Influence of the temperature cycle on local distortions in car panels caused by hot curing epoxies

Simulation of the development of local panel distortions due to hot-curing adhesives

“…Instead, it is assumed that the bulk modulus has less influence on stresses than the tensile or shear modulus in cases where the adhesive occupies an unconfined open geometry. That is the case for the bond line in the experimental set-up investigated here and and described by Priesnitz et al (2014a). The bulk modulus changes by a factor of about 2 to 3 during the glass-to-rubber transition, which is the much less than the 100-to 1000-fold changes of the shear and elongation modulus during that transition.…”

“…A model has been developed to simulate the cure processes investigated by Priesnitz et al (2014a). The constitutive equations for the adhesive in that model coincides with the ones used in a previous work of the authors (Priesnitz et al, 2014b) with minor modifications.…”

“…The simulation model is based on an earlier work by Priesnitz et al (2014b) and allows for chemically and thermally induced property changes of the adhesive. Priesnitz et al (2014a) provide experimental data on distortion development in different cure cycles, which is used as a comparison for the simulation results.…”

“…Hahn et al (1993) measured the shear modulus of an epoxy during cure. The displacement curve of a steel strip during the bonding process in different cure cycles was determined by Priesnitz et al (2014a); Chudaska and Hahn (1993) monitored the position of a composite panel. These publications show that distortions can occur early in the cure cycle when the structure is still heating up.…”

Adhesive Joints for Low- and High-Temperature Use: An Overview

“…Blanke [98] demonstrated that the geometry and fixture of the curing moulds as well as the temperature field distribution can be optimized to mitigate this phenomenon. Priesnitz et al [99] studied the influence of the adhesive shrinkage in the distortion of automotive doors after production. They found that the hot-cure one-part epoxy adhesives used for this purpose are responsible for distortions in two different phases.…”