The Mechanics of the Generation and Propagation of Thermoelastically Generated Lamb Waves in Plates and Panels

将进行实验/数值研究，以获得 了解生成的基本机制， 热弹性产生的兰姆波的传播， 需要利用这些波进行无损评估， 晶片、板和面板。 由于兰姆波在平面内传播， 一个板块和影响整个厚度，他们是优秀的， 确定缺陷的程度和严重性， 裂纹、分层和材料性能的局部变化。 宽带瞬态Lamb波将通过辐照 具有短持续时间纤维的板表面上的小区域 引导激光脉冲 由此产生的热冲击会产生一种波 然后由光纤干涉仪感测。 数据 分析将在频域中进行， 留在波上的缺陷是最明显的。 数字 实验方法相结合， 这些参数的产生和传播所涉及的 波和它们受缺陷影响的方式。 的 由此产生的知识将用于设计有效的手段， 产生具有所需特性的波浪，并优化 用于识别和表征缺陷的整个系统， 质量控制和安全保证。

An experimental/numeric study will be carried out for acquiring the understanding of the basic mechanics of the generation and propagation of thermoelastically generated Lamb waves that is needed to exploit these waves for nondestructive evaluation of wafers, plates and panels. Since Lamb waves propagate in the plane of a plate and affect the whole thickness, they are excellent for determining the extent and severity of defects such as surface cracks, delaminations and local changes in material properties. Broadband transient Lamb waves will be generated by irradiating a small area on the surface of a plate with a short duration fiber guided laser pulse. The resultant thermal shock generates a wave which is then sensed by a fiber-optic interferometer. Data analysis will be in the frequency domain where the imprints that defects leave on the wave are most clearly evident. The numeric and experimental methods will be combined to study the basic parameters involved in the generation and propagation of these waves and in the ways in which they are influenced by defects. The resultant knowledge will be used to design efficient means for generating waves with desirable characteristics and to optimize the overall system for identifying and characterizing defects both for quality control and safety assurance.