ON THE ACCURACY OF APPROXIMATE PLATE THEORIES FOR WAVE-FIELD CALCULATIONS IN COMPOSITE LAMINATES

Approximate plate theories have been extremely useful in providing ana lytical solutions to problems involving static and dynamic loadings of uniform or laminated plates of finite dimensions. The approximate the ories can also be used for solving wave propagation problems in limina tes of finite thickness and large lateral dimensions. We have recently developed a multiple transform technique coupled with a numerical eva luation scheme to calculate the resulting double integral expressions for the displacements and stresses produced in a composite laminate su bjected to dynamic loads. This technique is used to determine the wave field in the laminate due to a concentrated or distributed dynamic su rface load with and without the thin plate approximation. The accuracy of the approximate solution is shown to depend upon the pulse width o f the forcing function, the plate thickness, as well as the distance b etween the source and the field points. For a given force time history , the range of validity of the approximate solution is determined thro ugh comparison with the exact solution.