Politecnico di Torino Component modes synthesis applied to a thermal transient analysis of a turbine disc Botto, D. - Politecnico di Torino - Mechanics Department Troncarelli, E. - MSC.Software Italia

Overview Temperature Monitoring Algorithm Component Modes Synthesis Integration of MSC’s and Politecnico’s Codes Turbine disc thermal analysis Error vs. Modal Shapes Choice Final Remarks Politecnico di Torino

Temperature monitoring algorithm Thermal FE model development Reduction of the size of the problem Critical nodes temperature on line calculation Critical nodes: locations that are expected to determine the fatigue life of the component. Agreement with FE solution Errors limited to 10 K Politecnico di Torino

Component modes synthesis methodology - 1 Full FE model Partitioned model Critical nodes Non-critical nodes Politecnico di Torino

Component modes synthesis methodology - 2 Thanks to: Static reduction nodes eigenvector {To} linear superposition of {Ta} and {ho} Politecnico di Torino

Component modes synthesis methodology - 3 The reduced model is developed If all the eigenvectors {ho} are used, no reduction is achieved Politecnico di Torino

Politecnico di Torino Code Code Integration - 1 MSC.Patran Thermal Generate Thermal Model 1 MSC.Patran generate ad hoc Nastran bdf 2 Politecnico di Torino Code 4 MSC.Nastran Thermal Matrix Reduction 3 Politecnico di Torino

Code Integration - 2 MSC.Patran manages Thermal Super Element MSC.Patran Thermal and MSC.Nastran codes Politecnico di Torino code MSC.Patran Thermal customization Stiffness Thermal Matrix Richard Haddock -MSC LA- Easy of Use GUI Politecnico di Torino

Turbine disc model Developed by Characterised by: Fiat Avio with MSC.Patran Characterised by: Axi-symmetry hypothesis triangular elements - CTRIAX (about 6000 dof) Constant material properties Constant film coefficients 16 gas nodes (Input) 5 critical nodes (Output)

Analysis Mission Profile Gas Temperatures Nodal Temperatures Double ‘Accel-Decel’ Gas Temperatures Related to the mission profile (input data) Nodal Temperatures Time integration with MSC.Thermal Politecnico di Torino

Model reduction From the “complete” model (more than 6000 dof) To the reduced model (105 dof) Why first modal shapes ? Because they correspond to the highest decay times Politecnico di Torino

Error (5th critical node) Complete vs Reduced (105 dof) Model Error The error mainly affects the beginning of the ramp CMS is steeper than FEM Null error in Steady-state Politecnico di Torino

2nd modal shape Politecnico di Torino

4th modal shape Politecnico di Torino

15th modal shape Politecnico di Torino

27th modal shape Politecnico di Torino

Error (5th critical node) Complete vs Reduced (35 dof) Model Error Politecnico di Torino

Conclusions Component Modes Synthesis allows size reduction of a FE model The error can be controlled steady-state temperatures are matched exactly during transient the error can be limited by adding more modal shapes The method can be useful To Develop Monitoring Algorithms running in real time For faster computing allowing a larger number of simulations Politecnico di Torino

Thank You Politecnico di Torino