热残余应力对考虑微观孔隙碳纤维增强环氧树脂复合材料横向拉伸性能的影响

Effects of thermal residual stress on transverse tensile strength of unidirectional carbon fiber reinforced epoxy composites considering void

  • 摘要: 为研究由于材料固化产生的热残余应力对碳纤维增强环氧树脂复合材料横向拉伸性能预测结果的影响,发展了一种基于摄动算法的纤维和孔洞随机分布代表性体积单元(RVE)生成方法,建立更加接近真实材料微观结构的RVE模型。通过施加周期性边界条件,并赋予组分(纤维、基体和界面)材料本构关系,进而实现温度和机械荷载下模型的热残余应力和损伤失效分析。从结果中发现,材料固化过程会在纤维之间产生残余压应力,在模型孔隙周围产生沿加载方向的残余拉应力。所建立不含孔隙RVE模型的失效均是由于界面脱黏引起,材料固化在纤维之间产生的残余压应力会增加模型的预测强度。含有孔隙的RVE模型失效起始于孔隙周围的基体中,而材料固化在模型孔隙周围产生的热残余拉应力对含孔隙RVE模型预测的失效强度有降低作用。对于具有不同孔隙尺寸的RVE模型,模型的失效强度随着孔隙尺寸的增加而不断降低,但是热残余应力减弱了孔隙尺寸对模型预测结果的降低作用。对于具有不同长宽比椭圆形孔隙的RVE模型,热残余应力增加了孔隙长宽比对模型强度的降低作用。

     

    Abstract: To reveal the effects of manufacturing induced thermal residual stress(TRS) on the transverse tensile response prediction of carbon fiber reinforced epoxy composites, a representative volume element (RVE) generation method based on the random perturbation method was developed and RVE models which are more similar to the real microstructure were established. With periodical boundary conditions and the constitutive models of the constituents (fiber, matrix and interface), the thermal residual stress and progressive damage response of the models can be predicted under the thermal and mechanical loading conditions respectively. From the results, it can be found that the manufacturing process induces compressive stress in the matrix between two adjacent fibers and tensile stress around the voids along the loading direction. For the RVE models without voids, it is the interface debonding that contributes to the crack initiation and the thermal residual stress between two adjacent fibers increases the predicted strengths. The crack of the RVE models with voids all initiates from the matrix around the void and the manufacturing induced residual tensile stress around the void along the loading direction would contribute to the decrease of the predicted strengths from RVE models with voids. For the RVE models with different void sizes, with the increase of the void size, the failure strength decreases, and the thermal residual stress weakens the effects of void size on strength reduction. For the RVE models containing elliptical voids with different aspect ratios, the thermal residual stress would enhance the effects of aspect ratio on the strength reduction.

     

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