18AE53 Aircraft Structures-I syllabus for AE

Design for Static Strength Introduction: Normal, shear, biaxial and tri-axial stresses, Stress tensor, Principal Stresses, Stress Analysis, Design considerations, Codes and Standards. Static Strength: Static loads and factor of safety, Theories of failure: Maximum normal stress theory, Maximum shear stress theory, Maximum strain theory, Strain energy theory, and Distortion energy theory, failure of brittle and ductile materials.

Design for Impact and Fatigue Strength Impact Strength: Introduction, Impact stresses due to axial, bending and torsional loads, effect of inertia. Fatigue Strength: Introduction, S-N Diagram, Low cycle fatigue, High cycle fatigue, Endurance limit, modifying factors: size effect, surface effect, Stress concentration and its effects, Fluctuating stresses, Goodman and Soderberg relationship, stresses due to combined loading, cumulative fatigue damage.

Loads on Aircraft: Structural nomenclature, Types of loads, load factor, Aerodynamics loads, Symmetric manoeuvre loads, Velocity diagram, Function of structural components.

Aircraft Materials: Metallic and non-metallic materials, Use of Aluminum alloy, titanium, stainless steel and composite materials. Desirable properties for aircraft application.

Theory of Elasticity: Concept of stress and strain, derivation of Equilibrium equations, strain displacement relation, compatibility conditions and boundary conditions. Plane stress and Plane strain problems in 2D elasticity. Principle Stresses and Orientation of Principle Directions. Structures: Statically Determinate and Indeterminate structures, Analysis of plane truss, Method of joints, 3D Truss, Plane frames, Composite beam, Clapeyron’s Three Moment Equation.

Energy Methods: Strain Energy due to axial, bending and Torsional loads. Castigliano’s theorem, Maxwell’s Reciprocal theorem. Columns: Columns with various end conditions, Euler’s Column curve, Rankine’s formula, Column with initial curvature, Eccentric loading, south-well plot.

Course Outcomes:

At the end of the course the student will be able to:

1. CO1: Apply the basic concepts of stress and strain analysis.

2. CO2: Compute the impact stress.

3. CO3: Identify appropriate materials for suitable application based on properties.

Question paper pattern:

• The question paper will have ten full questions carrying equal marks.
• Each full question will be for 20 marks.
• There will be two full questions (with a maximum of four sub- questions) from each module.
• Each full question will have sub- question covering all the topics under a module.
• The students will have to answer five full questions, selecting one full question from each module.

Textbooks

1 Aircraft Structures for Engineering Students Megson, T.M.G Edward Arnold 1995

2 Theory of Elasticity Timoshenko and Goodier McGraw Hill Co

3 Design of Machine Elements V.B. Bhandari Tata McGraw Hill Publishing CompanyLtd., New Delhi 2nd Edition 2007

Reference Books

1 Machine Design Robert L. Norton Pearson Education Asia 2001

2 Analysis of Aircraft Structures – An Introduction Donaldson, B.K McGraw-Hill 1993

3 Strength of Materials Timoshenko, S Princeton D Von Nostrand Co 1990

4 Mechanical Engineering Design Joseph E Shigley and Charles R.Mischke McGraw Hill International 6th Edition 2009

5 Aircraft Structures Peery, D.J., and Azar, J.J McGraw, Hill 2nd edition,1993

6 Analysis and Design of Flight Vehicles Structures Bruhn. E.H Tri – state off set company, USA 1985