Effect of Bond Thickness on the Fracture Toughness of Adhesive Joints

2004 ◽  
Vol 126 (1) ◽  
pp. 14-18 ◽  
Author(s):  
Deok-Bo Lee ◽  
Toru Ikeda ◽  
Noriyuki Miyazaki ◽  
Nak-Sam Choi
Keyword(s):  
Fracture Toughness ◽  
Adhesive Joint ◽  
Damage Zone ◽  
Crack Tip ◽  
Adhesive Layer ◽  
Compact Tension ◽  
Optical Microscope ◽  
Adhesive Joints ◽  
Adhesive Layers ◽  
Modified Epoxy

The effect of bond thickness on the fracture toughness of adhesive joints was investigated from a microstructural perspective, using compact tension (CT) adhesive-joint specimens with different bond thicknesses. The adhesive material was a rubber-modified epoxy resin with 12.5 wt% carboxy-terminated butadiene acrylonitrile (CTBN) elastomer. The shapes of the rubber particles dispersed in adhesive layers of damaged and undamaged specimens were observed with an optical microscope. The damage was distributed along the interfaces between the adhesive layer and the two adherends. The results show that the primary causes of variations in the fracture toughness of an adhesive joint with the bond thickness are not only a damage zone around a crack tip but also the combination of a damage zone around a crack tip and additional damage zones along the interfaces.

Damage zone around crack tip and fracture toughness of rubber-modified epoxy resin under mixed-mode conditions

2002 ◽  
Vol 69 (12) ◽  
pp. 1363-1375 ◽  
Author(s):  
Deok-Bo Lee ◽  
Toru Ikeda ◽  
Noriyuki Miyazaki ◽  
Nak-Sam Choi
Keyword(s):  
Fracture Toughness ◽  
Epoxy Resin ◽  
Mixed Mode ◽  
Damage Zone ◽  
Crack Tip ◽  
Modified Epoxy

scholarly journals The Effect of Adhesive Layer Thickness on Joint Static Strength

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1499
Author(s):  
Marek Rośkowicz ◽  
Jan Godzimirski ◽  
Andrzej Komorek ◽  
Michał Jasztal
Keyword(s):  
Layer Thickness ◽  
Adhesive Joint ◽  
Elastic Strain ◽  
Joint Strength ◽  
Adhesive Layer ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Failure Stress ◽  
Adhesive Failure ◽  
Adhesive Layers

One of the most relevant geometrical factors defining an adhesive joint is the thickness of the adhesive layer. The influence of the adhesive layer thickness on the joint strength has not been precisely understood so far. This article presents simplified analytical formulas for adhesive joint strength and adhesive joint coefficient for different joint loading, assuming, inter alia: linear-elastic strain of adhesive layer, elastic strain of adherends and only one kind of stress in adhesive. On the basis of the presented adhesive joint coefficient, the butt joint was selected for the tests of the influence of adhesive thickness on the adhesive failure stress. The tests showed clearly that with an increase in the thickness of the tested adhesive layers (up to about 0.17 mm), the value of their failure stress decreased quasi linearly. Furthermore, some adhesive joints (inter alia subjected to shearing) may display the optimum value of the thickness of the adhesive layer in terms of the strength of the joint. Thus, the aim of this work was to explain the phenomenon of optimal adhesive layer thickness in some types of adhesive joints. The verifying test was conducted with use of single simple lap joints. Finally, with the use of the FE method, the authors were able to obtain stresses in the adhesive layers of lap joints for loads that destroyed that joints in the experiment, and the FEM-calculated failure stresses for lap joints were compared with the adhesive failure stresses determined experimentally using the butt specimens. Numerical calculations were conducted with the use of the continuum mechanics approach (stress-based), and the non-linear behavior of the adhesive and plastic strain of the adherends was taken into account.

