With Insulation Coating Component Temperature And Stress Analysis Of The Boundary Element Method And Its Applications

In this paper, a boundary element method (BEM) is developed for two-dimensional (2-D) thennal barrier coated structures. In late of 1990's, an efficient numerical method is developed to deal with nearly singular integrals in boundary integral equation (BIE) for composites. In this paper, this method is improved and used to deal with multi-layer structure under temperature field and centrifugal force, so that it can be used to analyze thermal barrier coated components of aeroengine. The volume integrals of temperature field and centrifugal force are transformed into boundary integrals, thus, the boundary element analyses of coated structures of aeroengine can be modeled and performed without volume cells. An numerical method dealing with the nearly-singular integrals over straight boundary elements in 2-D problems is improved to deal with the nearly-singular integrals over curved elements to further increase the accuracy and efficiency. At same time, the boundary integral equation formulae and codes for temperature field analysis are presented in this paper to calculate the temperature fields and temperature gradient for the further thermal-stress analysis of the structures. BEM formulae for interface crack analysis of thermal barrier coated structures are given in this paper. The method to evaluate nearly-singular integrals over crack tip elements and the formulae for calculating stress intensity factors (SIF) using displacements on crack faces are presented too. The formulae and the method given in this paper will be the references for the further research on BEM for characteristic analysis of interface crack. Typical numerical examples of 2-D multi-layer thin structures with temperature field and centrifugal force are analyzed by BEM presented in this paper to demonstrate the efficiency and accuracy of the method. It is shown that the method and codes given in this paper are very accurate and efficient in analyzing 2-D thin structures. Finally, a thermal barrier coated blade, as an example, is analyzed and designed by BEM given in paper, and the influences of material parameters (thermal expansion coefficients, Poisson's ratios and Young's modulus) and coating's thickness on thermal elastic stresses of the coated blade are discussed. Using the method given in this paper, micro- analysis of the composite can be performed to investigate the damage mechanism and the macro material parameter of composite.