Damage sensitivity of axially loaded stringer-stiffened curved CFRP panels

A fuselage representative carbon fibre-reinforced multi-stiffener panel is analysed under compressive loading. An intact and pre-damaged configuration is loaded into the postbuckling region and further on until collapse occurs. An analysis tool is applied that includes an approach for predicting interlaminar damage initiation and degradation models for capturing interlaminar damage growth as well as in-plane damage mechanisms. Analysis of the intact panel configuration predicts collapse due to fibre fracture in the stiffeners close to the panel clamps, which agrees well with the results from experimental testing. The pre-damaged configuration was proposed containing Teflon-coated layers to generate the initial debonds in the skin-stiffener interface. The outcome of the simulation of this configuration shows that crack growth is not predicted to occur, which agrees with the observations of the experiment. A parametric study is conducted to investigate the effect of the skin-stiffener debond parameters such as length, width and location on crack growth and the collapse behaviour of the panel. It is found that the sensitivity of the panel design to the damage parameters is highly dependent on the postbuckling mode shape or displacement pattern, and particularly the extent to which this influences the conditions at the crack front. More broadly, the analysis tool is shown to be capable of capturing the critical damage mechanisms leading to structural collapse of stiffened composite structures in the postbuckling region.

[1]  I..,et al.  The Phenomena of Rupture and Flow in Solids , 2011 .

[2]  W. Wagner,et al.  Simulation of delamination in stringer stiffened fiber-reinforced composite shells , 2008 .

[3]  Rolf Zimmermann,et al.  Buckling and postbuckling of stringer stiffened fibre composite curved panels – Tests and computations , 2006 .

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

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

[6]  M. De.  Handbuch der Physik , 1957 .

[7]  Richard Degenhardt,et al.  EXPERIMENTS ON BUCKLING AND POSTBUCKLING OF THIN-WALLED CFRP STRUCTURES USING ADVANCED MEASUREMENT SYSTEMS , 2007 .

[8]  Jian Li.  Three-Dimensional Effect in the Prediction of Flange Delamination in Composite Skin-Stringer Pull-off Specimens , 2002 .

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

[10]  P. Hansen,et al.  DCB, 4ENF and MMB Delamination Characterisation of S2/8552 and IM7/8552 , 1999 .

[11]  Pedro P. Camanho,et al.  Fracture analysis of composite co-cured structural joints using decohesion elements , 2008 .

[12]  Pedro P. Camanho,et al.  A continuum damage model for composite laminates: Part I - Constitutive model , 2007 .

[13]  P. Ladeveze,et al.  A damage computational approach for composites: Basic aspects and micromechanical relations , 1995 .

[14]  S. Rinderknecht,et al.  A FINITE ELEMENT MODEL FOR DELAMINATION IN COMPOSITE PLATES , 1995 .

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

[16]  Damodar R. Ambur,et al.  Intralaminar and interlaminar progressive failure analyses of composite panels with circular cutouts , 2002 .

[17]  Chiara Bisagni,et al.  A Finite Element Methodology for Analysing Degradation and Collapse in Postbuckling Composite Aerospace Structures , 2009 .

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

[19]  Numerical simulation of DLR-Benchmark : Axially compressed stiffened CFRP panel , 2005 .

[20]  Ronald Krueger,et al.  The Virtual Crack Closure Technique : History , Approach and Applications , 2002 .

[21]  Pedro P. Camanho,et al.  A continuum damage model for composite laminates: Part II – Computational implementation and validation , 2007 .

[22]  Larsgunnar Nilsson,et al.  Modeling of delamination using a discretized cohesive zone and damage formulation , 2002 .

[23]  Claudio Balzani,et al.  An interface element for the simulation of delamination in unidirectional fiber-reinforced composite laminates , 2008 .

[24]  Richard Degenhardt,et al.  COCOMAT—improved material exploitation of composite airframe structures by accurate simulation of postbuckling and collapse , 2006 .

[25]  A. Needleman.  An analysis of tensile decohesion along an interface , 1990 .

[26]  Fu-Kuo Chang,et al.  Damage Tolerance of Laminated Composites Containing an Open Hole and Subjected to Compressive Loadings: Part I—Analysis , 1991 .

[27]  Asd Wang,et al.  Fracture Mechanics of Transverse Cracks and Edge Delamination in Graphite-Epoxy Composite Laminates. , 1982 .

[28]  Z. Hashin.  Failure Criteria for Unidirectional Fiber Composites , 1980 .

[29]  Liyong Tong,et al.  An Assessment of Failure Criteria to Predict the Strength of Adhesively Bonded Composite Double Lap Joints , 1997 .

[30]  Adrian C. Orifici,et al.  Degradation models for the collapse analysis of composite aerospace structures , 2007 .

[31]  Peter Linde,et al.  Influence of modelling and solution methods on the FE-simulation of the post-buckling behaviour of stiffened aircraft fuselage panels , 2006 .