Torsional wave dispersion in multi-layered circular cylinders with the finite initial strains

Nowadays for the investigation of solutions to problems in science and engineering, nonlinear dynamic effects should be taken into consideration and initial stresses (strains) are one of those most important dynamic effects. The initial strains in construction materials may arise as a result of corresponding manufacturing procedures or as a result of the change in the environmental impacts like temperature. Multi-layered cylinders which are used in many areas of modern industry like power generation, chemical production facilities, to transfer various types of liquids (oil, gas, water), exposed to dynamic torsional loadings makes investigating the wave dispersion problem important in terms of both theoretical and application. The research presented in this thesis is intented to examine the effect of initial strains on torsional wave dispersion in multi-layered circular cylinders.In the present study, within the framework of the piecewise homogenous body model with the use of the Three-dimensional Theory of Elastic Waves in Initially Stressed Bodies (TLTEWISB) the torsional wave dispersion in the initially strained bi-material compound, hollow bi-material compound and hollow three-layered (sandwich) cylinders are investigated. The mechanical relations of the materials of the cylinders' components are described through their harmonic potential. Numerical results showing the effect of the initial strains on torsional wave dispersion were obtained and interpreted.The algorithms and programs which are needed to solve these problems and obtain those numerical results through MATLAB program are written by us. At the same time the accuracy of these algorithms are tested under the conditions of the relevant studies.So far, the effect of initial strains on the torsional wave dispersion in multi-layered circular cylinders with the finite initial strains is not investigated. In the previous studies which investigate the effect of the initial strains on the torsional wave dispersion in circular cylinders it was assumed that the initial strains were small and that significantly restricts both the theoretical and practical point of the application areas of the results obtained. In conclusion, the research in the present study is the first attempt in this field.