Manufacturing and Certification of Composite Primary Structures for - PowerPoint PPT Presentation

Manufacturing and Certification of Composite Primary Structures for Civil and Military Aircrafts A R Upadhya CSI R-NAL 1959-2009 Director Council of Scientific and Industrial Research National Aerospace Laboratories, Bangalore, India ICAS Biennial Workshop on “Advanced Materials & Stockholm, Sweden, Manufacturing – Certification & Operational Challenges” 5 th September 2011

Development of national strengths in aerospace sciences and technologies I f Infrastructure, facilities and expertise t t f iliti d ti In-house, Grant-in-aid, Sponsored projects Advanced technology solutions to Advanced technology solutions to national aerospace programmes Fighter aircraft, gas turbine engines, defense systems, defense services, launch vehicles and y , , satellites, space systems Sponsored projects Civil aeronautics development (since 1990s) Design and development of small and medium- sized civil aircraft - Promote a vibrant Indian civil a iation ind str aviation industry Government funding, Industry partnership Core competence at NAL spans practically the whole aerospace sector

DESIGN PROCESS & & DEVELOPMENT ANALYSIS STRUCTURAL MANUFACTURING TESTING NAL S CORE NAL’S CORE STRENGTH IN COMPOSITES NON- STRUCTURAL STRUCTURAL DESTRUCTIVE REPAIR EVALUATION STRUCTURAL ADVANCED HEALTH RESEARCH MONITORING MONITORING

Evolution of Composites at NAL 90 ‐ 110 Seater NCA Initial Development: Bridge Deck Plates, Radome Development, 14 Seater SARAS 14 Seater SARAS DO ‐ 228 Rudder with DLR Germany LCA ‐ Tejas 2 S 2 Seater HANSA t HANSA 1980-90 1993 2001 2004 2017

NAL’s HANSA, A Light All ‐ Composite Trainer Aircraft Trainer Aircraft Two-bladed constant speed Hoffmann propeller of � Length overall : 25 ft (7.6m) diameter 1730mm. � Wing span � Wing span : : 34 35 ft (10 47m) 34.35 ft (10.47m) � Empty weight : 550 Kg � All-up weight : 750 kg � Usable fuel capacity : 85 litres Rotax 914F3 (turbo charged engine with 100 BHP max. continuous power @ 5500 rpm) continuous power @ 5500 rpm) � Performance � Performance � Stall speed with 20° flaps : 43 KI AS � Max. cruise speed : 96 KI AS Certified under Certified under � � Max rate of climb Max. rate of climb : : 650 ft/ min 650 ft/ min � Endurance : 4 hours JAR-VLA in 2000 � Landing distance : 1770 ft (540 m) � Take-off distance : 1355 ft (415 m)

Advanced Technology Features HI NGELESS MAI N ROTOR ARI S- 6 DEGREE OF FREEDOM OF FREEDOM I NTEGRATED DYNAMI C SYSTEM ADVANCED COCKPI T CRASHWORTHY MODERN ENGI NE BEARI NGLESS CREW SEATS WI TH FADEC TAI L ROTOR EXTENSI VE USE OF COMPOSI TES

India makes it to Global Composites Scene with LCA-Tejas Program Courtesy: Boeing

LCA - ROLES & SALIENT FEATURES Offensive Air Support Maritime Air Defence Roles Reconnaissance • Close Air Support • Point I ntercept and Strike • I nterdiction • Escort • Air Superiority Operational Mass : 9000 Kgs Max. Mach No. : 1.8 Max War Load Max. War Load : 4500 Kgs : 4500 Kgs Max. Altitude : 15 Kms

TECHNOLOGIES Unstable Configuration Advanced Materials • High Agility & (Composite Wing, Fin, Maneuverability Maneuverability Digital Fly By Digital Fly By Elevons Fuselage Elevons, Fuselage, Rudder, Doors & Hatches) Wire Flight • Control laws Control System • Reduced Weight • Advanced Carefree Maneuverability • I ncreased Life • Reduced Signature R d d Si Advanced Avionics Flat Rated Engine • Easy Role Change • Easy Role Change • Easy Role Change E R l Ch General Systems Stealth Multi Mode Radar Glass Cockpit • Carbon brake disc • RCS • Advanced Sensors • Reduced Pilot Load • 4000 PSI Hyd System • I R • ECS for tropical • ECS for tropical Climate • Utility systems

Structural Optimization of Composite Wing Skins for Stress,Buckling, Aeroelasticity and Technological Constraints

45% by weight in composites Composite Parts made for LCA-Tejas by NAL

Benefits of Integration through Cocuring CSIR-NAL has developed Cocuring technology CSIR NAL has developed Cocuring technology within the country for Light Combat Aircraft (LCA-Tejas) and SARAS aircraft Light Combat Aircraft (LCA-Tejas) and SARAS aircraft • No holes- No stress concentration • Increased stiffness of structure • Better aerodynamic surface • R d Reduced assembly time d bl ti • Weight saving • • No fuel leakage No fuel leakage

NAL developed composites parts in LCA Tejas • Integral rib ‐ skin cocured construction • Resulted in weight savings of 35 % and a 20% weight reduction in and a 20% weight reduction in modified rudder • Fabrication done using prepregs with a hybridization of tooling technologies like tape winding and dissolvable core technology d di l bl t h l • Cost reduced by about 30 % Fin Fin inner details MLG Door Rudder Torque shaft

