Abstract
Epoxy resins filled with dielectric mineral particles are frequently used as insulating materials in power industry applications. Due to their excellent dielectric properties and relatively good thermal performance (resistance, ageing and conductivity) their usability is common and extensive. However, processing of epoxy resin based products is quite difficult, and often results in quality problems or even cracks. Normally, for such as complex products, manufacturinginduced residual stresses cannot be totally avoided, but numerical simulations may provide good estimation of their level. This paper deals with mechanical problems of power industry products and explains the methodology for numerical modeling of failure in silica filled epoxy systems subjected to severe temperature gradients. The exemplary product cast of Huntsman’s CY228 epoxy system was simulated using commercial ABAQUS software package. Special subroutines describing progress of polymerization, exothermic effects of the reaction, as well as viscoelastic-driven stress relaxation process were implemented into general purpose FEM code. In addition, the model describing probability of epoxy cracking was proposed, calibrated and introduced into the software package. This approach allowed modeling the authentic phenomena taking place during real production processes, and studying the influence of design and manufacturing parameters on product quality. The outcome of numerical analysis was compared with the results of strain-gauge measurements, showing good agreement. As a result the optimal settings of curing and post-curing operations could be evaluated, driving to minimal cast product distortion and low probability of failure.