PMI异形曲面构件太赫兹时域光谱检测

Terahertz time-domain spectral detection of PMI special-shaped curved components

摘要:

异形曲面构件在航空、航天、船舶等领域应用广泛，其粘接质量成为影响工作安全的重要因素。太赫兹凭借其独特的物理特性，近乎是对聚甲基丙烯酰亚胺(PMI)材料粘接质量进行检测的唯一手段。异形曲面构件上下表面曲率不一致，仅以上表面作为基准曲面进行路径规划时，无法对异形曲面构件粘接质量进行准确判断。对此，在下表面固定不同形状的金属片模拟粘接层中的缺陷，分别以异形曲面构件上下表面为基准曲面，采用机器人化太赫兹时域光谱检测系统进行检测。对上下表面2个基准曲面的太赫兹成像结果进行对比分析，结果表明，以下表面为基准曲面进行检测时，区域Ⅱ、Ⅲ处信号信噪比，较上表面为基准曲面检测时提高12.09 dB、10.39 dB；区域Ⅱ、Ⅲ处金属片实际检测面积与理论面积比值，较上表面为基准曲面检测时提高55.97%、80.81%，更好地满足了异形曲面构件的检测要求。这项工作将促进太赫兹成像在实践中的应用，并为相关领域的进一步研究提供支撑。

Abstract:

The special-shaped surface components are widely used in aviation, aerospace, shipbuilding and other fields, and their bonding quality has become an important factor affecting work safety. With its unique physical characteristics, terahertz technology is almost the only means to detect the bonding quality of Polymethaerylimide(PMI) materials. The curvatures of the upper and lower surfaces of the special-shaped surface components are inconsistent, which makes it impossible to accurately judge the bonding quality of the special-shaped surface components when only the upper surface is used as the reference surface for path planning. To tackle this problem, metal sheets of different shapes on the lower surface are fixed to simulate the defects in the bonding layer. Taking the upper and lower surfaces of the special-shaped curved surface components as the benchmark surfaces respectively, the robotic terahertz time-domain spectrum detection system is employed for detection. The terahertz imaging results of the two detection methods are compared and analyzed. The results show that when the lower surface is used as the benchmark surface for detection, the signal to noise ratios at area II and III are improved by 12.09 dB and 10.39 dB than that when the upper surface is the benchmark surface; the ratios of the actual detection area to the theoretical area of the metal sheet at area II and III are improved by 55.97% and 80.81% than that when the upper surface is used as the benchmark surface for detection. This better meets the detection requirements of special-shaped curved surface components. This work will promote the application of terahertz imaging in practice and provide a basis for further research in related fields.