Treyssède Fabien
LUNAM Université, IFSTTAR, GERS, GeoEND, F-44340 Bouguenais, France.
J Acoust Soc Am. 2016 Jul;140(1):498. doi: 10.1121/1.4955080.
Elastic guided waves are of interest for the non-destructive evaluation of cables. Cables are most often multi-wire structures, and understanding wave propagation requires numerical models accounting for the helical geometry of individual wires, the interwire contact mechanisms and the effects of prestress. In this paper, a modal approach based on a so-called semi-analytical finite element method and taking advantage of a biorthogonality relation is proposed in order to calculate the forced response under excitation of a cable, multi-wired, twisted, and prestressed. The main goal of this paper is to investigate how the energy transfers from a given wire, directly excited, to the other wires in order to identify some localization of energy inside the active wire as the waves propagate along the waveguide. The power flow of the excited field is theoretically derived and an energy transfer parameter is proposed to evaluate the level of energy localization inside a given wire. Numerical results obtained for different polarizations of excitation, central and peripheral, highlight how the energy may localize, spread, or strongly change in the cross-section as waves travel along the axis. In particular, a compressional mode localized inside the central wire is found, with little dispersion and significant excitability.
弹性导波在电缆无损检测中具有重要意义。电缆通常是多股结构，理解波的传播需要考虑单根导线螺旋几何形状、导线间接触机制以及预应力影响的数值模型。本文提出了一种基于所谓半解析有限元法并利用双正交关系的模态方法，以计算多股、扭绞且预应力作用下电缆在激励时的受迫响应。本文的主要目标是研究能量如何从直接受激的特定导线传递到其他导线，以便在波沿波导传播时识别有源导线内的能量局部化情况。理论推导了激励场的功率流，并提出了一个能量传递参数来评估给定导线内的能量局部化程度。针对不同极化（中心和周边）激励获得的数值结果，突出了波沿轴传播时能量在横截面中如何局部化、扩散或剧烈变化。特别是，发现了一种集中在中心导线内的压缩模式，其色散很小且具有显著的可激发性。
