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]

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.

Fracture Characteristics of Shear Adhesive Dissimilar Joint

2014 ◽  
Vol 606 ◽  
pp. 165-169
Author(s):  
Mohd Afendi ◽  
Ku Hafizan ◽  
M.S. Abdul Majid ◽  
R. Daud ◽  
N.A.M. Amin ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Shear Strength ◽  
Interface Crack ◽  
Adhesive Joint ◽  
Adhesive Layer ◽  
Stress Distributions ◽  
Adhesively Bonded ◽  
Shear Joint ◽  
Bonded Joint ◽  
Adhesively Bonded Joint

In this study, the effect of bond thickness upon shear strength and fracture toughness of epoxy adhesively bonded joint with dissimilar adherents was addressed. The bond thickness, t between the adherents was controlled to be ranged between 0.1 mm and 1.2 mm. Finite element analyses were also executed by commercial ANSYS 11 code to investigate the stress distributions within the adhesive layer of adhesive joint. As a result, shear strength of adhesive joint reduces with increasing bond thickness. The strength of shear adhesive joint was also depended on elastic modulus of adherent. Moreover, the failure of dissimilar adherents bonded shear joint originated at a location with critical stress-y which was the interface corner of ALYH75/epoxy. In the case of shear adhesive joint with an interface crack, the fracture also occurred at the ALYH75/epoxy interface even in the steel-adhesive-aluminum (SEA) specimens. Fracture toughness, Jc of aluminum-adhesive-steel (AES) joints was similar to those of SES and demonstrates strong dependency upon bond thickness. Furthermore, the interface crack in SEA specimen has relatively large fracture resistance if compared to those in AES specimen. Finally, Kc fracture criterion was found to be appropriate for shear adhesive joints associated with adhesive fracture.

Influence of Weld Mismatch on the Structural Integrity of Pipes for Reeling

2008 ◽  
Author(s):  
Gustavo M. Castelluccio ◽  
Sebastian Cravero ◽  
Hugo A. Ernst
Keyword(s):  
Fracture Toughness ◽  
Structural Integrity ◽  
J Integral ◽  
Finite Element Analyses ◽  
Single Edge ◽  
Inhomogeneous Materials ◽  
Elastic Plastic ◽  
Edge Notch ◽  
Integrity Analysis ◽  
Crack Position

Structural integrity analysis of tough materials based on Elastic-Plastic Fracture Mechanics (EPFM) has been successfully employed in the assessment of components. EPFM has originally been developed for homogeneous materials and its applicability to inhomogeneous materials has some peculiarities. In particular, Fitness for Service design of welded pipes requires to know the weld fracture toughness and to estimate accurately the J-integral applied on the actual structural member. In this work, finite element analyses of simulated welds have been carried out in order to qualify and quantify the lack of accuracy of experimental methodologies for measuring fracture toughness of welds and the influence of welds on the applied J-integral in a pipe under bending. Different weld widths and cracks positions are characterized for single edge notch specimens in tension (SE(T)) and pipes. It has been found that inhomogeneity affects elastic-plastic fracture parameters for cracks centered in welds of certain widths. Moreover, the applied J-integral on pipes with circumferential cracks depends significantly on the weld width and crack position.

Fracture Characterization of Adhesive Joints in Carbon/Epoxy Wind Turbine Blades

2012 ◽  
Author(s):  
Yi Hua ◽  
Linxia Gu
Keyword(s):  
Shear Modulus ◽  
Wind Turbine ◽  
Adhesive Joint ◽  
Turbine Blades ◽  
Adhesive Layer ◽  
Adhesive Joints ◽  
Wind Turbine Blades ◽  
Fracture Characterization ◽  
Initiation And Propagation

The objective of this work is to predict the fracture behavior of adhesive joints in the 4-ply carbon/epoxy wind turbine blades through finite element method. The influence of through-thickness flaw in the adhesive layer was examined. The contour integral method was used for evaluating the stress intensity factors (SIF) at the flaw tips, while the strength of the joint was assessed through the crack initiation and propagation simulation. The effect of adhesive shear modulus has also been investigated. Results suggested that the maximum stress occurred at the adhesive-shell interface and increased stress levels were observed in the case of adhesive layer with flaw. It also highlighted distinct edge effects along the thickness of the adhesive joint. Compared to the perfect adhesive, the static strength of the adhesive joint with flaw remained unchanged. Large shear modulus of the adhesive diminished the strength of the adhesive joint with the increased SIF.

