Date of Award
Doctor of Philosophy (PhD)
Fadi Abu-Farha, Committee Chair
The effects of Coefficient of Thermal Expansion (CTE) mismatch in multi-material adhesive joints, induced during the manufacturing process, are expected to hinder the peak performance of the adhesive in the service life of the vehicle. With a goal to study and capture these effects, several innovative experimental techniques were performed to record and quantify the manufacturing process induced effects on an adhesive bonded multi-material joint. The tests to capture the effects of curing process on the structure were run at coupon level using a single lap shear geometry and at component level on a scaled-down automotive roof component. The other set of tests were done to determine the effect of manufacturing induced residual stresses on the performance of the adhesive joint.
This work proposes a novel approach and a package of material models to model the properties of automotive adhesives during the heat curing process. The proposed material model package consists of a curing kinetics model, a cure and temperature dependent viscoelastic mechanical model and a temperature and rate dependent plastic model. The developed material models were coded into a user-defined material subroutine for LS-DYNA. The material card was used to run finite element simulations and was validated at coupon level and component level. The calibrated material models were fed into a finite element simulation and the prediction results were compared to the experiments on a single lap shear joint and on a complex scaled-down roof component under different scenarios. A good agreement between the numerical and experimental data was achieved.
Agha, Akshat, "Cure Dependent Viscoelastic-Plastic Modeling of Adhesives to Capture CTE Effects in Multi-Material Structures" (2019). All Dissertations. 2466.