Dynamic Fracture Toughness of a Unidirectional Graphite/Epoxy Composite

Abstract In this investigation, we studied the process of dynamic crack propagation in a fiber-reinforced composite material using the optical Coherent Gradient Sensing (CGS) technique combined with high-speed photography. The mode-I fracture toughness of the unidirectional graphite/epoxy composite, IM7/8551-7, as a function of the crack-tip speed, was measured quantitatively. It was found that up to the Rayleigh wave speed of the composite material, the mode-I fracture toughness is a decreasing function of the crack-tip velocity. This behavior is similar to that observed in the dynamic crack propagation along interfaces between two homogeneous solids.

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Effect of Graphene Addition on Crack Propagation Resistance in Glass Fibre Reinforced Polymer Matrix Composite

Volume 2: Materials; Joint MSEC-NAMRC-Manufacturing USA ◽

10.1115/msec2018-6563 ◽

2018 ◽

Author(s):

G. V. Vigneshwaran ◽

S. Balasivanandha Prabu ◽

R. Paskaramoorthy

Keyword(s):

Fracture Toughness ◽

Crack Propagation ◽

Fiber Surface ◽

Dip Coating ◽

Image Correlation ◽

Mode I ◽

Molding Process ◽

Mode I Fracture ◽

Crack Propagation Resistance ◽

Mode I Fracture Toughness

The effect of graphene nanoplatelets (GNPs) on enhancing the interlaminar fracture toughness of glass fiber/epoxy composites was investigated. The GnPs were physically deposited on the fiber surface by the dip coating technique. The composites were fabricated by hand layup technique followed by the compression molding process. Mode-I fracture test was conducted on the composite specimens. Crack propagation was studied by the digital image correlation (DIC) technique. Mode-I fracture toughness for composites loaded with 0.5 wt.% GnPs showed improvement by an average of 60% when compared to the pristine composites. It is concluded that the addition of GnPs produces a strong fiber/matrix interface bonding which effectively limits the crack propagation.

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Numerical Investigation of the Fracture Properties of Pre-Cracked Monocrystalline/Polycrystalline Graphene Sheets

Materials ◽

10.3390/ma12020263 ◽

2019 ◽

Vol 12 (2) ◽

pp. 263 ◽

Cited By ~ 2

Author(s):

Xinliang Li ◽

Jiangang Guo

Keyword(s):

Fracture Toughness ◽

Grain Boundary ◽

Misorientation Angle ◽

Strain Energy ◽

Unit Area ◽

Crack Tip ◽

Mode I ◽

Fracture Properties ◽

Mode I Fracture ◽

Mode I Fracture Toughness

The fracture properties of pre-cracked monocrystalline/polycrystalline graphene were investigated via a finite element method based on molecular structure mechanics, and the mode I critical stress intensity factor (SIF) was calculated by the Griffith criterion in classical fracture mechanics. For monocrystalline graphene, the size effects of mode I fracture toughness and the influence of crack width on the mode I fracture toughness were investigated. Moreover, it was found that the ratio of crack length to graphene width has a significant influence on the mode I fracture toughness. For polycrystalline graphene, the strain energy per unit area at different positions was calculated, and the initial fracture site (near grain boundary) was deduced from the variation tendency of the strain energy per unit area. In addition, the effects of misorientation angle of the grain boundary (GB) and the distance between the crack tip and GB on mode I fracture toughness were also analyzed. It was found that the mode I fracture toughness increases with increasing misorientation angle. As the distance between the crack tip and GB increases, the mode I fracture toughness first decreases and then tends to stabilize.

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