Advances in Development of J-Integral Experimental Estimation, Testing and Standardization

2011 ◽  
Author(s):  
Xian-Kui Zhu
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Structural Integrity ◽  
Experimental Testing ◽  
Estimation Method ◽  
J Integral ◽  
Fracture Testing ◽  
Integrity Assessment ◽  
Ductile Materials ◽  
Experimental Estimation

The J-integral is an important concept in the elastic-plastic fracture mechanics, and serves as a critical material parameter to quantify the toughness or resistance of ductile materials against fracture. The relation between the J-integral and crack extension has been widely used as the resistance curve of ductile materials in fracture mechanics design and in structural integrity assessment. Experimental testing and evaluation have played a central role in providing reliable fracture toughness properties to fracture mechanics analysis. Since the J-integral concept was proposed, extensive efforts of investigations have been made to develop its experimental estimation method, testing technique and standardization, as evident in the ASTM E1820 — a commonly used fracture toughness testing standard. In recent years, significant progresses of the J-integral fracture testing and experimental estimation have been achieved, and a part of them was accepted and updated in ASTM E1820. To better understand and use this fracture testing standard, the present paper gives a brief review of historical efforts and recent advances in the development of the J-integral experimental estimation and standard testing.

A Theoretical Model for Nondestructive Evaluation of Damage of Adhesive Joints

2006 ◽  
Vol 324-325 ◽  
pp. 339-342 ◽  
Author(s):  
Guo Shuang Shui ◽  
Yue Sheng Wang ◽  
Jian Min Qu
Keyword(s):  
Elastic Modulus ◽  
Theoretical Model ◽  
Adhesive Joint ◽  
Integral Transform ◽  
Nonlinear Coefficient ◽  
Adhesive Layer ◽  
Adhesive Joints ◽  
Ultrasonic Waves ◽  
Transform Method ◽  
Nonlinear Ultrasonic

In this paper, a new theoretical model is developed to characterize the damage of the adhesive joint. Elastic modulus of adhesive joints is an important parameter to represent damage characteristics. Based on the fact that the thickness of the adhesive layer is very small, it is reasonable to believe that damage will decrease the tension modulus of the adhesive joint while the compression modulus will keep unchanged. Modeling the adhesive joint as an interface with different modulus in tension and compression, and applying integral transform method, we solve the associated nonlinear boundary problem to obtain the nonlinear ultrasonic waves transmitting through the adhesive layer. With this nonlinear ultrasonic wave, variation of elastic modulus and damage variable of the adhesive layer are thereafter characterized nondestructively by a nonlinear coefficient.

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.

scholarly journals Advanced techniques for estimation of the tensile fracture toughness of adhesive joints

10.3221/1348 ◽  
2014 ◽  
Author(s):  
R.D.S.G. Campilho ◽  
M.D. Banea ◽  
L.F.M. da Silva
Keyword(s):  
Fracture Toughness ◽  
Adhesive Bonding ◽  
Optical Measurement ◽  
Crack Tip ◽  
Adhesive Joints ◽  
Tensile Fracture ◽  
J Integral ◽  
Linear Elastic ◽  
Integral Technique ◽  
Crack Tip Opening

Adhesive bonding has become more efficient in the last few decades due to the adhesives developments, granting higher strength and ductility. As a result, adhesives are being increasingly used in industries such as the automotive, aerospace and construction. Thus, it is highly important to predict the strength of bonded joints to assess the feasibility of joining during the fabrication process of components (e.g. due to complex geometries) or for repairing purposes. When using the Finite Element Method with advanced propagation laws, the tensile (Gnc) and shear (Gsc) fracture toughness of adhesive joints must be determined with accuracy. Several conventional methods to obtain Gnc and Gsc exist in the literature, mainly based on Linear Elastic Fracture Mechanics (LEFM). The J-integral technique is accurate to measure these parameters for adhesives with high ductility. In this work, the J-integral is used to obtain Gnc by the Double-Cantilever Beam (DCB) test. An optical measurement method is developed for the evaluation of the crack tip opening and adherends rotation at the crack tip during the test, supported by a Matlab® sub-routine for the automated extraction of these quantities. As output of this work, an optical method that allows an easier and quicker extraction of the parameters to obtain Gnc than the available methods is proposed (by the J-integral technique) and some results are presented regarding joints with different geometry and adherend material.

CARPENTER 883 PLUS

Alloy Digest ◽  
1994 ◽  
Vol 43 (7) ◽  
Keyword(s):  
Fracture Toughness ◽  
Physical Properties ◽  
Tensile Properties ◽  
Structural Integrity ◽  
Heat Treating ◽  
Die Steel ◽  
Aisi Type ◽  
Red Hardness ◽  
Hot Work Die

Abstract CARPENTER 883 PLUS is a 5% Chromium hot work die steel designed for applications requiring both toughness and good red-hardness. It achieves this with higher purity, homogeneity and greater structural integrity than standard AISI type H13. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on forming, heat treating, and machining. Filing Code: TS-529. Producer or source: Carpenter. See also Alloy Digest TS-469, January 1987.

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