Through-thickness compression response of uncured prepreg during manufacture by automated layup

Abstract

A better understanding of the mechanical properties of prepreg in the uncured state is required to establish process models for automated layup of thermoset prepregs. Such models would enable control of the bulk factor and defects, such as fibre waviness and voidage, during layup. Pressure application time and temperature during automated layup are typically low while the through-thickness strains can be high due to a reduction of gaps between the plies. A viscoelastic analysis for the through-thickness compression response of a toughened carbon/epoxy prepreg is compared against an elastic–plastic material behaviour with respect to automated layup for three representative temperatures. It is shown that a simple plastic material law with strain hardening can be used to accurately model the material response during automated layup of toughened epoxy prepreg. A finite-element model shows good agreement with experimental results.