Civil Engineering ETDs

Publication Date

Winter 12-2017

Abstract

Carbon fiber reinforced polymer (CFRP) composites are increasingly being used in a variety of industries such as aerospace and infrastructure. This investigation experimentally examines the effect of incorporating alumina nanoparticles (ANPs), non-functionalized multi-walled carbon nanotubes (NF-MWCNTs), and functionalized multi-walled carbon nanotubes (F-MWCNTs) on the off-axis stiffness and stress-relaxation of carbon fiber reinforced polymer (CFRP) composites. Epoxy- nanocomposites incorporating 0.0, 1.0, 2.0, and 3.0 wt.% ANPs; 0.0 0.5, 1.0, and 1.5 wt. % NF-MWCNTs; 0.0 0.5, 1.0, and 1.5 wt. % F-MWCNTs of the total weight of epoxy are examined. Off-axis tension stiffness and stress-relaxation tests were performed on CFRP coupons fabricated with ANPs-nanocomposites. Dynamic mechanical analysis (DMA) testing of neat epoxy and epoxy nanocomposites incorporating nanomaterials was used to identify the stiffness and relaxation behavior of the epoxy-nanocomposite matrix. Fourier transform infrared spectroscopy (FTIR) was used to observe chemical changes when nanomaterials are mixed with epoxy. It is shown that using ANPs at a concentration close to 2.0 wt.% can reduce the off-axis stiffness by ~30% and increase the off-axis stress- relaxation of CFRP by ~10%. Using NF-MWCNTs, it is shown that when incorporating 1.5 wt. % NF-MWCNTs, the stiffness decreases by ~60% and the off-axis stress relaxation of CFRP increases by ~12%. Finally, using F-MWCNTs, it is shown that the initial modulus of the CFRP composite decreases by ~25% and the relaxation increases by ~10% over a period of 1800 seconds.

Keywords

CFRP, NANOMATERIALS, DMA, STRESS RELAXATION

Document Type

Thesis

Degree Name

Civil Engineering

Level of Degree

Masters

Department Name

Civil Engineering

First Committee Member (Chair)

MAHMOUD REDA TAHA

Second Committee Member

WALTER GERSTLE

Third Committee Member

YU-LIN SHEN

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