A General approach to the wrinkling instability of sandwich plates

Sandwich plates are widely used in lightweight design due to their high strength and stiffness<br />to weight ratio. Due to the heterogeneous structure of sandwich plates, they can exhibit local instabilities<br />(wrinkling), which lead to a sudden loss of stiffness in the structure. This paper presents an analytical<br />solution to the wrinkling problem of sandwich plates. The solution is based on the Rayleigh-Ritz method,<br />by assuming an appropriate deformation field. In contrast to the other approaches up to now, this model<br />takes arbitrary and different orthotropic face layers, finite core thickness and orthotropic core material into<br />account. This approach is the first to cover the wrinkling of unsymmetric sandwiches and sandwiches<br />composed of orthotropic FRP face layers, which are most common in advanced lightweight design. Despite<br />the generality of the solution, the computational effort is kept within bounds. The results have been<br />verified using other analytical solutions and unit cell 3D FE calculations.