High-Order Theory Approach for Debonded Sandwich Panels—Part I: Formulation and Displacement Fields

Abstract A high-order theory is developed to model asymmetric sandwich panels with face/core debonds and to provide a solution for the energy release rate and mode mixty. This new theory is a novel re-formulation of the extended high-order sandwich panel theory (EHSAPT), in which faces and core were originally considered to be perfectly bonded. In the new formulation, a sandwich panel with an interfacial debond can be divided into three parts, namely, the debonded part, the substrate part, and the base part. A new high-order displacement pattern is developed to describe the core’s deformation in the substrate part, and it is compatible with the displacement field of the core in the base part. In addition, capturing the high-order shear deformation of the core, this new theory is able to take the transverse compressibility and axial rigidity of the core into account. In this Part I of this two-part research, we focus on the formulation and the displacement field. In Part II, the fracture parameters, namely, the energy release rate and the mode mixity will be addressed. Accordingly, in this paper, results for the deformation of the debonded panel are produced and compared with the ones given by the finite element method with a very fine mesh. The accuracy is proven for a wide range of core materials and for a wide range of debond lengths.