1. 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

2. 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

3. 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

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

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

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

7. 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

8. 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

9. 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)

10. 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

11. 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

12. 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

13. 2nd modal shape
Politecnico di Torino

14. 4th modal shape
Politecnico di Torino

15. 15th modal shape
Politecnico di Torino

16. 27th modal shape
Politecnico di Torino

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

18. 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

19. Thank You
Politecnico di Torino