单边裂缝钛合金/碳纤维/聚醚醚酮奈米复材积层板之疲劳破坏及残留性质探讨

Fatigue Response of Hybrid Ti/APC-2 Nanocomposite Laminates with Single-Edged Cracks

摘要: 本文旨在研制钛合金碳纤维含奈米微粒复材积层板以及无奈米微粒复材积层板并探讨其在不同单边裂缝尺寸下的机械性质。积层板是由一层0.55 mm APC-2预浸布与两层0.5 mm钛合金所构成。在APC-2预浸布表面均匀涂布SiO2奈米微粒制作奈米复材积层板，APC-2依十字迭[0/90]s堆栈，钛合金以铬酸阳极法进行表面处理，使钛合金与APC-2预浸布产生良好黏结，并以修正隔膜成型法进行热压固化完成制作，完成后的试片以放电加工切割单边裂缝尺寸，如1.5 mm、3.0 mm、4.5 mm、6.0 mm。试片以MTS 810万能材料试验机来行拉伸与疲劳测试。进行静态拉伸测试获致积层板极限强度及劲度等机械性质，并依实验结果绘制该裂缝尺寸下力量位移关系图；拉伸–拉伸疲劳测试采用负荷控制，正弦波负载，应力比为0.1，频率为5 Hz，最后将疲劳实验数据绘制不同裂缝尺寸下负载与疲劳振次关系图。综合所有实验结果获致以下结论：添加奈米微粒来提升极限强度，在含单边裂缝积层板上效果不显著；含奈米微粒积层板之抗疲劳性约略优于无奈米微粒积层板；机械性质随裂缝长增加而递减。

Abstract: The aims of this study are to fabricate Ti/APC-2 hybrid composite laminates with and without (W/WO) nanoparticles and to investigate the mechanical properties of Ti/APC-2 laminates with single-edged cracks due to ten-sile and cyclic tests. The composite laminates were three layers with one 0.55 mm thick APC-2 lay-ups covered by two 0.5 mm thick Grand 1 titanium alloy sheets. Nanoparticles SiO2 were dispersed uniformly on the interfaces of APC-2 with the optimal amount of 1 wt%. The stacking sequence of APC-2 was cross-ply [0/90]s. The single-edged cracks were cut by electrical discharge machine, such as 1.5 mm, 3.0 mm, 4.5 mm, and 6.0 mm. The mechanical properties, such as ultimate tensile strength, longitudinal stiffness, of plane composite laminates W/WO nanoparticles were ob-tained from the static tensile tests. Next, the load-displacement diagrams were plotted for the laminates with sin-gle-edged cracks. The fracture toughness of hybrid laminates was obtained. The constant stress amplitude tension-ten- sion cyclic tests were carried out by using load-control mode at a sinusoidal loading wave with frequency of 5 Hz and stress ratio R = 0.1. The received fatigue data were plotted in S-N curves for different single-edged cracks. From the results, for different crack lengths both ultimate strengths of Ti/APC-2 composite laminates and nanocomposite lami-nates are very close. Ti/APC-2 cross-ply nanocomposite laminates have better fatigue resistance than that of laminates without nanoparticles. The longer the crack length is, the more their properties are reduced, and also the fatigue lives shortened.