One of the main advantages of adhesive bonding is its high resistance. License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The experimental results and numerical analyses combined with the phenomenological models were used to establish mixedmode static and fatigue failure criteria for crack initiation and crack propagation for the adhesively bonded joints. Fatigue crack growth identification in bonded joints by using. The paper presents a concept for predicting fatigue strength of adhesive bonded joints based upon stresses that the joint interface may experience under operating conditions. Single lap shear fatigue tests have been carried out at a 7 kn load, load ratio 0. The tensile fatigue response of adhesively bonded doublelap and steppedlap joints dljs and sljs has been investigated. A fracture mechanics approach to adhesively bonded joints twi. Pultruded gfrp laminates were joined using an epoxy adhesive. Fatigue life prediction of adhesivelybonded fiber reinforced polymer structural joints under spectrum. The demand for reliable and safe structures necessitates deep knowledge in this area in order to avoid catastrophic structural failures. Fatigue crack growth in adhesively bonded joints with intermittent. A procedure for the simulation of fatigue crack growth in.
Fatigue crack propagation behavior of adhesively bonded. Ashcroft b a faculty of engineering and physical sciences j5, university of surrey, guildford. In this study, the fatigue crack growth rate was measured using adhesively bonded cfrpaluminum double cantilever beam dcb joints made with an acrylic adhesive. Fatigue crack propagation in adhesively bonded joints. In the frame of this work fatigue behavior of adhesively bonded joints composed of pultruded gfrp laminates is thoroughly investigated. The paper is divided into several related topics such as fatigue strength and lifetime analysis, fatigue crack initiation, fatigue crack propagation, fatigue durability, variable fatigue. The main aim of this article is to investigate the effect of frequency on fatigue crack propagation in adhesively bonded joints. The fatigue damage mechanism of composite to composite adhesively bonded joints was characterized. A finite element study of fatigue crack propagation in single. The first part of the book discusses the experimental investigation of the reliability of adhesively bonded composite joints, current research on understanding damage mechanisms, fatigue and fracture, durability and ageing as well as. Read the prediction of crack growth in bonded joints under cyclic fatigue loading i. Summary of work in which fatigue life and crack growth data were obtained for steel joints bonded with epoxy adhesive to compare with predicted values based on fracture mechanics concepts. An innovative approach to fatigue disbond propagation in.
Accurate prediction of fatigue life is a challenge due to the complicated nature of fatigue crack initiation and propagation, geometry of bonded joints, and. Dcb is a standard test specimen used to characterize mode i. Besides the sn curves, stiffness fluctuations were monitored during fatigue as well as crack initiation and propagation. Mixedmode fatigue crack growth in fm37 bonded joints. Fatigue life and backface strain predictions in adhesively. A study on fatigue crack propagation in thick composite adhesively bonded joints 1. Simulating mode i fatigue crack propagation in adhesivelybonded. Fatigue delamination growth for an adhesivelybonded. The fatigue behaviour of adhesivelybonded joints, which consisted of an epoxyfilm adhesive bonding fibrecomposite substrates, has been studied. Fatigue crack propagation behavior of adhesivelybonded cfrp. Two types of joints are examined, double lap joints dlj and stepped lap joints slp to point out the influence of different joint geometries in fatigue life. Fatigue tests were conducted on adhesively bonded cfrpaluminum doublecantilever beam dcb specimens to investigate the effect of adherend thickness on the fatigue crack growth rate.
The fatigue crack propagation has been strongly investigated for bonded joints, and its life depends on the extension of the bonded interface, the load type and the load level 14, 15. Fatigue failure of adhesivelybonded structural joints for. Three different bonded joints are considered in this study, namely double cantilever beams, single lap joints and double lap joints. Dljs showed low and almost linear stiffness degradation during fatigue life. Fatigue behaviour of adhesively bonded joints and its. Effect of humidity on the fatigue behaviour of adhesively. Three different bonded joints are considered in this study, namely double cantilever beams, single. A constitutive equation, known as the modified crack layer mcl model, is employed to extract parameters characteristic of the adhesive joints resistance to fdp. A numerical model has been developed for simulating fatigue crack growth debonding in adhesively bonded composite joints subjected to mode. This paper presents a method for predicting fatigue crack propagation in single lap adhesively bonded composite joints with an initial fullwidth preexisting disbond using finite element analysis and numerical integration of the fatigue crack growth rate law. Crack growth rate and crack path in adhesively bonded joints. An innovative approach to characterize the resistance of adhesively bonded joints to fatigue disbond propagation fdp is presented. Home key engineering materials advances in fracture and damage mechanics iii fatigue crack propagation in adhesively bonded.
