Evaluation of a critical impact energy in GFRP under fatigue loading
Evaluation of a critical impact energy in GFRP under fatigue loading
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DOI：
10.1016/j.compscitech.2014.07.010
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发表时间：
2014-10-06
影响因子：
9.1
通讯作者：
Fiedler, B.
中科院分区：
文献类型：
--
作者：
Kosmann, N.;Riecken, B. T.;Fiedler, B.
纤维增强聚合物结构中的缺陷，例如冲击损伤，对疲劳行为有重大影响。冲击可能发生在复合材料结构的使用寿命期间，并导致具有不同纤维取向的相邻层之间的分层以及层内的基体裂纹。由玻璃纤维无卷曲织物制成的样品是通过真空辅助树脂传递模塑法生产的。使用带有半球形头部的落锤会造成低速冲击损坏。样本在疲劳载荷下进行测试，应力比为 R = -1（拉伸-压缩）。目的是将纤维增强聚合物疲劳测试中的损伤发展特征描述为冲击能量、寿命和应力水平的函数。因此，绘制了疲劳测试期间由于基体裂纹、分层、纤维失效和样品温度变化导致的刚度下降与负载循环次数的关系图。在具有规定载荷循环次数的间断疲劳试验中，确定了冲击损伤对基体裂纹发展的影响，并将其与刚度退化相关联。此外，在中断测试期间进行了热弹性应力分析，以确定冲击损坏区域的应力集中。 (C) 2014 Elsevier Ltd. 保留所有权利。
Defects in fibre reinforced polymer structures, such as impact damages, have a major influence on the fatigue behaviour. Impacts may occur during the lifetime of composite structures and lead to delaminations between adjacent layers with different fibre orientations and to matrix cracks within the layers. Specimens made of a glass fibre non crimp fabric were produced by vacuum assisted resin transfer moulding. Low velocity impact damage was introduced by use of a drop weight with a hemispherical head. The specimens were tested under fatigue loading with a stress ratio of R = -1 (tension-compression). The aim was to characterise damage development in fatigue testing of fibre reinforced polymers as a function of impact energy, lifetime and stress level. Therefore, the stiffness degradation during fatigue testing due to matrix cracks, delaminations, fibre failure and temperature development of the specimens was plotted vs. the number of load cycles. In interrupted fatigue tests with defined numbers of load cycles the influence of impact damages on matrix crack development was determined and correlated with stiffness degradation. Furthermore, thermoelastic stress analysis was performed during the interrupted tests in order to determine stress concentrations in the area of impact damage. (C) 2014 Elsevier Ltd. All rights reserved.