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Abstract
A refined finite element model and a new post processing sub program to determine mixed mode stress intensity factors and their variation along a surface crack front in components and structures is presented. The proposed finite element model employs a fine mesh of singular isoparametric pentahedral solid element with user specified number and size from one crack face to another and a number of such segments along a surface crack front. A compatible mesh of regular elements namely hexahedral solid element and pentahedral solid element is used to discretize the rest of the domain under consideration. Consistent with the use of the singular element, formulae to compute the Mode I, Mode II and Mode III stress intensity factors using displacements only of flagged nodes on flagged singular elements are implemented in a special purpose post processing sub program named SIF 1-2-3. In the present work the finite element models developed using ANSYS, a commercial FEA program, and the stress intensity factors determined using SIF 1-2-3 are validated using benchmarks. This finite element model is then used to calibrate a proposed test method to measure Mode I, Mode II and Mode III fracture toughness of engineering materials.
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References
- Raju, I. S and Newman, J. C., "Methods for Analysis of Cracks in Three Dimensional Solids", Journal of Aeronautical Society of India, Vol.36, No.3, August, 1984.
- Ingraffea, A. R and Manu, C., "Stress Intensity Factor Computation in Three Dimensions with Quarter Point Elements", Int. J. Numerical Methods in Engineering, Vol.15, 1980, pp.1427-1445.
- Krueger, R., "Virtual Crack Closure Technique: History, Approach and Applications", Applied Mechanics Reviews, Vol.57, 2004, pp.1092-143.
- Badari Narayana, K., Dattaguru, B., Ramamurthy, T.S and Vijaya Kumar, K., "A General Procedure for Modified Crack Closure Integral in 3D problems with Cracks", Eng. Fracture Mech., 48, 1994, pp.167- 176.
- Dattaguru, B., Lok Singh, K and Palani, G.S., "Genelarisation of MVCCI Approach for LEFM Problems Using Numerical Integration", Journal of Aerospace Sciences and Technologies, Vol.61, No.1, 2000, pp.100-110.
- Parks, D. M., "A Stiffness Derivative Finite Element Technique for Determination of Crack Tip Stress Intensity Factors", Int. J. Fracture, 109,1974, pp.487-502.
- Koers, R. W. J., "Use of Modified Standard 20-node Isoparametric Brick Elements for Representing Strain/Stress Fields at a Crack Tip for Elastic and Perfectly Plastic Materials", Int. J. Fracture, Vol.40, 1989, pp. 70-110.
- Sanford, R.J., Principles of Fracture Mechanics, Pearson Education, NJ, 2003.
- Richard, H.A and Benitz, K., "A Loading Device for the Creation of Mixed Mode in Fracture Mechanics", Int. J. Fracture, Vol.22, 1983, pp.R55-R58.
- Buchholz, F. G., "Finite Element Analysis of a 3D Mixed Mode Fracture Problem by Virtual Crack Closure Integral Methods, Fracture Mechanics", Proceedings of the Indo-German Workshop, Indian Institute of Science, Bangalore, March, 1994, pp. 7-12.
- Judge, R. C. B and Marsden, B. J., "Three-Dimensional Test Cases in Linear Elastic Fracture Mechanics", NAFEMS, UK, 1993.
- Simha, K. R. Y., "Fracture Mechanics for Modern Engineering Design", Universities Press, Hyderabad, 2001.
References
Raju, I. S and Newman, J. C., "Methods for Analysis of Cracks in Three Dimensional Solids", Journal of Aeronautical Society of India, Vol.36, No.3, August, 1984.
Ingraffea, A. R and Manu, C., "Stress Intensity Factor Computation in Three Dimensions with Quarter Point Elements", Int. J. Numerical Methods in Engineering, Vol.15, 1980, pp.1427-1445.
Krueger, R., "Virtual Crack Closure Technique: History, Approach and Applications", Applied Mechanics Reviews, Vol.57, 2004, pp.1092-143.
Badari Narayana, K., Dattaguru, B., Ramamurthy, T.S and Vijaya Kumar, K., "A General Procedure for Modified Crack Closure Integral in 3D problems with Cracks", Eng. Fracture Mech., 48, 1994, pp.167- 176.
Dattaguru, B., Lok Singh, K and Palani, G.S., "Genelarisation of MVCCI Approach for LEFM Problems Using Numerical Integration", Journal of Aerospace Sciences and Technologies, Vol.61, No.1, 2000, pp.100-110.
Parks, D. M., "A Stiffness Derivative Finite Element Technique for Determination of Crack Tip Stress Intensity Factors", Int. J. Fracture, 109,1974, pp.487-502.
Koers, R. W. J., "Use of Modified Standard 20-node Isoparametric Brick Elements for Representing Strain/Stress Fields at a Crack Tip for Elastic and Perfectly Plastic Materials", Int. J. Fracture, Vol.40, 1989, pp. 70-110.
Sanford, R.J., Principles of Fracture Mechanics, Pearson Education, NJ, 2003.
Richard, H.A and Benitz, K., "A Loading Device for the Creation of Mixed Mode in Fracture Mechanics", Int. J. Fracture, Vol.22, 1983, pp.R55-R58.
Buchholz, F. G., "Finite Element Analysis of a 3D Mixed Mode Fracture Problem by Virtual Crack Closure Integral Methods, Fracture Mechanics", Proceedings of the Indo-German Workshop, Indian Institute of Science, Bangalore, March, 1994, pp. 7-12.
Judge, R. C. B and Marsden, B. J., "Three-Dimensional Test Cases in Linear Elastic Fracture Mechanics", NAFEMS, UK, 1993.
Simha, K. R. Y., "Fracture Mechanics for Modern Engineering Design", Universities Press, Hyderabad, 2001.