Numerical simulation of laser-generated ultrasonic by finite element method in the transparent coating-substrate system
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摘要: 在分析了网格大小和时间步长这两个重要参数和求解稳定性的基础上,采用有限元方法建立了透明薄膜/基底系统的热传导方程和热弹性方程的有限元模型。考虑了薄膜和基底的物理参数随温度的变化,得到了激光照射透明薄膜/基底系统温度场空间分布,由此计算出由热弹效应激发的超声对心波形。结果表明,透明薄膜厚度的增加,会影响到激光激发的对心超声波形;当薄膜厚度增大时,对心超声波形中的双极脉冲波形振幅变大,波形宽度加大。该方法为透明薄膜/基底系统的定量检测和无损评价提供了理论依据。Abstract: The finite element model of the thermal conductive equation and the thermo-elastic equation in the system consisting of a transparent coating and a opaque substrate is established based on the analysis of the stability of solution and two important parameters,meshing size and time step.Taking into account the temperature dependence of material properties,the transient temperature is obtained.The near-axis normal waveforms at the epicenter generated by thermo-elastic effect are obtained.The influence of the coating thickness on the waveform is analyzed.
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Keywords:
- laser physics /
- ultrasound /
- finite element method /
- coating-substrate system
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