Evaluation of Mesoscopic Fracture Toughness based on Strain Measurement in Epoxy Resin Phase near Crack Tip of CFRP using Raman Spectroscopy.

A rubber-modified epoxy resin is widely used as adhesive and matrix materials for fiber composite material. The structural reliability of composite material depends on the fracture toughness of the matrix resin. In this study, the fracture toughness and the damage zone around a crack tip in rubber-modified epoxy resin were investigated. The volume fractures of rubber (CTBN1300×8) in the rubber-modified epoxy resin were 0%, 5% and 15% under several loading speeds. The fracture toughness(KIC) and the fracture energy(GIC) were measured by using 3-point bending specimens. The 4-point bending specimens were also used to observe damage zones at the vicinity of a crack tip in modified resins. The results show that the values of the fracture toughness and the sizes of damage zones at 5% and 15% rubber content decrease with increase in loading speed.

Download Full-text

Determination of crack tip position by digital image correlation at static and cyclic fracture toughness tests of aluminum alloys

Deformation and Fracture of Materials ◽

10.31044/1814-4632-2018-7-30-38 ◽

2018 ◽

pp. 30-38 ◽

Cited By ~ 1

Author(s):

V. V. Avtayev ◽

◽

N. O. Yakovlev ◽

V. S. Yerasov ◽

N. Yu. Podzhivotov ◽

...

Keyword(s):

Fracture Toughness ◽

Aluminum Alloys ◽

Digital Image Correlation ◽

Digital Image ◽

Crack Tip ◽

Image Correlation ◽

Cyclic Fracture ◽

Cyclic Fracture Toughness ◽

Tip Position

Download Full-text

Effect of rice husk (treated/untreated) and rice husk ash on fracture toughness of epoxy bio-composite

Journal of the Mechanical Behavior of Materials ◽

10.1515/jmbm-2020-0018 ◽

2020 ◽

Vol 29 (1) ◽

pp. 177-185

Author(s):

Neeraj Bisht ◽

Prakash Chandra Gope

Keyword(s):

Fracture Toughness ◽

Epoxy Resin ◽

Rice Husk ◽

Rice Husk Ash ◽

Matrix Material ◽

Secondary Reinforcement ◽

Filler Loading ◽

Particle Reinforcement ◽

Pure Epoxy ◽

Fibre Treatment

AbstractPresent work studies the effect of particle reinforcement on fracture toughness of bio-composites. The filler used has been taken as rice husk. Epoxy resin has been taken as matrix material. Composites with varying filler loading of 10, 20, 30 and 40 wt.% were fabricated. The fracture toughness was seen to be increasing with increase in filler loading. However beyond 20% there was a decrease in fracture toughness with increase in filler loading. The effect of fibre treatment on toughness was also observed. Rice husk fibres pre-treated with NaOH were used. It was observed that fracture toughness further improved due to treatment. The increase in fracture toughness was significant. Fracture toughness increased from 1.072 to 2.7465 MPa√mm for 20% reinforcement and after treatment it increased to 2.876 MPa√mm. It was observed that concentration of treatment media also affects the fracture toughness. Further the effect of hybridization was observed by addition of rice husk ash as a secondary reinforcement. The fracture toughness of the resulting composites was remarkably higher than that of pure epoxy.

Download Full-text

An experimental method to determine the intralaminar fracture toughness of high-strength carbon-fibre reinforced composite aerostructures

The Aeronautical Journal ◽

10.1017/aer.2018.78 ◽

2018 ◽

Vol 122 (1255) ◽

pp. 1352-1370 ◽

Cited By ~ 9

Author(s):

H. Liu ◽

B.G. Falzon ◽

G. Catalanotti ◽

W. Tan

Keyword(s):

Fracture Toughness ◽

Tensile Strength ◽

Crack Tip ◽

Damage Mechanism ◽

Calibration Method ◽

Compact Tension ◽

Tensile Fracture ◽

High Tensile Strength ◽

Physical Test ◽

Area Method

ABSTRACTCarbon fibres with high tensile strength are being increasingly utilised in the manufacture of advanced composite aerostructures. A Modified Compact Tension (MCT) specimen is often deployed to measure the longitudinal intralaminar fracture toughness but a high tensile strength often leads to premature damage away from the crack tip. We present an approach whereby the MCT specimen is supported by external fixtures to prevent premature damage. In addition, we have developed a novel measurement technique, based on the fibre failure strain and C-scanning, to determine the crack length in the presence of surface sublaminate delamination which masks the crack tip location. A set of cross-ply specimens, with a ((90/0)s)4 layup, were manufactured from an IMS60/epoxy composite system Two different data reduction schemes, compliance calibration and the area method, are used to determine the fibre-dominated initiation and propagation intralaminar fracture toughness values. Propagation values of fracture toughness were measured at 774.9 ± 5.2% kJ/m2 and 768.5 ± 4.1% kJ/m2, when using the compliance calibration method and the area method, respectively. Scanning Electron Microscopy (SEM) is carried out on the fracture surface to obtain insight into the damage mechanism of high-tensile-strength fibre-reinforced unidirectional composites. The measured tensile fracture toughness value is used in a fully validated computational model to simulate the physical test.

Download Full-text