接头尺寸对玻璃纤维/热塑性树脂复合材料机械连接性能的影响接头尺寸对玻璃纤维/热塑性树脂复合材料机械连接性能的影响

对玻璃纤维/聚酰胺（GF/PA）、玻璃纤维/聚甲醛（GF/POM）、玻璃纤维/聚丙烯（GF/PP）这三种玻璃纤维增强热塑性树脂基复合材料进行机械连接试样的常规拉伸试验，以及低周疲劳拉伸试验，并对疲劳前后的试样断裂面进行SEM观察，研究了接头尺寸（宽径比w/d （试样宽度/开孔直径）和端径比e/d （试样端距/开孔直径））对机械连接件破坏载荷和破坏模式的影响。实验结果表明:玻璃纤维增强纤热塑性树脂复合材料机械连接件的承载能力在一定的宽径比时会随着e/d的增加而增加，当w/d≥3、e/d≥2时趋于稳定；破坏模式以拉伸破坏为主；低周疲劳拉伸对GF/POM和GF/PA机械连接试样拉伸强度产生一定的影响，而对GF/PP的拉伸强度无明显影响，低周疲劳拉伸对玻璃纤维增强热塑性树脂复合材料机械连接试样的破坏模式没有影响。SEM观察显示，随着疲劳载荷水平的增加，GF/POM和GF/PA的断裂面上被抽拔纤维数量增加，而GF/PP断裂面纤维与基体的存在状态无明显变化。 

Effect of joint dimension on the mechanically fastened joint properties of glass fiber/thermoplastic resin composites

The mechanically fastened joint specimen tensile test of three kinds of glass fiber reinforced thermoplastic resin composites including glass fiber/polyamide (GF/PA), glass fiber/polyformaldehyde (GF/POM) and glass fiber/polypropylene (GF/PP) were conducted. Additionally, low cycle fatigue tensile test was carried out for three kinds of composite mechanical joints, and the fracture surface of the sample before and after fatigue was observed by SEM, to investigate the effect of joint dimension (sample width/hole diameter(w/d) and edge distance/hole diameter(e/d)) on the failure load of mechanically fastened joint and failure mode. It is found that:The bearing capacity of the mechanically fastened joint of glass fiber reinforced thermoplastic resin composites increases with the increase of e/d at a certain w/d, and tends to be stable when w/d ≥ 3 and e/d ≥ 2. The failure mode is mainly tensile failure. Low cycle tensile fatigue has a certain effect on the tensile strength of GF/POM and GF/PA mechanically jointed specimens, but has no significant effect on that of GF/PP. On the other hand, low cycle fatigue stretch has no obvious effect on the failure mode of the mechanically bonded specimens of glass fiber reinforced thermoplastic resin. SEM observation shows that, with the increase of the fatigue load level, the number of pulled fibers on the fracture surface of GF/POM and GF/PA increases, while there is no significant effect on the existence of fiber and matrix in GF/PP.