Analysis and Optimization of a Hybrid Fan Blade Permas Users Conference 27.04.06 28.04.06 Strassbourg DLR German Aerospace Center, Stuttgart Institute of Structures and Design J. Ehrmanntraut, F. Kocian, V. Plevnik, T. Schmidt, D. Schwinn
Topics Single spool LPC (Low Pressure Compressor) based on EJ200 turbo jet engine Mass reduction in first stage by implementation of CFRP (Carbon Fibre Reinforced Plastics) FEM modelling and structural analysis of a hybrid blade Modification of dynamic response of a titanium blade by topology optimization Introduction of a new monolithic stacked rotor Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 2
LPC Low Pressure Compressor (EJ200 Turbo Jet Engine) Titanium BLISK Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 3
Titanium in the front region due to erosion and foreign object damage Hybrid Blade CFRP (Carbon Fibre Reinforced Plastics) in the rear region for mass reduction (CF-PEEK Prepreg) ± 45 and 0 lay-up optimized for torsion and bending stiffness Consolidation of CFRP and joining to the titanium in one process step Target: mass reduction Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 4
pressure side view Hybrid Blade Asymmetric Double Lap Shear Joint CFRP part suction side view joining area titanium part Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 5
AA Hybrid Blisk: Pressure Side View FEM Model: Blade: - 2746 HEXE8, 287 QUAD4, 782 SHELL4 elements - 25 properties Disc: - 6334 HEXE8 elements Material : - Ti64, CF-PEEK (based on unidirectional thermoplastic prepreg) Loading: - inertial rotation, aerodynamic pressure, temperature load Cyclic symmetry by MPC JOIN Blade/disc joint by MPC ISURFACE Suppressed DOF 2,3 (cyl. coor. system) Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 6
Approach for QUAD4 (Ti) - SHELL4 (CFRP) Coupling in Double Lap Shear Joint Region Different deformation mechanisms of isotropic and orthotropic materials by transverse loading Dominance of bending deformation in titanium and shear deformation in CFRP leads to different rotation at element nodes Incorrect increase of stiffness by coupling of all DOFs => MPC RIGID only DOFs 1,2,3 Separation of element reference and laminate middle surface in SHELL4 elements by ξ =1 Using forces on dependent nodes Titanium Titanium for further evaluation of joining area CFRP CFRP Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 7
Hybrid Blade: Meshing of Double Lap Shear Joint Region Section AA (scaled) HEXE8 MPC RIGID (1,2,3) ξ = 1 suction side outer ply (first ply in stacking sequence) ξ = 1 QUAD4 MPC ILIN2 (1,2,3) MPC VST (1,2,3,4,5,6) SHELL4 pressure side MPC RIGID (1,2,3) Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 8
Stress Distribution in Double Lap Shear Joint Region force on dependent node F A 1 A3 A 2 A 4 normal vector n 1 F 1j F 1j out of plane A = 1 4 i= 1 A σ ( peel) i = ; 4 j= 1 F F 1 j 1 j A1 = F A ( out A of plane) 1 ; τ ( shear) 1 = 4 j= 1 F 1 j ( in A 1 F 1j in plane plane) Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 9
Summary for FEM Modelling of Hybrid Joints 1. HEXE8 elements in the front titanium region 2. QUAD4 elements for titanium in joining area 3. SHELL4 elements for CFRP 4. HEXE8 - QUAD4 transition by MPC VST and MPC ILIN2 5. QUAD4 - SHELL4 coupling in joining area by MPC RIGID (1,2,3) 6. Evaluation of forces on dependent nodes for stress calculation in the joining area 7. Conversion of forces on dependent nodes to element forces 8. Splitting of element forces in in plane and out of plane 9. Calculation of peeling and shear stresses Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 10
Hybrid Blisk: V. Mises Stress Distribution in Titanium Part [MPa] nonlinear analysis inertial rotation, aerodynamic pressure temperature load continuous v. Mises stress distribution in the volume/shell region suction side pressure side Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 11
Peeling Stress Distribution in Double Lap Shear Joint Region nonlinear analysis, inertial rotation, aerodynamic pressure and temperature load 4.18 [MPa] 2.63 [MPa] maximum 4.18 MPa pressure side -1.79 suction side -1.77 Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 12
Shear Stress Distribution in Double Lap Shear Joint Region nonlinear analysis, inertial rotation, aerodynamic pressure and temperature load 23.0 [MPa] 14.2 [MPa] maximum 23.0 MPa pressure side 0.48 0.44 suction side Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 13
