Title page for ETD etd-01132005-132131

Document Type

Master's Dissertation

Author

Viljoen, Awie

URN

etd-01132005-132131

Document Title

Analysis and Optimum Design of stiffened shear webs in airframes

Degree

MEng (Mechanical and Aeronautical Engineering)

Department

Mechanical and Aeronautical Engineering

Supervisor

Advisor Name	Title
Mr A G Visser	Co-Supervisor
Prof A A Groenwold	Supervisor

Keywords

genetic algorithm
structural optimization
FORTRAN program
shear web
aircraft structures
non-linear finite element analysis
NACA
diagonal tension
Grisham algorithm
post-buckling analysis

Date

2004-03-03

Availability

unrestricted

Abstract

The analysis and optimum design of stiffened, shear webs in aircraft structures is addressed. The post-buckling behaviour of the webs is assessed using the interactive algorithm developed by Grisham. This method requires only linear finite element analyses, while convergence is typically achieved in as few as five iterations. The Grisham algorithm is extensively compared with empirical analysis methods previously used for aircraft structures and also with a refined, non-linear quasi-static finite element analysis.
The Grisham algorithm provides for both compressive buckling in two directions as well as shear buckling, and overcomes some of the conservatism inherent in conventional methods of analysis. In addition, the method is notably less expensive than a complete non-linear finite element analysis, even though global collapse cannot be predicted. While verification of the analysis methodology is the main focus of the stud, an initial investigation into optimization is also made. In optimizing stiffened thin walled structures, the Grisham algorithm is combined with a genetic algorithm. Allowable stress constraints are accommodated using a simple penalty formulation.

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Filename		Size	28.8 Modem	56K Modem	ISDN (64 Kb)	ISDN (128 Kb)	Higher-speed Access
	00front.pdf	2.84 Mb	00:13:08	00:06:45	00:05:54	00:02:57	00:00:15
	01chapter1.pdf	13.77 Mb	01:03:45	00:32:47	00:28:41	00:14:20	00:01:13
	02chapter2.pdf	7.96 Mb	00:36:50	00:18:56	00:16:34	00:08:17	00:00:42
	03chapter3.pdf	37.56 Mb	02:53:53	01:29:25	01:18:15	00:39:07	00:03:20
	04chapter4.pdf	785.96 Kb	00:03:38	00:01:52	00:01:38	00:00:49	00:00:04
	05chapter5.pdf	19.12 Mb	01:28:30	00:45:31	00:39:49	00:19:54	00:01:41
	06chapter6.pdf	3.61 Mb	00:16:43	00:08:36	00:07:31	00:03:45	00:00:19
	07chapter7.pdf	415.70 Kb	00:01:55	00:00:59	00:00:51	00:00:25	00:00:02
	08bibliography.pdf	205.64 Kb	00:00:57	00:00:29	00:00:25	00:00:12	00:00:01
	09appendices.pdf	3.08 Mb	00:14:14	00:07:19	00:06:24	00:03:12	00:00:16