Issue 13

Ahanchian Mohammad et alii, Frattura ed Integrità Strutturale, 13 (2010) 31-35; DOI: 10.3221/IGF-ESIS.13.04 35 Maximum Von Misses stress and breaking force for different cases are presented in Tab. 2. The lowest amount of breaking force occurs in the largest crack size showing that we are near critical crack size. The value of stresses determine by conventional method and ANSYS simulation are presented and demonstrate that the differences are less than 1% which prove the accuracy of written code. Crack length, µm Breaking Force, N Mechanical Loading Mechanical & Thermal Loading CM* MPa ANSYS MPa Error CM MPa ANSYS MPa Error 3.5 1.94 12.14 12.22 0.71% 12.02 11.92 0.84% 7 2.28 12.76 12.66 0.85% 12.65 12.56 0.70% 10.5 0.85 10.91 11.01 0.95% 10.81 10.90 0.87% *CM: Conventional Method Table 2 : Maximum Von Misses stress distribution and breaking force for different cases. C ONCLUSION he computational results presented in this research demonstrate the capabilities of the energy criterion towards modeling fracture in microstructure composites such as optical fiber. Critical forces in each case are obtained and it is clear that applying temperature condition would prevent the fracture process and fracture occurs under higher stresses as a result the optical fiber should be protected from low temperatures by adding cladding. It also protects from mechanical loading. Moreover, Prediction of crack branching and propagation is summarized and compared. The maximum stress magnitudes which instigate the crack are presented and compared. This shows that how big mechanical loading could our design withstand. Consequently, there are some parameters that mitigate crack propagation which are higher temperature, lower stresses and smaller grain size. This theory is a result of investigation by conventional method. When the temperature increases, a higher stress is required for a crack to propagate. Another point is that large crack size with 45 degree, is critical length and crack propagation occurs under minimum value of mechanical force and shows that production control should be improved properly. R EFERENCES [1] S. B. Grassino, What is Optical Fibers Made of?, University of Southern Mississippi (2003). [2] R. Paschota, Journal of Optik & Photonik, 2 (2008). [3] A. D. Yablon, “Optical Fiber Fusion Splicing” (2005) 181. [4] R. Bai, C. Yan, 5 th Australasian Congress on Applied Mechanics, ACAM 2007. [5] C. Yan, R.X. Bai, P. K.D.V. Yarlagadda, H. Yu, 9 th Global Congress on Manufacturing and Management (GCMM 2008) Surfers Paradise, Australia. [6] C. P. Chen, T. H. Chang, Journal of Materials chemistry and physics, ISSN 0254-0584, 77 (1) (2003) 110. [7] O. C. Zienkiewicz, R. L. Yaylor, The Finite Element Method, Forth ed., McGraw-Hill (1994). [8] F. P. Incorpera, D. P. Dewitt , Introduction to Heat Transfer, Translation of Third Edition Isfahan University,1 (2003). [9] J. E. Shigley, C. R. Mischke, Mechanical Engineering Design, Tehran (2001). [10] D. A. Anderson, J. C. Tannehill, R. H. Pletcher, Fracture Mechanics, Hemisphere, Washington, DC (1984). [11] C. Atkinson, F. G. Leppington, Int. J. Solids Struct., 13 (1977) 1103. [12] http://www.pdhcenter.com/courses/m155/m155.pdf , ‘Brittle Fracture Mechanism’, DOE-HDBK-1017/2-93 Brittle Fracture. [13] C. Yan, X. D. Wang, L. Ye, K. Lyytikainen, J. Canning, The 18 th Annual Meeting of the IEEE, Lasers and Electro- Optics Society LEOS 2005, 529. [14] G. P. Cherepanov, Mechanics of Brittle Fracture, McGraw-Hill, New York (1979). T