A bonded joint finite element for a symmetric double lap joint subjected to mechanical and thermal loads

A bonded joint finite element (FE) for a symmetric double lap joint is developed that is capable of predicting field quantities in the lap region. The element is a hybrid method and incorporates features of classical analytical and numerical methods. The element stiffness and load vector formulations have unique, load dependent, non-linear shape functions based on an analytical solution. The adaptive shape functions are formulated in terms of the dimensionless mechanical load fraction documentclass{article}footskip=0pcpagestyle{empty}begin{document}$(bar{bar{phi}}_P)$end{document} and total load documentclass{article}footskip=0pcpagestyle{empty}begin{document}$(bar{bar{phi}}_{rm {tot}})$end{document} and are capable of predicting the thermal and mechanical load response. The bonded joint element has been implemented as a user element in the Abaqus ® commercial FE code. A comparison of the stress predictions for the bonded joint element and a conventional 2D FE model is presented and are found to be in good agreement. Therefore, the element provides a computationally efficient and mesh-independent stress prediction. The single element reproduces the analytical solution with minimal analyst input and can be easily incorporated into early design and sizing studies. Copyright © 2009 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63072/1/2561_ftp.pd

Deformation and fracture of adhesive layers constrained by plastically-deforming adherends

The use of an embedded-process zone (EPZ) model to investigate the mode I cohesive parameters for plastically-deforming, adhesively-bonded joints is demonstrated in this paper. It is shown that for the particular systems investigated, the cohesive parameters are consistent with an adhesive layer deforming in accordance with its bulk constitutive properties (as constrained by the adherends). In other words, these systems provide examples where the cohesive tractions exerted by an adhesive layer can be calculated simply from considerations of the constrained deformation of the adhesive. Consistent with such calculations, the peak stress in the adhesive layer decreases as the level of the constraint decreases (either with an increase in the thickness of the adhesive layer or with a decrease in the thickness of the adherends). It is also shown that owing to a compensating effect in which the critical displacement for failure varies with the constraint, the energy absorbed by the adhesive layer (the 'intrinsic' toughness of the joint) is essentially independent of the geometry in these systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43697/1/10861_2004_Article_vsp_01694243_v14n13_s1.pd

Mixed-mode evaluation of ductile adhesive joints by the single-leg bending test

1st Virtual European Conference on FractureIn the design of adhesive structures, it is extremely important to accurately predict their strength and fracture properties (critical strain energy release rate in tension, GIC, and shear, GIIC). In most cases, the loads occur in mixed-mode (tension plus shear). Thus, it is of great importance the perception of fracture in these conditions, namely of the strain energy release rates in tension, GI, and shear, GII, relative to different crack propagation criteria or fracture envelopes. This comparison allows to determine the most suitable energetic propagation criterion to be used in cohesive zone models (CZM). The main objective of this work is to verify, by CZM, which is the power law parameter (α) that best suits the energetic crack propagation criterion for CZM modelling, using single-lap joints (SLJ) and double-lap joints (DLJ) with aluminium adherends and bonded with a ductile adhesive. With this purpose, numerical simulations of the SLJ and DLJ are carried out, and the maximum load (Pm) is compared with experiments. For the tested materials and geometries, the energetic criterion resulting from the experimental work provided matching numerical results and, thus, the fracture envelope was validated.info:eu-repo/semantics/publishedVersio

The Static Failure of Adhesively Bonded Metal Laminate Structures: A Cohesive Zone Approach

Data on distribution, ecology, biomass, recruitment, growth, mortality and productivity of the West African bloody cockle Anadara senilis were collected at the Banc d'Aguuin, Mauritania, in early 1985 and 1986. Ash-free dry weight appeared to be correlated best with shell height. A. senilis was abundant on the tidal flats of landlocked coastal bays, but nearly absent on the tidal flats bordering the open sea. The average biomass for the entire area of tidal flats was estimated at 5.5 g·m−2 ash-free dry weight. The A. senilis population appeared to consist mainly of 10 to 20-year-old individuals, showing a very slow growth and a production: biomass ratio of about 0.02 y−1. Recruitment appeared negligible and mortality was estimated to be about 10% per year. Oystercatchers (Haematopus ostralegus), the gastropod Cymbium cymbium and unknown fish species were responsible for a large share of this. The distinction of annual growth marks permitted the assessment of year-class strength, which appeared to be correlated with the average discharge of the river Senegal. This may be explained by assuming that year-class strength and river discharge both are correlated with rainfall at the Banc d'Arguin.

Determining the toughness of plastically deforming joints

An analysis is presented for the fracture of an adhesively bonded double-cantilever beam that fails with extensive plastic deformation of the adherends. The analysis permits a value for the toughness of the joint to be distinguished from the energy absorbed by the plastic deformation. Specifically, this value for toughness can be determined from post-fracture observations of the deformation and from a knowledge of the constitutive properties of the adherends. The analysis has been used to determine experimentally the toughness of plastically deforming joints formed using three different adhesives to bond a series of different thicknesses of aluminium and steel. In each case, it was found that, despite large differences in the extent of deformation, the value for toughness was dependent only on the materials used to form the joint. The toughness was independent of the thickness of the adherends.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44745/1/10853_2004_Article_175816.pd

Co-rotational Formulation for Bonded Joint Finite Elements

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97052/1/AIAA2012-1449.pd

Effects of adhesive thickness on global and local Mode-I interfacial fracture of bonded joints

AbstractThe interfacial fracture of adhesively bonded structures is a critical issue for the extensive applications to a variety of modern industries. In the recent two decades, cohesive zone models (CZMs) have been receiving intensive attentions for fracture problems of adhesively bonded joints. Numerous global tests have been conducted to measure the interfacial toughness of adhesive joints. Limited local tests have also been conducted to determine the interface traction-separation laws in adhesive joints. However, very few studies focused on the local test of effects of adhesive thickness on the interfacial traction-separation laws. Interfacial toughness and interfacial strength, as two critical parameters in an interfacial traction-separation law, have important effect on the fracture behaviors of bonded joints. In this work, the global and local tests are employed to investigate the effect of adhesive thickness on interfacial energy release rate, interfacial strength, and shapes of the interfacial traction-separation laws. Basically, the measured laws in this work reflect the equivalent and lumped interfacial fracture behaviors which include the cohesive fracture, damage and plasticity. The experimentally determined interfacial traction-separation laws may provide valuable baseline data for the parameter calibrations in numerical models. The current experimental results may also facilitate the understanding of adhesive thickness-dependent interface fracture of bonded joints