Bartoszyk-ISIM_Bonded_Joints.ppt
- 1. Current Progress on the Design and Analysis of the JWST ISIM Bonded Joints for Survivability at Cryogenic Temperatures Andrew Bartoszyk, Swales Aerospace FEMCI 2005 Workshop May 5, 2005
- 2. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 2 JWST/ISIM Stress Team Andrew Bartoszyk, Swales Aerospace – Stress Analysis John Johnston, NASA GSFC – Analysis Lead Charles Kaprielian, Swales Aerospace – Stress Analysis Cengiz Kunt, Swales Aerospace – Stress Analysis Lead Joel Proebstle, Swales Aerospace – Stress Analysis Benjamin Rodini, Swales Aerospace – Composite Materials Daniel Young, Swales Aerospace – Stress Analysis
- 3. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 3 Design and Analysis Challenges • Design Requirements – Metal/composite bonded joints required at a number of nodal locations on the JWST/ISIM composite truss structure to accommodate bolted instrument interfaces and flexures. – Survival temperature at 22K (~ – 400o F); – 271K total DT from RT. – Composite truss tube with high axial stiffness (~23 msi) and low axial CTE (~ 0 ppm/K). – Multiple thermal cycles throughout design life of structure. In order to survive launch loads, joints cannot degrade more than an acceptable amount. • Design/Analysis Challenges – Large thermal mismatch stresses between metal fitting and composite tube at cryogenic temperature (22K). – Analysis and design experience is very limited for metal/composite bonded joints at temperatures below liquid nitrogen (~80K). – Thermo-elastic material properties and strengths for composites and adhesives at 22K are not available and difficult to test for.
- 4. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 4 T-Joint (Gusset & Clips) Saddle Plug ISIM Basic Joint Assemblies
- 5. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 5 Basic Plug Joint Details Metal Fitting (Invar 36) E = 18.8 msi a = +1.5 ppm/K Hybrid Composite Tube Eaxial = 23 msi Ehoop = 6.7 msi aaxial = -0.13 ppm/K ahoop = +3.7 ppm/K Szz = 2.9 ksi (20 MPa) Szx = Syz = 5.8 ksi (40 MPa) Adhesive Bond (EA9309) E = 1.1 msi G = 0.4 msi a = 47.8 ppm/K Fsu = 11.6 ksi (80 MPa) • Stiffness and strength properties are given for 22K. • Thermal expansion properties are secant CTE from RT to 22K. 75 mm square composite tube w/ nominal 4.6 mm wall thickness interlaminar strengths
- 6. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 6 Composite Modeling and Mesh Size • Mesh size: 2.5 mm square in-plane • Surface plies at bonded interfaces modeled individually • Aspect ratio 2.5/0.071 35 • Laminate core modeled with thicker elements • Adhesive modeled with one element through the thickness • Same mesh size used in all joint FEMs including development test FEMs • Stress recovery: Element centroid for interlaminar, corner for others View A-A Symmetry Constraint Ply 1 – Explicit Props (T300/954-6 Uni Ply) Ply 2 – Tube Smeared Props (T300/954-6 Uni Ply) Ply 3 – Tube Smeared Props (M55J/954-6 Uni Ply) Ply 1 Ply 2 Ply 3 x y Adhesive (0.3 mm thick) Invar Fitting
- 7. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 7 F33 F13 > FRSS > F23 F23 FRSS s33 t13 t23 Lamina Failure Criteria – Bonded Joints 1 2 23 23 2 13 13 2 33 33 F F F t t s Design Space F13 33 11 22 t13 / t23 = 1.5 1 2 2 33 33 RSS RSS F F t s Under thermal loads, metal/composite bonded joints typically fail in composite interlaminar stresses.
- 8. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 8 Interlaminar Failure Prediction An empirical Interlaminar Failure Criterion is used for critical lamina: where s33 is peel stress, trss is resultant transverse shear stress, and F terms are material constants dependent on interlaminar strengths, which are being determined by testing. FRSS tRSS F33 s33 1 2 2 33 33 RSS RSS F F t s State 1 (peel-shear interaction) State 2 (compressive normal and shear) Margin Calculations Stress State 1 Stress State 2 1 RSS RSS FS F MS t 1 1 2 2 33 33 RSS RSS F F FS MS t s
- 9. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 9 Bonded Joint Design & Sizing Flow Preliminary Design: Tube Layout, Cross Section, Laminate, Joint CAD Concepts Preliminary Basic Design Thermal Survivability SFc > 1.0 (> 1.5 Goal) Identify Basic Joint Elements: Plug, Saddle, T-Joint Concepts Estimate Cryo Properties Phase 1B Double Strap Design Phase 1B Double Strap Testing Material Characterization Correlate Cryo Properties & Revise Analysis Optimize Basic Design MS > 0 Preliminary Basic Design Launch Loads MS > 0 “Good” SFc Calculate & Envelope Joint Launch Loads Verify Under GH&T Loads Phase 1C – Strength Degradation Testing Phase 2 – Breadboard Joint Testing Flight Joint Detailed Design & Analysis no yes START FINISH FS – Factor of Safety (Requirement) SFc – Calculated Safety Factor MS – Margin of Safety SFc = Allowable/Stress MS = SFc/FS - 1
