Mohaghegh Motlagh, Seyed Amin
(2014)
An Investigation in Structural Shape Morphing by Modulus Variation.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
This work addresses structural shape morphing, defined as change of shape due to modulus manipulation. The goal is to incorporate variable-modulus materials into a structure, and utilize the controllable modulus change to enhance the ability to morph the structure with limited actuator numbers, locations, and force levels to desired shapes that could not be achieved in the native structure. A significant portion of the work is to demonstrate the capability of the proposed strategy to broaden the space of achievable shapes within the elastic range. In order to quantify the morphed shapes, a specific planar structure with defined boundary condition is used as the model. The focus of this study is not the temporal change of the material’s phase or the structure’s shape, but rather the resulting shape of the structure due to modulus change and applied force.
The problem of inverse morphing is thoroughly investigated; that is, finding the spatial distribution of elastic modulus values and the actuation forces that produce a desired shape and minimize the shape error cost function. Genetic algorithm is used to solve this inverse problem.
Finally, a numerical algorithm to solve the morphing of an arbitrary structure is proposed. In this algorithm, computational and numerical programs are interchangeably used to build the structure’s model and to solve the shape morphing problem. As a case study, a practical device is selected, drawn from a hydrokinetic energy harvesting application, and a 2D model is created. The structure’s shape change due to modulus manipulation is numerically investigated. At the end, path-dependency in sequential shape morphing has been explored in a mass-spring model as well as in the example structure.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
29 January 2014 |
| Date Type: |
Publication |
| Defense Date: |
31 October 2013 |
| Approval Date: |
29 January 2014 |
| Submission Date: |
4 December 2013 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
170 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Mechanical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Structural Shape Morph, Optimization, Genetic Algorithm (GA), Finite Element Analysis, Inverse Solution, Variable-modulus Structures |
| Date Deposited: |
29 Jan 2014 18:53 |
| Last Modified: |
15 Nov 2016 14:16 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/20176 |
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