四步法三维编织复合材料弯曲疲劳行为实验研究

摘要

The bending fatigue behavior of a kind of 3 - D braided composite was tested by MTS 810.23 instrument. All the tests were run at a stress ratio R(δmin,/δmax) = 0. 1 . The bending fatigue frequency was 3 Hz. The Data was got through quasi - static three - point bending and fatigue tests under different stress levels. Analyzing the Data which achieved during the MTS 810.23 bending fatigue tests ,we could get the α - N curve and the deflection of maximum and minimum curves . Fatigue mechanism was revealed based on comparing the material damage mode under different stress levels. The experimental results :under the load of 50% stress level ,there is still no damage in the sample after more than 106 cycles . The number of 80% ,70% and 60% under the stress of material failure are 12 833,50 370 and 101 652 respectively. Under the material fatigue loading, the stiffness degradation and deflection show the same tendency . The material bending fatigue limit is 50% , the α - N curve submits three stops. The material under low stress level of the fatigue life of the discrete is higher than the high stress level.%采用MTS 810.23仪器对一种四步法三维编织复合材料结构在应力比为R（σmin/σmax）=0.1、频率为3Hz正弦波条件下进行三点弯曲疲劳测试,研究三维编织复合材料弯曲疲劳性能。通过实验仪器测试准静态三点弯曲和不同应力下三点弯曲疲劳性质得到Data数据,通过对数据分析获得σ-N曲线和最大最小挠度曲线,对比不同应力水平下材料破坏形态从而揭示材料弯曲疲劳机理。实验结果：50%应力水平下,试样经过106次以上的循环仍然没有破坏,80%、70%和60%应力下材料失效的圈数分别是12 833、50 370、101 652。材料疲劳加载下刚度降解和挠度变化趋势相似,材料弯曲疲劳极限为50%,材料σ-N曲线呈三段式,材料低应力水平下疲劳寿命离散性高于高应力水平。