- 10. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 10 Bonded Joint Analysis Correlation - Procedure X Y Z V1 X Y Z V1 X Y Z 3.564 1.969 0.373 -1.223 -2.819 -4.415 -6.011 -7.607 -9.203 V1 G5 Output Set: 19K & -9.096kN Contour: Solid X Normal Stress X Y Z 16.69 14.72 12.75 10.77 8.802 6.83 4.857 2.885 0.913 -1.06 -3.032 -5.004 -6.976 -8.949 -10.92 -12.89 -14.87 V1 G5 Output Set: 30K & 150MPa Contour: Solid X Normal Stress 3. Test Coupon Analysis 5. Flight Joint Analysis Test Failure Load (Mech & Thermal) Design Limit Load (Mech & Thermal) 4. Failure Curve 2. Coupon Testing 1. Coupon Analysis & Design (Match Flight Joint Critical Stresses) -15.0 -10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 Interlaminar RSS Shear (MPa) Interlaminar Normal (MPa) ISIM Basic Joints M55J/954-6 Failure Curve (RSS shear) Gusset SF = 1.52 Saddle SF = 1.92 Clip SF = 1.54 Plug SF = 2.04 -15.0 -10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 Interlaminar Shear (MPa) Interlaminar Normal (MPa) Test Data (Average) Assumed Failure Curve (90deg shear) Assumed Failure Curve (0deg shear) Assumed Failure Curve (RSS shear) FWT Test @77K Saddle DSJ Peel Test @19K (90deg direction shear) Saddle DSJ Shear Test @19K (90deg direction shear)
- 11. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 11 Basic Plug Joint Detailed Stress Analysis Node Count – 5,570 DOFs – 16,710 1/16 Slice Phase 2 Plug Joint ISIM Plug Joint
- 12. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 12 Basic Plug Joint - FEM A A View A-A Symmetry Constraint Symmetry Constraint Ply 1 – Explicit Props (T300/954-6 Uni Ply) Ply 2 – Tube Smeared Props (T300/954-6 Uni Ply) Ply 3 – Tube Smeared Props (M55J/954-6 Uni Ply) Ply 1 Ply 2 Ply 3 z y x x y Adhesive (0.3 mm thick)
- 13. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 13 Basic Plug Joint - Applied Loads Load Case Type D T (K) Fz (N) Remarks 1 Thermal -271 0 RT to cold survival temperature (22K) 2 Thermal & I/F & 1g -271 4513 Thermal plus worst case tension (I/F & 1g) and worst case compression (I/F & 1g) 3 Thermal & I/F & 1g -271 -9096 4 Launch 0 83200 Absolute max axial load from ISIM beam element model loads run (includes additional effective axial load due to moment load) Fz (applied as pressure load on face) Symmetry Constraint z x
- 14. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 14 Basic Plug Joint - Margin Summary Load Case Failure Mode Allowable (MPa) Abs Max (MPa) MS Comments Thermal & Mechanical (-271K + I/F + 1g) Ply-1 (T300) s-t interlaminar + 0.40 Ply-3 (M55J) s-t interlaminar + 0.32 Invar (Blade) VM yield 275 115 + 0.91 assume strength properties at cryo to equal properties at room temperature VM ultimate 414 115 + 1.57 Launch Ply-1 (T300) s-t interlaminar + 0.92 s11 1380 162 + 3.73 max corner stress. allowables are based on explicit props. s22 81 12.4 + 2.63 Ply-3 (M55J) s-t interlaminar + 0.38 Tube s11 439 157 + 0.55 max corner stress. allowables are based on tube smeared props. s22 241 42 + 2.19 Invar (Blade) VM yield 275 167 + 0.32 max corner stress in blade, localize stress raisers at blade/hub interface not included VM ultimate 414 167 + 0.77 • Margins presented at PDR, Jan 2005.
- 15. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 15 X Y Z 3.564 1.969 0.373 -1.223 -2.819 -4.415 -6.011 -7.607 -9.203 V1 G5 Output Set: 19K & -9.096kN Contour: Solid X Normal Stress 22.66 19.83 17. 14.17 11.34 8.508 5.678 2.848 0.0178 V1 G5 sxx (MPa) z y tRSS (MPa) Invar fitting Invar fitting MS = +0.32 (shear dominated failure) Basic Plug Joint Ply 3 Interlaminar Stress Plots – Thermal & I/F
- 16. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 16 SF and Failure Curve – Basic Joint Assemblies -15.0 -10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 Interlaminar RSS Shear (MPa) Interlaminar Normal (MPa) ISIM Basic Joints Assumed Failure Curve (RSS shear) Gusset SF = 1.52 Saddle SF = 1.84 Clip SF = 1.54 Plug SF = 1.99
- 17. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 17 DSJ Test Data and Estimated Failure Curve FRMS F23 Clip Peel& Shear D/S Clip Shear D/S -15.0 -10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 Interlaminar Shear (MPa) Interlaminar Normal (MPa) B-Basis Data ISIM Basic Joints 2,3 Failure Curve (90deg shear) 1,3 Failure Curve (0deg shear) RSS Shear Failure Curve FWT Double-Strap Peel 900 Double-Strap Shear 900 F23 FRSS F13
- 18. A. Bartoszyk/Swales FEMCI Workshop – May 5, 2005 18 Remarks and Conclusions • Material characterization testing and joint development testing are in progress. Test results will be critical for analysis correlation and the final design/analysis of the ISIM metal/composite bonded joints. • A Phase-2 test program is underway and will include thermal survivability testing of basic joints including a plug joint. • An evaluation of strength degradation due to multiple thermal cycles will also be included in the joint development test program. • The ISIM Structure successfully passed PDR (Preliminary Design Review) in January 2005, design requirements have been met. Critical Design Review is scheduled for December 2005.