Utilisation Factor in CFRP Region Tsai-Wu Criterion nonlinear analysis, inertial rotation, aerodynamic pressure and temperature load 1.0 1.0 maximum approx. 80% pressure side 0.0 suction side 0.0 Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 14
Hybrid Blade: Campbell-Diagram EO 53 Campbell Diagram BLISK17 hybrid Vibration analysis Consideration of nonlinear effects caused by inertial rotation, aerodynamic pressure and temperature load 2000 1500 2C 1C 1F 2F Frequency Hz 1000 1T EO 5 EO 4 2F EO 3 1T 1C 500 EO 2 1F EO 1 deformation magnitude 0 43% Nn 60% Nn 100% Nn 0 50 100 150 200 Shaft speed rot/s Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 15
Topics Single spool LPC (Low Pressure Compressor) based on EJ200 turbo jet engine Mass reduction in first stage by implementation of CFRP (Carbon Fibre Reinforced Plastics) FEM modelling and structural analysis of a hybrid blade Modification of dynamic response of a titanium blade by topology optimization Introduction of a new monolithic stacked rotor Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 16
Modification of Dynamic Eigenfrequencies of Titanium Blade using Topology Optimization FEM Model: Blade: Disk: - 15008 elements (HEXE8) - 21528 elements (HEXE8) Material : Ti64 Loading: - inertial rotation, aerodynamic pressure, temperature load Cyclic symmetry by MPC JOIN Blade/disc joint by MPC ISURFACE Suppressed DOF 2,3 (cyl. coor. system) Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 17
Titanium Blade: Campbell Diagram Vibration analysis Consideration of nonlinear effects caused by inertial rotation, aerodynamic pressure and temperature load Interaction between second flexural and first torsion mode in the whole operating range (risk of twist bend coupling) Frequency Hz 2500 2000 1500 Campbell Diagram C03i4_h23_ti_cold EO 53 70% Nn ADP 110% Nn EO 5 1000 1T EO 4 2F EO 3 500 EO 2 1F EO 1 2F 1T 0 0 50 100 150 200 250 Shaft speed rot/s Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 18
Modification of Dynamic Eigenfrequencies of Titanium Blade using Topology Optimization Design elements (DHEXE8) with variable filling ratio (density, stiffness) in the inner part of titanium blade Definition of design objective function by $DCFUNCTION: [ f(1t) f(2f) ] => AbsMax Combination of vibration analysis with TOPO Analysis of results and modification of the inner part of the titanium blade by deleting FEM-elements with negligible filling ratio Verification of topology optimization results by a vibration analysis outer blade elements not shown design region Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 19
Modification of Dynamic Eigenfrequencies of Titanium Blade using Topology Optimization filling ratio f after 30 iterations, convergence achieved deleting of FEM elements with negligible filling ration in the top blade region Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 20
Optimized Titanium Blade: Campbell Diagram 2500 Campbell Diagram C03i4_h23_ti_topo_1 EO 53 70% Nn ADP 110% Nn Separation of second flexural and first torsion mode in the whole operating range! Frequency Hz 2000 1500 EO 5 1000 1T EO 4 2F EO 3 500 1F EO 2 EO 1 0 0 50 100 150 200 250 Shaft speed rot/s Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 21
Realization Concept of Optimized Rotor: Monolithic Stacked Rotor Several planar discs building the whole rotor Each planar disc is sustainable of its own Accessibility allows any cavities in blades and discs Repair of the rotor by replacing any planar discs Joining of the planar discs by brazing or welding Combination of different materials to hybrid structures Implementation of damping mechanisms Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 22
Conclusion: Simple approach for modelling of hybrid joints leads to good results Approach for QUAD4 (Ti) - SHELL4 (CFRP) coupling applicable to similar joining structures Successful verification of approach for QUAD4 (Ti) - SHELL4 (CFRP) coupling by simple test specimens Dynamic eigenfrequencies separation of titanium blade achieved by topology optimization Computer Supported Component Design Permas Users Conference 2006 J. Ehrmanntraut foil 23
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