Advertisement

Numerical and Experimental Analysis of Double-Sided Stepped Lap-Repaired CFRP Laminates Under Tensile Loading

  • Matta Seshadri
  • M. RamjiEmail author
Conference paper

Abstract

Adhesive layer plays a critical role in the strength restoration of the scarf repaired carbon fibre-reinforced plastic (CFRP) laminates. In this work, Araldite 2015 is used. Hence, it is crucial to model the behaviour of adhesive layer accurately in case of numerical model. Modelling of adhesive layer by cohesive zone law characterises the fracture behaviour of the bonded joint accurately. In this paper, cohesive zone law parameters for mode I and mode II are determined by comparing numerical predictions to experimental observations of a double cantilever beam (DCB) for mode I and end notched flexure (ENF) for mode II fracture test. In this work, Araldite 2015 (supplied by Huntsman) is used for repair work. Strain energy release rate for both mode I and mode II is determined by performing DCB and ENF test, respectively. Traction–separation law for mode I is generated by direct method which involves differentiation of the relation between the strain energy release rate and crack tip opening displacement which is measured using digital image correlation (DIC) technique. Traction–separation law for mode II is generated by inverse method which involves fitting the numerical and experimental load–displacement curves. The obtained cohesive law is used to model the adhesive layer in numerical analysis of double-sided stepped lap joint repair of CFRP laminate subjected to tensile loading. The numerical predictions are validated by comparing the load–displacement curve obtained from the experimental study. A good agreement exists between numerical and experimental results confirming that the proposed cohesive law for mode I and mode II can be applied to model adhesive layer with CFRP as adherend.

Keywords

Cohesive zone law Strain energy release rate Digital image correlation Double-sided stepped lap joint 

List of symbols

a

Crack length

ae

Equivalent crack length

a0

Initial crack length

B

Width of the specimen

C

Compliance of the specimen

C0

Initial compliance

Ef

Flexural modulus

GI

Mode I strain energy release rate

GIC

Mode I fracture toughness

GII

Mode II strain energy release rate

GIIC

Mode II fracture toughness

h

Height of single adherend

L

Total specimen length

P

Applied load on the specimen

w

Crack tip opening displacement (CTOD)

δ

Displacement of the specimen

δ0

Damage initiation relative displacement

δc

Ultimate relative displacement

Δ

Correction factor for root rotation effect

ta

Adhesive thickness

σ

Normal traction

Notes

Acknowledgements

The first author thank Dr. Viswanath R Chintapenta, Assistant Professor, Indian Institute of Technology Hyderabad for his guidance, lab mates in engineering optics lab and central workshop staff at Indian Institute of Technology Hyderabad.

References

  1. 1.
    M.D. Banea, L.F.M. da Silva, Adhesively bonded joints in composite materials: an overview. Proc. Inst. Mech. Eng. Part L: J. Mater. Design Appl. 223 (2009)Google Scholar
  2. 2.
    L.F.M. da Silva, P.J.C. das Neves, R.D. Adams, J.K. Spelt, Analytical models of adhesively bonded joints—Part I: Literature survey. Int. J. Adhes. Adhes. 29, 319–330 (2009)Google Scholar
  3. 3.
    X. He, A review of finite element analysis of adhesively bonded joints. Int. J. Adhes. Adhes. 31, 248–264 (2011)CrossRefGoogle Scholar
  4. 4.
    L.F.M. da Silva, R.D.S.G. Campilho, Advances in Numerical Modeling of Adhesive Joints (Springer, Berlin, 2012)CrossRefzbMATHGoogle Scholar
  5. 5.
    M.F.S.F. de Moura, J.P.M. Gonçalves, A.G. Magalhães, A straightforward method to obtain the cohesive laws of bonded joints under mode I loading. Int. J. Adhes. Adhes. 39, 54–59 (2012)CrossRefGoogle Scholar
  6. 6.
    M.F.S.F. de Moura, J.J.L. Morais, N. Dourado, A new data reduction scheme for mode I wood fracture characterization using the double cantilever beam test. Eng. Fract. Mech. 75, 3852–3865 (2008)CrossRefGoogle Scholar
  7. 7.
    M.F.S.F. de Moura, R.D.S.G. Campilho, J.P.M. Gonçalves, Crack equivalent concept applied to the fracture characterization of bonded joints under pure mode I loading. Compos. Sci. Technol. 68, 2224–2230 (2008)CrossRefGoogle Scholar
  8. 8.
    G.F. Dias, M.F.S.F. de Moura, J.A.G. Chousal, J. Xavier, Cohesive laws of composite bonded joints under mode I loading. J. Compos. Struct. 106, 646–652 (2013)CrossRefGoogle Scholar
  9. 9.
    M. Kashfuddoja, R.G.R. Prasath, M. Ramji, Study on experimental characterization of carbon fibre reinforced polymer panel using digital image correlation: a sensitivity analysis. J. Opt. Lasers Eng. 62, 17–30 (2014)CrossRefGoogle Scholar
  10. 10.
    M.F.S.F. de Moura, R.D.S.G. Campilho, J.P.M. Gonçalves, Pure mode II fracture characterization of composite bonded joints. Int. J. Solids Struct. 46, 1589–1595 (2009)CrossRefzbMATHGoogle Scholar
  11. 11.
    K. Song, C.G. Dávila, C.A. Rose, Guidelines and parameter selection for the simulation of progressive delamination, in 2008 Abaqus Users’ Conference Google Scholar
  12. 12.
    J.P.M. Gonçalves, M.F.S.F. de Moura, A.G. Magalhães, P.M.S.T. De Castro, Application of interface finite elements to the three-dimensional progressive failure analysis of adhesive joints. Fatigue Fract. Eng. Mater. Struct. 26, 479–486Google Scholar
  13. 13.
    D. Li, G. Qing, Y. Liu, A three-dimensional semi-analytical model for the composite laminated plates with a stepped lap repair. Compos. Struct. 93, 1673–1682 (2011)CrossRefGoogle Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Engineering Optics Lab, Department of Mechanical and Aerospace EngineeringIIT HyderabadHyderabadIndia

Personalised recommendations