Abstract
Adhesively bonded joint has gained increasing popularity due to weight reduction and relief of stress concentration. However, damage in the mode of adhesive failure and cohesive failure, as well as the adherend failure, could still occur, and it has been realized that the reliability of the adhesively bonded joint depends on numerous complex and even nonlinearly interacting factors. Consequently, the prediction of load‐bearing capacity and damage localization for an adhesively bonded joint can be difficult due to the not well‐known effects of the variations or uncertainties in the imperfected adhesive‐adherent bonding surfaces or the environmental conditions as well as the material and geometrical nonlinearities. Although abundant uncertainties are present, the standard analysis tool in industries is still deterministic finite element analysis (FEA). The routine practice of such analysis is applying a cohesive zone model (CZM) implemented with a proper traction‐separation law to predict the onset and gradual degradation of adhesion which may underpredict or overpredict the load‐bearing capacity of an adhesively bonded joint. In this study, deterministic FEA with a CZM is first applied to predict the load‐displacement curve of an adhesively bonded polyurethane‐to‐steel double butt joint. A comparison of the prediction with the experiment reveals the inability of a deterministic approach for accurately predicting the load‐bearing capability of the joint and the failure propagation route. Then, uncertainty analysis using polynomial chaos expansion (PCE) is applied to examine if it can enhance the prediction of the joint failure. The results show the predictions generated by the uncertainty analysis correlate better than the deterministic analysis with the test data, hence demonstrating the potential of uncertainty analysis in improving the prediction of the failure mode and load‐bearing capability of an adhesively bonded polyurethane‐to‐steel double butt joint.
Highlights
Bonded joints have been widely adopted in numerous industrial applications, e.g., automotive industry, architecture, and aerospace
While coupled with abundant uncertainties arising from adhesive application process, adherent surface roughness, temperature, and humidity, the numerical analysis of an adhesively bonded joint is still largely treated as a deterministic problem
First by applying a deterministic approach to predict the bending moment bearing capacity of an adhesively bonded polyurethane-to-steel double butt joint, we show the deterministic approach overpredicts the strength of the joint. e predicted stiffness is prominently higher than the measured value. is discrepancy can be attributed to the polyurethane foam being not fully closed which leads to the actual bonding area between the polyurethane foam and the other steel adherent which is only partial of the nominal bonding area. is partial bonding would inevitably deteriorate the quality of adhesion causing a decrease in the actual joint strength
Summary
Bonded joints have been widely adopted in numerous industrial applications, e.g., automotive industry, architecture, and aerospace. Depending on the situation whether the problem can be simplified as a plane stress problem, the deterministic approach uses either 2D or 3D finite element analysis (FEA) coupled with an adhesive failure criterion [8] or a failure initiation-propagation-separation simulating scheme [5] to predict the strength and failure mode of adhesive joints. E objective of the present work is, to explore the potential of an uncertainty analysis coupled with numerical models in improving the prediction of load-bearing capacity of an adhesively bonded joint. For this purpose, experiments are carried out to determine the mechanical properties of the adherent and the adhesive and the load-bearing capacity of the joint. The potential of the present approach in enhancing the adhesive strength prediction is discussed
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