MAE 157 LIGHTWEIGHT STRUCTURES (Required for AE and ME; Elective for CE and MSE)

Catalog Data: MAE 157: Lightweight Structures (Credit Units: 4) W Fundamentals of torsion and bending. Analysis and design of thin-walled and composite beams. Stress analysis of aircraft components. Stiffness, strength, and buckling. Introduction to the Finite Element method and its application to plates and shells. Prerequisite: MAE150 or CEE150 or ENGR150. (Design units: 2)

Textbook: THG Megson, Aircraft Structures for Engineering Students, 4th Ed., Butterworth-Heinemann, 2007.

References: CT Sun, Mechanics of Aircraft Structures, Wiley, 1998. HD Curtis, Fundamentals of Aircraft Structural Analysis, McGraw-Hill, 1997. Coordinator: Lorenzo Valdevit, Satya N. Atluri Course objectives: The aim of the course is to empower students with the necessary tools to

design minimum-weight structures under any loading constraints. Although analytical solutions will be presented for one-dimensional structures under simple loads, the Finite Element method will be emphasized as the ideal platform for the solution of nearly any structural problem.

Relationship to Program Outcomes: This course relates to Program Outcomes a, c, d, e, i, and k; with

additional Mechanical Engineering outcomes 2, 3 & Aerospace Engineering outcomes 1: http://undergraduate.eng.uci.edu/degreeprograms/mechanical/mission http://undergraduate.eng.uci.edu/degreeprograms/aerospace/mission

Course Outcomes: Students will:

- Calculate the stress distribution in one-dimensional structural elements under any combination of axial, bending, shear and torsional loads.

- Calculate the maximum design loads that a structure can tolerate, using the appropriate failure criteria for yielding and buckling.

- Appreciate the concepts of statical determinacy and indeterminacy - Understand the approximations involved in the structural idealization of

aircraft components. - Design minimum-weight structures subject to multiple requirements

(strength, stiffness, size, etc…). - Understand the main concepts of elastic buckling, and appreciate that

lightweight structures are subject to multiple buckling modes (e.g. local VS global buckling).

- Learn the fundamentals of the Finite Element method, and develop a working knowledge of a commercial package for the static analysis of lightweight structures (including eigenvalue analysis for the prediction of the critical buckling loads).

- Solve structural problems using applied engineering mathematical concepts – calculus, trigonometry, linear (matrix) algebra, differential equations, coordinates transformation.

- Work in a team environment, by participating in a design project culminating in written report and oral presentation

Prerequisites By Topic: Statics of solid bodies. Analysis of structures. Mechanics of materials. Stress

and strain. Lecture Topics: Introduction to aircraft construction. The objective of minimum weight and

lightweight structures: examples from aircraft design Advanced strength of materials applied to one-dimensional elements: - Torsion: Shear stress distribution in thin-walled shafts - Bending: Normal stress distribution for non-symmetric sections - Bending: Shear stress distribution in thin-walled beams Introduction to continuum structures from a statical determinacy standpoint. Summary of 2D elasticity: plane stress/strain, principal stresses/strains, Mohr’s circle Failure criteria: yielding (Von Mises,) and buckling Introduction to the Finite Element method for elastic continua Finite elements description (and solution) of plates and shells (with ABAQUS)

Class Schedule: Meets for 3 hours of lecture and 1 hour of discussion each week for 10 weeks. Computer Usage: A commercial programming language (e.g. MATLAB) will be used to

optimize the dimensions of a minimum-weight structure under realistic design constraints. In addition, students will learn how to use a commercial Finite Element code (e.g. ABAQUS, or MSC.Nastran) for the structural analysis of more complex lightweight structures.

Professional Component: Contributes toward the Mechanical Engineering Topics courses and Major

design experience. Contributes toward the Aerospace Engineering Topics courses and Major design experience.

Design Content Description Approach: A team-oriented design project is aimed at the optimization and accurate analysis of a

minimum-weight structure subject to a number of realistic loads and constraints. A light-weight structure that meets ideal design criteria (i.e. mass, deflection, strength, etc.) is to be designed by groups of four or more students. Two full lectures are devoted to the design project. Topics to be covered are: problem definition, design variables, design constraints, the optimization procedure, and interpretation of results. In the second half of the quarter, all discussion sessions supplement and office hours give first priority to the team-oriented design project. Students have full access to structural analysis software during both sessions.

Grading Criteria: Problem Sets: 20% Design Project: 20% Midterm (2) Exams: 30% (15% each) Final Exam: 30% 100% *Attendance is an important factor.

Homework Grading Policy: conceptually sound problem-solving process 70%, Accuracy of answers 30% of score, On-time policy – no late homework accepted.

Estimated ABET Category Content: Mathematics and Basic Science: ___ credit units or ___% Engineering Science: _2__ credit units or __50_% Engineering Design: _2__ credit units or __50_%

Prepared by: Lorenzo Valdevit Date: July 2009 CEP Approved: Fall 2008