三维编织复合材料的疲劳性能

FATIGUE PROPERTIES OF THREE DIMENSIONAL BRAIDING COMPOSITES

研究了三维编织复合材料的疲劳性能和编织结构对疲劳性能的影响.进行了应力比为0.1、实验频率为10 Hz的拉-拉疲劳性能测试.结果表明,三维编织复合材料的疲劳强度约为其抗拉强度的60%～80%,比金属材料的疲劳强度的相对值高.编织角是影响三维编织结构复合材料疲劳性能的一个主要因素.随着编织角的增大,疲劳过程中易出现各种损伤,而且伴随明显的升温现象.编织角大的试件在疲劳实验过程中模量变化明显,并且呈现逐渐升高的趋势,这与金属材料的双模量变化规律不同.在疲劳次数为100万次后,试件的剩余强度高于静载拉伸强度,这主要是由于在疲劳测试过程中,试件内编织纱线的取向更接近受力方向所致.

The dynamic mechanical properties fatigue properties and the effect of braiding structures on the fatigue properties of three dimensional braiding composites were studied, Tensile tensile fatigue tests were carried out at different maximum stress ratios , All the tests were run at a stress ratio R（σmin/σmax ）=0.1, The fatigue frequency was 10Hz, The results show that the fatigue strength of three dimensional braiding composites is 60%～80% of its static strength, which is higher than that of metal material, The braiding angles have a great influence on the fatigue properties of 3-D braiding composites. The fatigue damage will be easy and the hysteresis heat will occur for the large braiding angle composites. The strain stress curves of the specimens with large braiding angles are non-lincar. and the rnodulus is increasing with the testing time increasing. The variational rule of fatigue properties of three dimensional composites contrasted with the metal＇s rules. After one million times of fatigue tests, the residual strength of the specimens is higher than the static test strength, which is due to fiber bundles being reoriented to a lower angle toward the tensile loading direction after the fatigue test.