关键词: 临界现象/
脉冲序列/
调制全透声
English Abstract
Studies on the mechanism of acoustic pulse train and full transmission
Cao Song-Hua1,2,Wu Jiu-Hui1,2,
Wang Yu1,
Hou Ming-Ming1,2,
Li Jing1,2
1.School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710049, China;
2.State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an 710049, China
Received Date:23 October 2015
Accepted Date:30 November 2015
Published Online:05 March 2016
Abstract:Critical phenomenon in a one-dimensional periodic stratified structure with time-varying elastic modulus functions is found out for acoustic waves. By using the classical separation of variables method to solve the one-dimensional wave equation, and taking the time-varying elastic modulus functions into consideration, a critical value can be found of the varying amplitude of the time-varying elastic modulus functions. Near the critical value, due to the alternation of the characteristic exponent, the reflectivity of the one-dimensional periodic stratified structure changes in essence. Below or at the critical value, the incident wave can be converted into a periodic and millisecond pulse train, particularly when the varying amplitude is at the critical value. In addition, the layer number can be up to 16. Under these circumstances, complete pulse train of 0 or 1 is generated with respect to time; in the end, when above the critical value, the reflectivity decreases rapidly to 0 within 50 milliseconds, indicating that, at one moment, the incident wave can be totally transferred through the structure as if the stratified structure becomes transparent, which means a modulational transparency. In conclusion, by altering the varying amplitude of the time-varying elastic modulus functions, three different phenomena are generated. These excellent properties could find potential applications of one-dimensional periodic stratified structure in the acoustic transducer and the control of the acoustic wave.
Keywords: critical phenomenon/
acoustic pulse train/
full transmission
