Thermal stress problems ın FGMS

Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Faculty of Engineering, Department of Mechanical Engineering, Turkey

Approval Date: 2019

Student: Esra Nur Akdoğan



In this thesis transient temperature distribution, thermal stresses and thermal stress intensity factors (TSIFs) of an infinitely long functionally graded material (FGM) strip containing periodic cracks under thermal shock are studied. Thermal shock is applied by imposing a sudden change in the boundary temperatures. Solution of the present thermoelasticity problem is considered in three successive steps. First the thermal (conduction) problem is solved and the transient temperature distribution is determined. This is followed by the determination of thermal stresses by solving quasi-static elasticity problem. In the last step thermal stress intensity factors (TSIFs) are calculated. In this work, the main focus is the calculation of the transient temperature distribution and the resulting thermal stresses. Since the thermomechanical properties are considered to be functions of a spatial variable, a perturbation technique developed in [1] and [2] is adopted to find an analytical solution of transient heat conduction equation in Laplace domain. Inverse Laplace transformation is achieved by using "residue theorem". After numerically calculating the transient temperature distribution, thermal stresses are computed in the absence of any cracks for the FGM strip subjected to thermal shock. Then, by introducing the thermal stresses as the crack surface tractions in the singular integral equation which is derived in an earlier thesis [3], the TSIFs are determined.