JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

UNIT - I

Introduction and Airworthiness Requirements: Structural design and sizing stages, Principal Structural components of aircraft Design requirements- structural integrity, stiffness, service life, Constraints- baseline aerodynamic configuration, external loading, weight, operating conditions, conformity to government regulations. Design for durability, damage tolerance. Airworthiness requirements - loads, safety margins, material properties, methods of estimation construction, operation, maintenance, training-procedures. Critical load conditions. Limit and ultimate loads- definition, significance. Aircraft materials- mechanical properties- design data-allowable, allowable bases. Failure theory. Flight loads- atmospheric, manoeuvre - construction of flight envelope.

UNIT - II

External Loads – Estimation, Fasteners and Structural Joints: Wing loads- air load span wise distribution, effect of fuselage, engine nacelle, wing stores, control surfaces, landing, taxi, dynamic gust loads, wing weight distribution. Empennage loads- gust, manoeuvre, control surface. Fuselage loads- distribution of weight, fore body loads, after body loads, internal pressure, propulsion loads. Landing gear loads- landing conditions, ground handling loads, retraction loads. Miscellaneous loads. Airplane weight data, stiffness data. Theories of Failure. Fasteners and fittings- role, significance, general design considerations, criteria for allowable strength. Margins of safety. Fastener systems, types, fastener information, dimensions, material, allowable strength- tensile, shear, bending, bearing, Rivets, bolts and screws, nuts- detail design considerations. Fastener selection. Fittings- lugs, bushings and bearings- loading, design and analysis. Joints- spliced, eccentric, gusset, welded, brazed, bonded-types, methods of joining, failure modes. Fatigue design considerations. Stress concentration- causes, methods of reduction. Fastener load distribution and bypass load- severity factor, structural joint life prediction. Shim control and requirement.

UNIT - III

Design of Wing, Tail Unit Structures: The wing- role- summary of wing loads, structural Components- wing box, leading and trailing edges. Wing layout- location of spars, ailerons and flaps, rib spacing and direction, root rib bulkhead, span wise stiffeners, wing covers- skin-stringer panels, integrally stiffened panels, access holes, and attachment of leading edge and trailing edge panels. Spars- general rules of spar design. Ribs and bulkheads- rib spacing and arrangement. Wing root joints, carry through structure. Fighter wing design- problems with swept wings Wing box, root rib bulkhead- estimation of loads, stress analysis, design parameters, optimization, sizing, margins of safety. Leading and trailing edge assembly- control surfaces, flaps- structure.

R16 B.TECH AERONAUTICAL ENGG.

UNIT - IV

Design of Fuselage, Landing Gear, Engine Mounts: Function of fuselage-loading, general requirements. Ultimate strength of stiffened cylindrical structure- review, Principal structural components- skin and stringers, frame and floor beam, pressure bulkhead, wing and fuselage intersection- lay out, loading, stress analysis, sizing. Forward fuselage, aft fuselage structures, fuselage openings- windows, doors- design considerations. Landing gear- purpose, types, general arrangement, loads- design considerations- ground handling, take-off, landing, braking, pavement loading, support structure. Stowage and retraction, gear lock kinematic design. Shock absorbers- function, types, components, operation, loads, materials, design. Wheels and brakes, tire selection Engine mounts- types-wing pod, rear fuselage, tail, fuselage mount, loads, design considerations.

UNIT - V

Fatigue Life, Damage Tolerance, Fail-Safe Design- Weight Control and Balance: Catastrophic effects of fatigue failure- examples- modes of failure-design criteria- fatigue stress, fatigue performance, fatigue life. Fatigue design philosophy- fail-safe, safe life. Service behaviour of aircraft structures- effect of physical and load environment design and of detail of fabrication Structural life methods of estimation- the scatter factor- significance Fail-safe design-the concept, requirements, damage tolerance- estimation of fatigue strength

TEXT BOOKS:

• 1. Niu, M.C., Airframe Structural Design, second edition, Hong kong Conmlit Press, 1988, ISBN: 962-7128- 09-0.
• 2. Niu, M.C., Airframe Stress Analysis, and Sizing, second edition, Hong kong Conmlit Press, 1997, ISBN: 962-7128-08-2.

REFERENCES

• 1. Bruhn, E.H., Analysis and Design of Flight Vehicles Structures, Tri - state Offset Company, USA, 1965.
• 2. Peery, D.J, and Azar, J.J., Aircraft Structures, second edition, Mc Graw-Hill, N.Y., 1993.
• 3. Megson, T.H.G., Aircraft Structures for Engineering Students, Butterworth- Heinemann/ Elsevier, 2007.
• 4. Raymer, D.P., Aircraft Design: A Conceptual Approach, 3rd edn., AIAA Education Series, AIAA, 1999, ISBN: 1-56347- 281-0.
• 5. Fielding, J.P., Introduction to Aircraft Design, Cambridge University Press, 2005, ISBN: 0-521-657222-9. R16 B.TECH AERONAUTICAL ENGG.