Tensile and Fracture Characterization of PETI-5 and IM7/PETI-5 Graphite/Epoxy Composites Under Quasi-Static and Dynamic Loading Conditions

Tensile and fracture responses of the phenylethynyl terminated imide oligomer (PETI-5) are studied. Since this polymer is a candidate aerospace structural adhesive as well as a matrix material in composite systems, neat as well as fiber reinforced forms of PETI-5 are studied under static and dynamic loading conditions. A split-Hopkinson tension bar apparatus is used for performing tensile tests on dogbone specimens. The dynamic fracture tests are carried out using a drop tower in conjunction with 2D image correlation method and high-speed digital photography on edge cracked specimens in three-point bend configuration. A toughened neat epoxy system, Hexcel 3900, is also studied to provide a baseline comparison for neat PETI-5 system. The tensile stress-strain responses show PETI-5 to have excellent mechanical characteristics under quasi-static and dynamic loading conditions when compared with 3900. Fracture behavior of PETI-5 under quasi-static and impact loading conditions also shows superiority relative to 3900. The dynamic fracture behavior of a PETI-5 based graphite fiber reinforced composite, IM7/PETI-5, is also studied and the results are comparatively evaluated relative to the ones corresponding to a more common aerospace composite system, T800/3900-2 graphite/epoxy. Once again, the IM7/PETI-5 system shows excellent fracture performance in terms of dynamic crack initiation and growth behaviors.

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Mode II Interlaminar Fracture Behavior of Fiber Reinforced Polyamide Composites under Static and Dynamic Loading Conditions

Journal of Reinforced Plastics and Composites ◽

10.1177/073168449901801505 ◽

1999 ◽

Vol 18 (15) ◽

pp. 1415-1427 ◽

Cited By ~ 15

Author(s):

Mitsugu Todo ◽

Takashige Nakamura ◽

Kiyoshi Takahashi

Keyword(s):

Dynamic Loading ◽

Fracture Behavior ◽

Mode Ii ◽

Loading Conditions ◽

Fiber Reinforced ◽

Interlaminar Fracture ◽

Dynamic Loading Conditions ◽

Static And Dynamic Loading

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Dynamic Crack Initiation And Growth In Cellulose Nanopaper

10.21203/rs.3.rs-600089/v1 ◽

2021 ◽

Author(s):

Chengyun Miao ◽

Haishun Du ◽

Xinyu Zhang ◽

Hareesh Tippur

Keyword(s):

Crack Initiation ◽

Crack Growth ◽

Dynamic Loading ◽

Image Correlation ◽

Thin Strip ◽

Dynamic Crack ◽

Loading Conditions ◽

Structural Applications ◽

Cellulose Nanopaper ◽

Dynamic Loading Conditions

Abstract Cellulose nanopaper (CNP) made of cellulose nanofibrils (CNF) has gained extensive attention in recent years for its lightweight and superior mechanical properties alongside sustainable and green attributes. The mechanical characterization studies on CNP at the moment have generally been limited to tension tests. In fact, thus far there has not been any report on crack initiation and growth behavior, especially under dynamic loading conditions. In this work, crack initiation and growth in self-assembled CNP, made from filtration of CNF suspension, are studied using a full-field optical method. Dynamic crack initiation and growth behaviors and time-resolved fracture parameters are quantified using Digital Image Correlation (DIC) technique. The challenge associated with dynamic loading of a thin strip of CNP has been overcome by an acrylic holder with a wide pre-cut slot bridged by edge-cracked CNP. The ultrahigh-speed digital photography is implemented to map in-plane deformations during pre- and post-crack initiation regimes including dynamic crack growth. Under stress wave loading conditions, macroscale crack growth occurs at surprisingly high-speed (600-700 m/s) in this microscopically fibrous material. The measured displacement fields from dynamic loading conditions are analyzed to extract stress intensity factors (SIF) and energy release rate (G) histories. The results show that the SIF at crack initiation is in the range of 6-7 MPa(m)1/2, far superior to many engineering plastics. Furthermore, the measured values increase during crack propagation under both low- and high-strain rates, demonstrating superior fracture resistance of CNP valuable for many structural applications.

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