Defect localization in fibre-reinforced composites by computing external volume forces from surface sensor measurements
Defect localization in fibre-reinforced composites by computing external volume forces from surface sensor measurements
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DOI：
10.1088/0266-5611/31/2/025006
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发表时间：
2015-02
期刊：
影响因子：
2.1
通讯作者：
F. Binder;F. Schöpfer;Tal Schuster
中科院分区：
文献类型：
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作者：
F. Binder;F. Schöpfer;Tal Schuster
我们提出了一种前瞻性方法，通过集成在结构表面的传感器获得的测量结果计算外部体积力，来检测和可视化纤维增强复合材料中的缺陷。碳纤维增强复合材料等各向异性材料广泛用于轻质结构，这些材料可能会出现光学无法检测到的损坏。我们方法的关键思想是解释此类结构中的缺陷，就好像它们是由外部体积力引起的一样。这个想法是基于这样的观察：传播的弹性波通过反射波来干扰受损区域。从这个意义上说，损害可以被视为一个额外的来源。因此，识别引起该波的外部体积力应该可以揭示缺陷的位置。这种方法导致确定双曲初始边值问题的不均匀性的逆问题。我们通过最小化吉洪诺夫函数来解决这个不适定问题，该函数考虑了表面测量的观察点。在本文中，我们解决了直接问题的可解性，陈述并分析了旨在计算外力的基于偏微分方程的优化问题，并使用共轭梯度法开发了其解决方案的数值实现。具有不同传感器调整的简单模型案例的第一个数值结果表明，缺陷实际上是可以检测到的。从这个意义上说，本文可能被视为未来研究的起点，未来研究应该理解更深入的数值研究和问题分析。
We suggest a prospective method for detecting and visualizing defects in fibre-reinforced composites by computing external volume forces from measurements acquired by sensors that are integrated on the surface of the structure. Anisotropic materials like carbon fibre-reinforced composites are widely used in light weight construction which can exhibit damages that are not optically detectable. The key idea of our method is the interpretation of defects in such structures as if they were induced by an external volume force. This idea is based on the observation that a propagating elastic wave interferes with a damaged area by reflecting the wave. In that sense a damage can be seen as an additional source. Thus identifying the external volume force which has caused this wave is supposed to reveal the location of the defect. This approach leads to the inverse problem of determining the inhomogeneity of a hyperbolic initial-boundary value problem. We tackle this ill-posed problem by minimizing a Tikhonov functional which takes the oberservation points of our surface measurements into account. In the article we address the solvability of the direct problem, state and analyze the PDE-based optimization problem that aims for computing the external force and develop a numerical realization of its solution using the conjugate gradient method. First numerical results for a simple model case with different sensor adjustments show that the defects in fact are detectable. In that sense this article might be seen as starting point of future research which should comprehend deeper numerical studies and analysis of the problem.