Failure of a Ductile Adhesive Layer Constrained by Hard Adherends

1999 ◽  
Vol 122 (1) ◽  
pp. 80-85 ◽  
Author(s):  
Toru Ikeda ◽  
Akira Yamashita ◽  
Deokbo Lee ◽  
Noriyuki Miyazaki
Keyword(s):  
Fracture Toughness ◽  
Composite Materials ◽  
Thin Layer ◽  
Adhesive Joint ◽  
Structural Integrity ◽  
Adhesive Layer ◽  
Adhesive Joints ◽  
Hard Material ◽  
J Integral

The evaluation of a fracture from a thin layer constrained by a hard material is important in relation to the structural integrity of adhesive joints and composite materials. It has been reported that the fracture toughness of a crack in a ductile adhesive joint depends on the bond thickness, but the mechanism has not yet been elucidated clearly. In this study, the J-integral and the near-tip stress of a crack in an adhesive joint are investigated. It is determined that a decrease of the bond thickness increases the stress ahead of a crack rip, which results in the decrease of fracture toughness. [S0094-4289(00)01201-9]

Failure Analysis on Rubber-Modified Epoxy Resin under Various Loading Speed Conditions

2005 ◽  
Vol 297-300 ◽  
pp. 1907-1912 ◽  
Author(s):  
Deok Bo Lee ◽  
Joo Hyung Kim
Keyword(s):  
Fracture Toughness ◽  
Composite Material ◽  
Epoxy Resin ◽  
Structural Reliability ◽  
Fiber Composite ◽  
Damage Zone ◽  
Crack Tip ◽  
Rubber Content ◽  
The Matrix ◽  
Modified Epoxy

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.

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

2018 ◽  
Vol 122 (1255) ◽  
pp. 1352-1370 ◽  
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.

Finite Element Modeling of Damage Formation in Rubber-Toughened Polymer

2005 ◽  
Vol 297-300 ◽  
pp. 1019-1024
Author(s):  
Mitsugu Todo ◽  
Yoshihiro Fukuya ◽  
Seiya Hagihara ◽  
Kazuo Arakawa
Keyword(s):  
Finite Element ◽  
Damage Zone ◽  
Damage Model ◽  
Crack Tip ◽  
Optical Microscope ◽  
Toughening Mechanism ◽  
Element Analysis ◽  
Zone Formation ◽  
Macro Scale ◽  
Rubber Toughened

Microscopic studies on the toughening mechanism of rubber-toughened PMMA (RTPMMA) were carried out using a polarizing optical microscope (POM) and a transmission electron microscope (TEM). POM result showed that in a typical RT-PMMA, a damage zone was developed in the vicinity of crack-tip, and therefore, it was considered that energy dissipation due to the damage zone development was the primary toughening mechanism. TEM result exhibited that the damage zone was a crowd of micro-crazes generated around rubber particles in the vicinity of notch-tip. Finite element analysis was then performed to simulate such damage formations in crack-tip region. Macro-scale and micro-scale models were developed to simulate damage zone formation and micro-crazing, respectively, with use of a damage model. It was shown that the damage model introduced was successfully applied to predict such kind of macro-damage and micro-craze formations.

Organoclay-reinforced polyethersulfone-modified epoxy-based hybrid nanocomposites

2011 ◽  
Vol 23 (7) ◽  
pp. 526-534 ◽  
Author(s):  
Yang Wang ◽  
Boming Zhang ◽  
Jinrui Ye
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Electron Microscope ◽  
Optical Microscope ◽  
Mechanical Analysis ◽  
Hybrid Nanocomposites ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Modified Epoxy ◽  
Scanning Electron

Hybrid nanocomposites were successfully prepared by the incorporation of polyethersulfone (PES) and organoclay into epoxy resin. They had higher fracture toughness than the prepared PES/epoxy blend and organoclay/epoxy nanocomposites. The microstructures of the hybrid nanocomposites were studied. They were comprised of homogeneous PES/epoxy semi-interpenetrating network (semi-IPN) matrices and organoclay micro-agglomerates made up of tactoid-like regions composed of ordered exfoliated organoclay with various orientations. The former was confirmed with dynamic mechanical analysis, scanning electron microscopy and transmission electron microscopy, while the latter was successfully observed with X-ray diffraction measurements, optical microscope, scanning electron microscope and transmission electron microscope. The improvement of their fracture toughness was due to the synergistic toughening effect of the PES and the organoclay and related to their microstructures.

Stress around a Crack Tip in Rubber-Modified Epoxy Resin (Effect of Bond Thickness on Fracture Toughness)

2000 ◽  
Vol 2000.13 (0) ◽  
pp. 349-350
Author(s):  
Daisuke IKEMOTO ◽  
Deok bo LEE ◽  
Toru IKEDA ◽  
Noriyuki MIYAZAKI
Keyword(s):  
Fracture Toughness ◽  
Epoxy Resin ◽  
Crack Tip ◽  
Modified Epoxy
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