Strength requirement is one of the most important criteria in the design of gas turbine casing. Traditionally, deterministic analyses are used in strength assessment, with boundary conditions and loads set as fixed design values. However, real boundary conditions and loads in the operation can often differ from the fixed design values, such that the mechanical integrity of the turbine casing can vary from the strength and fatigue calculations.
In this work, the effect of the variability of the boundary conditions and loads is investigated on the static thermal stress problem of gas turbine casings using a probabilistic approach. The probability distribution is estimated using a Monte Carlo simulation based on the distribution of boundary conditions and loads obtained from field measurements. The finite element analysis is used to calculate the stress corresponding to different boundary conditions and a surrogate model is built to reduce the computational time of Monte Carlo simulations. This methodology is applied to a real engineering case which better quantifies the strength assessment result.