Multi-level experimental and numerical analysis of composite stiffener debonding. Part 1: Non-specific specimen level

• Published in: Composite structures Vol. 90; no. 4; pp. 381 - 391
• Main Authors: Bertolini, Julien, Castanié, Bruno, Barrau, Jean-Jacques, Navarro, Jean-Philippe
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2009; Elsevier
• Subjects: Buckling; Engineering Sciences; Exact sciences and technology; Finite element analysis; Fracture mechanics; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Materials and structures in mechanics; Mechanics; Physics; Skin/stiffener debonding; Solid mechanics; Structural and continuum mechanics; Skin/stiffener debonding; Fracture mechanics; Finite element analysis; Flange; Stratified material; Ageing; Cohesive end; Rupture; Crack closure effect; Experimental study; Modeling; Postbuckling; Reinforced structure; Engineering design; Finite element method; Variable section; Virtual work principle; Interface crack; Aircraft; Delamination; Buckling; Fuselage; Bending test; Stiffener; Fracture Mechanics; Finite Element analysis
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2009.04.001

A multi-level analysis of skin/stiffener debonding is used for the fuselage design of future aircraft during postbuckling. The specimens composed of a laminate (the skin) to which an over-thickness (the flange) had been added were subjected to four-point bending, which led to interface failure between the flange and the skin. These tests were performed with several configurations and parameters, such as the orientation of the plies located at the interface, temperature (−50, 20 and 70 °C), ageing and manufacturing mode: co-cured or co-bonded. The flange shape (tapered or not) and thickness were also considered. Test data are presented and analyzed and critical configurations are identified. Finite element models were developed and the flange debonding loads computed, firstly by use of cohesive models and then through a fracture mechanics approach (Virtual Crack Closure Technique). In both cases, the Benzeggagh–Kenane criterion was selected and proved its efficiency but the fracture mechanics approach was an order of magnitude less time consuming, which will enable future modelling to include larger sizes.