the raw materials,two kinds of thin-walled CF/PP tubes with different fiber angles were manufactured by hot molding process,and the quasi-static bias-extension tests for CF/PP prepregs and CF/PP laminates,and the three-point bending tests for CF/PP tubes were preformed,and experimental results show that the increase in fabric fiber angle caused by the forming process leads to the decrease in shear strength and the increase in failure strain of the CF/PP laminates,which further results in the reduction in peak force and the increase in failure displacement of CF/PP tubes.Then,the hypoelastic forming constitutive model for CF/PP prepreg,the progressive damage bending constitutive model for CF/PP laminate and the"forming-bending"coupling constitutive model for CF/PP tube were developed and validated.The numerical results indicate that the shear plastic strain of the non-orthogonal CF/PP tube manufactured with restraints of blank holding force is 69%higher than that of the orthogonal sample without blank holding force,and the increase in fiber angle results in the significant increase in shear plastic strain,which further significantly increases the bending failure displacement of the non-orthogonal CF/PP tube.