A Reliable Pre-Processing for the Simulation of Friction Joints in Turbomachineries and its Validation: A Case Study With Policontact

Abstract

Industry and University collaborates to develop methods to simulate the nonlinear dynamics of components in rotating assemblies like turbine or compressor modules in the presence of friction joints. This collaboration produced fruitful results providing a family of numerical solvers with the goal of foreseeing the safety margins against High Cycle Fatigue failure. Softwares are therefore intended as design tools to exploit the damping effect of joints by controlling geometrical features, materials and contact loads. Contact models, reduction techniques to handle complex blade geometries modeled by Finite Element softwares, and numerical techniques to solve the nonlinear equations of motion are refined to provide the level of vibration amplitude as fast as possible by keeping the representativeness of the physical phenomena that are involved. A reliable compromise between speed and accuracy must be confirmed by several ‘gates’ to pass through during all the simulation process, in particular during pre-processing phase. The objective of this paper is to propose a good practice made of a list of actions to check the goodness of the mathematical basis to obtain reliable results from simulation. Experience gained thanks to the long-lasting collaboration between Politecnico di Torino and GE Avio for the development of the software Policontact provides a case study of an effective synthesis between two requirements that are often opposed to each other: complex mathematical models to simulate the nonlinear forced response of rotating components on one side and a robust, confident implementation of an easy-to-use tool intended for industrial staff with complementary background on the other side.