Elastic wrinkling of sandwich columns and beams with unbalanced laminated fibre reinforced face plates (face plates of AsBoDs@ AsBlDs and AsBsDs types).
ESDU 87013 introduces a program@ ESDUpac A8713@ that treats either balanced face plates or two classes of unbalanced face plates. It is provided on disc in the software volume both as Fortran code and compiled to run in ESDUview@ a user-friendly shell running under MS DOS that prompts for input data on screen. The equations solved are included and were derived using elastic@ thin plate@ small deflection theory assuming the face plate material to be homogeneous with the principal axes of orthotropy aligned with the edges of the beam or column. For columns the face plates are assumed to form a balanced lay-up about the centre plane while for beams the tension face is assumed to be a rigid boundary for the core against wrinkling of the compression face. Through-the-thickness shear deformation is neglected and it is assumed the core will hold the face plates flat until they wrinkle. Graphs show the influence of the major input variables on wrinkling loads including the influence of the face plate/core adhesive layer. The output includes the wrinkling wavelengths which are compared with the beam or column length; for thin sandwich beams behaviour is dominated by Euler buckling and this condition is identified by the program when it occurs. The input to the program is described in detail@ its validation is discussed@ and specimen input and output of several worked examples are included.