Structural Mechanic Aspects of CFRP Fuselage Structures

Transcription

1 Structural Mechanic Aspects of CFRP Fuselage Structures ESAComp User s Meeting 2007, April 24th 25th, Advances in Design and Analysis of Composite Structures Alexander Kling DLR Braunschweig Structural Mechanics Section, COE Composite Structures

2 Overview Introduction Competences and Working Areas in Structural Mechanics at DLR Validation Experimental Methods Non-Destructive Testing (NDT) Virtual Testing Global-Local Approach Fast Tools for Design Structural Health Monitoring (SHM) Summary and Conclusions 2

3 Challenges and Motivation for High-Performance Lightweight Structures Weight [%] New Metal Technologies Today s Metal Technologies -10 Costs [%] Future Fibre Composite Technologies Today s Fibre Composite Technologies Targets: Weight Reduction Cost Reduction Saving of Resources 3

4 Utilization of Composites A Steep Slope Composites Faserverbundanteil with respect am to Strukturgewicht structural weight 50% 40% 30% 20% 10% 0% B787 A350 A400M A380 A320 A B777 A A300 A B757 B767 MD80 B B MD Jahr First des Flight Erstfluges Quelle: NASA, Airbus und Boeing 4

5 Competences and Working Areas in Structural Mechanics Health Monitoring Validation and Qualification Virtual Testing Modelling and Simulation of whole Life Cycle Simulation Based Design Deformation, Stress and Failure Analysis Stability Analysis Working Areas Damage Tolerance Thermal Analysis NDT/SHM Validation Experimental Structural Analysis (EXSACOM) Competences 5

6 Spectrum of Working Areas Health Monitoring Validation and Qualification Virtual Testing Modelling and Simulation of whole Life Cycle Simulation Based Design Experimental Methods Numerical Methods Efficient testing facilities Qualifikation of structural concepts Structural Health Monitoring (SHM) Fast Design Tools Virtual Structures Structural Exploitation Validation 6

7 Validation There is an industrial need of validated analysis tools Deformation, Stress and Failure Analysis Stability Analysis Damage Tolerance Thermal Analysis Validation Solve the right equations Experimental Structural Analysis (Test Field, Buckling Device, Thermex, Ultrasonic Facilities ARAMIS, ) NDT/SHM Validation Experimental Structural Analysis (EXSACOM) 7

8 Experimental Methods Qualification Exp. Characterization Exp. Phenomenological Experiment Validation Experiment t= 0 ms t= 1,25 ms t= 2,5 ms t= 5 ms t= 7,5 ms t= 10 ms Experiment Nonl. FEM Analysis 8

9 Non-Destructive Testing (NDT) MUSE Working Areas: Coupling by air Mobile System (MUSE) Detection of porosity Damages after collapse of a stiffened panel 9

10 Increasing Number of Material Systems Monolithic Textiles Sandwich Hybrids 10

11 Antenna Structure Made of Perforated Sandwich test Real sandwich material Detailed material characterization (exp. and analysis) Homogenized global analysis 11

12 Virtual Testing Set up of virtual test to: Reduce time and cost intensive experiments To optimize test set-up: Validation experiments Pre-test analysis First time right FEM Full field exp. Measurement (ARAMIS) Shear loaded A340 panel Axially loaded cylinder 12

13 Global-Local Approach (Submodeling) Matlab mesh generator Global model Nl. FEM (ABAQUS) stiffened cfrp panel Nl. FEMs ABAQUS + stress based failure criteria Submodeling approach (ABAQUS) Matlab mesh generator Local Models with focus on the stringer-skin interface Python script to obtain simple stress based indication of critical areas in the stringerskin interface 13

14 Fast Tools for Design Stability Analysis E.g. IBUCK: Semi-analytical design tool to simulate the buckling and post-buckling behaviour of stiffened panels 14

15 Fast Tools for Design Impact (1) CODAC = Composite Damage Tolerance Analysis Code Analysis of impact damages and residual strength for composite structures Based on the FE-method Impact Low-velocity Impacts Tool-Drop Debris (Takeoff or Landing) Fiber breakage Matrix failure Delamination 15

16 Fast Tools for Design Impact (2) Impact simulation on composite sandwich panels Comparison of num. and exp. results show good results 37mm 18,5mm no degradation with degradation of core Simulation 15,1 22,4mm F / kn Experiments, 4J Test without degradation with core degradation (upper bound) 0.5 with degradation of core and skin t / ms with core & skin degradation (lower bound) 16

17 Structural Health Monitoring (SHM) Objectives: Simplified inspection Continuous monitoring Concepts: Lamb-wave analyses CFK-plate with piezoceramic actors and sensors 17

18 Summary and Conclusions Brief insight into some relevant structural mechanic aspects for CFRP fuselage structures have been given. Validated analysis tools essential for save, efficient (cost and time) design State of the art experimental methods State of the art NDT/SHM methods State of the numerical methods Global-Local (submodeling) approach can be used as an elevator up and down in the Rouchon pyramid 18

19 Thank you for your attention +49 (0) 531/