Using FEMAP on the NESC Composite Crew Module

Transcription

1 , President, Structural Design & Analysis, Inc. Using FEMAP on the NESC Composite Crew Module Femap Symposium 2014 May 14-16, Atlanta, GA, USA Unrestricted Siemens AG 2014 FEMAP SYMPOSIUM 2014 Discover New Insights

2 Agenda What was the Composite Crew Module (CCM)? Design Overview Analysis Overview Analytical Tools Finite Element Models Flight Load Case Summary Critical Margins of Safety Full Scale Static Test Test Condition Selection Test Results Page 2

3 January 2007 NASA Administrator chartered the NESC to form an agency team to design and build a composite crew module, gain hands-on design, build, and test experience, in anticipation that future exploration system may be made of composite materials. Mike Kirsch

4 NESC Composite Crew Module As modeled in Pro-E As built in Iuka Page 4

5 Design Overview

6 Service Module/Alternate Launch Abort System (SM/ALAS) Fittings (6 pl ) Design Overview LIDS Ring Drogue Chute I/F (1) Gussets (6) Main Chute I/F (3) Docking Windows (2) Tunnel Ceiling Conic Side Windows (2) Hatch Opening (1) Barrel Page 6

7 System Dimensions Page 7

8 CEV Internal Packaging Backbone Packaging Crew Pallet Consoles Page 8

9 Lower Shell Loading Backbone carries pressure load no ring frame (~100 lbs savings) Membrane pressure head lobe shapes (~50 lbs savings) Leverages and enhances SM/ALAS reinforcements Backbone connection allows load sharing with Heat Shield (~1000 lbs heat shield savings) Internal Pressure 50% load sharing on backbone Water Landing Page 9

10 LIDS Interface Ring LIDS Interface Ring Supports TLI and Drogue parachute loads Bolted to Gusset Web and Caps 5 Tunnel taper to control bondline to tunnel Six discrete 60 doublers paste bonded to Ring and Tunnel Avoids high temperature cure with Aluminum Joint tested at element test level Discrete Doublers Page 10

11 Forward Bay Gusset Primary load path from shell to LIDS Ring Stabilizes ceiling, tunnel, and fwd bay Support and strength to Main Parachute fittings Provides hard points for Crew Pallet supports on IML Provides attachment structure for fwd bay subsystems Flat laminate panel and caps Pi-preforms bond shear webs to cap and shell Honeycomb panel Gusset Cap Pi-Preforms Page 11

12 Shell Face Sheets Mostly fabric with some uni Face sheets 4 plies minimum Solid 8 plies minimum Solid laminate to 70 plies Bearing pad-ups Integral beam caps Not to Scale: Ply Drops 20:1 Core Tapers 7 degree Page 12

13 Splice Pressure Shell Face sheet Pressure Shell Core Acreage Longeron Splice Doubler (non-autoclave cure) EA 9394 Potting Compound Page 13

14 Analysis Overview

15 Analytical Tools Model Pre- and Post-Processing done using FEMAP Nearly every PATRAN user converted to FEMAP once they saw what FEMAP could do and how easy it was to use NX and MSC NASTRAN used, depending on the analyst running the model HyperSizer used extensively for trade studies and margin writing, but FEMAP was used to maintain all analytical master models We learned how to make HyperSizer and FEMAP play nice together Fibersim was used extensively in design with data fed back to analysis Page 15

16 Master FEM Finite Element Models Coarse Mesh, overall loads/stiffness Detailed FEM Local Detailed Models (8+) Element & Component Test Models (4+) More than 15 models used to completely analyze the structure Page 16

17 Master FEM Contains about 29,400 elements, 27,250 nodes Overall Model CCM Portion Colors represent areas of constant lay-up (PCOMP) Page 17

18 Detailed FEM Contains over 200,000 nodes and elements Fairly fine mesh Includes: Covers Ply drops Fasteners Page 18

19 Detailed Finite Element Model Ply level detail throughout the model Page 19

20 Local Detailed FEMs Page 20

21 EDS, Lander CEV Loading Events Vehicles are not to scale. MOON 100 km Low Lunar Orbit Lander Performs LOI LOI Ascent Stage Expended Low Earth Orbit Earth Departure Stage Expended TLI At Burn Out TLI Initial Burn Reentry Service Module Expended EARTH Launch Entry and Landing Landing Page 21

22 Abort Conditions Extended Coast Period Stabilize Reorient & Fin Jettison Stabilize Descent using RCS Max q 65 kft 30 kft 18 kft Reduced Pitch Maneuver Reorient & Fin Jettison Jettison ACM Burnout Deploy Stabilize Controlled Coast Pitch Maneuver (using ACM) Jettison Tower/Shell & Deploy Chutes Abort motor fires, ACM & Roll RCS engage Pitch maneuver to achieve adequate separation & downrange Page 22

23 Loads Freebody Main Chute Load 64,400 lbs TLI Loads, 1.4 g s Drogue Load 34,200 lbs Launch Abort Load 134,000 lbs Maximum Internal Pressure, 31.1 psi Maximum Delta Load 76,000 lbs Service Module Load 101,000 lbs Water Landing, 28.2 g s Page 23

