Abdellah Mohammed Y, Hassan Mohamed K, Mohamed Ahmed F, Khalil Khalil Abdelrazek
Mechanical Engineering Department, College of Engineering and Islamic Architecture, Umm Al-Qura University, Makkah 21955, Saudi Arabia.
Mechanical Engineering Department, Faculty of Engineering, South Valley University, Qena 83521, Egypt.
Polymers (Basel). 2021 Apr 12;13(8):1251. doi: 10.3390/polym13081251.
Glass fiber reinforced polymer (GFRP) composite laminates are considered the key material in many industries such as the infrastructure industries and the aerospace sector, and in building structures due to their superior specific strength and lightweight properties. The prediction of specimens' nominal strength with open holes is still an attractive and questionable field of study. The specimen size effect is referred to its strength degradation due to the presence of holes when specimen geometry gets scaled. The non-destructive test used to measure the nominal strength of such material is a great tool for fast selection purposes, but not secure enough for several purposes. Furthermore, the destructive tests which are more expensive and time-consuming should be avoided in such structures. The present work aims to predict the nominal strength of open-hole GFRP's composite using modal analysis of their natural frequency as non-destructive tests. At this end, the natural frequency, which is measured using modal analysis procedures, is combined with both linear elastic fracture mechanics (LEFM) and the theory of elasticity to predict the nominal strength of open-hole composite laminates. This advanced model employs two parameters of surface release energy resulting from a simple tension test and Young's modulus based on vibration modal analysis. It is well established that these types of materials are also subjected to a size effect in dynamic response. Inversely to the known static loading size effect, the size effect in dynamic response increases with specimen size. The novel model gives excellent and acceptable results when compared with experimental and finite element ones. Size effects curves of a nominal strength of these laminates have a very close relative value with those obtained from finite element and analytical modeling. Moreover, the received design tables and graphs would be highly applicable when selecting suitable materials for similar industrial applications.
玻璃纤维增强聚合物（GFRP）复合材料层压板因其卓越的比强度和轻质特性，被视为基础设施行业、航空航天领域以及建筑结构等众多行业的关键材料。对带有开孔的试样名义强度进行预测，仍然是一个引人关注且存在疑问的研究领域。试样尺寸效应是指当试样几何尺寸缩放时，由于孔洞的存在导致其强度下降。用于测量此类材料名义强度的无损检测是快速筛选的有力工具，但在某些方面还不够可靠。此外，在这种结构中应避免采用更昂贵且耗时的破坏性试验。当前工作旨在通过对开孔GFRP复合材料的固有频率进行模态分析（作为无损检测）来预测其名义强度。为此，将通过模态分析程序测得的固有频率与线弹性断裂力学（LEFM）和弹性理论相结合，以预测开孔复合材料层压板的名义强度。这个先进的模型采用了简单拉伸试验得出的表面释放能量和基于振动模态分析的杨氏模量这两个参数。众所周知，这类材料在动态响应中也会受到尺寸效应的影响。与已知的静态加载尺寸效应相反，动态响应中的尺寸效应随试样尺寸的增大而增大。与实验结果和有限元结果相比，该新型模型给出了出色且可接受的结果。这些层压板名义强度的尺寸效应曲线与通过有限元和解析建模获得的曲线具有非常接近的相对值。此外，所得到的设计表格和图表在为类似工业应用选择合适材料时将具有很高的适用性。
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