Zelenyak Andreea-Manuela, Schorer Nora, Sause Markus G R
University of Augsburg, Institute of Physics, Universitätsstr. 1 Nord, 86159 Augsburg, Germany.
Institute for Materials Resource Management, Mechanical Engineering, Universitätsstr. 1, 86159 Augsburg, Germany.
Ultrasonics. 2018 Feb;83:103-113. doi: 10.1016/j.ultras.2017.06.014. Epub 2017 Jun 20.
This paper presents a method for embedding realistic defect geometries of a fiber reinforced material in a finite element modeling environment in order to simulate active ultrasonic inspection. When ultrasonic inspection is used experimentally to investigate the presence of defects in composite materials, the microscopic defect geometry may cause signal characteristics that are difficult to interpret. Hence, modeling of this interaction is key to improve our understanding and way of interpreting the acquired ultrasonic signals. To model the true interaction of the ultrasonic wave field with such defect structures as pores, cracks or delamination, a realistic three dimensional geometry reconstruction is required. We present a 3D-image based reconstruction process which converts computed tomography data in adequate surface representations ready to be embedded for processing with finite element methods. Subsequent modeling using these geometries uses a multi-scale and multi-physics simulation approach which results in quantitative A-Scan ultrasonic signals which can be directly compared with experimental signals. Therefore, besides the properties of the composite material, a full transducer implementation, piezoelectric conversion and simultaneous modeling of the attached circuit is applied. Comparison between simulated and experimental signals provides very good agreement in electrical voltage amplitude and the signal arrival time and thus validates the proposed modeling approach. Simulating ultrasound wave propagation in a medium with a realistic shape of the geometry clearly shows a difference in how the disturbance of the waves takes place and finally allows more realistic modeling of A-scans.
本文提出了一种在有限元建模环境中嵌入纤维增强材料实际缺陷几何形状的方法，以模拟主动超声检测。当通过实验使用超声检测来研究复合材料中缺陷的存在时，微观缺陷几何形状可能会导致难以解释的信号特征。因此，对这种相互作用进行建模是提高我们对所采集超声信号的理解和解释方式的关键。为了模拟超声波场与诸如孔隙、裂纹或分层等缺陷结构的真实相互作用，需要进行实际的三维几何形状重建。我们提出了一种基于3D图像的重建过程，该过程将计算机断层扫描数据转换为适当的表面表示形式，以便嵌入有限元方法进行处理。使用这些几何形状的后续建模采用多尺度和多物理场模拟方法，从而产生可以直接与实验信号进行比较的定量A扫描超声信号。因此，除了复合材料的特性外，还应用了完整的换能器实现、压电转换以及对连接电路的同步建模。模拟信号与实验信号之间的比较在电压幅度和信号到达时间方面提供了非常好的一致性，从而验证了所提出的建模方法。在具有实际几何形状的介质中模拟超声波传播清楚地表明了波的扰动方式的差异，最终实现了对A扫描更真实的建模。
