


Politecnico di Torino  
Academic Year 2017/18  
02CODMT Aircraft structures 

Master of sciencelevel of the Bologna process in Aerospace Engineering  Torino 





Subject fundamentals
The main objective of this Course is to make the student able to understand the main issues related to the modeling of static behavior and elastic stability of the aircraft structures as a whole and by considering their basic components; develop ability to perform preliminary evaluations and detailed analysis of strain and stress states in typical structural aircraft components by using approaches of increasing complexity. A further goal is to introduce the student to the issues.

Expected learning outcomes
Aim of the Course is to provide to the student the needed basic knowledge to approach critically and autonomously the analysis of the structural behavior of typical aeronautical structures and substructures by making use of classical analytical methods and finite element method.
In particular, the methodologies provided will allow the student to carry out the analysis of the static behavior (calculation of the states of stress and strain) and the limits of elastic stability (critical loads and associated modes of failure) of onedimensional elements, stiffened plates and plates made of composite materials and sandwich, typical structural elements of aircraft structures. The analysis will be performed using graphical and tabular data, simple MATLAB codes, and autonomously developed PATRAN/NASTRAN FEM models.The active participation to the experimental laboratory tests will allow the student to acquire also the feeling with the problems arising when designing and performing a laboratory test and the basic knowledge of the needed basic components used to perform a simple material characterization test. At the end of the Course, the student should be able to critically evaluate the adequacy of the analysis tools used, the quality of the results obtained, the issues concerning the design and carrying out of simple experimental tests. 
Prerequisites / Assumed knowledge
The course makes reference to concepts, notions and methodologies from the courses of basic mechanics, matrix algebra and numerical computing, aircraft constructions. 
Contents
 A general survey of the design and analysis of aircraft structures. The objectives of aircraft structural analysis. Airworthiness. Load classification (static, dynamic, thermal, etc) and sources. Structural safety ((stiffness criteria, strength criteria, elasticity criteria) and related design criteria (failsafe, safelife, damage tolerance).
 Materials for aerospace structures.  Functions of principal components of aircraft structures: wings, fuselages, empennages (tail units). A general overview of typical solutions.  Wing and fuselage stress analysis by the modified engineering beam theory (idealized thinwalled beams).  Kirchhoff's plate theory, stiffened and sandwich plates.  Elastic stability of rods, unstiffened and stiffened, laminated and sandwich flat plates.  Introduction to the finite element method (FEM). Onedimensional finite elements (rod, bar, beam). Twodimensional membrane and Kirchhoff’s plate finite elements. 3D finite elements. 
Delivery modes
The lessons are integrated by classroom exercises, numerical exercises at the Politecnico computer labs, and experimental tests at the LAQ 'AERMECSistemi strutturali aeromeccanici' laboratory (www.aesdo.polito.it) of the Aeronautics and Space Engineering Department.
' Introduction to MATLAB (brief summary of useful MATLAB commands and matrix algebra). ' Stress analysis of thinwalled beam sections. ' Elastostatic analysis with MATLAB of symmetric, crossply rectangular plates, simplysupported on all sides and transversely loaded. ' Elastostatic analysis of sandwich beams. ' Critical loads of unstiffened and stiffened rectangular plates under different loading and boundary conditions. ' Hand solution of a static problem with rod finite elements. ' Implementation of a MATLAB program for FEM analysis of plane truss (ROD elements) and plane framed structures (BEAM elements). ' FEM Analysis (PATRAN/NASTRAN) of flat plates with holes. ' Tensile test on a specimen under traction. 
Assessment and grading criteria
Assessment and grading criteria
Aim of the examination is to verify the adequate knowledge of the methodology and the ability to apply it by the student, in addition to the ability to understand and describe the structural problems treated in the course. The examination consists only of a written test (max 30/30) on the whole program of lectures and exercises (exercises in the classroom, LAIB and LAQ). The written exam is divided into a number of questions. As a rule, the student must give the written answers in no more than 120 min. During or at the end of the written test, the candidate can decide whether to retire, or be assessed. The examination has been passed when the written scores is not less than 18/30. The evaluation is recorded. If the score is lower than 18/30, the student must take again the written test. Oral examination (optional) Those who get a score not less than 21/30 in the written test, may also ask for an oral exam, in the same written examination call. At the oral examination students are requested to bring the written reports of all the exercises (exercises in the classroom, LAIB and LAQ) and programs in Matlab. As for the written test, the oral examination is on the whole program of lectures and exercises (exercises in the classroom, LAIB and LAQ). The score of the oral examination is in the range 3/30 and +3/30. The final score follows from the algebraic summation of the written and oral scores and is recorded. 