NAL developed composites parts in LCA Tejas Fuselage Top Skin Air Channel Dividing Wall Co-cured CFC Circular Duct

LCA CFC Wing Assembly

TEST FACILITIES DEVELOPED FOR LCA Lightning test rig Composite Lay ‐ up Shop Autoclave C ‐ Scan Test Facilities Facilities Structural Coupling Test Main Airframe Static Test Ground Vibration Test Half Wing Test Full Aircraft Test

Feature Level Testing for LCA • Fatigue testing for 5 life cycle • Environmental aging g g Spar 3 pt bending Spar-3 pt. bending • Static testing under Hot Wet L-Joint, BLK# 18 BLK# 18 CFC-CFC joint Y-Joint, Circular Duct Spar opening CFC M t l j i t I CFC-Metal joint I CFC-Metal joint I I Skin Stiffener T-Shear T T- Pull T-Shear Skin-Spar Joint

WING ROOT FITTING BOX ‐ DRY ASSEMBLY & FINAL ASSEMBLY WI NG BUCKLI NG TEST BOX O/ B Elevon test box WI NG FUEL TANK SEALI NG TEST BOX • Fatigue and burst pressure testing of Drop Tank Nose BOX LEVEL TESTS cone

Testing of LCA Wing - FLEXI BLE TEST RI G TO SI MULATE STI FFNESS EFFECTS - I SOSTATI C EQUI LI BRI UM SYSTEM - I NSTRUMENTED REACTI ONS SI MULTANEOUS EXTERNAL & REACTI ON LOADI NG

Development of a Light Transport Aircraft 14 seater multi 14 seater multi- -role LTA role LTA - - SARAS SARAS � Hybrid (metal + composite) airframe � CFC flaps, control surfaces, fairings � P&WC PT6A-67A turbo-prop engine � 1200 SHP � 1200 SHP 2.65 φ (5 bladed) constant speed propeller � � Max. cruise speed : 550 km / h � Max. cruise altitude : 9 km � Max. R/C, ISA, SL : 700 m / min. � � Endurance Endurance : : ~ 5h 5h � T.O. distance, ISA, SL : 700 m � Landing distance, ISA, SL : 850 m Design to meet FAR-23 requirements

Materials used for LCA and SARAS programmes AS4/ 914 Prepreg materials from Hexcel 1. composites Pvt Ltd; 180 deg C curing systems; D Dry T g = 175 deg C T 175 d C Unidirectional fabric from Hexcel Composites Unidirectional fabric from Hexcel Composites 2. and Resin from Axson France for the VERI Ty process; 80 deg C cure followed by 180 deg C p ; g y g post cure: Dry T g of 145 deg C Rohacell foam for stringers and access covers 3. VERI Ty process mechanical properties within 2 % of y p p p prepreg properties

Composite Parts in SARAS Aircraft HORIZONTAL STABILIZER Radome FRONT TOP SKIN ELEVATOR FLOOR BOARD WING New Processing INBOARD FLAP Technology: OUTBOARD VERITy FLAP FLAP AILERON REAR PRESSURE BULK HEAD FIN 35% by weight in composites

HT Components of SARAS Cocured Inter Spar Box with Bottom Skin With 2 Spars, 11 Ribs, 7 Stringers p p , , g Size: 5.5mx 1m Cocured Top Skin with Stringers Cocured Top Skin with Stringers Metal Composite Weight 92 Kg 70 Kg (24% ) No. of parts 243 11 No. of Fasteners 10,500 2900 HT Tip Cocured with Stringers

Horizontal Tail of SARAS: Cocured Bottom Section Horizontal Tail aft box Comparative chart Metal Composites p Weight 32.0 kgs. 24.0 kgs. No. of parts 75 1 Dimensions: 5.5mx1m. The skin is co- No. of 5200 Nil cured with stringers, ribs and spars. cured with stringers, ribs and spars. fasteners fasteners Assembly 4 weeks Nil

Tooling Concepts Basic outer CFC Mould I nternal Flexible tools Skin stringer spar I ntegration Skin stringer I ntegration Final bag for curing

Vertical Tail of SARAS Cocured Inter Spar Box with 6 Cocured Inter Spar Box with 6 Spars and a Mid Rib Metal Composite Size: 2.8mx1.8m Weight of I S 65 Kg 50 Kg Box Box (23% ) (23% ) No. of parts 130 01 No. of Fasteners No. of Fasteners 1100 1100 0 0 Total VT weight 126 Kg 101Kg (20% )

Master Model For Mould Rh & LH Mould Assembly Cured Component Skin Bonded With Spars & Mid Ribs Final Bagging for Curing Final Bagging for Curing

Cocured CFC Pressure Bulkhead of SARAS Ring 1.8 m diameter dome having a depth of 175 having a depth of 175 Dome Dome shaped mm, with thickness rear wall varying from 1.2 to 3 00 mm 3.00 mm Accuracy of outer contour and gusset spacing = + / - 0.5 mm Metal Composite Weight Weight 34 Kg 34 Kg 17 Kg (50% ) 17 Kg (50% ) No. of Fasteners 700 0

All the above were fabricated using Prepregs and All th b f b i t d i P d Autoclave Moulding Technology Challenge: How to cut costs??? Ch ll H t t t ??? O One solution- Liquid Moulding Technology l ti Li id M ldi T h l