Journal of Failure Analysis and Prevention

, Volume 16, Issue 4, pp 635–646 | Cite as

Prediction of Stress Intensity Factor on Precracked Composite Wing Rib Made up of Carbon-Epoxy IM7-8552

  • V. Sivakumar
  • Khooshboo P. Dani
  • Suddapally Sriram
Technical Article---Peer-Reviewed
  • 154 Downloads

Abstract

The stress intensity factor (SIF), K, is an important parameter to predict the stress state (“stress intensity”) near the tip of a crack caused by a remote load or residual stresses. It can determine the probability of crack propagation and failure of the material. To study the use of high-strength material, IM7/8552 in the crack prone region is the main focus of this present study. A semi-elliptical surface flaw in a typical Boeing-747 rib section having circular cut out and experiencing an in-plane shear loading of 10.21 MPa was considered for analysis. A parametric study on crack initiation is done by having different size of cracks at different locations across the layers. The values of SIF for all the three modes were calculated using the contour integral method. In the present study, we have considered IM7-8552/carbon-epoxy composite due to its high performance and intermediate modulus property. As there are no theoretical solutions for mixed mode loading problems, finite element packages like HYPERMESH and ABAQUS were used to obtain the SIF along the crack edge. The corresponding stress intensity factor values were compared to the fracture toughness of the material to determine the probability of crack initiation. It was observed that the mode of failure changes along with shape of the crack. The analysis results showed a high probability of failure. A comparative study on T300-5208/carbon-epoxy and IM7-8552/carbon-epoxy was performed. IM7-8552/carbon-epoxy composite showed higher resistance to failure. By modifying the fiber orientations, stress concentrations were minimized to a tangible limit.

Keywords

Crack initiation Delamination Stress intensity factor Finite element method Fiber orientation 

List of Symbols

K

Stress intensity factor

KIc

Critical stress intensity factor for Mode-1

KIIc

Critical stress intensity factor for Mode-2

KIIIc

Critical stress intensity factor for Mode-3

Jaux

Auxiliary J-integral

Jint

Interaction integral

Jtot

Total J-integral

c

Semi-major axis

a

Semi-minor axis

E1, E2, and E3

Principal Young’s moduli in fiber direction and other two transverse directions, respectively

G12, G13, and G23

Shear modulus associated with plane 1–2, 1–3 and 2–3, respectively

ν12, ν13, and ν23

Poisson’s ratio associated with plane 1–2, 1–3 and 2–3, respectively

u, v, and w

Displacements in x, y, and z directions and w, respectively

References

  1. 1.
    T.L. Anderson, Fracture Mechanics Fundamentals and Applications (CRC Press, Boca Raton, 1991)Google Scholar
  2. 2.
    M. Jafari, J. Rezaeepazhand, Stress concentration in metallic plates with special shaped cut-out. Int. J. Mech. Sci. 52, 96–102 (2010)CrossRefGoogle Scholar
  3. 3.
    K.P. Rao, R. Pandey, S. Thakur, K.S. Ramanath, Stress Concentration and Stability Studies in Composite Ribs with Flanged Cut-Outs (CAE Group, Infosys Technologies Ltd, Banglore, 2001)Google Scholar
  4. 4.
    V. Sivakumar, R.K. Arjun, V. Ishwarya, S. Nithya, S. Sundar, B.N. Thilak, Optimisation of cut-out shape on composite plate under in-plane shear loading. J. Fail. Anal. Prev. 12(2), 204 (2012)CrossRefGoogle Scholar
  5. 5.
    Jhonny E. Ortiz et al., Boundary element method for J-integral and stress intensity factor computations in three-dimensional interface cracks. Int. J. Fract. 133, 197–222 (2005)CrossRefGoogle Scholar
  6. 6.
    Z. Mikulik et al., Fracture mechanics based predictions of initiation and growth of multi-layered delaminations in a composite specimen. Int. J. Fract. 170, 145–157 (2011)CrossRefGoogle Scholar
  7. 7.
    V. Sivakumar, G. Bharath Kumar, A. Gauthem, Crack initiation study on aircraft composite rib with semi-elliptical surface flaw. J. Fail. Anal. Prev. 15(6), 906–914 (2015)CrossRefGoogle Scholar
  8. 8.
    ABAQUS, ABAQUS/Standard User’s Manuals, Dasault systems, USAGoogle Scholar
  9. 9.
    James Ratcliffe, Characterization of the Edge Crack Torsion(ECT) Test for Mode III Fracture Toughness Measurement of Laminated Composites (National Research Council, NASA Langley Research Centre Hampton, Hampton, 2004)Google Scholar
  10. 10.
    C. Liu et al., Measurement of the fracture toughness of a fiber reinforced composite using the Brazilian disk geometry. Int. J. Fract. 87, 241–263 (1997)CrossRefGoogle Scholar

Copyright information

© ASM International 2016

Authors and Affiliations

  • V. Sivakumar
    • 1
  • Khooshboo P. Dani
    • 1
  • Suddapally Sriram
    • 1
  1. 1.Department of Aerospace Engineering, Amrita School of EngineeringAmrita Vishwa VidyapeethamCoimbatoreIndia

Personalised recommendations