Analysis of Isothermal Processes for the Accelerated Production of Composite Structure

The thesis contributes to the development of manufacturing approaches for structural
CFRP aerospace components using dry fibre processes such as resin transfer moulding
(RTM). It focuses on key challenges of isothermal processing, where parts are
demoulded close to curing temperature and subsequently subjected to rapid cooling
outside the production tool. FEM simulations are used for multiphysics calculations,
supported by experiments, to investigate these phenomena.

To model the separation of the composite part from the metal tool by impact, dynamic
mechanical calculations are performed using an explicit solver to determine the
system’s dynamic response. This involves analysing the oscillation of the part and
tool based on mathematical approaches for low-velocity impacts. The risk of
impact-induced damage during demoulding is evaluated using an implicit solver in
combination with the three-dimensional Puck inter-fibre failure criterion.

In addition, the study examines the effects of rapid and non-uniform cooling after
demoulding. The resulting inhomogeneous temperature fields lead to thermally induced
stresses, which are evaluated together with residual stresses from the manufacturing
process. Their potential to cause damage is analysed using the Puck failure
initiation criterion.

• By (author) Johannes Jakob Stolz