Abstract

Creep is the permanent deformation of a component under a static load maintained for a period of time. Creep is usually of concern to engineers and metallurgists when evaluating components that operate under high stresses or high temperatures . Boiler tube, turbine blade, pump rotor, concrete etc. structures are needed to be creep tested before going into service. Creep test ensures the material used in the structure fulfills the requirements of strength and stability. In the recent times alloys are preferred by engineers than pure materials because of their special properties. These materials should also be creep tested before replacing the previous material. Creep analysis is mostly significant in the ship structures which are subjected to high temperature and stress. Structures like engine foundation, boiler tube, propeller blade, plates welded with one another etc. normally work under extensive working conditions. It is shown in this thesis, is a procedure, by following it one can get results of creep analysis different of structures at various conditions. At first a standard problem of a model of the intersection of a pipe with a cylindrical pressure vessel has been worked out and the properties of the model has been observed while the system operates at elevated temperature and carries internal pressure. In the first step a static analysis is performed, during which the internal pressure is applied. In the second step a quasi-static transient analysis is carried out to determine the creep behavior of the pressurized vessel and pipe. Then a verification test was performed to show whether the procedure exhibit similarity with collected experimental data. To show stress and temperature dependence of creep with time several curves were generated at different variables. These curves are helpful to understand the creep behavior more precisely. Then two propeller blade designs were analyzed to compare their creep behavior. This can be used to decide which design is better having less creep deformation. A plate welded with another forming a T-joint was worked out in another analysis. Static analysis showed the safety limit of load it can withstand for the given boundary condition and temperature. Creep analysis at loads lower than safety load showed how creep spread over the structure.