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Cryogenic tensile and fracture properties of carbon nanofiber (CNF)/poly-dicyclopentadiene (poly-DCPD) composites have been investigated experimentally. Flat tensile specimens and single-edge notched tensile (SENT) specimens of CNF/poly-DCPD composites with 0.25, 0.5, and 1.0 vol% CNFs were fabricated by an ultrasonic method and tested at room temperature (RT) and liquid nitrogen temperature (77 K). The effect of ultrasonication time on the cryogenic tensile and fracture properties of CNF/poly-DCPD composites was discussed. A scanning electron microscope (SEM) was also used to observe the fracture surface morphology of poly-DCPD composites. [ABSTRACT FROM PUBLISHER]

This article focuses on understanding the Mode II interlaminar fracture and damage behavior of glass fiber reinforced polymer (GFRP) woven laminates at cryogenic temperatures. A four point bend, end notched flexure (4ENF) test is performed at room temperature (RT), liquid nitrogen temperature (77 K) and liquid helium temperature (4K), and an R-curve characterization is conducted for determining the mode II cryogenic fracture properties of GFRP woven laminates. The test configuration is also analyzed by finite element analysis coupled with damage. The damage distributions within the 4ENF specimens are predicted, and the effect of damage on the Mode II energy release rate is examined. This work is the first application of failure criteria (Hoffman criterion and maximum strain criterion) to the description of the R-curve behavior and interlaminar fracture toughness values of woven laminate ENF specimens at cryogenic temperatures. [ABSTRACT FROM AUTHOR]

This study focuses on understanding the cryogenic fracture and damage behavior of woven fabric GFRP laminates. Fracture toughness tests were conducted in three-point bending using single-edge-notched bend (SENB) specimens at room, liquid nitrogen, and liquid helium temperatures. The effects of temperature and specimen size on the apparent fracture toughness were evaluated. A three-dimensional finite element analysis coupled with damage was also employed to study the nonlinear load-displacement response and the damage evolution of SENB specimens, and to examine the effects of temperature, specimen size and damage on the fracture mechanics parameter. The predictions were compared with the experimental data. [ABSTRACT FROM AUTHOR]

The interlaminar fracture and damage behavior of glass fiber-reinforced polymer (GFRP) woven laminates at cryogenic temperatures has been investigated theoretically and numerically. The corrected beam theory and finite element analysis (FEA) have been used to calculate the Mode I interlaminar fracture toughness (IFT) of double cantilever beam (DCB) specimens at room temperature, liquid nitrogen temperature (77 K), and liquid helium temperature (4 K). The effect of temperature on the Mode I IFT was investigated. A FEA coupled with damage was also employed to study the damage distributions within the specimen and to examine the effect of damage on the Mode I energy release rate. The corrected beam theory or FEA shows good agreement with the previous experimental compliance of the DCB specimen. The numerical results show that damage causes a decrease in the energy release rate. This work is the first application of failure criteria (Hoffman criterion and maximum strain criterion) to the analysis of the cryogenic behavior of woven laminate DCB specimens. [ABSTRACT FROM AUTHOR]