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

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 263 ◽  
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.

scholarly journals Dynamic Fracture Toughness of a Unidirectional Graphite/Epoxy Composite

2001 ◽  
Author(s):  
C. Liu ◽  
A. J. Rosakis ◽  
M. G. Stout
Keyword(s):  
Fracture Toughness ◽  
Composite Material ◽  
Crack Propagation ◽  
Epoxy Composite ◽  
Crack Tip ◽  
Dynamic Crack Propagation ◽  
Mode I ◽  
Dynamic Crack ◽  
Mode I Fracture ◽  
Mode I Fracture Toughness

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.

Mechanical behavior of an additively manufactured poly-carbonate specimen: tensile, flexural and mode I fracture properties

2019 ◽  
Vol 26 (2) ◽  
pp. 267-277 ◽  
Author(s):  
Iman Sedighi ◽  
Majid R. Ayatollahi ◽  
Bahador Bahrami ◽  
Marco A. Pérez-Martínez ◽  
Andres A. Garcia-Granada
Keyword(s):  
Fracture Toughness ◽  
Mechanical Behavior ◽  
Fracture Behavior ◽  
Fused Deposition Modeling ◽  
Mode I ◽  
Content Type ◽  
Fracture Properties ◽  
Mode I Fracture ◽  
Mode I Fracture Toughness ◽  
Fused Deposition

Purpose The purpose of this paper is to investigate the effect of layer orientation on the tensile, flexural and fracture behavior of additively manufactured (AM) polycarbonate (PC) produced using fused deposition modeling (FDM). Design/methodology/approach An experimental approach is undertaken and a total number of 48 tests are conducted. Two types of tensile specimens are used and their mechanical behavior and fracture surfaces are studied. Also, circular parts with different layer orientations are printed and two semi-circular bending (SCB) samples are extracted from each part. Finally, the results of samples with different build directions are compared to one another to better understand the mechanical behavior of additively manufactured PC. Findings The results demonstrate anisotropy in the tensile, flexural and fracture behavior of the additively manufactured PC parts with the latter being less anisotropic compared to the first two. It is also demonstrated that the anisotropy of the elastic modulus is small and can be neglected. Tensile strength ranges from 40 MPa to 53 MPa. At the end, mode I fracture toughness prediction curves are provided for different directions of the FDM samples. Fracture toughness ranges from 1.93 to 2.37 MPa.mm1/2. Originality/value The SCB specimen, a very suitable geometry for characterizing anisotropic materials, was used to characterize FDM parts for the first time. Also, the fracture properties of the AM PC have not been studied by the researchers in the past. Therefore, fracture toughness prediction curves are presented for this anisotropic material. These curves can be very suitable for designing parts that are going to be produced by 3D printing. Moreover, the effect of the area to perimeter ratio on the tensile properties of the printed parts is investigated.

scholarly journals Effect of Testing Method Type and Specimen Size on Mode I Fracture Toughness of Kimachi Sandstone

2019 ◽  
Vol 135 (5) ◽  
pp. 33-41 ◽  
Author(s):  
Minami KATAOKA ◽  
Yuzo OBARA ◽  
Leona VAVRO ◽  
Kamil SOUCEK ◽  
Sang-Ho CHO ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Specimen Size ◽  
Mode I ◽  
Mode I Fracture ◽  
Mode I Fracture Toughness ◽  
Testing Method

scholarly journals The effect of modified tannic acid (TA) eco-epoxy adhesives on mode I fracture toughness of bonded joints

2021 ◽  
Vol 96 ◽  
pp. 107122
Author(s):  
Mohamed Nasr Saleh ◽  
Nataša Z. Tomić ◽  
Aleksandar Marinković ◽  
Sofia Teixeira de Freitas
Keyword(s):  
Fracture Toughness ◽  
Tannic Acid ◽  
Mode I ◽  
Bonded Joints ◽  
Mode I Fracture ◽  
Mode I Fracture Toughness ◽  
Epoxy Adhesives
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