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Abstract

This thesis considers the theoretical and experimental analysis of plane layered structures subjected to impact. A new approach combining the finite element technique with the theories of propagation wave, which is appropriate for design purposes, has been proposed. This approach is suitable for the analysis of multi-layered half-space structures subjected to impact forces. Such structures include aircraft pavements or runways. It is intended to be a realistic and a versatile method to be used for the analysis and design of structures or structural components which may be considered to act as plane or axisymmetric systems subjected to impact.

Some special features related to the propagation of elastic waves in solids are considered. In addition, problems involving the response of multi-layered structures which arise from the different types of waves created at interfaces have been discussed. A review of the analytical solutions of wave propagation in solids and multi-layered structures are summarized in this thesis.

A numerical model has been developed using the finite element technique. This technique has certain advantages for analysis of a multi-layered half-space structure subjected to an impact force. The simulation of complex applied load distribution, the representation of stress wave propagation and the reflection and refraction at interfaces are included. The different stiffness and damping characteristics in each layer are represented. The theory which has been developed has been incorporated in a complete program called DFEM to study the dynamic response and also important features such as the damping, reflection and refraction of stress waves.

The accuracy of the results obtained is demonstrated by comparison with results obtained by other published methods. In addition, an experimental investigation was carried out by using the dynamic photoelasticity technique which provides a convenient method to study stress wave propagation. A series of a multi-layered models were tested to further substantiate the theoretical results. The model dimensions and materials were chosen to minimize the effects of reflection from both boundary and free surfaces. The degree of correlation obtained shows that the theoretical developments proposed in this thesis may be applied successfully to the analysis of plane multi-layered structures subjected to impact.

The objective of the method of analysis which has been developed was the direct analysis of pavement or runway structures. Therefore, the basic methods which deal with the design of flexible airfield pavements are summarized. A dynamic factor has been assessed which depends on the time of impact force and maximum tyre deflection to be used in the analysis and design of airfield pavements.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > T Technology (General) T Technology > TA Engineering (General). Civil engineering (General) T Technology > TE Highway engineering. Roads and pavements
Departments:	School of Science & Technology > Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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