https://recipp.ipp.pt/bitstream/10400.22/3445/7/ART_RaulCampilho_2013_DEM.pdf

Modelling adhesive joints with cohesive zone models: effect of the cohesive law shape of the adhesive layer

The analysis of adhesively bonded joints started in 1938 with the closed-form model of Volkersen. The equilibrium equation of a single lap joint led to a simple governing differential equation with a simple algebraic equation. However, if there is yielding of the adhesive and/or the adherends and substantial peeling is present, a more complex model is necessary. The more complete is an analysis, the more complicated it becomes and the more difficult it is to obtain a simple and effective solution. The finite element (FE) method, the boundary element (BE) method and the finite difference (FD) method are the three major numerical methods for solving differential equations in science and engineering. These methods have also been applied to adhesive joints, especially the FE method. This book deals with the most recent numerical modelling of adhesive joints. Advances in damage mechanics and extended finite element method are described in the context of the FE method with examples of application. The classical continuum mechanics and fracture mechanics approach are also introduced. The BE method and the FD method are also discussed with indication of the cases they are most adapted to. There is not at the moment a numerical technique that can solve any problem and the analyst needs to be aware of the limitations involved in each case.

Advances in Numerical Modelling of Adhesive Joints

Effect of manufacturing parameters on mechanical properties of 316L stainless steel parts fabricated by selective laser melting: A computational framework

The available techniques for strength prediction of bonded joints have improved over the years. Cohesive zone models (CZM) coupled to finite element method (FEM) analyses surpass the limitations of stress/strain and fracture criteria, and simulate damage growth. CZMs require the instantaneous energy release rates in tension (G n) and shear (G s) along the fracture paths and respective fracture energies in tension (G n c) and shear (G s c), and crack growth is ruled by traction-separation laws that are established at the failure paths. Additionally, the cohesive strengths must be defined (t n 0 for tension and t s 0 for shear) relating to the onset of damage. A few techniques are available for the estimation of these parameters (e.g., the property identification technique, the direct method and the inverse method) that differ in complexity and expected accuracy of the results. In this work, the influence of the cohesive law parameters of a triangular CZM used to model a thin adhesive layer in bonded joints...

Modelling of Single-Lap Joints Using Cohesive Zone Models: Effect of the Cohesive Parameters on the Output of the Simulations

An adaptive decoupling approach for reliability-based design optimization

Determination of cohesive parameters for a mixed-mode cohesive zone model

Reliability-based design optimization using convex linearization and sequential optimization and reliability assessment method

In this study, an effective method for reliability-based design optimization is proposed enhancing sequential optimization and reliability assessment (SORA) method by a family of methods of moving asymptotes (MMA) approximations. In SORA, reliability estimation and deterministic optimization are performed sequentially. And the sensitivity and function value of probabilistic constraint at the most probable point (MPP) are obtained in the process of finding reliability information. In this study, a family of MMA approximations are constructed by utilizing the sensitivity and function value of the probabilistic constraint at the MPP. So, no additional evaluation of the probabilistic constraint is required in constructing MMA approximations. Moreover, no additional evaluation of the probabilistic constraint is required in the deterministic optimization of SORA by using a family of MMA approximations. The efficiency and accuracy of the proposed method were verified through numerical examples.

Reliability-based design optimization using a family of methods of moving asymptotes

Heat-resistant adhesive RTV88 is a hyper-elastic material and so far there have been little research on using RTV88 in adhesive joints. In this study, the effect of surface roughness on the adhesive strength of RTV88 was examined. Aluminum adherends were first sandblasted in order to generate rough surfaces, and then tensile–shear tests on Al/RTV88 single lap joints were performed. The shear strength was shown to be influenced by surface roughness. Peel failure was dominant when the surface roughness was at a low level. However, cohesive failure was the major type of failure when the surface roughness was at a high level. Effective area, peel failure area, and cohesive failure area were introduced to explain the effects of surface roughness on the adhesive strength. An empirical relation for the failure force was proposed, based on these parameters. Tensile tests of the RTV88 bonding was performed in order to obtain the necessary data. Finally, the empirical relation for the failure force was verified by ...

Effect of Surface Roughness on the Adhesive Strength of the Heat-Resistant Adhesive RTV88

In this study, an effective method for reliability-based design optimization (RBDO) is proposed enhancing sequential optimization and reliability assessment (SORA) method by convex approximations. In SORA, reliability estimation and deterministic optimization are performed sequentially. The sensitivity and function value of probabilistic constraint at the most probable point (MPP) are obtained in the reliability analysis loop. In this study, the convex approximations for probabilistic constraint are constructed by utilizing the sensitivity and function value of the probabilistic constraint at the MPP. Hence, the proposed method requires much less function evaluations of probabilistic constraints in the deterministic optimization than the original SORA method. The efficiency and accuracy of the proposed method were verified through numerical examples.

/pdf/reliability-based-design-optimization-using-convex-2etty3dr76.pdf

Tae Min Cho

Papers

Determination of cohesive parameters for a mixed-mode cohesive zone model

Reliability-based design optimization using convex linearization and sequential optimization and reliability assessment method

Reliability-based design optimization using a family of methods of moving asymptotes

Effect of Surface Roughness on the Adhesive Strength of the Heat-Resistant Adhesive RTV88

Reliability-based design optimization using convex approximations and sequential optimization and reliability assessment method