ETMBA / F.Blume/ EHTC 2011 / /14/11/2011/ Eurocopter rights reserved

Transcription

1 Multibody simulation of the power boosted control section of a medium sized helicopter EHTC, November 2011, Bonn Felix Blume, Eurocopter Deutschland GmbH

2 Outline Introduction and basis information Motivation for Multibody Simulation Development of Rigid Body Model Loads Validation First Results Status/Open Actions 2

3 Introduction Presenter information: Felix Blume, Development Engineer, Stress Department Analysis Rotors and Blades Blades Rotors Flight Control (power boosted and not power boosted) Hydraulics Gearboxes Drive Train Company information: Eurocopter Deutschland GmbH, EADS Group 4300 Employees Mainsite Donauwörth EC135, EC145, BO105, Tiger, NH90 3

4 Basis Information 4

5 Basis Information Bearingless Main Rotor EC135 Lead-lag damper Flexbeam (flexible in torsion and flapwise / lead-lag direction) Hub Rotor without mechanical flapping and lead-lag hinge Control Cuff Feathering with flexible composite element Pitch Link 5

6 Basis Information Power Boosted Control Section Mast Pitch Link Scissor Swashplate Pilot input force amplified by 3 hydraulic actuators (1 for each axis) Limit Load on Pitch Link 8500 N Limit load on collective booster axis N Scissor transfers rotating motion to bearing ring Three Booster Axis 6

7 Motivation for Multibody Simulation External loads (blade loads) are calculated from the aerodynamic department based on flight test results, scaling and CFD Interface loads measured during flight test In early phase of new design, no new flight test data available Current Status: Linear scaling of all interface loads for certain swashplate positions Exact load distribution is difficult to calculate for all swashplate positions Consequence: Calculated loads are conservative 7

8 Motivation for Multibody Simulation Interface loads to be determined by stress department based on blade loads and different swashplate positions by using advanced tools/methods Decision of introducing a Multibody Simulation Tool: Software : Altair MotionView (included already in Hyperworks) First two models created with support of Altair Building up competences for Multibody Simulation We are just at the beginning 8

9 Development of Rigid Body Model Geometrical Data Imported from Catia V5 37 solid bodies Meshed with Hypermesh Assignment of Properties (Aluminium and Titanium) Calculation of mass and inertia (Mass= 53kg) Length of mast 918 mm 9

10 Development of Rigid Body Model 37 Rigid Bodies 12 revolute joints 14 ball joints 5 inline joints 7 constant velocity joints 4 cylindrical joints Some joints are statically overdetermined, but in reality there is an existing play, i.e. not fully blocked) 10

11 Development of Rigid Body Model Defined motions: Rotation rotormast: 415 RPM Max. translational movement of the 3 control axis: Longitudinal: +/ mm Lateral: mm/ mm Collective: +/- 21 mm Max. blade angle: 17 Fwd 11

12 Development of Rigid Body Model 12

13 Loads External loads calculated by aerodynamic department Blade loads (flapping, leadlag and torsional moments, centrifugal force) Resulting control force in the rotating pitch link Loads calculation based on existing flight test data Harmonic analysis Scaled to different RPM values and geometrical blade data 13

14 Loads Limit Load curve Load on pitch link 1 for one full rotation (360 ) Rotation Angle = 0 when blade number one above tailboom Load is shifted with 72 phases between each pitch link 14

15 Loads Load introduction Limit Load curve is applied on each Pitch Link Load shifted with 72 phase clockwise Rotor is turning counter clockwise FPL1 FPL2 15

16 Loads Limit Load Manoeuvre: Turning Flight with VNE (Velocity Never Exceed) and max. bank angle Control inputs: Longitudinal: Lateral : Collective: mm 2.5 mm 18.7 mm 16

17 Loads 17

18 Validation Check of correct kinematic behaviour without external loads Clearance Reactive forces Gravity check Check of force sign convention with external load Comparison with flight test data (with similar rotor system) Comparison with analytically calculated forces for selected swashplate positions Final validation when flight test data is available 18

19 First Results Force Interface Bearing Ring / Pitch Link 19

20 First Results Booster forces vs. rotation angle Lateral Axis Longitudinal Axis Collective Axis 20

21 Status / Open Actions Status First Validation performed Booster loads calculated Open Actions Interface loads for the remaining parts Stress calculation of the parts (FEM and Analytical) Introduction of Flexbodies for some parts (Booster Levers) Conclusion Multibody Simulation has raising importance for stress calculation of dynamic systems

22 Status / Open Actions Thank you for your attention. Questions?