The Combined Effects of Environmental Conditioning and Sustained Load on Mechanical Properties of Wet Lay-Up Fiber Reinforced Polymer
Abstract
:1. Introduction
2. Experimental Program
2.1. Experimental Materials and Specimens
2.2. Sustained Load
- The exact loading value was determined in advance. To avoid creep rupture of the FRP materials, the sustained stress was limited by ACI 440.2R-08 [32]. Considering the creep limits for the FRP materials, 30% and 60% of the ultimate load for CFRP (corresponding strains were 618 με and 1236 με, respectively), 30% of ultimate load for GFRP (corresponding strain was 915 με) were used in this study.
- The sustained load was applied by tightening nuts. However, a sustained load cannot be kept unchanged due to the creep or relaxation of the FRP materials. Therefore, to assess the effects of creep or relaxation on the applied load, the strains of FRP specimens were monitored using a self-made arched strain clamp within 10 days. The results indicated that the applied load fell off measurably, but not excessively (varying between 1% and 3% of their ultimate load).
2.3. Environmental Exposure
2.4. Tensile Test
3. Results
3.1. Tensile Strength
3.2. Elongation
3.3. Tensile Modulus
4. Discussion
4.1. Predictive Equations
4.2. Comparison of Predictive Values with Design Values
5. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Material | Nominal Thickness (mm) | Young’s Modulus (GPa) | Tensile Strength (MPa) | Failure Strain (%) | |||
---|---|---|---|---|---|---|---|
AVG | COV (%) | AVG | COV (%) | AVG | COV (%) | ||
CFRP sheet | 0.111 | 214.4 | 6.0 | 4331 | 6.0 | 2.06 | 5.4 |
GFRP sheet | 0.169 | 63.1 | 6.0 | 2138 | 5.8 | 3.53 | 7.4 |
Environmental Type | FRP Type | Loading Level | Exposure Duration/Times | Number of Specimens |
---|---|---|---|---|
Freeze–thaw cycles | CFRP | 0, 30%, 60% | 0, 50, 100, 200, 300 times | 90 |
GFRP | 0, 30% | 60 | ||
Hygrothermal aging | CFRP | 0, 30%, 60% | 0, 30, 90, 180, 360 days | 90 |
GFRP | 0, 30% | 60 | ||
Wet–dry cycles | CFRP | 0, 30%, 60% | 0, 30, 90, 180, 360 times | 90 |
GFRP | 0, 30% | 60 |
Environmental Type | Loading Level | CFRP | GFRP | ||
---|---|---|---|---|---|
Predictive Equation | R2 | Predictive Equation | R2 | ||
Freeze–thaw cycles | 0 | 0.802 | 0.855 | ||
30% | 0.999 | 0.915 | |||
60% | 0.974 | ||||
Hygrothermal aging | 0 | 0.953 | 0.968 | ||
30% | 0.930 | 0.970 | |||
60% | 0.780 | ||||
Wet–dry cycles | 0 | 0.838 | 0.980 | ||
30% | 0.781 | 0.956 | |||
60% | 0.942 |
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Li, S.; Hu, J.; Ren, H. The Combined Effects of Environmental Conditioning and Sustained Load on Mechanical Properties of Wet Lay-Up Fiber Reinforced Polymer. Polymers 2017, 9, 244. https://doi.org/10.3390/polym9070244
Li S, Hu J, Ren H. The Combined Effects of Environmental Conditioning and Sustained Load on Mechanical Properties of Wet Lay-Up Fiber Reinforced Polymer. Polymers. 2017; 9(7):244. https://doi.org/10.3390/polym9070244
Chicago/Turabian StyleLi, Shan, Jiyue Hu, and Huitao Ren. 2017. "The Combined Effects of Environmental Conditioning and Sustained Load on Mechanical Properties of Wet Lay-Up Fiber Reinforced Polymer" Polymers 9, no. 7: 244. https://doi.org/10.3390/polym9070244