Experimental validation of a compression flow model of Non-Newtonian adhesives

ABSTRACT

Currently, adhesive bonding processes are developed and optimised in a time-consuming trial and error procedure, which rarely leads to an optimal solution due to the high complexity of the adhesive flow behaviour during application. The ideal adhesive layer has precise geometric specifications; entrapped air bubbles or overfilling of the bond should be avoided. Numerical methods, such as Computational Fluid Dynamics (CFD), are only capable of calculating squeeze-flow processes to a limited extent. Apart from high computing times, mesh and convergence problems often occur due to the small ratio of adhesive layer thickness to adhesive layer length and width. The Generalised Partially Filled Gap (GPFG) model, published in a companion paper uses fundamental characteristics of every bonding process to derive clever assumptions, and thus provide an efficient simulation tool for adhesive squeeze-flow. The GPFG model simplifies the squeeze-flow to a two-dimensional problem, as the flow in thickness direction can be neglected for most bonding processes – without significant loss of accuracy compared to analytical or CFD solutions. The experimental validation of the model is presented in this study. Both stresses and flow geometry were evaluated, and a very good agreement between experiments and model was proven.

KEYWORDS:

• Shear thinning
• squeeze-flow
• Yasuda-law
• narrow gaps
• Hele-Shaw cell
• rheology

Acknowledgements

This work was supported by the Deutsche Forschungsgemeinschaft, Project ID: 445254897

Additional information

Funding

This work was supported by the Deutsche Forschungsgemeinschaft [445254897].