碳纤维增强树脂基复合材料加工表面粗糙度对疲劳性能的影响

Effect of Machined Surface Roughness on Fatigue Performance of Carbon Fiber Reinforced Polymer Composite

采用磨削和铣削(顺铣、逆铣)加工工艺获得不同表面粗糙度S_(a)的碳纤维增强树脂基(CFRP)复合材料试样并进行拉-拉疲劳试验,基于刚度退化模型分析了加工表面粗糙度对疲劳性能的影响。结果表明:磨削、顺铣和逆铣试样的S_(a)分别为1.2,3.2,5.9μm;磨削试样0°纤维铺层表面纤维缺失,存在空隙,铣削试样在45°纤维铺层表面存在较多凹坑,其中顺铣试样凹坑更多且更深;磨削试样的疲劳寿命最高,逆铣试样次之,顺铣试样最低;随着S_(a)的增大,CFRP复合材料试样表面裂纹迅速萌生扩展,刚度退化初始阶段的退化速率升高,刚度退化I阶段更快结束,试样的疲劳寿命降低。

Carbon fiber reinforced polymer composite(CFRP)samples with different surface roughness S_(a) were obtained by grinding and milling(up-milling and down-milling)processes,and tensile-tension fatigue tests were carried out.The effect of machined surface roughness on fatigue performance was studied based on the stiffness degradation model.The results show that the S_(a) of the grinding,up-milling and down-milling samples were 1.2,3.2,5.9μm,respectively.Some fibers of the 0°fiber layer of the grinding samples were missing,resulting in voids.The milling samples had many pits on the surface of the 45°fiber layer,and the pits in the down-milling samples were more and deeper.The fatigue life of the grinding samples was the highest,followed by the up-milling samples,and the down-milling samples was the lowest.With increasing S_(a),the surface cracks of the CFRP samples rapidly initiated and propagated,the degradation rate of the initial stage of stiffness degradation increased,the stage I of stiffness degradation ended sooner,and the fatigue life of the samples decreased.