Application of cohesive modeling in joining technology
Licentiate thesis, 2012
This thesis summarizes the development of cohesive modeling of joints. It presents some new developments regarding the effects of non-zero thickness of adhesive layers and a novel approach of using the concept of cohesive modeling to characterize the failure behavior of rivet joints.
The failure behavior of a thick adhesive layer loaded in mode I (peel), mode II (shear) and mixed-mode are studied. Analytical relations are derived for the energy release rate of DCBa-, ENFb- and MCBc-tests for pure peel, shear and mixed modes of loading, respectively. Consequently, cohesive laws are derived from the energy release rate. The results are used to predict the failure of three sets of TRBd-tests with similar and dissimilar adherents bonded with a thick layer of adhesive and loaded in mixed mode. Moreover, a model to characterize the failure behavior of rivet joints is investigated and presented.
Data from DCB-, ENF- and MCB-experiments are evaluated and used to simulate and predict the failure behavior of TRB-tests. The results of simulations are verified by the results of three sets of TRB-experiments. To this end, sixteen TRB-experiments are carried out in this work.
The main achievement of this thesis is validating the use of cohesive modeling to model adhesively bonded joints with dissimilar adherents bonded with a thick layer of adhesive. The proposed model for studying the failure behavior of rivet joints is also found to show good agreement with numerical analyses.
a Double Cantilever Beam b End Notch Flexure c Mixed-mode Cantilever Beam
d Tensile Reinforced Bending
mixed-mode cohesive failure
Thick adhesive layer