Kink band formation and band broadening in fiber composites under compressive loading

This work examines buckling and kink-band formation in graphene nanosheets (GNSs). GNSs are nanoscale flakes composed of graphene sheets. Expanded graphite was first made, which can be torn apart into GNSs by sonication. A simple but effective approach was adopted to incur buckling in GNSs. Microscopic observations revealed three major modes: the kinking induced by bending, the bulging, and the kink-band caused by in-plane compression. The conditions to cause these modes are discussed. When buckled, the graphene layers undergo sharp kinking. However, the graphene layers can survive kinking without fracture due to their exceptional flexibility. The kink-band in GNSs resembles the kink-band in carbon-fiber composites. However, the scale, the material properties, the micro-structures, and the energy terms involved in forming the kink-band are different.

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Kink-band formation in directionally solidified Mg/Mg2Yb and Mg/Mg2Ca eutectic alloys with Mg/Laves-phase lamellar microstructure

Journal of Magnesium and Alloys ◽

10.1016/j.jma.2021.02.006 ◽

2021 ◽

Author(s):

Koji Hagihara ◽

Kosuke Miyoshi

Keyword(s):

Lamellar Microstructure ◽

Kink Band ◽

Laves Phase ◽

Eutectic Alloys ◽

Directionally Solidified ◽

Band Formation

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Inducement of kink-band formation in directionally solidified Mg/Mg17Al12 eutectic alloy - Inspired by the deformation behavior of the long-period stacking ordered (LPSO) phase

Materials Science and Engineering A ◽

10.1016/j.msea.2020.140087 ◽

2020 ◽

Vol 798 ◽

pp. 140087

Author(s):

Koji Hagihara ◽

Kyohei Hayakawa ◽

Kosuke Miyoshi

Keyword(s):

Eutectic Alloy ◽

Deformation Behavior ◽

Kink Band ◽

Directionally Solidified ◽

Band Formation ◽

Lpso Phase ◽

Long Period

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Dynamic Behavior of Fiber Reinforced Composites Under Multiaxial Compression

10.1115/imece1999-0907 ◽

1999 ◽

Author(s):

Kenji Oguni ◽

G. Ravichandran

Keyword(s):

Failure Mode ◽

Kink Band ◽

Fiber Reinforced Composites ◽

Fiber Direction ◽

Strain Rates ◽

Reinforced Composites ◽

Fiber Reinforced ◽

Band Formation ◽

Multiaxial Compression ◽

Axial Splitting

Abstract Results from an experimental investigation on the mechanical behavior of a unidirectional reinforced polymer composite with 50% volume fraction E-glass/vinylester under uniaxial and proportional multiaxial compression are presented. Specimens are loaded in the fiber direction using a servo-hydraulic material testing system for low strain rates and a Kolsky (split Hopkinson) pressure bar for high strain rates, up to 3000 s−1. The results indicate that the compressive strength of the composite increases with increasing levels of confinement and increasing strain rates. Post-test optical and scanning electron microscopy is used to identify the failure modes. The failure mode that is observed in unconfined specimen is axial splitting followed by fiber kink band formation. At high levels of confinement, the failure mode transitions from axial splitting to kink band formation and fiber failure. Also, a new energy based analytic model for studying axial splitting phenomenon in unidirectional fiber-reinforced composites is presented.

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