Fatigue crack propagation rate of cfrpaluminum adhesively bonded dcb joints with acrylic and epoxy adhesives 1. The second harmonics generation of the fundamental s0 mode is much more sensitive to the fatigue cracks than a0 mode 6. The model employs a cohesive zone model described by a modified bilinear traction. Fatigue crack growth in adhesively bonded compositemetal double. Fatigue crack growth for bonded joints the fatigue crack propagation has been strongly investigated for bonded joints, and its life depends. Fatigue crack propagation behavior of adhesivelybonded. Fatigue crack growth simulation in adhesively bonded composite joints. A common fatigue crack propagation curve for adhesively bonded joints is a logarithmic plot of crack growth rate against the maximum strain energy release rate over time figure. A fracture mechanics approach to adhesively bonded joints. The crack measurement techniques and the calculation methods for. The fatigue crack propagation in adhesively bonded, thick composite joints was investigated experimentally using double cantilever beam and single lap joint specimens. This work deals with the simulation of the fatigue crack growth fcg in bonded joints. Fatigue crack growth identification in bonded joints by. Fatigue is widely recognised as one of the most common causes of mechanical failure and hence the issue of fatigue in bonded joints must be addressed if adhesives are to find wider usage in structural applications.
Fatigue crack propagation in adhesively bonded joints core. The first part of the book discusses the experimental investigation of the reliability of adhesivelybonded composite joints, current research on understanding damage mechanisms, fatigue and fracture, durability and ageing as well as implications for design. Damage mechanics iii fatigue crack propagation in adhesively. Tapered single lap joints made of relatively thick composite laminate adherends. Dec 04, 2017 the fatigue damage process in the dljs was dominated by a fatigue crack initiation process.
The techniques are based on using fea combined with either fracture mechanics theory or the cohesive zone model. However, the lack of knowledge regarding fatigue and fracture behaviour, and the shortage of tools for credible fatigue design, hinders the potential benefits of adhesively bonded joints. Predicting fatigue damage in adhesively bonded joints. For both joint types, the dominant failure mode was a fibertearoff failure that occurred in the outer mat layers of the gfrp laminates. The crack growth was modelled using a fracture mechanics model based on finite element models. Adhesively bonded joints are gaining importance in the structural joining processes competing against welding and bolting processes. Fatigue tests were conducted on adhesivelybonded cfrpaluminum.
To compare fatigue crack growth behavior with heatcured type adhesive, fatigue testing was also conducted for dcb joints with an epoxy adhesive. Jan 01, 2003 read the prediction of crack growth in bonded joints under cyclic fatigue loading i. In the present situation, the effect of adherend thickness on fatigue or fracture toughness has been still unclear. Read a study on fatigue crack propagation in thick composite adhesively bonded joints, international journal of fatigue on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Fatigue crack growth simulation in adhesively bonded. Including all of the detail of adhesively bonded joints into a model of a component will complicate an analysis because of several factors. The first part of the book discusses the experimental investigation of the reliability of adhesively bonded composite joints, current research on understanding damage mechanisms, fatigue and fracture, durability and ageing as well as implications for design. Adhesive bonding has become a powerful joining technique during the last few decades. Adhesively bonded joints are often employed to join parts in composite structures. Ashcroft b afaculty of engineering and physical sciences j5, university of surrey, guildford, surrey gu2 7xh, uk. Due to the increasing interest in adhesively bonded joints, mainly in the transports industry, there is a need to deep the knowledge about the fatigue behaviour of adhesive joints. To acquire fatigue endurance and crack growth data from a galvanneal steel adherendepoxy adhesive system against which to compare fatigue life predictions based on fracture mechanics concepts.
In 3d solid models, thin bondlines will require large numbers of elements model the adhesive. In this research, the mechanical and fracture behavior of adhesively bonded doublelap and steppedlap joints dljs and sljs composed of pultruded gfrp laminates and an epoxy adhesive were experimentally and numerically investigated under both quasistatic and fatigue loadings. Abstract a numerical model has been developed for simulating fatigue crack growth debonding in adhesively bonded composite joints. In this work a procedure based on the cohesive damage model is developed for the simulation of fatigue crack growth in bonded joints for different mixed mode iii conditions. Modelling fatigue in adhesively bonded joints springerlink. The prediction of crack growth in bonded joints under.
In particular a cohesive damage model is implemented in the commercial software abaqus, in order to take into account for the damage produced by fatigue loading. Fatigue and fracture of adhesivelybonded composite joints. Mixedmode static and fatigue failure criteria for adhesively. Fatigue debond growth in adhesively bonded single lap joints 81 there have been many attempts to model the relation between the fatigue crack propagation rate, d a d n. May 01, 20 read a study on fatigue crack propagation in thick composite adhesively bonded joints, international journal of fatigue on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Cohesive zone model for highcycle fatigue of adhesively. Predicting fatigue damage in adhesively bonded joints using a. The joints have features that are much smaller than the dimensions of the structure. To correlate the structural performance of the joints. Jhin master of applied science mechanical and industrial engineering university of toronto 2012 abstract the relationship between crack path and test method was examined by comparing the. Lamb wavebased structural health monitoring of delamination. The fatigue response of environmentally degraded adhesively.
