| In this thesis,the related problems of smart laminated composite plate and shell structures incorporating simultaneous interfacial diffusion and sliding are studied.Laminated composites are well known for their high stiffness,strength and light-weight.Consequently,they are usually used as load bearing part of the smart system.On the other hand,piezoelectric materials can be used as the sensing and actuating part of the smart system due to their own direct and inverse piezoelectric effects.Furthermore,interfacial diffusion and sliding are known to be the predominant mechanism for many phenomena observed in composite materials at high temperatures.So it is of great importance to study the transient responses of laminated composites with interfacial diffusion and sliding for assessing the safety and integrity of structures.The state-space method,the Euler equation and the Stroh-type sextic formalism are employed to address these problems.First,the time-dependent problem of a laminated ortho tropic elastic cylindrical shell bonded to piezoelectric actuator and sensor with interfacial diffusion and sliding subjected to electromechanical loading is studied.The state-space method is employed to solve this problem.Both the time-dependent variation of electric potential due to the direct and the inverse piezoelectric effects are investigated.The relaxation times and the transient electroelastic fields of displacements,stresses and electric potential are calculated for a three-layered and five-layered smart cylindrical shells.It is found that interfacial diffusion and sliding can effectively reduce the initial high stress concentrations as the evolution time is long enough.The derived solution can be used as benchmark results for various approximate shell theories and numerical methods.And then the time-dependent deformations of a simply supported angle-ply laminates in cylindrical bending with interfacial diffusion and rate-dependent sliding are studied by means of the Stroh-type sextic formalism and the state-space approach.The elastic field in a certain layer is expressed by using the Stroh-type sextic formalism.The state-space equation can then be expediently constructed for an N-layered laminate.By solving the state-space equation,all the relaxation times of the laminate and the time-dependent displacements and stresses everywhere in the laminate are obtained.What’s more,numerical results for five-layered laminates are presented. |
PDF Full Text Request