Vibration of imperfect composite and sandwich laminates with in-plane partial edge load

The free vibration of imperfect composite and sandwich laminates subjected to in-plane partial edge loading is studied. An efficient finite element model recently developed by the authors based on a refined plate theory is used for the present purpose. In this theory, the transverse shear stresses are continuous at the layer interfaces with stress free conditions at plate top and bottom surfaces. The imperfection is considered in the form of in-plane displacement jumps at the layer interfaces, which is characterized by a linear spring-layer model. It is very interesting to note that the plate model having all these refined features requires unknowns only at the reference plane. However, this theory demands C1 continuity of transverse displacement at the element edges, which is difficult to satisfy arbitrarily in any existing finite element. A new triangular element developed by the authors is used to deal with the problem.