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Abstract

A method is proposed to obtain the strain energy release rate and the stresses ahead of the crack in a laminated composite plate due to free edge delamination under Mode I type loading situations. A shear deformable beam finite element with nodes offset to either the top or bottom side has been developed. The thermal effects originating from the curing process are included in the formulation of the problem. Two different methods are used to calculate the strain energy release rate. The first method uses the J-integral evaluated around a zero-area path surrounding the cracktip and the strain energy release rate is expressed in terms of the force and moment resultants in the elements surrounding the crack-tip. The second method is similar to the virtual crack closure method, and the strain energy release rate is expressed in terms of the forces transmitted by a rigid element placed at the crack-tip and the displacements of the nodes behind the crack-tip. The stresses ahead of the crack are obtained by using discrete spring elements in the uncracked portion of the beam. The results calculated are in good agreement with results obtained from other studies of the same problem. The advantage of the present method lies in its simplicity; in addition it requires less computational effort than the methods that use solid elements.

References

Agarwal, B. D. and Broutman, L. J. (1990), Analysis and Performance of Fiber Composites, John Wiley & Sons, New York, NY.

Hellan, K. (1984), Introduction to Fracture Mechanics, McGraw-Hill, New York, New York, 1984.

Kanninen, M. F. (1985), Advanced Fracture Mechanics, Oxford University Press, New York, NY.

Pinheiro, M. A. (1991), "Finite Elements for Free Edge Delaminating and Anisotropic Delaminated Beams," Doctoral Dissertation, Department of Aerospace Engineering, Mechanics & Engineering Science, University of Florida, Gainesville, Florida.

Pagano, N. J. (1989), Interlaminar Response of Composite Materials, Elsevier Science Publishing Company, New York, New York.

Pipes, R. B. and Pagano, N. J. (1970) "Interlaminar Stresses in Composite Laminates under Uniform Axial Extension," J. Composite Materials, Vol. 4, No. 4, p. 538-538.

Raju, I. S. (1986), "Q3DG A Computer Program for Strain Energy Release Rate for Delaminating Growth in Composite Laminates," NASA CR 178205.

Sankar, B. V. (1991), "A Finite Element for Modeling Delaminations in Composite Beams," Computers & Structures, Vol. 38, No. 2, pp. 239-246.

Sankar, B. V. and Pinheiro, M. A. (1990), "An Offset Beam Finite Element for Fracture Analysis of Delaminations," AIAA Paper Number: AIAA-90-1024-CP. Proceedings of AIAA/ASME/ASCE/AHS/ASC 31st SDM Conference, Long Beach, California, pp. 1227-1233.

10.

Timoshenko, S. P. and Goodier, J. M. (1970), Theory of Elasticity, McGraw-Hill, New York, NY, pp. 50-53.

11.

Whitney, J. M. (1986), "Stress Analysis of Mode I Edge Delaminating Specimen for Composite Materials," AIAA Journal, Vol. 24, No. 7, pp. 1163-1168.

12.

Whitney, J. M. (1987), Structural Analysis of Laminated Anisotropic Plates, Technomic Publishing Company, Lancaster, PA.

Beam Finite Element for Analyzing Free Edge Delaminations

Abstract

References