Checking date: 11/06/2021

Course: 2021/2022

Stability and integrity of aerospace structures
(15345)
Study: Bachelor in Aerospace Engineering (251)

Coordinating teacher: CINI , ANDREA

Department assigned to the subject: Department of Bioengineering and Aerospace Engineering

Type: Electives
ECTS Credits: 6.0 ECTS

Course:
Semester:

Requirements (Subjects that are assumed to be known)
Advanced Mathematics Aerospace Materials I and II Introduction to Structural Analysis Aerospace Structures
Objectives
- Understanding of the concept of instability and the loading conditions in which it appears. - Ability to calculate the onset of instability in aerospace structures. - Understanding the effects that cycling loading, stress level and geometric configuration have on the life of structural members. - Understanding the mechanism by which cracks grow and variables that affect their growth rate. - Ability to calculate when aerospace structures will fail when subjected to cycling loading. - Knowledge of design concepts and inspection methods that will safeguard aerospace structures from catastrophic failure.
Skills and learning outcomes
Description of contents: programme
1) Stress Analysis of Aircraft Components - Structural Idealization - Wing spar and box beams - Wings - Fuselage 2) Structural Stability - Columns: Elastic buckling of ideal columns. Euler Curve. Inelastic buckling of columns. Euler-Engesser Curve. Real effects on column stability: Imperfections. Local Buckling and Crippling. The Johnson-Euler curve. - Plates: Elastic buckling of plates (compression, bending, shear and combined loading). Plastic effects in plate buckling. Effect of panel curvature. Panel failure: compression and shear panels. Diagonal Tension. 3) Structural Integrity: - Constant and variable amplitude fatigue: SN Curves. Stress concentrations. Cycle counting. Cumulative damage rules. Residual stresses. Design Criteria. - Linear Elastic Fracture Mechanics: Energy release rate and Stress Intensity Factors. Plastic zone size. Fracture Toughness and failure prediction. Thickness effects on Fracture Toughness. The plane strain Fracture Toughness test. - Fatigue Crack Growth: Fatigue crack growth rate curve. Stress ratio effects. Paris Law and other analytical representations. - Damage Tolerance Analysis: Life prediction. Closed form integration for constant Beta and Paris Law. Retardation effects. Design Criteria.
Learning activities and methodology
Theory sessions. Problem sessions working individually and in groups. Experimental and numerical Lab-sessions.
Assessment System
• % end-of-term-examination 60
• % of continuous assessment (assigments, laboratory, practicals...) 40
Calendar of Continuous assessment
Basic Bibliography
• Anderson, T. L.. Fracture Mechanics: Fundamentals and Applications. CRC Press. 1995
• Megson. Aircraft Structures for Engineering Students. Elsevier. 2012
• Ralph I. Stephens, et. al.. Metal Fatigue in Engineering. Wiley. 2001
• Timoshenko & Gere. Theory of Elastic Stability. McGraw Hill. 1985
Additional Bibliography
• Broek, David. The practical use of fracture mechanics. Springer. 1989
• Bruhn, E.F.. Analysis and design of flight vehicle structures. Jacobs. 1973
• James Gere and Stephen Timoshenko. Mechanics of Materials. PWS Publishing. 1990 (or newer).
• Jan R. Wrigth. Introduction to Aircraft Stability and Loads. John Wiley & Sons. 2007
• John M. Barsom and Stanley T. Rolfe. Fracture and Fatigue Control in Structures. ASTM. 1999
Electronic Resources *
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The course syllabus may change due academic events or other reasons.