Dynamic response of sandwich and laminated composites with imperfect interface and delamination.

摘要

Analyses of free vibrations, forced vibrations and structural damping characteristics of sandwich and laminated composites with imperfect interface and delaminations are presented. A refined high-order theory for the vibration of sandwich beams and plates to specifically deal with a transversely flexible core has been introduced. The effect of imperfect viscoelastic interface on the structural damping of a sandwich beam is studied. Analytical models of vibrations of sandwich and laminated plates with delaminations are developed.;The refined vibration theory embodies a general systematic approach to the analysis of sandwich beam and plate having high-order effects owing to the non-linear pattern of the longitudinal and transverse deformation of the thick core. Inertia effects due to all the displacements are taken into account. As such it improves on the available classical and shear deformation theories. It is used to corporate the imperfect interface model and vibration damping approach to exam the interface layer effect on the structural damping of the sandwich beam. Results show that the imperfect interface affects vibration damping significantly.;Based on this theory the free vibration behavior of a sandwich plate with a through-width delamination is examined. The shear deformation effect and compressive in-plane force effect have been taken into account in the analysis. Two analytical models of different deformation modes are discussed. Fundamental frequencies and vibration mode shapes are calculated and the physical admissible model is identified. It is found that delamination length, delamination location and core thickness have significant effect on vibration characteristics.;Finally, vibration analysis of laminated composite beams with delaminations based on a layer-wise finite element model is presented. Parallel algorithm design for the finite element analysis is discussed and efficient approximation algorithms are developed. The fundamental natural frequencies of laminated composites with delamination are examined for the effects of delamination length and compressive in-plane loading.