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| Numerical simulation of the nonlinear effects of micro-cracks and ultrasonic waves in the structure |
| Received:September 07, 2017 Revised:December 18, 2017 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7511/jslx20170907001 |
| KeyWord:micro-crack nonlinear ultrasonics nondestructive testing no-collinear mixing |
| Author | Institution |
| 李立 |
北京工业大学 机电学院, 北京 |
| 焦敬品 |
北京工业大学 机电学院, 北京 |
| 吴斌 |
北京工业大学 机电学院, 北京 |
| 何存富 |
北京工业大学 机电学院, 北京 |
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| Abstract: |
| Aiming at the detection of micro-cracks in structures,the nonlinear mixing effect of micro-cracks and ultrasonic waves in structures is studied from a finite element model.Based on the classical nonlinear theory,the theoretical conditions for mixing effect of two longitudinal ultrasonic waves are obtained.The conditions of mixing generated by the interaction between two longitudinal waves and micro-cracks were studied through the finite element simulation.The effects of static stresses,friction coefficient and crack direction on the mixing effect were analyzed.It is found that the mixing nonlinear condition caused by the interaction between ultrasonic waves and micro-cracks agrees with the condition of mixing generation under classical nonlinear theory.The static stress at the crack interface has a significant effect on the amplitude of the differential frequency shear wave.The nonlinear mixing effect becomes strongest when the static stress is close to the maximum stress obtained by the non-crack model.The friction coefficient of the crack interface has little influence on the nonlinear mixing effect of the ultrasonic wave.The direction of shear wave in the simulation results is basically the same as the theoretical mixing frequency components predicted by the classical nonlinear theory and hardly affected by the variation of the crack direction.The direction of propagation of the mixing frequency components shear waves varies with the direction of the crack.The research work in this paper is a useful exploration for the detection of micro-cracks and direction recognition. |