Baid Harsh, Schaal Christoph, Samajder Himadri, Mal Ajit
AlphaSTAR Corporation, Long Beach, CA 90804, USA.
Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA 90095, USA.
Ultrasonics. 2015 Feb;56:409-16. doi: 10.1016/j.ultras.2014.09.007. Epub 2014 Sep 22.
Composite materials are increasingly being used in advanced aircraft and aerospace structures. Despite their many advantages, composites are often susceptible to hidden damages that may occur during manufacturing and/or service of the structure. Therefore, safe operation of composite structures requires careful monitoring of the initiation and growth of such defects. Ultrasonic methods using guided waves offer a reliable and cost effective method for defects monitoring in advanced structures due to their long propagation range and their sensitivity to defects in their propagation path. In this paper, some of the useful properties of guided Lamb type waves are investigated, using analytical, numerical and experimental methods, in an effort to provide the knowledge base required for the development of viable structural health monitoring systems for composite structures. The laboratory experiments involve a pitch-catch method in which a pair of movable transducers is placed on the outside surface of the structure for generating and recording the wave signals. The specific cases considered include an aluminum plate, a woven composite laminate and an aluminum honeycomb sandwich panel. The agreement between experimental, numerical and theoretical results are shown to be excellent in certain frequency ranges, providing a guidance for the design of effective inspection systems.
复合材料越来越多地应用于先进飞机和航空航天结构中。尽管复合材料有许多优点，但它们在结构制造和/或服役期间往往容易出现隐藏损伤。因此，复合材料结构的安全运行需要仔细监测此类缺陷的产生和扩展。由于导波传播距离长且对传播路径中的缺陷敏感，利用导波的超声方法为先进结构中的缺陷监测提供了一种可靠且经济高效的方法。本文采用解析、数值和实验方法研究了兰姆型导波的一些有用特性，旨在为开发可行的复合材料结构健康监测系统提供所需的知识库。实验室实验采用了一种收发分离法，即将一对可移动换能器放置在结构外表面以产生和记录波信号。所考虑的具体案例包括铝板、编织复合材料层压板和铝蜂窝夹层板。实验、数值和理论结果在某些频率范围内显示出极好的一致性，为有效检测系统的设计提供了指导。
