Development of cohesive zone models for the prediction of damage and failure of glass/steel adhesive joints (original) (raw)
Related papers
International Journal of Fracture, 2010
An overview of recent development of cohesive modelling is given. Cohesive models are discussed in general and specifically for the modelling of adhesive layers. It is argued that most cohesive models model a material volume and not a surface. Detailed microscopic and mesomechanical studies of the fracture process of an engineering epoxy are discussed. These studies show how plasticity on the mesomechanical length scale contributes to the fracture energy in shear dominated load cases. Methods to measure cohesive laws are presented in a general setting. Conclusions and conjectures based on experimental and mesomechanical studies are presented. The influence of temperature and strain rate on the peak stress and fracture energy of cohesive laws indicates fundamentally different mechanisms responsible for these properties. Experiments and mesomechanical studies show that in-plane straining of an adhesive layer can give large contributions to the registered fracture energy. Finite element formulations including a method to incorporate this influence are discussed.
Influence of the Cohesive Law Parameters on the Strength Prediction of Adhesively-Bonded Joints
Materials Science Forum, 2012
Adhesive joints are largely employed nowadays as a fast and effective joining process. The respective techniques for strength prediction have also improved over the years. Cohesive Zone Models (CZM's) coupled to Finite Element Method (FEM) analyses surpass the limitations of stress and fracture criteria and allow modelling damage. CZM's require the energy release rates in tension (G n ) and shear (G s ) and respective fracture energies in tension (G n c ) and shear (G s c ). Additionally, the cohesive strengths (t n 0 for tension and t s 0 for shear) must also be defined. In this work, the influence of the CZM parameters of a triangular CZM used to model a thin adhesive layer is studied, to estimate their effect on the predictions. Some conclusions were drawn for the accuracy of the simulation results by variations of each one of these parameters.
The problem of a failure criterion for glass-metal adhesive bonds
2011
Although there is an increasing desire to apply structural adhesive bonds in glass constructions, the lack of a reliable failure criterion is a major obstacle. Since the average overlap shear strength values normally provided cannot be applied as a general limit for arbitrary adhesive bond geometries, extensive testing has to be performed on any new design to ensure its structural performance and safety. Not only the building industry, also maritime, aeronautical and car industries are struggling with this issue. To supply a contribution, this paper provides a numerical analysis of the stress distributions in an adhesive layer during a single lap shear test as was performed at Ghent University. Firstly, an appropriate mesh and element type was chosen after which the influence of different geometries on the peak shear stress was investigated. Additionally, simulations with different stiffness levels for the adhesive were performed. From the numerical analysis, it could be concluded t...
Analytical models of adhesively bonded joints—Part I: Literature survey
International Journal of Adhesion and Adhesives, 2009
The literature survey presented in Part I describes the major analytical models for adhesively bonded joints, especially for single lap joints. By consulting the summary table given in Part I, the designer can choose from a wide range of models which is the best for a particular situation. However, the information given in the summary table is not sufficient for a proper selection. The designer also needs to know the time required for setting up an analysis and solving it. Another important factor is the accuracy of strength prediction. Therefore, models of increasing complexity were selected from the summary table and a comparative study was made in terms of time requirements and failure prediction for various cases. Three main situations were considered: elastic adherends and adhesive, elastic adherends with nonlinear adhesive, and nonlinear analyses for both adherends and adhesive. The adherends were both isotropic (metals) and anisotropic (composites). The effects of the overlap length and the adhesive thickness were also considered.
Reviews of Adhesion and Adhesives, 2018
In the context of increasing the strength-to-mass ratio of lightweight structures, the adhesively bonded joining technology appears to be an attractive solution. Nevertheless, the adhesive bonding method is important when the structural integrity of joints has to be ensured. In the literature, the cohesive zone models (CZMs) are shown to be able to predict both the static and fatigue strengths of adhesively bonded joints. The strength prediction is dependent on material laws and associated material parameters, characterizing the bondline behaviour mainly under pure mode I, mode II and mixed-mode I/II. The characterization methods are thus crucial. This paper aims at assessing the capabilities to identify the parameters of a particular CZM for both the inverse method, based on the energy balance associated with the path independent J-integral, and of a direct method described in this present work. The particular CZM has a classical shape based on the definition of a bilinear law for ...
A review on failure theories and simulation models for adhesive joints
The Journal of Adhesion, 2021
In the framework of the Cost Action CERTBOND (Reliable roadmap for certification of bonded primary structures), a wide group of researchers from 27 European Countries have had the opportunity to work on the topic of certification of bonded joints for primary structural applications from different engineering sectors such as the aerospace, automotive, civil engineering, wind energy and marine sectors. Since virtual testing and optimization are basic tools in the certification process, one of the key objectives of CERTBOND is to critically review some of the available models and failure theories for adhesive joints. The present paper summarizes the outcome of this task. Nine different models/theories are described in detail. Specifically, reviewed are the Classical Analytical Methods, the Process Zone Methods, Linear Elastic Fracture Mechanics (LEFM), the Virtual Crack Closure Technique (VCCT), the Stress Singularity Approach, Finite Fracture Mechanics (FFM), the Cohesive Zone Method (CZM), the Progressive Damage Modeling method and the Probabilistic methods. Also, at the end of the paper, the modeling of temperature effects on adhesive joints have been addressed. For each model/theory, information on the methodology, the required input, the main results, the advantages and disadvantages and the applications are given.
Assessment of the Cohesive Contact method for the analysis of thin-walled bonded structures
International Journal of Adhesion and Adhesives, 2012
Several finite element (FE) techniques for the structural analysis of bonded joints and structures have been proposed in the literature. This paper deals with the assessment of a new surface interaction technique that models the adhesive as a pure contact with cohesive properties. This technique is a new feature of the FE software ABAQUS. The work has two objectives. Firstly, to assess the applicability, efficiency and accuracy of this Cohesive Contact (CC) method in the analysis of three dimensional, thinwalled bonded structures. Secondly, to compare the CC method with a similar technique, called Tied Mesh (TM) method, previously proposed by the authors. By considering as benchmark standard and ad hoc bonded joints and structures, the CC method is checked against a full FE model in the elastic field and with the outcome of experimental tests in the post-elastic field. Also, the TM method is implemented for all these geometries, in order to obtain a comparison. The results show that the CC method gives a fair prediction both in the elastic and post-elastic field, with lower accuracy than the TM method.