An integrated kinetic-Fe vulcanization model to predict the optimal curing of thick rubber pads for applications in seismic isolation

Thick rubber pads for cheap isolation of low rise buildings require an optimal vulcanization along the thickness. The present paper is aimed at presenting an integrated three-step approach for the optimization of curing in presence of items exhibiting considerable thickness. It requires a preliminary standard experimental characterization in a rheometer, conceived to tune a simple kinetic steady-state model finally nested into a Finite Element FE heat transmission code, which allows to simulate the curing process in full 3D heat transmission problems. The kinetic model is a phenomenological approach based on 3 kinetic constants, aimed at predicting the initial curing rate, maximum crosslinking and reversion. Kinetic constants are deduced fitting normalized experimental rheometer curves. FE transient curing computations are carried out on a thick rubber pad, used for the production of unbonded low cost seismic isolation devices. The entire 3D geometry is discretized with a refined mesh, in order to realistically reproduce the vulcanization occurring in an industrial mold. From simulation results, interesting design considerations can be drawn, allowing to establish time and temperature of curing as a function of the rubber thickness and chemical composition.