2018/4/27 Structural Loads-Category 圈上活文大学 Structural Loads 国上茶大坐 A better understanding ofoperating environment and better tools for External loads load prediction has lead to enhanced performance,better economies and improved passenger comfort. Regulatory requirements e2omartnrSgpobaetachtteugetepectedoadievelklmt l8gnsedopretctdetaledstresa/stranlevebndetaled sign d load path accuracy,Optimal design 益品 Rg.142 LII op knd ery-Dr. Wenbin Song External and Internal Loads 上清大学 Typical Mission Segments 国上活大学 .08 Shear,moment,torque End-loads of structural elements Local pressure loads Attachments loads of Attachment loads of ..main components ..components which do eg.Pylon,HTP NOT influence a/c behaviour eg.moveables Dr.Wenbin Song Typical Loading actions' 图上承我大学 Velocity-load (V-n)Graph 国上海大坐 Load factor n=L/W For a typical flight mission ofone aircraft Load-velocity graph 1.Ground turn Each aircraft has its own V-n 2. Take-offroll (on an undulating runway) graph,which varies with weight altitude 3. Steady balanced flight manoeuvres 4.Pilot induced dynamic flight manoeuvres A 5.Turbulence or discrete atmospheric gust encounter 6. Transient inputs such as engine or control failure 7.Dynamic landing impact, 8.Steady or Dynamic application ofbraking 9.Dynamic crash landings +25 10.Steady towing.jacking and picketing. For heacoplers,from-3.5 Sh 22018/4/27 2 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics Structural Loads - Category A better understanding of operating environment and better tools for load prediction has lead to enhanced performance, better economics and improved passenger comfort. © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics Structural Loads • External loads – Lessons from fleet incidents – Collection of in-service flight data such as fleet utilization statistics and maintenance data – Regulatory requirements – Internal guidelines – Moving towards more probabilistic such as the use of expected load levels, limit load, the maximum load expected in service, gust intensities, etc. – Improved load prediction methods • Total airplane finite element models and computational fluid dynamics simulations • Correlation between analysis, flight test data and in-flight data • Increased load conditions (more than 100 in early days to over 1000) • Structural optimization • Internal loads – used to predict detailed stress/strain levels in detailed structural design – Finite element methods – Detailed load path，High accuracy，Optimal design 8 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics Shear, moment, torque End-loads of structural elements & Local pressure loads Attachments loads of Attachment loads of . . . main components . . . components which do eg. Pylon, HTP NOT influence a/c behaviour eg. moveables aerodynamic distribution inertia distribution External and Internal Loads © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics Segment Altitude Flap Se tting Speed Thrust Weight 1 Static SL zero zero zero OWE+Payl+fuel 2 Control check SL zero zero zero OWE+Payl+fuel 3 Towing SL zero zero zero OWE+Payl+fuel 4 Pushback SL zero zero zero OWE+Payl+fuel 5 Pivot turn SL zero zero idle OWE+Payl+fuel 6 Ground Turn SL zero zero idle OWE+Payl+fuel 7 Braked Roll SL zero zero idle OWE+Payl+fuel 8 Taxi Out SL zero zero idle OWE+Payl+fuel 9 Take-Off Roll SL Take-off zero Take-Off OWE+Payl+fuel 10 Rotation SL Take-off 1.05 Rot Take-Off OWE+Payl+fuel 11 Lift-Off SL Take-off 1.10 Rot Take-Off OWE+Payl+fuel 12 LG Retraction 1000 Take-off 0.7max Take-Off OWE+Payl+fuel 13 Flap down dep. 1000 Take-off V=”F” Take-Off OWE+Payl+fuel 14 Flap retraction 1000 Take-off V=”F” Take-Off OWE+Payl+fuel 15 Initial climb 1000 zero recom. Take-Off OWE+Payl+fuel 16 Climb 5000 zero recom. Max.Climb TOW-fuelburn 17 Final Climb 50% cruise zero recom. Max.Climb TOW-fuelburn 18 Cruise cruise zero recom. T=drag TOW-fuelburn 19 Initial descent 50% cruise zero Vmo. T=drag TOW-fuelburn 20 Final descent 5000 zero 250kt. T=drag TOW-fuelburn 21 Flap extension 1000 landing V=”F”. T=drag OWE+Payl+fuel res 22 Flap down approach 1000 landing V=”F”. T=drag OWE+Payl+fuel res 23 Gear Extension 1000 landing 1.3 Vs. T=drag OWE+Payl+fuel res 24 Flare zero landing 1.3 Vs. idle OWE+Payl+fuel res 25 Touchdown zero landing 1.3 Vs. idle OWE+Payl+fuel res 26 Roll-out zero landing % VL. reverse OWE+Payl+fuel res 27 Taxi zero zero 20 kt idl1 OWE+Payl+fuel res 28 Ground Turn zero zero 20 kt idl1 OWE+Payl+fuel res 29 Pivot zero zero zero idl1 OWE+Payl+fuel res 30 Parking zero zero zero zero OWE+Payl+fuel res Typical Mission Segments © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics For a typical flight mission of one aircraft 1. Ground turn 2. Take-off roll (on an undulating runway) 3. Steady balanced flight manoeuvres 4. Pilot induced dynamic flight manoeuvres 5. Turbulence or discrete atmospheric gust encounter 6. Transient inputs such as engine or control failure 7. Dynamic landing impact, 8. Steady or Dynamic application of braking 9. Dynamic crash landings 10. Steady towing, jacking and picketing. Typical ‘Loading actions’ © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics Velocity-load (V-n) Graph • Load factor n=L/W • Load-velocity graph • Each aircraft has its own V-n graph, which varies with weight altitude  For commercial transport airplanes, from -1 to +2.5  For light airplanes, from -1.5 to +3.8  For aerobatic airplanes, from -3 to +6  For helicopters, from -1 to +3.5