2021 Fiscal Year Final Research Report
Detection of contact-type failure of large-scale structure based on nonlinear wave modulation using multi-excitation using decentralized control
| Project/Area Number |
20K14682
|
|---|
| Research Category |
Grant-in-Aid for Early-Career Scientists
|
| Allocation Type | Multi-year Fund |
|---|
| Review Section |
Basic Section 20010:Mechanics and mechatronics-related
|
|---|
| Research Institution | The University of Shiga Prefecture |
|---|
Principal Investigator |
|
|---|
| Project Period (FY) |
2020-04-01 – 2022-03-31
|
| Keywords | 超音波 / 非線形振動 / 損傷検出 / 自励駆動 / 固有振動 / 多点加振 / 分散制御 |
|---|
| Outline of Final Research Achievements |
In this study, I developed the multi-excitation method using decentralized control with local feedback control for excitation of ultrasonic natural vibrations and the detection method of contact-type failure based on nonlinear wave modulation using developed multi-excitation method. Firstly, the multi-excitation method was developed. The analog circuit of local feedback control was designed. Therefore, it was confirmed that the ultrasonic natural vibration can be excited. Moreover, the change of natural vibration modes was realized by forced entrainment. Next, the detection experiment of contact-type failure based on nonlinear wave modulation using sexcited ultrasonic natural vibrations. It was confirmed that the oscillated frequency of ultrasonic vibrations is varied in synchronization with varying of the natural frequencies caused by nonlinear wave modulation. Therefore, the variation width of oscillated frequencies increases with the development of contact-type failure.
|
| Free Research Field |
機械力学・振動制御
|
| Academic Significance and Societal Importance of the Research Achievements |
大型構造物に生じる疲労き裂やボルト緩みなどは，損傷面が接触しており検出が困難である場合がある．このような接触型損傷を精度よく検出することは，構造物の劣化度合いを正確に評価するために重要である．微小な接触型損傷を精度よく検出する手法の一つに，超音波振動の振幅や位相に生じる変調（非線形波動変調）に基づく手法があるが，大型構造物では超音波固有振動の励起が困難であるため適用できなかった．本研究では，超音波固有振動で自動的に発振し，固有振動モードに合わせて加振力が自動的に調整される分散制御型多点加振を実現し，非線形波動変調に基づく接触型損傷検出法の大型構造物への適用を可能にした．
|
