A friction model for thermostamping commingled glass-polypropylene woven fabrics

The effects of processing parameters on the friction coefficient between commingled glass-polypropylene plain-weave fabric composites (Twintex (R)) and the steel tool during thermostamping processes were investigated. The investigation focused on the effects of fabric velocity, normal force and resin viscosity under conditions similar to those in thermostamping processes. The effect of resin viscosity on the resulting friction coefficient was evaluated through changes in tool temperature and initial fabric temperature. The results from these experiments could be related to trends predicted by Stribeck-curve theory. Based on the effects of those parameters and the Stribeck-curve theory, an empirical friction model was developed and incorporated into ABAQUS as a user-defined friction subroutine. This paper describes the development of that friction model for use in finite element models of the thermostamping process. It also discusses the results of a parametric study conducted using the friction model with a finite element model of the thermostamping process. These results show the importance of properly accounting for changes in friction at the metal-fabric interface in numerical simulations of the thermostamping process. (c) 2006 Elsevier Ltd. All rights reserved.