Characterizing delamination of fibre composites by mixed mode cohesive laws

A novel method is used for the determination of mixed mode cohesive laws and bridging laws for the characterisation of crack bridging in composites. The approach is based on an application of the J integral. The obtained cohesive laws were found to possess high peak stress values. Mixed mode cohesive stresses were found to depend on both the normal and tangential crack opening displacements. The bridging laws, which are to be used together with a mode mixity dependent crack tip fracture energy, were found to possess relative low bridging stresses; the peak normal bridging stress was approximately 2 MPa during pure Mode I and the maximum shear stress during pure Mode II was about 10 MPa.

[1]  Lars Berglund,et al.  Application of bridging-law concepts to short-fibre compositesPart 1: DCB test procedures for bridging law and fracture energy , 2000 .

[2]  Anthony G. Evans,et al.  The role of fiber bridging in the delamination resistance of fiber-reinforced composites , 1992 .

[3]  Tove Jacobsen,et al.  Large scale bridging in compos-ites: R-curve and bridging laws , 1998 .

[4]  P. Camanho,et al.  Numerical Simulation of Mixed-Mode Progressive Delamination in Composite Materials , 2003 .

[5]  Bent F. Sørensen,et al.  Micromechanical model of cross-over fibre bridging – Prediction of mixed mode bridging laws , 2008 .

[6]  D. Hull,et al.  Effects of fibre bridging on GIC of a unidirectional glass/epoxy composite , 1989 .

[7]  J. Rice.  A path-independent integral and the approximate analysis of strain , 1968 .

[8]  A. Needleman.  A Continuum Model for Void Nucleation by Inclusion Debonding , 1987 .

[9]  D. S. Dugdale.  Yielding of steel sheets containing slits , 1960 .

[10]  J. L. Högberg.  Mixed mode cohesive law , 2006 .

[11]  M. D. Thouless,et al.  Mixed-mode fracture analyses of plastically-deforming adhesive joints , 2001 .

[12]  Z. Suo,et al.  Mixed mode cracking in layered materials , 1991 .

[13]  Bent F. Sørensen,et al.  Determination of mixed mode cohesive laws , 2006 .

[14]  Ignace Verpoest,et al.  Interlaminar fracture toughness of CFRP influenced by fibre surface treatment: Part 1. Experimental results , 1995 .

[15]  Zhigang Suo,et al.  Remarks on Crack-Bridging Concepts , 1992 .

[16]  Bent F. Sørensen,et al.  Mode I intra-laminar crack growth in composites — modelling of R-curves from measured bridging laws , 2001 .

[17]  Zhigang Suo,et al.  Delamination R-curve phenomena due to damage , 1992 .

[18]  Kenneth M. Liechti,et al.  COHESIVE ZONE MODELING OF CRACK NUCLEATION AT BIMATERIAL CORNERS , 2000 .

[19]  Shankar Kalyanasundaram,et al.  On crack-initiation conditions for mode I and mode II delamination testing of composite materials , 2000 .

[20]  P. Olsson,et al.  On the determination of the constitutive properties of thin interphase layers — An exact inverse solution , 1989 .

[21]  G. Simpson,et al.  Mixed mode fracture toughness of GFRP composites , 2006 .

[22]  Erik Serrano,et al.  Influence of bondline brittleness and defects on the strength of timber finger-joints , 1999 .

[23]  A. Waas,et al.  Mixed-mode cohesive-zone models for fracture of an adhesively bonded polymer–matrix composite , 2006 .

[24]  J. Hutchinson,et al.  The influence of plasticity on mixed mode interface toughness , 1993 .

[25]  G. I. Barenblatt.  THE MATHEMATICAL THEORY OF EQUILIBRIUM CRACKS IN BRITTLE FRACTURE , 1962 .

[26]  Qingda Yang,et al.  Cohesive models for damage evolution in laminated composites , 2005 .

[27]  B. Cox,et al.  Mixed mode delamination of polymer composite laminates reinforced through the thickness by z-fibers , 2002 .

[28]  M. Benzeggagh,et al.  Measurement of mixed-mode delamination fracture toughness of unidirectional glass/epoxy composites with mixed-mode bending apparatus , 1996 .

[29]  Ignacio Carol,et al.  NORMAL/SHEAR CRACKING MODEL: APPLICATION TO DISCRETE CRACK ANALYSIS , 1997 .

[30]  Bent F. Sørensen,et al.  DCB-specimen loaded with uneven bending moments , 2006 .

[31]  Bent F. Sørensen,et al.  Cohesive law and notch sensitivity of adhesive joints , 2002 .