Durão Luis M P, Matos João E, Loureiro Nuno C, Esteves José L, Fernandes Susana C F
ISEP, Instituto Politécnico do Porto, Rua Dr. António Bernardino de Almeida, 4249-015 Porto, Portugal.
Associate Laboratory for Energy, Transports and Aerospace (LAETA-INEGI), Rua Dr. Roberto Frias 400, 4200-465 Porto, Portugal.
Materials (Basel). 2023 Mar 28;16(7):2688. doi: 10.3390/ma16072688.
Fiber reinforced composites are widely used in the production of parts for load bearing structures. It is generally recognized that composites can be affected both by monotonic and cyclic loading. For assembly purposes, drilling is needed, but holes can act as stress concentration notches, leading to damage propagation and failure. In this work, a batch of carbon/epoxy plates is drilled by different drill geometries, while thrust force is monitored and the hole's surrounding region is inspected. Based on radiographic images, the area and other features of the damaged region are computed for damage assessment. Finally, the specimens are subjected to Bearing Fatigue tests. Cyclic loading causes ovality of the holes and the loss of nearly 10% of the bearing net strength. These results can help to establish an association between the damaged region and the material's fatigue resistance, as larger damage extension and deformation by cyclic stress contribute to the loss of load carrying capacity of parts.
纤维增强复合材料广泛应用于承载结构部件的生产。人们普遍认识到，复合材料会受到单调加载和循环加载的影响。出于组装目的，需要钻孔，但孔可能会成为应力集中缺口，导致损伤扩展和失效。在这项工作中，一批碳/环氧板采用不同的钻头几何形状进行钻孔，同时监测推力并检查孔的周边区域。基于射线图像，计算损伤区域的面积和其他特征以进行损伤评估。最后，对试样进行轴承疲劳试验。循环加载会导致孔的椭圆化以及轴承净强度损失近10%。这些结果有助于建立损伤区域与材料疲劳抗性之间的关联，因为循环应力导致的更大损伤扩展和变形会导致部件承载能力的损失。
