一般結構材料在長年使用下，經風吹雨淋、太陽曝曬等外在因素可能導致材料的退化。所以在安全考量下，如何在不破壞結構本體的前提下，檢查這些材料本身的性質是一件非常要緊的事。本文乃利用反向問題的概念，先利用Hwu and Gai(2003)所發展的機翼模型與有限元素法軟體-ANSYS，得出自然頻率和靜態應變與材料常數之關係訓練類神經網路；如此即可從埋設在機翼結構物的感測器得到自然頻率與應變值，配合訓練好的類神經網路，可以反算當時結構物的彈性係數。這樣一來便可藉由材料常數的改變迅速得知機翼結構之安全性以避免災害的產生。

　　Generally, load-carrying members of structures will encounter degeneration of material properties in changing service environments. To improve the safety of structure, it is necessary to examine material properties of structures in non-destructive way. In this thesis, we employ the concept of inverse analysis. The detectors of the inverse problems are the natural frequencies and static strains. The information about the relations between detectors and material properties can be obtained by analytical solution (Hwu and Gai,2003) and commercial finite element software ANSYS. Based on these data, we can train artificial neural networks to determine elastic properties of composite wing structures with sensors embedded into structures. To prevent accidents we hope the safety of wing structures can be realized by changes of material properties.

1.Achenbach, J. D., “Quantitative Nondestructive Evaluation”, Int. J. Solids and Structures, Vol.37, pp.13-27, 2000.

2.ANSYS 7.0 Documentation：ANSYS Element Reference.

3.ASTM C273-61, “Shear Test in Flatwise Plane of Flat Sandwich Constructions or Sandwich Cores”, Annual Book of ASTM Standards, Vol.15, pp.6-10, 1983.

4.ASTM D638-98, “Standard Test Method for Tensile Properties of Plastics”, Annual Book of ASTM Standards, Vol.8, 1999.

5.Balasubramaniam, K. and Rao, N. S., “Inversion of Composite Material Elastic Constants from Ultrasonic Bulk Wave Phase Velocity Data Using Genetic Algorithm”, Composites Part B, Vol.29, pp.171-180, 1998.

6.Chen, W. S. and Hwu, C. and Cheng, S. H., “Test and Design of the Neural Network Training Algorithm CGLM”, Proceedings of the 20th National Conference on Mechanical Engineering, Taipei, Taiwan, pp.859-866, 2003.(in Chinese)

7.Grediac, M. and Paris, P. A., “Direct Identification of Elastic Constants of Anisotropic Plates by Modal Analysis：Theoretical and Numerical Aspects”, J. of Sound and Vibration, Vol.195, pp.401-415,1996.

8.Hagan, M. T. and Menhaj, M. B., “Training Feedforward Networks with the Marquardt Algorithm”, IEEE Transactions on Neural Networks, Vol.5, No.6, pp.989-993, 1994.

9.Haykin, S., Neural Networks a Comprehensive Foundation, Prentice Hall, 1999.

10.Hwang, S. F. and Chang, C. S., “Determination of Elastic Constants of Materials by Vibration Testing”, Composite Structures, Vol.49, pp.183-190, 2000.

11.Hwu, C. and Gai, H. S., “Vibration Analysis of Composite Wing Structures by a Matrix Form Comprehensive Model”, AIAA Journal, Vol.41, No.11, pp.2261-2273, 2003.

12.Hwu, C. and Bi, T. Y., Re-Examination of the Buckling and Vibration of the Delaminated Composite Sandwich Beams”, the Chinese Journal of Mechanics, Series B, Vol.17, No.1, pp.27-38, 2001.(in Chinese)

13.Hwu, C. and Tsai, “Aeroelastic Divergence of Stiffened Composite Multicell Wing Structures”, Journal of Aircraft, Vol.39, No.2, pp.242-251, 2002.

14.Jones, R. M., Mechanics of Composite Materials, Scripta, Washington DC., 1975.

15.Liang, Y. C. and Hwu, C., “On-Line Identification of Holes/Cracks in Composite Structures”, Smart Materials and Structures, Vol.10, pp.599-609, 2001.

16.Rao, S. S., Engineering Optimization Theory and Practice, John Wiley & Sons, Inc., 1996.

17.Vaddadi, P. and Nakamura, T. and Singh R. P., “Inverse Analysis for Transient Moisture Diffusion through Fiber-Reinforced Composites”, Acta Materialia, Vol.51, pp.177-193, 2003.

18.Wang, W. and Ishikawa, H. and Yuki, H., “An Inverse Method for Determining Material Properties of a Multi-Layer Medium by Boundary Element Method”, Int. J. Solids and Structures, Vol.38, pp.8907-8920, 2001.

19.Xu, Y. G. and Liu, G. R., “Determination of the Material Properties of Multilayered Thin Films Using the Elastic Wave Propagation Approach”, J. of Micromechanics and Microengineering, Vol.12, pp.723-729, 2002.

20.梁燕祝，“二維複材結構之孔洞或裂縫辨識”，博士論文，成功大學航空太空工程研究所，1999。

21.謝嘉新，“由靜態應變反算彈性係數之研究”，碩士論文，成功大學航空太空工程研究所，1997。

22.畢天佑，“含脫層夾心樑之挫曲與振動分析” ，碩士論文，成功大學航空太空工程研究所，1999。

23.蓋欣聖，“複材機翼結構之振動分析及控制”，碩士論文，成功大學航空太空工程研究所，2002。

24.陳威昇，“類神經網路訓練程序之些許建議”， 碩士論文，成功大學航空太空工程研究所，2003。

25.羅華強，“類神經網路-MATLAB的應用”，清蔚科技，2001。

26.杜黎蓉、林博正，“CATIA”，全華科技圖書股份有限公司”，2002。