Abstract
In aeronautics, sandwich structures are widely used for secondary structures like flaps or landing gear doors. In the case of landing gear doors, the junction is made by a local reinforcement called an insert. This insert is made by a resin molded in the Nomex™ sandwich core. Such structures are still designed mainly using test results and the lack of an efficient numerical model remains a problem. The purpose of this study is on the one hand to perform experiments in order to be able to identify the failure modes and on the other hand to propose an efficient numerical model. Pull-out tests with cycling were conducted and 3D displacement measured by optical methods. The potential failure modes are numerous (delamination, local fiber breaking, skin/core debonding, core crushing, core shear buckling, potting failure, etc.). Experiments demonstrated that, for the lower loads, the non-linearity and the hysteresis are mainly due to core shear buckling. From this observation, the nonlinear behavior of the core is identified by a 3 point-bending test. The shear-modulus damage law is then implemented on a non-linear finite element model and an acceptable correlation of the tests is achieved. As a consequence, some improvements of the technology will be proposed, manufactured and tested.
Similar content being viewed by others
References
Zenkert, D., The handbook of sandwich construction, EMAS Publishing.
Noirot, F., Ferrero, J.-F., Barrau, J.-J., Castanie, B. and Sudre, M., ‘Analyse d’inserts pour les structures sandwich composites’, Mec. Ind. 1, 2000, 241–249.
Insert Design Handbook, ESA PSS 03-1202, 1987.
Thomsen, O. T., ‘Sandwich Plates with ‘Through-the-Thickness’ and ‘Fully-Potted’ Insert: Evolution of Differences in Structural Performance’, Comp. Struc. 40(2), 1998, 159–174.
Thomsen, O. T. and Ritz, W., ‘Analysis and Design of Sandwich Plates with Inserts – A High-Order Sandwich Plate Theory Approach’, Composites Part B 296, 1998, 795–807.
‘Design of Flat Circular Sandwich Panels Loaded at an Insert’, in US Military Handbook, Vol. 23A, 1974.
Youngquist, W. G. and Kuenzi, E. W., ‘Stresses Included in a Sandwich Panel by Load Applied at an Insert’, Forest. Forest Products Laboratory, Report No. 1845, Madison 5, Wisconsin, 1955.
SHUR-LOK Corp., ‘Sandwich Panel Fasteners’, Design manual, 1981.
SHUR-LOK Corp., ‘Fasteners for Sandwich Structure’, Ed. 10th, 1987.
WITTEN Co., Inc., ‘Product Guide for High Performance Inserts for Composites’, 1999.
Andre, S., ‘Synthese du programme devaluation d’inserts fortes epaisseurs pour application RTM. La recherche aerospatiale’, 1996.
Astrom, B. T. and Mcgarva, L. D., ‘Insert Integration in Thermoplastic-Based Foam Core Sandwich Components’, Journal of Sandwich Structures and Materials 1(July) 1999.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bunyawanichakul, P., Castanie, B. & Barrau, J.J. Experimental and Numerical Analysis of Inserts in Sandwich Structures. Appl Compos Mater 12, 177–191 (2005). https://doi.org/10.1007/s10443-005-1122-6
Issue Date:
DOI: https://doi.org/10.1007/s10443-005-1122-6