3D laser vibrometry point data and 3D Local interaction simulation approach data of a aluminium stiffened panel with and without disbonds

Lamb waves were induced in two 1.25m x 1.25m stiffened aluminium panels; one with a disbond, one without a disbond. Three excitation frequencies of 100kHz, 250kHz and 300kHz were used and measured using a Polytec 3D scanning laser vibrometer (PSV-500-M) at a sample rate of 2.56MHz. 5 excitation sites were used along the length of the midpoint between the edge of the panel and the stiffener which reduced the effects of edge reflections interacting with the stiffener and the first wave packet. The excitation was induced using a PANCOM Pico-Z transducer and excited using a MISTRAS Group Ltd micro-DISP system. 825 measurement points were measured at points across the face of the panel which had the stiffener attached. Retro reflective glass spheres were attached to the face of the panel to improve the back scatter of laser light, hence improving the received signal. The measured signals were averaged over 200 measurements at each point to improve the signal-to-noise ratio. The measured data is velocity data given in mm/s and accessed through Polytec PSV software. This can be exported in the software to .txt or universal files for further manipulation. Both in-plane and out-of-plane data was recorded. A representative model was also created using the Local Interaction Simulation Approach (LISA). Commercially available cuLISA3D software which interfaced with MATLAB 2012b. Only the inner section of the panels were modelled to reduce computational overheads. The model was created using the physical properties of aluminium using a global cube edge length of 0.5mm. The adhesive layer was omitted for simplicity in this model. The disbond was modelled by creating a reduction in stiffness which produce comparative results to the experiments. All excitation sites were modelled as point nodes, both in-plane and out-of-plane data was recorded.

本实验在两块1.25m×1.25m的加筋铝板中激发出兰姆波（Lamb waves），其中一块带有脱粘缺陷，另一块无脱粘缺陷。实验采用100kHz、250kHz与300kHz三种激励频率，使用Polytec三维扫描激光测振仪（PSV-500-M）进行信号采集，采样率设为2.56MHz。在铝板边缘与加筋条之间中点的长度方向上设置了5个激励点，以削弱边缘反射波与加筋条及首波包之间的相互干扰效应。激励信号通过PANCOM Pico-Z换能器产生，并由MISTRAS Group有限公司的micro-DISP系统完成激励。在贴有加筋条的铝板表面共布设825个测量点；为提升激光的后向散射效果以优化接收信号质量，在铝板表面粘贴了回射玻璃微珠。为提升信噪比，每个测量点的采集信号均进行200次重复测量后的平均处理。实测数据为以mm/s为单位的速度数据，可通过Polytec PSV软件读取，该软件支持将数据导出为.txt格式或通用格式文件以供后续处理。实验同时采集了面内与面外振动数据。本研究同时采用局部相互作用模拟法（Local Interaction Simulation Approach, LISA）构建了代表性数值模型，所用商业软件cuLISA3D可与MATLAB 2012b进行接口对接。为降低计算开销，仅对铝板的内部区域进行建模。模型以铝的物理属性为参数构建，全局立方体单元的边长设为0.5mm。为简化建模流程，本次数值模型省略了粘接层。脱粘缺陷通过设置刚度折减进行建模，可得到与实验结果匹配的仿真结果。所有激励点均以点节点形式进行建模，同时采集面内与面外振动数据。