24 Critical Load Cases Abort, Pressure, Drogue & TLI Main Parachute Blast Overpressure Page 24

25 Minimum Flight Margins (Pi Peak) LC (Hoffman) LC (Hoffman) LC (Hoffman) LC (Core Shear) LC601 Page 25

26 Minimum Flight Margins (Shear/Tension) LC (Hoffman) LC (Hoffman) LC (Core Shear) LC (Shear/Tension) LC302 Page 26

27 Full-Scale Static Test

28 Goals & Objectives Test as much structure as possible Within schedule and budget constraints Test critical margins where possible Test in an order that best ensures success Predict strains in critical areas and use those areas for correlation to mathematical models Page 28

29 Test Set Up Page 29

30 Test Condition Selection Four conditions selected Maximum Internal Pressure (red) Most critical abort (High Altitude) (green) One Parachute Case (yellow) One Drogue Case (blue) And... Local Insert Case Page 30

31 Test Matrix Test Load Test Level Max Internal Pressure 15.5 psi Limit Abort, -Z SM/ALAS Fitting 15.5 psi/50 kips Limit Main Parachute, Fitting psi/46 kips Limit Max Internal Pressure 31.1 psi Ultimate Lower Shell Insert Test 5.3 kips Ultimate Drogue attach point 48 kips Ultimate Perform impacts at 18 critical locations 6 ft lbs Max Internal Pressure 31.1 psi Ultimate Main Parachute, Fitting psi/ 64 kips Ultimate 4x life cycling (22 pressure and 9 parachute) 17.1 psi/51 kips Limit + Perform impacts to lesser of barely detectable levels < /= 26 ft lbs 4x life cycling (22 pressure and 9 parachute) 17.1 psi/51 kips Limit + Max Internal Pressure, High Altitude Abort 32 + psi Failure Page 31

32 MicroStrain Static Test Results All conditions showed very good load match between predictions and strains SG301 SG302 SG303 SG451 SG452 SG Pred 302 Pred 303 Pred 451 Pred 452 Pred 551 Pred SG Pred Gages 551, 552 Tunnel IML Gages 301, 302, 303 Gages 451, 452 Percent Limit Load Page 32

33 Fiber Optic Layout Backbone Cap Longeron 5 Longeron Approximately 615 in/51.25 ft/ 1562 cm Approx 9 in of nonsensing fiber from end of connectors 3.6 Longeron B1a B1b Fiber routed 0.6 from edge of backbone cap Page 33

34 Fiber Optic Results Splice Splice/Backbone Cap Backbone Cap Max Pressure of Predicted Strains Max Pressure Predicted Strains Max Pressure Page 34

35 Failure Test Discussion

36 Bar Chart Definitions The Prediction Bar Chart summarizes the failure predictions for the burst test The bottom of the thin line represents the pressure that must be attained to demonstrate true ultimate performance of a particular failure mode and location Adjusting test pressure to account for temperature and moisture knockdowns The bottom of the colored bar represents our 99% failure prediction 99% of the population should exceed this value The top of the color bar represents the mean failure prediction The top half of the bar was not drawn on the chart, 50% of the structure would be expected to exceed the top of the chart The color of the bar represents the apparent severity of the failure mode Red = assumed catastrophic failure Yellow = assumed catastrophic failure mode, but low confidence in the actual predicted failure value Green = assumed benign failure mode, such as core yielding, bolt bearing, any mode where load would redistribute rather than a brittle failure Page 36

37 Pressure at Failure, psi Failure Predictions Page 37

38 Successful pressure test to failure! Failure occurred with internal pressure at 53.9 psi, nearly 340% limit load Large audible noise with immediate, but small pressure drop of 1 psi, followed by termination of supply pressure No sign of leakage and shell held vacuum during drain procedure No visible sign of failure internal or external Page 38 Sec 1-

39 Failure test cont d Load redistribution indicated by sudden change in measured strains No signs of anomalies on the lower shell even in repair areas No signs of anomalies around areas previously impacted to 26 foot pounds Validated that the CCM structure achieved design ultimate load after four times life cycling with known damage, repairs, and manufacturing anomalies Validated high altitude abort condition on backbone beams beyond design ultimate load level (41 psi) Validated vacuum pressure to beyond design ultimate load Splice joint, pi joints, and docking tunnel joints exceeded minimum design criteria Page 39 Sec 1-

40 MicroStrain Docking Window Strains Docking Windows 9000 SG306 SG307 SG312 Gage 567 Gage 560 These gages are in areas of strain gradient 8000 SG560 SG559 Gage SG Pred 307 Pred 312 Pred Gage Pred 559 Pred 567 Pred Gage 307 Gage Percent Limit Load Page 40

41 MicroStrain Shoulder Radius OML Shoulder Radius OML 1500 Gage 305 Gage Gage SG407 SG458 0 SG SG305 SG352 SG Pred 458 Pred 502 Pred 305 Pred 352 Pred Gage Pred Gage 407 Gage Percent Limit Load Page 41

42 MicroStrain Pressure, Psi Shoulder Radius OML Shoulder Radius OML Ceiling Disbond Supply Valve Closed Dump Valve Opened SG305, Bay A SG352, Bay B SG407, Bay C SG458, Bay D SG502, Bay E SG558, Bay F Official Pressure Time (Frame) Page 42

43 Core Stress (Non-Linear) at Failure Ld Through-Transmission Ultrasound OML thermography IML thermography Page 43

44 Summary/Conclusions CCM Design was complex, but well characterized by our analytical models The use of advanced, integrated tools greatly eased the design and analysis effort FiberSIM and HyperSizer were both new tools to most of the team A detailed NASTRAN model improved strain predictions and eased any testing concerns FEMAP proved to be invaluable to the analysis effort and was nearly universally adopted by each analyst Page 44