一种改进的三维四向编织复合材料单胞模型及宏观弹性常数预测方法

发布时间：2018-08-24 16:52

【摘要】：提出了一种考虑打紧工艺导致纤维束截面形状沿其轨迹方向连续变化的三维四向编织复合材料改进单胞模型,并用于宏观弹性常数预测方法。首先,基于编织工艺过程分析,确定了单胞内部的纤维束布局形式;然后,从几何上推导了纤维束受挤压部位的位置坐标,并假设纤维束在受挤压前截面为圆形,受挤压部位发生圆形到椭圆的过渡变化,导致纤维轨迹产生弯曲,建立了纤维束截面为圆形和椭圆连续变化的改进单胞模型。通过该模型推导单胞编织参数和几何尺寸的数学关系,由此得出的几何特征数据与试件实测数据较为吻合,花节长度的预测值相对误差小于4%,相比于不考虑纤维束挤压变形的单胞模型更接近实际情况。最后,基于该改进的单胞模型,预测了三维四向编织复合材料的宏观弹性常数,并进一步研究了编织角和纤维体积分数对弹性常数的影响规律。
[Abstract]:An improved unit cell model of three dimensional four direction braided composites considering the continuous variation of fiber beam cross section along its trajectory due to tightening process is proposed and applied to the prediction of macroscopic elastic constants. Firstly, based on the analysis of braiding process, the fiber bundle layout in the unit cell is determined. Then, the position coordinates of the extruded fiber bundle are derived from the geometry, and the section of the fiber bundle is assumed to be circular before being extruded. The transition from circle to ellipse occurs in the extruded position, which leads to the bending of fiber trajectory. An improved unit cell model with circular and elliptical continuous changes of fiber bundle section is established. The mathematical relationship between unit cell braiding parameters and geometric dimensions is derived by this model. The geometric characteristic data obtained from the model are in good agreement with the measured data. The relative error of the predicted value of flower node length is less than 4, which is closer to the actual situation than the unit cell model which does not take into account the extrusion deformation of fiber bundles. Finally, based on the improved unit cell model, the macroscopic elastic constants of three-dimensional four-direction braided composites are predicted, and the effects of braiding angle and fiber volume fraction on elastic constants are further studied.
【作者单位】：北京航空航天大学能源与动力工程学院;航空发动机结构强度北京市重点实验室;先进航空发动机协同创新中心;
【基金】：国家自然科学基金(51675024;51305012;51375031) 航空科学基金(2014ZB51) 国防基础科研计划(B2120132006)
【分类号】：TB332

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