Off-Axis Fatigue of Graphite/Epoxy Composite
Off-Axis Fatigue of Graphite/Epoxy Composite
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DOI：
10.1520/stp27624s
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
J. Awerbuch;H. Hahn
中科院分区：
文献类型：
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作者：
J. Awerbuch;H. Hahn
研究了AS/3501-5A石墨/环氧树脂复合材料的离轴静态和疲劳行为，以表征基体/界面控制的失效。测试了七种不同的离轴角：0、10、20、30、45、60和90度。初始（静态）和疲劳后的剩余强度与S-N关系一起获得。断裂面进行了检查，通过显微照片和立体（三维）扫描电子显微镜（SEM）的照片，以描绘故障模式，这些检查的结果进行了讨论。离轴静强度，包括散射，充分表征了一个多项式和无量纲的强度参数。基本上，没有观察到强度或模量退化的样本生存疲劳载荷的10 - 6个周期，无论离轴角或疲劳应力水平。当疲劳应力水平相对于静强度归一化时，所有数据似乎都落在相同的S-N曲线上。疲劳失效发生时没有任何警告或可见损坏。基体破坏特征随离轴角的变化而变化，表现为锯齿状、轴向和横向裂纹。在所有离轴角下观察到寿命的大分散;然而，由于本研究中使用的样本数量不足以提供有意义的统计S-N数据，因此需要对石墨/环氧复合材料的离轴（和角层）行为进行更详细的调查。
Off-axis static and fatigue behavior of AS/3501-5A graphite/epoxy was studied in an effort to characterize the matrix/interface-controlled failure. Seven different off-axis angles were tested: 0, 10, 20, 30, 45, 60, and 90 deg. Initial (static) and post-fatigue residual strength were obtained together with S-N relationships. Fracture surfaces were examined through photomicrographs and stereo (three-dimensional) scanning electron microscope (SEM) photographs, in order to delineate failure modes, and the results of these inspections are discussed. The off-axis static strength, including scatter, was fully characterized by a polynomial and a nondimensional strength parameter. Essentially, no strength or modulus degradation was observed in the specimens surviving fatigue loading of 10 6 cycles regardless of the off-axis angle or fatigue stress level. When fatigue stress level is normalized with respect to static strength, all data seem to fall on the same S-N curve. Fatigue failure occurred without any warning or visible damage. Matrix failure characteristics vary with off-axis angle and appear in the form of serrations and axial and transverse cracks. Large scatter in life was observed at all off-axis angles; however, since the number of specimens employed in the present study is not sufficient to provide meaningful statistical S-N data, a more detailed investigation of the off-axis (and angle ply) behavior of graphite/epoxy composites is warranted.