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Skin/Stringer Interface Damage Characterization of Stiffened Composite Structures

WARUNA SENEVIRATNE, VISHNU SASEENDRAN, MOHAMED SHAFIE, JOHN TOMBLIN

Abstract


With stiffened composite panels being widely used in aerostructures, critical failure mechanics of the skin/stringer interface need to be thoroughly understood. The interface is design critical and must demonstrate the ability to sustain design limit load throughout the service life. Buckling and out-of-plane deformations, localized in a stiffened panel can initiate separation at the interface. In addition, presence of inherent manufacturing flaws or operational impact events can lead to premature separation and result in failure. Hence, to ensure structural integrity, thorough damage characterization of skin/stringer interface must be performed. The general building block certification approach used for analysis and test validation does not contain standardized test methods beyond the coupon level. In this study, a Seven-Point Bend (7PB) based test methodology is employed to induce localized buckling-based skin separation. The 7PB methodology is utilized to evaluate panels fabricated using both co-bonding and secondary-bonding methods. The experimental work is complimented by a cohesive zone model (CZM) where the disbond initiation and progressive damage growth at the skin/stringer interface is simulated. Delamination is observed at the interface, originating centrally and progressing asymmetrically along the length of the stringer until failure occurred. The zero-thickness cohesive elements based model implemented within this work was able to capture damage initiation and predicted the final damage map. The 7PB test methodology is demonstrated to be robust and can be introduced as a standard test practice to evaluate sub-elements.


DOI
10.12783/asc36/35929

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References


P. J. Minguet, and T.K. O’Brien. 1996 “Analysis of Test Methods for Characterizing Skin/Stringer

Debonding Failures in Reinforced Composite Panels,” Composite Materials: Testing and Design:

Twelfth Volume, ASTM International, p: 105-124.

C. Bisagni, R. Vescovini, and C.G. Dávila. 2011 “Single-Stringer Compression Specimen for the

Assessment of Damage Tolerance of Postbuckled Structures,” Journal of Aircraft, 48(2):495-502.

C.Q. Rousseau, D.J. Baker, and J.D. Hethcock. 2001 “Parametric Study of Three-Stringer Panel

Compression-After-lmpact Strength,” Composite Structures: Theory and Practice. ASTM

International.

J.C.F.N. van Rijn and J.F.M. Wiggenraad. 2000. “A Seven-Point Bending Test to Determing Strength

of Skin-Stiffener Interface in Composite Aircraft Panels,” NLR-TP2000-044, National Aerospace

Laboratory (NLR).

J. Bertolini, B. Castanié, J.J. Barrau, J.P. Navarro, and C. Petiot. 2009. “Multi-Level Experimental

and Numerical Analysis of Composite Stiffener Debonding. Part 2: Element and Panel Level,”

Composite Structures, 90(4):392-403.

C.J. Kosztowny, C.G. Dávila, K.C. Song, C. A. Rose. 2019. “Experimental and Numerical Analysis

of Skin-Stiffener Separation Using a Seven Point Bend Configuration”, in Proceedings of the AIAA

SciTech 2019 Forum, p: 1767-1781.

S. Wanthal, J. Schaefer, B. Justusson, I. Hyder, S. Engelstad and C. Rose, 2017. “Verification and

Validation Process for Progressive Damage and Failure Analysis Methods in the NASA Advanced

Composites Consortium”, in Proceedings of the 32nd American Society for Composites Conference,

West Lafayette, IN.

C.G. Dávila, F.A. Leone, K.C. Song, J. G. Ratcliffe, and C.A. Rose, 2017. “Material Characterization

for the Analysis of Skin/Stiffener Separation”, in Proceedings of the 32nd American Society for

Composites Conference, West Lafayette, IN.

J. Zalameda, and W. Winfree. 2018. “Detection and Characterization of Damage in Quasi-Static

Loaded Composite Structures Using Passive Thermography”, Sensors, 18(10):3562-3579.

L.J. Kootte, and C. Bisagni. 2020. “A Methodology to Investigate Skin-Stringer Separation in

Postbuckled Composite Stiffened Panels”, in Proceedings of the AIAA SciTech 2020 Forum, p: 1-14.

W. Seneviratne, V. Saseendran, S. Perera, B. Saathoff, and L. Rubesinghe, 2019. “Numerical Studies

on Buckling and Post-Buckling Behavior of Stiffened Curved Composite Panel with Repairs”, in

Proceedings of the 34th American Society for Composites Conference, Atlanta, GA.

J. Tomblin, W. Seneviratne, and G. R. Pillai. 2009. “Effects of Disbonds, Lightning Strikes, and Low-

Velocity Impact Damage on Adhesively Bonded Composite Joints,” DOT/FAA/AR-09/4.

R. Krueger. 2004. “Virtual crack closure technique: history, approach, and applications”. Applied

Mechanics Reviews, 57(2), 109-143.

L.R. Deobald, G.E. Mabson, S. Engelstad, M. P. Rao, M. Gurvich, W. Seneviratne, S. Perera et al.

“Guidelines for VCCT-based interlaminar fatigue and progressive failure finite element

analysis”. National Aeronautics and Space Administration, Langley Research Center. NASA/TM–

-219663.

A. Turon, P. P. Camanho, J. Costa, and C. G. Dávila. 2006 "A damage model for the simulation of

delamination in advanced composites under variable-mode loading." Mechanics of materials 38(11):

-1089.

P. W. Harper, L. Lu, and S. R. Hallett. 2012. "A study on the influence of cohesive zone interface

element strength parameters on mixed mode behaviour." Composites Part A: Applied Science and

Manufacturing, 43(4): 722-734.

ABAQUS/Standard User's Manual, Version 2019. Simulia, 2019.

R. Krueger, 2015. “A summary of benchmark examples to assess the performance of quasi-static

delamination propagation prediction capabilities in finite element codes.” Journal of Composite

Materials, 49(26):3297-3316.

M.H. Nguyen, P. Davidson, and A.M. Waas, 2020. “Experimental and numerical study on the tensile

failure behavior of toughened interlayer composite laminates with automated fiber placement (AFP)

induced gap and overlap defects.” International Journal of Material Forming,14: 105-119.

L.J. Kootte, C. Bisagni, C.G. Dávila, and V. Ranatunga, 2018. “Study of Skin-Stringer Separation in

Postbuckled Composite Aeronautical Structures”, in Proceedings of the 33rd American Society for

Composites Conference, Seattle, WA.

W. Seneviratne, J. Tomblin, V. Saseendran, and M. Shafie, 2021. “Investigation of Skin/Stringer

Interface Separation in Stiffened Composite Structures”, in Proceedings of the SAMPE 2021.


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