Civil Engineering ETDs

Publication Date

Summer 7-1-2017

Abstract

Strain energy deployable composite structures are of great importance to the aerospace community due to their light weight, high stiffness, impressive flexibility, compact stowage configuration, and ability to self-deploy. These attributes make composite deployable hinges ideal for aerospace applications that can benefit from decreased payload and decreased structural complexity through a reduction in deployment parts. However, successful application of these deployable structures requires an in-depth understanding of their mechanical behavior throughout stowage and deployment processes. Upon release from a high strain stowage configuration, high deployment accelerations caused by a great amount of stored strain energy could potentially damage the structure or detach its supported accessories. Alternatively, insufficiently limited amounts of stored strain energy could result in the failure of the structure to achieve complete deployment. The mechanical response of the deployable composite during stowage contributes considerably to its deployment mechanics. The viscoelastic properties of the composite material affect the amount of stored strain energy in the structure during stowage as a function of time, further complicating the predictability of the structure’s deployment response. For these reasons, mechanical and numerical investigations are required prior to utilizing these structures in practical applications. Many challenges, including high costs and complex environmental controls, must be overcome if one is to recreate realistic space-like conditions in a laboratory setting in order to obtain a predictive measure of the structure’s deployment response following stowage. Therefore, accurate and reliable numerical simulations depicting the mechanical response of these deployable composite structures are becoming increasingly desirable within the aerospace structures community. The research presented herein provides a methodology for numerically simulating the stowage and deployment mechanics of a three-layer carbon fiber reinforced polymer composite strain energy deployable hinge using finite element modeling. Simulations are created using Abaqus/CAE software paired with a user-defined material subroutine. Simulation input parameters are determined through a series of material testing procedures. The model is validated using a novel experimental procedure performed with a tabletop testing apparatus designed specifically to capture the mechanical response of a deployable hinge structure throughout the phases of high strain stowage and dynamic deployment.

Keywords

finite element, stress relaxation, Prony series, UMAT, FlexLam, aerospace

Document Type

Thesis

Language

English

Degree Name

Civil Engineering

Level of Degree

Masters

Department Name

Civil Engineering

First Committee Member (Chair)

Mahmoud Reda Taha

Second Committee Member

Timothy Ross

Third Committee Member

Thomas Murphey

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