GFRP复合材料-轻木夹芯梁弯曲疲劳性能试验

摘要

为研究真空导入成型的玻璃纤维增强树脂基复合材料-Balsa 轻木(GFRP-Balsa)夹芯梁弯曲疲劳性能,进行了普通无格构、单格构增强、双格构增强三种类型共42根试件在不同荷载等级下的四点弯曲疲劳试验,得到夹芯梁的弯曲疲劳破坏模式、疲劳寿命和损伤演化规律,分析了三种类型夹芯梁在弯曲疲劳载荷下不同的损伤机制.研究结果发现,无格构夹芯梁的失效模式统一为芯材剪切和面板脱粘,格构增强夹芯梁的失效模式随格构设置及载荷等级变化,主要有上面板屈曲或压坏、下面板拉断等;采用指数经验模型拟合夹芯梁的疲劳荷载-寿命(S-N)曲线,得到三种类型夹芯梁的寿命预测公式;夹芯梁的位移演化历经"位移瞬降-平稳演化-损伤萌生至破坏"三个阶段,相对于无格构试件,格构增强试件在疲劳失效前有较明显预兆.%In order to study the flexural fatigue behavior of glass fiber reinforced polymer(GFRP)-Balsa sandwich beams prepared by a vacuum assisted resin infusion process,four-point fatigue bending tests for 42 specimens under different load levels were carried out.The fatigue failure modes,fatigue life and damage evolution of the sandwich beams were obtained.The damage mechanism of the three types of sandwich beams under bending fatigue load was analyzed.The failure modes of the beams without lattice-web are unified for the core shear failure and debonding, while those of the beams with lattice-web reinforced are varies with the number of lattice-web and the load level, which is buckling or partial crushing of upper facesheet or tensile failure of lower facesheet.The fatigue load-life(S-N)curves of sandwich beams were fitted by exponential empirical model,and the life prediction formulas of three kinds of sandwich beams were obtained.The displacement evolution of the sandwich beams undergoes three stages of"transient fall-stable evolution-damage initiation to failure".Compared with the specimens without lattice-web, the lattice-web reinforced specimens have obvious signs before fatigue failure.