Background

Given the inherent manufacturing variabilities and potential for in-service damage of composite parts, the identification of the elastic properties of composites is important to ensuring the safety and the proper performance of the part.

Objective

The primary objective of this manuscript is to determine, nondestructively, the elastic properties of composite parts, whether as in-situ components that are part of a larger system, or as laboratory coupons.

Methods

The proposed technique is based on multimode and dispersive ultrasonic guided waves propagating along a single direction, and the inversion of their phase velocity dispersion curves. The inversion procedure utilizes an efficient Semi-Analytical Finite Element method to solve the forward problem, and a Simulated Annealing algorithm as the optimization tool. The method is particularly well-suited for the characterization of composite laminates. In particular, the manuscript presents experimental evidence of the effectiveness of this technique, that was suggested earlier in a solely numerical work previously conducted by the authors.

Results

The test results show that reasonable accuracy can be obtained in the identification of four in-plane and three out-of-plane engineering constants of a quasi-isotropic laminate and a highly anisotropic laminate utilizing the single wave propagation direction. Non-obvious sensitivities of certain wave modes to particular constants are explained on the basis of stress coupling phenomena that are revealed by the SAFE wave propagation models.

Conclusions

The study gives experimental evidence of the suitability of ultrasonic guided wave inversion schemes to identify the engineering constants of laminated composites, with the potential to properly characterize parts in-situ, because of the insensitivity of guided waves to boundary conditions located outside of the transmitter–receiver path.

中文翻译：

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超声导波数据反演识别复合材料的弹性

背景

考虑到固有的制造差异性和复合材料零件在使用中损坏的可能性，复合材料的弹性特性的识别对于确保零件的安全性和适当的性能非常重要。

客观的

该手稿的主要目的是非破坏性地确定复合零件的弹性特性，无论是作为较大系统一部分的原位零件，还是作为实验室试样。

方法

所提出的技术是基于沿单个方向传播的多模色散超声导波及其相位速度色散曲线的反演。反演程序利用有效的半解析有限元方法解决正向问题，并使用模拟退火算法作为优化工具。该方法特别适合于复合层压板的表征。特别是，该手稿提供了该技术有效性的实验证据，这在作者先前进行的纯数字工作中已得到了初步证明。

结果

测试结果表明，利用单波传播方向识别准各向同性叠层板和高度各向异性叠层板的四个面内和三个面外工程常数可以获得合理的精度。基于SAFE波传播模型揭示的应力耦合现象，解释了某些波模对特定常数的非显而易见的敏感性。

结论

这项研究提供了实验证明，由于导波对位于发射机外部的边界条件不敏感，因此超声波导波反演方案适合于识别层状复合材料的工程常数，并有可能正确地表征零件的特性。接收者路径。