Experimental Investigation and Modeling of the Thermal Effect on the Mechanical Properties of Polyethylene-Terephthalate FRP Laminates

Abstract

Recent advancements in material sciences have led to the development of new fiber-reinforced polymer (FRP) systems that, unlike traditional FRPs, are specifically tailored to have large fracture strains that are advantageous for external strengthening applications. One such system is polyethylene terephthalate (PET) FRP, which can attain a nominal fracture strain of 7%. In this work, the mechanical properties of PET laminates were investigated when exposed to temperatures ranging from 25°C to 125°C. Test results indicate that PET-FRP exhibits a nonlinear stress-strain response that could be divided into three phases with three moduli (E 1 , E 2 , and E 3 ) and corresponding three tensile strengths (σ 1 , σ 2 , and σ 3 ). The results also demonstrate how the aforementioned mechanical properties degrade around the glass transition temperature of the epoxy from so ft ening in the matrix. Interestingly, test results indicate that PETs exhibit an increase in rupture strain (from 9% to 14%) when the test temperature increases from 25°C to 125°C. To properly document these observations into design tools, temperature-dependent material models for moduli and tensile strengths are derived.

The Influence of the Curing Conditions on the Behavior of Jute Fibers Reinforced Concrete Cylinders

“…13, the model (1) (Eq. ( 5)) of Mhanna et al [25] gave results close to the experimental results. On the other hand, the second model (Eq.…”

“…As shown in Table 3, the maximum values of tensile strength have been increased in the case of 30 °C and 50 °C, compared to laminates cured at room temperature (specimens cured at 20 °C). This increase was also noted by Mhanna et al [25] who explained that the mechanical properties of epoxy improve at higher temperatures below Tg due to increased production of crosslinkages which led to the rapid initiate chemical reactions.…”

“…( 6)) and third model (Eq. ( 7)) of Mhanna et al [25] as well as the models of Hawileh et al [29], Yu and Kodur [30], did not predict the experimental results. For the two curves given by the Yu and Kodur [30] models, whether for the case of CFRP or CFRP strips, rods divide into two parts.…”

“…R n is a power law factor based on the residual resin content. The use of composite materials based on carbon fibers, basalt or a combination of carbon and basalt or polyethylene terephthalate generates different behaviors, which give rise to new models to predict the mechanical properties as in terms of temperature variation, including those of Mhanna et al [25], Hawileh et al [29], and Yu and Kodur [30]. In the study initiated by the group of Mhana et al [25], the PET-FRP laminates have displayed a nonlinear behavior that opposes the linear response of the CFRP and BFRP materials used by Hawileh et al [29], Yu and Kodur [30].…”

“…Mhanna et al [25] have developed three models because the stress-strain response has exhibited a nonlinear behavior which led to dividing curves into three phases with three moduli (E 1 , E 2 and E 3 ):…”