AS2070: Aerospace Structural Mechanics
Jan-May, 2026

• Dr. Nidish Narayanaa Balaji
  • nidish@iitm.ac.in, Room 139 AE building
• TA: Niranjan Gulla, Poorvika U.
• Textbook References
  1. Module 1
     • Buckling of Bars, Plates and Shells (1975) by Brush and Almroth [1]
     • Theory of Elastic Stability (2009) by Stephen P. Timoshenko [2]
     • Aircraft Structures for Engineering Students (2013) by T. H. G. Megson [3]
  2. Module 2
     • Mechanics of Composite Structures (2003) by Kollar and Springer [4]
     • Principles of Composite Material Mechanics (2012) by Ronald F. Gibson [5]
  3. Module 3
     • Fracture Mechanics: An introduction (2005) by Gdoutos [6]
     • Elements of Fracture Mechanics (2009) by Kumar [7]
• This website does have some notes that I have prepared, but note that these are more for my reference than yours.
  • You should assume that they come with mistakes that I will rectify as the semester progresses.
  • Your primary references must only be your textbooks.

• The lectures will be split into three modules:

  Sno.	Topic	Lectures	Assignments
  1	Elastic Stability	11	1-2
  2	Laminated Composites	11	1-2
  3	Introduction to Failure	11	1-2
  	Total	33	3-6

  • The weekly split-up (nominally) is
    • 3 Lectures
    • 1 Tutorial

• The End Semester Examination will carry 40% weightage for the overall.
• The quizzes (together) will carry 30% weightage.
• The assignments (together) will carry 15% weightage.
• A Course Project will carry 15% weightage.

• The weighted overall grades will be scaled by the maximum score. A letter grade will be assigned based on the following rubric.

  	[95, 100]	[85, 95)	[75, 85)	[65, 75)	[55, 65)	[45, 55)
  Grade	S	A	B	C	D	E

Upon my honor I state that I have received no unauthorized support and can attest that the submission reflects my understanding of the subject matter.

• The honor code may be signed either by hand or just initials (in case of typed submission), but the key is that you should mean it.
• Honor code violations will not be taken lightly.

• Each module will have at least one assignment and at most 2.
• Late Submission Policy
  • No late submissions will be encouraged. If you miss the deadline, you miss the submission.
  • Exceptions will be considered only if I receive written communication through Moodle before the submission date.

• The first week of classes will provide an executive overview of the three modules to be taught in the class.
• You will be given one week's time to decide which module you want to work on for your project.

• The problem statement for the project is:

  Develop an experimental demonstration of pedagogical value that highlights some of the concepts covered in class.

• I will group you in teams of 5-6 based on your preferences.
• The deliverables are:
  • a demonstration of the experiment.
  • a 15 minute presentation to class.
  • a 1-2 page summary (keep this very brief).

• We shall try to use the DiGii app for attendance. If this does not work, I will be using an Attendance App on a tablet to record attendance.
  • My app logs the time of press also, so attendance will be computed as the ratio of the number of seconds spent in class and the total number of class hours.
• Please be aware of institute policy regarding attendance matters, I can not provide any flexibility here.

• Semester Calendar
• https://archive.nptel.ac.in/content/storage2/courses/101104010/
• https://fracturemechanics.com/
• Video on Fatigue testing
• Attendance App

• What is stability?
• Buckling of columns
• Energy Perspectives to Stability
• Snap-Through Buckling
• Flat Plates

• Classification of composite materials
  1. Continuous fiber composite laminate
     • Interlaminar strength is matrix dominated.
  2. Woven fiber composites
     • Strength compromized but no risk of delamination.
  3. Chopped fiber composites
     • Poorer strength but cheaper.
  4. Hybrid composites
  5. Sandwich structure
     • High strength faces bonded through a lightweight foam/honeycomb core.
     • High flexural stiffness-to-weight ratios.
• Materials in Composites
  1. Fibers
     • Fiberglass-Reinforced Plastics (FRPs)
       • Low cost, "basic" composites
     • "Advanced" composites: Carbon, SiC, aramid polymer, etc.
       • Higher modulus, strength; lower density.
     • Carbon Nanotubes, Nanofibres.
  2. Matrix, Filler
     • Polymers
       • Thermosets: Epoxy, Polyester, etc.
         • Highly cross-linked 3D molecular network which doesn't melt again.
       • Thermoplastics: Polyetherketone (PPEK), PolyPhenyl Sulphide (PPS), etc.
         • Polymer chains that do not cross-link. Will melt, can be reshaped.
     • Metal, ceramic, or carbon matrix for higher temperature applications.
• Effective Moduli, Effective Strength.
• Constitutive relationships.
• Classical Laminate Theory (Subject to Time)

• Structure of Materials
  • Lattice, Defects
• Introduction to Fatigue
  • S-N Curve
  • Miner's Rule
  • Stress Concentration
• Introduction to Fracture Mechanics
  • Modes of Fracture
  • Crack Growth

• Link to pdf

This tutorial is meant as an introduction to the design process involving much of what is learnt in this class (specifically modules 1 and 3).

• Latest Version

The reports and presentation (where available) of projects from past semesters are documented here. Do have a look and reach out to your seniors to understand what they would do differently, given their experience.