Page 18 - ILK Research Report 2020

Doctorate Dr.-Ing. Oliver Weißenborn

Development of a novel foam impregnation process

for the manufacturing of textile-reinforced polyurethane
based sandwich structures with complex geometry

Supervising Professor: Prof. Dr.-Ing. habil. Maik Gude

The sandwich construction method with the separation layers, methods in the framework of statistical design
of the component cross-section into highly rigid and high of experiments were applied and thus test specimens
strength cover layers and a shear resistant core with low manufactured following optimized production parame-
density represents an established principle for the design ters. Based on this, an experimental analysis of relevant
of lightweight structures. Due to their high density-specific material- and structural-specific mechanical parameters
mechanical properties, continuous fibre-reinforced plas- was conducted. The results built the input for the devel-
tics in the outer layers and polymer foams in the core of opment of suitable models, predicting the deformation
the sandwich structure are of outstanding importance for behaviour under bending and impact loads. The compre-
cross-industry applications. hensive results were transferred into application-oriented
design guidelines for the design of sandwich composite
Classical manufacturing processes for complex geome- structures manufactured using the foam impregnation
tries using thermoset matrix systems are usually based technology. The high amount of material-specific degrees
on multi-stage and thus discontinuous process steps, of freedom, such as the resulting core layer density, the
whereby the sandwich core and core layers are often fibre type and the fibre mass content in the area of the
manufactured separately from each other, partly manually semi-finished reinforcements, offer a wide range of pos-
and with separate moulds. In the present work, a novel sibilities for designing tailor-made composite structures.
manufacturing process based on foamable polyurethane
is developed in which a simultaneous production of sand- By implementing a prototypical demonstrator structure
wich cover layers and core takes place. The scientific basis with high geometric complexity, the developed models for
for the foam impregnation process has been laid in com- predicting the degree of impregnation in the cover layers
prehensive process studies. In order to identify significant were validated. At the same time, the high potential for
parameters influencing the degree of impregnation and cross-industry applications in the field of robust and com-
the morphology of the textile-reinforced sandwich cover plex shaped structural components can be demonstrated.

Prototypical demonstrator structure with complex geometry consisting
of foam impregnated textile-reinforced cover layers and polyurethane
Schematic representation of the foam impregnation process core layer

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