Evaluation of Reliability of Rupture and Expected Value of Fracture Speed of Ceramic Turbine Wheel Taking the Effect of Residual Stresses

Abstract

In this paper, Weibull uni-axial and multiaxialdistribution function including residualstresses is developed and applied to evaluatethe reliability of fracture and expected valueof fracture rotating speed of turbine rotorwheel having blades manufactured fromceramic material and have inner crack. Theresidual stress is measured by X-Ray method.Third cases are considered, first taking onlythe effect of rotational loading (radial andtangential stresses) in ceramic disc, secondtaking the effect of rotational and thermalstresses in ceramic disc, and third taking theeffect of rotational and thermal stresses inceramic blade. As a result, there is aconvergence between results gets from uniaxialand multi-axial distribution function,and the residual stresses will reduce the riskof fracture of wheel and blade. The expectedvalues of rupture strength of ceramic blade ishigher than of that of disc material, thereforethe failure occurs in blade first than in discmaterial in service survival