Executive Summary : | Turbine blades, which are pre-twisted in geometry and subjected to extreme temperatures and thermal shocks, are increasingly being replaced by functionally graded materials (FGMs) due to advancements in manufacturing techniques. FGMs consist of ceramic and metal constituents, with properties graded in a certain spatial direction. The ceramic component acts as heat-resistant, while the metal component provides stiffness to the structures. An accurate dynamic analysis is needed before designing and manufacturing FGM turbine blades, considering the effect of severe temperature and high rotational velocity. The design stage must consider the thermally induced vibration and transient thermal stress. Porosities occur within FGM materials, making it crucial to consider them when estimating their material properties. The pre-twisted geometry of FGM blades makes formulation more complicated. The finite element method (FEM) allows for easier modeling of complex geometrical shapes like turbine blades. However, there are few studies on thermal shock analysis of porous functionally graded pre-twisted/turbine rotating blades. This work aims to develop a simple and accurate finite element formulation for thermal shock analysis of porous FGM pre-twisted rotating blades. The outer surface of the FGM turbine blade is subjected to thermal shocks, while the inner surface is kept at a reference temperature or thermally insulated. The nonlinear temperature profile along the thickness direction will be obtained from Fourier's law of heat conduction under unsteady state conditions. The effects of thermal shock magnitude, rotational velocity, twist angle, porosity, blade thickness, and volume fraction index on thermal vibrations and transient thermal stresses are investigated in detail. |