Mechanical Behavior of GFRP Laminates Exposed to Thermal and Moist Environmental Conditions: Experimental and Model Assessment

Abstract

This paper presents an experimental and analytical study about the mechanical response at a different temperature on glass fiber-reinforced polymer laminates. The effect of different environmental conditions on compressive, tensile, stiffness, and viscoelastic behavior (storage modulus, loss modulus and damping ratio) of laminates were investigated. Before testing, laminates were preserved in a deep freezer at −80 °C, −20 °C, 0 °C, and room temperature (25 °C) for up to 60 days. Results confirmed that temperatures ranging from −80 to 50 °C, which were below the glass transition temperature of the epoxy resin, did not significantly affect the compressive, tensile, and stiffness performance of all laminates. When the testing temperature increased to 100 °C, the properties were decreased significantly due to the damaging of the fiber/matrix interface. Additionally, results obtained from dynamic mechanical analyses tests showed a drop-in storage modulus, high peaks in loss modulus and high damping factor at the glass transition region of the epoxy resin. The highest storage modulus, two phases of glassy states and highest damping ratio on the −80/G group of laminates were obtained. The accuracy of experimental results was assessed with empirical models on the storage modulus behavior of laminates. The empirical model developed by Gibson et al. provided accurate estimates of the storage modulus as a function of temperature and frequency. The remaining empirical models were less accurate and non-conservative estimations of laminates stiffness.

Thermal aging effect on mechanical properties of polyamide 6 matrix composites produced by TFP and compression molding

“…The results showed that temperature had the greatest effect on the deterioration of tensile strength in GFRPs, followed by exposure time 18 . Similarly, another study using ANOVA tables on tensile tests performed on GFRP laminates at temperatures ranging from −80°C to 100°C found that temperature had a statistically significant contribution and should be considered when evaluating the tensile strength properties of GFRP materials under varying temperatures 20 . As can be seen, regression and ANOVA analysis play a critical role in determining mechanical parameters.…”

“…19 Tefera et al analyzed the tensile and compression properties of GFRP laminates under thermal and moist environmental conditions using analysis of variance. 20 The highest tensile stress and stiffness response of laminates were observed at the 0 C test. Then, tensile stresses were reduced by 27.24%, 53.28%, 239.39%, and 1596.28% when the temperature increased from the 0 C to 100 C test.…”

“…18 Similarly, another study using ANOVA tables on tensile tests performed on GFRP laminates at temperatures ranging from À80 C to 100 C found that temperature had a statistically significant contribution and should be considered when evaluating the tensile strength properties of GFRP materials under varying temperatures. 20 As can be seen, regression and ANOVA analysis play a critical role in determining mechanical parameters. R 2 and R 2 (adj) values for tensile strength were found to be 98.07% and 97.47%.…”

“…They also proposed a prediction model based on regression analysis for experimental results 19 . Tefera et al analyzed the tensile and compression properties of GFRP laminates under thermal and moist environmental conditions using analysis of variance 20 . The highest tensile stress and stiffness response of laminates were observed at the 0°C test.…”

Flexural and Viscoelastic Properties of FRP Composite Laminates under Higher Temperatures: Experiments and Model Assessment

“…It is important to know the compressive and tensile behaviour of FRP materials before using them for composite structures. Particularly, the flexural behaviours of glass- and carbon-reinforced hybrid epoxy composite laminates were investigated extensively under room temperature tests in [ 14 , 15 , 16 , 17 ]. The flexural and tensile moduli of hybrid composite laminates were decreased as the hybrid ratio increased [ 18 , 19 , 20 ].…”