Title page for ETD etd-3123162539751141

Type of Document

Dissertation

Author

Dano, Marie-Laure

Author's Email Address

Marie-Laure.Dano@gmc.ulaval.ca

URN

etd-3123162539751141

Title

SMA-Induced Deformations In general Unsymmetric Laminates

Degree

PhD

Department

Engineering Science and Mechanics

Advisory Committee

Advisor Name	Title
M. W. Hyer	Committee Chair
D. H. Morris	none
E. R. Johnson	none
F. Lalande	none
O. H. Griffin, Jr.	none

Keywords

instability
modeling of smart structures
shape control
snap through

Date of Defense

1997-04-22

Availability

unrestricted

Abstract

General unsymmetric laminates exhibit large

natural curvatures at room temperature.

Additionally, inherent to most unsymmetric

laminates is the presence of two stable

configurations. Multiple configurations and

stability issues arise because of the geometric

nonlinearities associated with the large

curvatures. The laminate can be changed from

one stable configuration to the other by a

simple snap-through action. This situation offers

the opportunity to use shape memory alloys

(SMA) attached to the laminate to generate the

snap-through forces and change the shape of

the laminate on command. Presented is a

model which can predict SMA-induced

deformations in general unsymmetric laminates

and, particularly, the occurrence of the snap

through. First, a methodology is developed to

predict the deformations of flat general

unsymmetric epoxy-matrix composite laminates

as they are cooled from their elevated cure

temperature. Approximations to the strain fields

are used in the expression for the total potential

energy, and the Rayleigh-Ritz approach is used

to study equilibrium. To further study the

laminate deformations, finite-element analyses

are performed. Experimental results are

presented which confirm the predictions of the

developed theory and the finite-element

analyses regarding the existence of multiple

solutions and the magnitude of the

deformations. Results are compared with those

of several other investigators. Next, the

deformation behavior of general unsymmetric

laminates subjected to applied forces is

studied. The principle of virtual work is used to

derive the equilibrium equations relating the

laminate deformations to the applied forces. By

solving the equilibrium equations as a function

of the force level, relations between the

laminate deformations and the applied force are

derived, and the force level at which the

laminate changes shape is determined. Finally,

an existing SMA constitutive model is

implemented into the developed theory to

predict the deformations of simple structures to

SMA-induced forces. Experiments on a

narrow aluminium plate with an externally

attached SMA actuator are conducted. The

experimental results show good agreement with

the predictions from the developed theory.

Next, the deformation behavior of general

unsymmetric laminates subjected to SMA

actuators is predicted using the developed

theory. Experiments using SMA actuators to

generate the snap through of unsymmetric

laminates are conducted. Good correlation with

the developed theory is obtained.

Files

Filename		Size	Approximate Download Time (Hours:Minutes:Seconds)
Filename		Size	28.8 Modem	56K Modem	ISDN (64 Kb)	ISDN (128 Kb)	Higher-speed Access
	Etd.pdf	6.49 Mb	00:30:03	00:15:27	00:13:31	00:06:45	00:00:34