Optimal search for worst mistuning patterns in mistuned bladed discs based on large-scale finite element models

A method for searching For the worst frequency mistuning patterns (providing the highest response levels) in bladed disc assemblies is described. The method is intended for use with finite element models having a large number of degrees of freedom that could only be used currently for tuned bladed discs. The problem is formulated and solved as an optimization problem with the use of information about the sensitivity of maximum response levels with respect to mistuning variation. An effective analytical approach is developed to calculate the sensitivity coefficients without a significant increase in computational effort. Numerical studies are carried out for realistic finite element models of a bladed disc assembly to illustrate the method