Abstract:

ESDU 89013 introduces a Fortran program, ESDUpac A8913. The program calculates the stiffnesses of laminated plates (or a sandwich panel) from the properties of the layers, with no restriction on the lay-up arrangement. The theory is outlined and assumes that points on a normal to the mid-surface before bending remain in a straight line, although not normal to the mid-surface, after bending. This allows rotation in shear to be added to rotation due to classical plate bending. Example calculations are included together with graphs showing the effect of lay-up on the shear stiffnesses. A full description of the input and output of the program is provided, with details of various warning messages that may be generated, and the testing to which the program was subjected is discussed. Values of transverse shear stiffness are important in calculating deflections caused by through-thickness shear stresses, particularly for laminated plates for which the transverse stiffnesses, which depend on the properties of the matrix material bonding the fibres together, are low.