Li Mingliang, Deng Mingxi, Gao Guangjian, Xiang Yanxun
Department of Physics, Logistics Engineering University, Chongqing 401331, China.
Department of Physics, Logistics Engineering University, Chongqing 401331, China.
Ultrasonics. 2018 Jan;82:171-177. doi: 10.1016/j.ultras.2017.08.005. Epub 2017 Aug 18.
The appropriate mode pairs of primary and double-frequency circumferential guided waves (CGWs) have been investigated and selected for generation of the cumulative second harmonics, which are applicable for quantitative assessment of damage/degradation in a circular tube. The selection criteria follow the requirements: the higher efficiency of cumulative second-harmonic generation (SHG) of primary CGW propagation, and the larger response sensitivity of cumulative SHG to material damage/degradation [characterized by variation in the third-order elastic (TOE) constants]. The acoustic nonlinearity parameter β of CGW propagation and the change rate of normalized β versus the TOE constants of tube material are, respectively, used to describe the efficiency of SHG and its response sensitivity to damage/degradation. Based on the selection criteria proposed, all the possible mode pairs of primary and double-frequency CGWs satisfying the phase velocity matching have been numerically examined. It has been found that there are indeed some mode pairs of CGW propagation with the larger values both of β and the change rate of normalized β versus the TOE constants. The CGW mode pairs found in this paper are of practical significance for quantitative assessment of damage/degradation in the circular tube.
已对一次和双频周向导波（CGW）的合适模式对进行了研究和选择，以产生累积二次谐波，这些谐波适用于圆形管道中损伤/退化的定量评估。选择标准遵循以下要求：一次CGW传播的累积二次谐波产生（SHG）效率更高，以及累积SHG对材料损伤/退化的响应灵敏度更大[以三阶弹性（TOE）常数的变化为特征]。CGW传播的声学非线性参数β以及归一化β相对于管材TOE常数的变化率，分别用于描述SHG的效率及其对损伤/退化的响应灵敏度。基于所提出的选择标准，对所有满足相速度匹配的一次和双频CGW的可能模式对进行了数值研究。已经发现，确实存在一些CGW传播的模式对，其β值以及归一化β相对于TOE常数的变化率都较大。本文中发现的CGW模式对对于圆形管道中损伤/退化的定量评估具有实际意义。
