Viscoplastic Analysis of Adhesive Joints (original) (raw)
Related papers
International Journal of Engineering and Applied Sciences
The widespread use of adhesive bonded connections has been used in a range of technical fields. In this paper, the interfacial stress distribution of adhesive bonded joint is presented. When determining whether or not a structure is dependable for use in operation, the stresses that act along the bond line of an adhesively bonded lap joint are of the utmost importance. The purpose of this study is to develop finite element solutions that are able to anticipate shear and peel stresses using the theory of elasticity as their foundation. The effect of adhesive properties on stress distribution is investigated by using different adhesive materials. By analysing five different adhesive materials it is concluded that ‘adhesive I’ is more reliable for operation.
Experimental and numerical investigations on adhesively bonded joints
IOP conference series, 2016
Two types of adhesively bonded joints were experimental and numerical investigated. Firstly, the adhesives were characterized through a set of tests and the main elastic and mechanical properties were obtained. After that, the stress distributions at interface and middle of adhesive layer were determined using a linear elastic FEA. The numerical data were fitted by a power law in order to determine the critical values of intensity of stress singularity.
Finite-element models of viscoelasticity and diffusion in adhesively bonded joints
International Journal for Numerical Methods in Engineering, 1988
The paper contains a description of the finite-element model based on Schapery's non-linear viscoelastic constitutive equation for the adhesive, a non-linear generalized Fickean diffusion model and an updated Lagrangian formulation of a two-dimensional stress state, to analyse adhesively bonded joints. The finiteelement analysis program, called NOVA, is used to analyse a number of adhesive joints, and the results are compared with existing experimental results and analytical solutions.
Engineering Structures, 2018
Functionally graded (FG) adherends are beneficial to adhesively bonded joints, as different material composition through the adherend thickness can manipulate the interfacial stress distribution. It is a fact that both shear and peeling stresses along the adhesive/adherend interface at the free edges play important roles in the structural integrity of a joint. Previous studies have shown that both shear and peeling stresses can be uniformly distributed near the edges of a joint with FG adherends if the right adherend composition is selected through the adherends' thickness. However, the effect of the viscoelastic behavior of the adhesive layer has been neglected in those studies. This study establishes a viscoelastic analytical model for adhesively bonded single-lap joints with FG adherends. In this model, the adhesive layer is simulated as a three-parameter viscoelastic foundation using a standard linear solid (SLS) model to account for both creep and relaxation behaviors in the adhesive. This model satisfies the zero-shear-stress boundary at the free edges of the adhesive and predicts different peel stresses along two adherend/adhesive interfaces. Excellent agreement with finite element analysis (FEA) has been achieved by the present model, confirming the accuracy of the model. The viscoelastic behavior of the adhesive layer affects stress concentration near the edges of a joint at early ages, suggesting that the present model can properly capture the stress relaxation in adhesively bonded joints with FG adherends. The parametric studies show that FG material configuration and the mechanical properties of adhesive layers play an important role in the uniformity of shear stress distribution along the length of single-lap joints with FG adherends. The present viscoelastic solution can predict more uniform stress distribution and is a valuable tool in design optimization of joints with FG adherends.
Analysis of the Influence of Hydrostatic Stress on the Behaviour of an Adhesive in a Bonded Assembly
2010
Generally, adhesives are viscoelastic-plastic materials, for which the development of viscosity and plasticity varies depending on the type of adhesive and the stress state. Various models exist to represent the yield surface, or the so-called elastic limit, taking into account the two stress invariants, hydrostatic stress and von Mises equivalent stress. Moreover, to develop precise pressure-dependent constitutive models, it is necessary to have a large experimental database in order to accurately represent the adhesive strains which are strongly dependent on the tensile-shear loading combination. Under quasi-static loadings, for a given strain rate range viscous effects can be neglected, but only a few experimental results are available to model the behaviour of the adhesive in a bonded assembly accurately under realistic loadings. Moreover, edge effects often have a large influence on the mechanical response. This paper presents the possibility of combining the use of an experimental device, which strongly limits the influence of the edge effects, with a pressure vessel especially designed to study the influence of hydrostatic stress. The latter allows pressures up to 100 MPa to be applied during mechanical testing. Comparisons with results obtained with a modified Arcan device are presented. Such results are useful for the development of 3D pressure-dependent models for the yield function and for the analysis of more complex loading.
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.
Study of the Impact of Surface Topography on Selected Mechanical Properties of Adhesive Joints
Coatings, 2024
Manufacturers of adhesives for industrial use determine the strength of adhesive joints during shear tests. Most often, components made of the same material are joined. In contrast, the roughness of the surfaces to be joined results from the use of a specific surface treatment technology. In adhesive manufacturers’ recommendations for metal-to-metal joints, surface technologies can be found without specifying numerical requirements for roughness. Modern techniques for shaping the geometric accuracy of components allow the formation of determined irregularities on the surface, which are characterised by their height and mutual distribution. Furthermore, regular irregularities can be obtained by using the appropriate tool and technological machining parameters. In this way, surfaces with similar load-bearing capacity, core volume, texture or expected hydrophobic properties can be produced by various methods. However, a basic prerequisite is the careful definition of the numerical requirements, both for the basic roughness indices and those of a complementary nature. As a rule, the strength of the adhesive joint is also lower than the strength of the adhesive itself. The strength of an adhesive joint depends on the ‘mechanical anchorage’ of the adhesive and the adhesion phenomenon on the surface. The research assumes that it is possible to induce an interaction between the geometric state of the surface and the properties of the adhesive, so as to guarantee the maximum strength of the adhesive joint. To verify this, a series of experimental tests were developed and carried out for two different adhesives characterised by different viscosities and offered bond strength. Based on the tests carried out, recommendations were made to the designers of adhesive joints, where, in addition to the height of the surface irregularities, the properties related to fluid retention and the shape of the irregularities in the valleys should be determined.
Strain rate-dependent deformation and failure process of adhesive joints
36th International Electronics Manufacturing Technology Conference, 2014
Rate-dependent deformation and failure process of adhesive joints are investigated in this study. For this purpose, acrylic foam pressure sensitive adhesive (PSA) was employed with aluminum adherents. Tensile and shear loading of the adhesive joint was applied at displacement rates ranging from 5 to 500 mm/min. Results show that the failure process under tensile loadings start with initiation of cavities, hardening through fibrillation process and final fracture of the fibrils. For shear loading the failure process is a combination of fibrillation processes, shear flow, and by interfacial sliding. Both modulus and strain energy density at fracture reach maximum value at a displacement rate of 100 mm/min under tension, while continuously increase with displacement rate under shear loading. Adhesive failure dominates at low loading rate (below 10 mm/min.), while mixed-mode and cohesive failure are common at faster loading rates above 250 mm/min. Finite element employing Yeoh constitutive model adequately predicts viscous shear deformation of the PSA joints.