Advanced calculation of the room-temperature shapes of unsymmetric laminates

It is well known that the room-temperature shapes of unsymmetric laminates do not always conform to the predictions of classical lamination theory. In stead of being saddle shaped, as classical lamination theory predicts, the room-temperature shapes of unsymmetrically laminated composites are often c ylindrical in nature. In addition, a second cylindrical shape can sometimes be obtained from the first by a simple snap-through action. Since 1981 sev eral models, which are restricted to rectangular plates and sometimes only some special lay-ups, have been developed. The Finite Element Analysis (FEA ) has just recently been used for the calculation of the room-temperature s hapes of unsymmetric laminates, because more sophisticated finite element c odes are now available and the calculations can be made in an acceptable ti me. Using the FEA there are no restrictions concerning the laminate geometr y or the lay-up and the snap-through effect can be modeled. Additionally th e edge-effects can also be monitored in the FEA results. Unsymmetric lamina tes can become important for aircraft applications especially for the aeroe lastic tailoring.