JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

Pre-Requisites

Theory of Structures

Course Objectives:

• Understand the aircraft structural components and its behavior under different loading conditions.
• Obtain knowledge in plate buckling and structural instability of stiffened panels for airframe structural analysis.
• Explain the thin walled section and structural idealization of panels and differentiate from the type of loads carried.
• Solve for stresses and deflection in aircraft structures like fuselage, wing and landing gear.

Course Outcomes:

• Types of structure used in aircraft and various loads experienced by components

UNIT - I

Introduction to Aircraft Structural Components and Energy Methods: Aircraft Structural components and loads, functions of structural components, airframe loads; Types of structural joints, type of loads on structural joints; Aircraft inertia loads; Symmetric manoeuvre loads, gust loads. Monocoque and semi monocoque structures, stress in thin and thick shells; Introductions to energy principles, Castilians theorems, Maxiwells reciprocal theorem, unit load method, Rayleigh Ritz method, total potential energy method, flexibility method.

UNIT - II

Thin Plate Theory, Structural Instability: Analysis of thin rectangular plates subject to bending, twisting, distributed transverse load, combined bending and in-plane loading: Thin plates having small initial curvature, energy methods of analysis. Buckling of thin plates: Elastic, inelastic, experimental determination of critical load for a flat plate, local instability, instability of stiffened panels, failure stresses in plates and stiffened panels. Tension field beams- complete diagonal tension, incomplete diagonal tension, post buckling behaviour.

UNIT - III

Bending, Shear and Torsion of Thin Walled Beams: Unsymmetrical bending: Resolution of bending moments, direct stress distribution, position of neutral axis; Deflections due to bending: Approximations for thin walled sections, temperature effects; Shear loaded thin walled beams: General stress, strain and displacement relationships, direct stress and shear flow system, shear centre, twist and warping. Torsion of beams of closed section: Displacements associated with Bredt- Batho shear flow; Torsion of open section beams; Warping of cross section, conditions for zero warping; Bending, shear, torsion of combined open and closed section beams.

UNIT - IV

Structural Idealization: Structural idealization: Principal assumptions, idealization of panel, effect on the analysis of thin walled beams under bending, shear, torsion loading- application to determining deflection of open and closed section beams. Fuselage frames - bending, shear and torsion.

UNIT - V

Analysis of Fuselage, Wing and Landing Gear: Wing spar and box beams, tapered wing spar, open and closed sections beams, beams having variable stringer areas; wings – three boom shell in bending, torsion and shear, tapered wings, deflections, cutouts in wings; Cutouts in fuselages;

R18 B.TECH. AERONAUTICAL ENGG.

Fuselage frame and wing rib; principle of stiffener, web constructions. Landing gear and types; Analysis of landing gear.

TEXT BOOKS:

• 1. T. H. G. Megson, ―Aircraft Structures for Engineering Studentsǁ, Butterworth-Heinemann Ltd, 5th Edition, 2012.
• 2. E. H. Bruhn, ―Analysis and Design of Flight vehicles Structuresǁ, Tri-state off set company, USA, 4th Edition, 1965.

REFERENCE BOOKS:

• 1. B. K. Donaldson, ―Analysis of Aircraft Structures - An Introductionǁ, Mc Graw Hill, 3rd Edition, 1993.
• 2. S. Timoshenko, ―Strength of Materials, Vols I and IIǁ, Princeton D. Von Nostrand Co., Reprint, 1977. R18 B.TECH. AERONAUTICAL ENGG.