Date of Award

Spring 1-1-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

First Advisor

Francisco Lopez Jimenez

Second Advisor

Rong Long

Third Advisor

Kurt Maute

Abstract

Soft ber reinforced composites are very suitable materials for space deployable structures.

These materials are characterized by a very compliant matrix that allows the bers

to highly deform so microbuckling under bending can appear without failure. This mechanism

acts as a stress-reliever, so the material can be folded to very high curvatures without

damage. However, the existing models are not able to accurately capture the mechanical

behavior of these materials.

A new micromechanical model is proposed for this materials under bending. The

model considers both the pre and post buckling regimes using a large strain formulation.

The strain energy is calculated as the sum of the energy in the matrix and the bers. The

energy of the matrix is calculated using homogenization methods and the energy of the bers

is approximated using classical beam theory. The obtained energy model is a function of

the position of the neutral axis, the buckling wavelength and a function that denes where

buckling appears through the thickness. These parameters are calculated by minimizing the

energy.

The results obtained from the theoretical model are compared with numerical simulations.

The comparison shows good agreement for the pre-buckling regime but it does not

predict well the curvature when buckling appears. The in

uence of some problem parameters

such as the volume fraction and the shear modulus of the materials is also studied.

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