A Shell/3D Modeling Technique for the Analysis of Delaminated Composite Laminates

A shell/3D modeling technique was developed for which a local solid finite element model is used only in the immediate vicinity of the delamination front. The goal was to combine the accuracy of the full three-dimensional solution with the computational efficiency of a shell finite element model. Multi-point constraints provided a kinematically compatible interface between the local 3D model and the global structural model which has been meshed with shell finite elements. Double Cantilever Beam, End Notched Flexure, and Single Leg Bending specimens were analyzed first using full 3D finite element models to obtain reference solutions. Mixed mode strain energy release rate distributions were computed using the virtual crack closure technique. The analyses were repeated using the shell/3D technique to study the feasibility for pure mode I, mode II and mixed mode I/II cases. Specimens with a unidirectional layup and with a multidirectional layup were simulated. For a local 3D model, extending to a minimum of about three specimen thicknesses on either side of the delamination front, the results were in good agreement with mixed mode strain energy release rates obtained from computations where the entire specimen had been modeled with solid elements. For large built-up composite structures the shell/3D modeling technique offers a great potential for reducing the model size, since only a relatively small section in the vicinity of the delamination front needs to be modeled with solid elements.

[1]  I. S. Raju,et al.  Strain energy release rate distributions for double cantilever beam specimens , 1991 .

[2]  Their Composites,et al.  Composite materials : testing and design : eleventh volume , 1993 .

[3]  I. Raju,et al.  Effect of Shear Deformation and Continuity on Delamination Modelling with Plate Elements , 1998 .

[4]  M. Manoharan,et al.  Strain Energy Release Rates of an Interfacial Crack Between Two Orthotropic Solids , 1989 .

[5]  I. Raju,et al.  Convergence of strain energy release rate components for Edge-Delaminated composite laminates , 1988 .

[6]  B. Davidson,et al.  A single leg bending test for interfacial fracture toughness determination , 1996 .

[7]  John D. Whitcomb.  Three-Dimensional Analysis of a Postbuckled Embedded Delamination , 1989 .

[8]  M. Koenig,et al.  Computation of local energy release rates along straight and curved delamination fronts of unidirectionally laminated DCB- and ENF-specimens , 1993 .

[9]  S. Rinderknecht,et al.  Two- and Three-Dimensional Finite Element Analyses of Crack Fronts in a Multidirectional Composite ENF Specimen , 1997 .

[10]  M. Kanninen,et al.  A finite element calculation of stress intensity factors by a modified crack closure integral , 1977 .

[11]  Tk O'Brien,et al.  Composite Interlaminar Shear Fracture Toughness, G IIc : Shear Measurement or Sheer Myth? , 1998 .

[12]  P. Robinson,et al.  A New Mode Iii Delamination Test for Composites , 1992 .

[13]  B. Davidson,et al.  Three-dimensional analysis of center-delaminated unidirectional and multidirectional single-leg bending specimens , 1995 .

[14]  Shaw-Ming Lee.  An Edge Crack Torsion Method for Mode III Delamination Fracture Testing , 1993 .

[15]  B.D. Davidson,et al.  An Analytical Investigation of Delamination Front Curvature in Double Cantilever Beam Specimens , 1990 .

[16]  T. O'brien,et al.  Interlaminar fracture toughness: the long and winding road to standardization , 1998 .

[17]  T. Krishnamurthy,et al.  Fracture mechanics analyses for skin-stiffener debonding , 1996 .

[18]  Barry D. Davidson,et al.  Effect of stacking sequence on energy release rate distributions in multidirectional DCB and ENF specimens , 1996 .

[19]  Kunigal N. Shivakumar,et al.  Three-dimensional elastic analysis of a composite double cantilever beam specimen , 1988 .

[20]  H. Grebner,et al.  2D- and 3D-Applications of the Improved and Generalized Modified Crack Closure Integral Method , 1988 .

[21]  James R. Reeder,et al.  A Bilinear Failure Criterion for Mixed-Mode Delamination , 1993 .

[22]  R H Martin,et al.  Incorporating interlaminar fracture mechanics into design , 2000 .

[23]  I. Raju.  Calculation of strain-energy release rates with higher order and singular finite elements , 1987 .

[24]  Pierre J. A. Minguet,et al.  Testing and Analysis of Composite Skin/Stringer Debonding Under Multi-Axial Loading , 1999 .

[25]  Ronald Krüger,et al.  Three Dimensional Finite Element Analysis of Multidirectional Composite DCB , SLB and ENF Specimens , 1994 .

[26]  H. Parisch.  A continuum‐based shell theory for non‐linear applications , 1995 .

[27]  Satya N. Atluri,et al.  Computational Mechanics ’88 , 1988 .

[28]  S. Rinderknecht,et al.  Computational Structural Analysis and Testing: An Approach to Understand Delamination Growth , 1996 .

[29]  Satish A. Salpekar,et al.  Combined effect of matrix cracking and stress-free edge on delamination , 1991 .

[30]  J. H. Crews,et al.  Redesign of the Mixed-Mode Bending Delamination Test to Reduce Nonlinear Effects , 1992 .

[31]  George Z. Voyiadjis,et al.  Damage in composite materials , 1993 .

[32]  T. O'Brien.  Characterization of delamination onset and growth in a composite laminate , 1982 .

[33]  Carlos G. Davila,et al.  Solid-to-shell transition elements for the computation of interlaminar stresses , 1994 .

[34]  B. Davidson,et al.  Three Dimensional Analysis and Resulting Design Recommendations for Unidirectional and Multidirectional End-Notched Flexure Tests , 1995 .

[35]  Martin Rh,et al.  Composite Materials: Fatigue and Fracture, Fourth Volume , 1993 .

[36]  Rh Martin,et al.  Round Robin Testing for Mode I Interlaminar Fracture Toughness of Composite Materials , 1993 .