Fatigue tests were conducted on adhesivelybonded cfrpaluminum doublecantilever beam dcb specimens to investigate the effect of adherend thickness on the fatigue crack growth rate. Three different bonded joints are considered in this study, namely double cantilever beams, single lap joints and double lap. An incident lamb wave interacts with a fatigue crack, and the second or third harmonics are generated. Fatigue crack propagation rate of cfrpaluminum adhesively. In this study, the fatigue crack growth rate was measured using adhesively bonded cfrp aluminum double cantilever beam dcb joints made with an acrylic adhesive. The joints were aged in deionised water at a temperature of 50. In situ health monitoring of adhesively bonded joints during fatigue using carbon nanotube network roham mactabi a thesis in the department of mechanical and industrial engineering presented in partial fulfillment of the requirements for the degree of master of applied science mechanical engineering at concordia university. In the case of a joint experiencing only peel stresses, a fracture mechanics fm approach simply requires the evaluation of mode i crack driving force as a function of crack length in the joint and the knowledge of the mode i fatigue crack growth fcg behaviour 2.
Development of a monitoring system for crack growth in. Fatigue failure of a doublelap joint involves two stages. In situ health monitoring of adhesively bonded joints during. Fatigue crack propagation rate of cfrp aluminum adhesively bonded dcb joints with acrylic and epoxy adhesives 1.
A current challenge is the shm of adhesively bonded composite joints, either 3layer systems of. A study on fatigue crack propagation in thick composite. Experimental samples were made from carbon fibre composite substrates bonded with an epoxy adhesive. Fatigue debond growth in adhesively bonded single lap joints.
Components of the specimens were unidirectional composite, aluminum plate and a filmtype epoxy adhesive. An investigation on fatigue crack growth monitoring of bonded joints has been conducted employing a novel carbon nanotube adhesive film, chosen for their proven exceptional properties for sensing purposes. The mechanics of the possible modes of fatigue damage propagation in these joints when subjected to constant amplitude cyclic mechanical loading were investigated. Dcb is a standard test specimen used to characterize mode i fracture in adhesivelybonded joints. Abdel wahab mm, ashcroft ia, crocombe ad and smith pa 2003 fatigue crack propagation in adhesively bonded joints. This paper addresses numerical and experimental examination of the role of zigzag interface shapes on the load bearing capacity and fatigue life of adhesively bonded single lap joints. Ashcroft b afaculty of engineering and physical sciences j5, university of surrey, guildford.
Fatigue damage of adhesively bonded joints, in addition to crashworthiness, has therefore become subject of unquestionable relevance. Effect of humidity on the fatigue behaviour of adhesively bonded aluminium joints 175 latin american journal of solids and structures 14 2017 174187 in incredible structural efficiency and durability present in some aircrafts that could not have been achieved with conventional riveted structures hartsmith 2011. To do so, series of fatigue crack growth tests for two different amounts of tightening torque in aluminum alloy 2024t3 precracked joints have been carried out to record the fatigue crack. Fatigue of adhesively bonded epoxyaa6061t651 joints. Fatigue debond growth in adhesively bonded single lap joints 81 there have been many attempts to model the relation between the fatigue crack propagation rate, dadn, and the stress intensity range. Crack growth rate and crack path in adhesively bonded. One of the major advantages of adhesive bonding, compared to riveting or welding, lies in its superior fatigue resistance. Effect of interface nonflatness on the fatigue behavior of. Three different bonded joints are considered in this.
Adhesively bonded joint, composite, fatigue crack propagation. The approach outlined here incorporates a fatigue damage model based on maximum fatigue load conditions and hence requires a significantly less computational effort in comparison with the models based on the cyclebycycle analysis. Citeseerx document details isaac councill, lee giles, pradeep teregowda. A study on fatigue crack propagation in thick composite adhesively bonded joints article in international journal of fatigue 50. The primary inputs to predict crack growth rates are fracture mechanics based test data and finite element data of bonded joints. The study of changes in the fatigue response on adhesively bonded joints due to varying degrees of relative humidity is an important step in understanding how joints will behave in the longterm, and although there is already some data on the subject it is not enough to draw clear conclusions costa et al. Modelling of adhesively bonded joints april 2001 twi. Fatigue crack propagation behavior of adhesively bonded cfrpcfrp and cfrpaluminum joints flexural rigidity of the adherend 8,9. Fatigue delamination growth for an adhesively bonded composite joint under mode i loading. Adhesively bonded doublecantilever beam dcb samples were tested in fatigue at various frequencies between 0. The advantages of adhesively bonded joints over mechanically fastened joints has encouraged the aerospace industry to use the former in structural components and systems. The backface strain technique was employed to monitor damage initiation and propagation in the joints.
Experimental studies, international journal of adhesion and adhesives on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Fracture and fatigue of adhesivelybonded fiberreinforced. Predicting the servicelife of adhesivelybonded joints. Simulating mode i fatigue crack propagation in adhesively. Fatigue crack propagation behavior of adhesively bonded cfrpaluminum joints was investigated by ishii et al. Pdf the current paper presents research aiming at characterizing the fatigue behaviour of adhesively bonded joints. The above trend is similar to that for the present fatigue tests. A finite element study of fatigue crack propagation in. However, longterm behaviour of adhesively bonded joints is still an open question.
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