Elucidation of subharmonic generation mechanism and challenge to new ultrasonic nondestructive evaluation

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K14018
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Structural engineering/Earthquake engineering/Maintenance management engineering
• Research Institution: Gunma University
• Principal Investigator: SAITOH Takahiro 群馬大学, 大学院理工学府, 准教授 (00535114)
• Co-Investigator(Kenkyū-buntansha): 中畑 和之 愛媛大学, 理工学研究科(工学系), 教授 (20380256)
• Co-Investigator(Renkei-kenkyūsha): MARUYAMA Shin-ichi (60344925)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 非線形超音波 / 高調波 / 分調波 / 境界要素法 / 粒子法 / 非破壊評価

Outline of Final Research Achievements

In recent years, a new ultrasonic nondestructive evaluation method that utilizes nonlinear ultrasonic behavior generated in cracks or at a bi-material interface defect has emerged. However, the mechanism of generating subharmonics is theoretically still not well understood. Therefore, in this research, dynamic contact problems of a bi-material interface defect and a crack with contact boundary conditions are investigated by using numerical methods such as the convolution quadrature time-domain boundary element method (CQBEM), moving particle semi-implicit simulation, and elastodynamic finite integration technique. In addition, some crack shape reconstruction methods are developed based on the inverse scattering theory, and the applicability is considered. Numerical results show that the subharmonic generation is depend on the angle of incident ultrasonic waves, quasi-natural resonance frequency, and contact boundary conditions.

Free Research Field

応用力学、計算力学、非破壊評価