三维编织复合材料悬臂梁的振动特性

Vibration characteristics of 3D braided composites cantilever beam

基于三维四向和五向编织复合材料的细观结构和单胞模型,对三维四步法矩形截面编织复合材料悬臂梁的振动阻尼性能进行了理论分析,研究了编织角、纤维体积分数等工艺参数对材料振动阻尼特性的影响,并与实验结果进行了对比。对三细胞模型进行了改进,采用混合律得到了材料的总体刚度,进而得到一阶固有频率。此外,还分别计算了一个周期内不同走向纱线和基体振动消耗的能量,以及总振动能量,得到了材料的损耗因子。结果表明,对于三维四向和五向编织复合材料,一阶固有频率随编织角的增加而减小,随纤维体积分数的增加而增大;而损耗因子随编织角的增加而增大,随纤维体积分数的增加而减小,并表现出明显的非线性变化规律。

The vibration properties of 3D four-step rectangular cross-sectional braided composites cantilever beam with experimental verification were studied.Based on the meso-structure and unit cell model of four-directional and five-directional composites,the law of vibration characteristics influenced by material parameters（i.e.braiding angle and fiber volume fraction） was explored by the theoretical analysis.By analyzing and modifying the three-cell model,the first order natural frequency was obtained from global stiffness using the rule of mixture method,while loss factor was obtained by calculating the consumed energy by yarns with different orientations and matrix,and the whole vibration energy in a vibration cycle.Comparing the calculation results with the experimental results,the first order natural frequency increases with fiber volume fraction,but decreases with braiding angle;while loss factor increases non-linearly with braiding angle,but decreases with fiber volume fraction.