Non-linear finite element analysis of inserts in composite sandwich structures

• Published in: Composites. Part B, Engineering Vol. 39; no. 7; pp. 1077 - 1092
• Main Authors: Bunyawanichakul, P., Castanié, B., Barrau, J.-J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2008; Elsevier
• Subjects: A. Honeycomb; A. Sandwich structures; Applied sciences; C. Finite element analysis; D. Mechanical testing; Engineering Sciences; Exact sciences and technology; Forms of application and semi-finished materials; Laminates; Materials and structures in mechanics; Mechanics; Polymer industry, paints, wood; Technology of polymers; A. Honeycomb; A. Sandwich structures; D. Mechanical testing; C. Finite element analysis; Strengthening; Pull out resistance; Nylon; Aromatic polymer; Sandwich structure; Mechanical properties; Compressive strength; Experimental study; Insert; Modeling; Composite material; Finite element method; Bending strength; Honeycomb structure; Non linear model; Numerical simulation; Measurement method; Fracture mode
• ISSN: 1359-8368; 1879-1069
• DOI: 10.1016/j.compositesb.2008.05.004

In aeronautics, sandwich structures are widely used for secondary structures like flaps, landing gear doors or commercial equipment. The technologies used to join these kinds of structures are numerous: direct bonding or joining, tapered areas, T-joints, etc. The most common is certainly the use of local reinforcement called an insert. The insert technologies are numerous and this study focuses on high load bearing capacity inserts. They were made with a resin moulded in the Nomex™ sandwich core. Such structures are still designed mainly empirically and the lack of efficient numerical models remains a problem. In this study, pull-out tests were conducted on a representative sample and the non-linearities and the types of failure were analysed. Core shear bucking, failures of the potting and perforation of the composites skins are the main modes of failure. For each mode, local experimental and numerical analysis was carried out that led to the identification of the independent non-linear behaviour of each component. Including the results in a global non-linear finite element model gave good prediction of the failure scenario and an acceptable correlation with the tests.