Contributing to the Optimization of the Preform LCM Process Chain: Permeability of Reinforcing Textiles

Harald Grössing

Research output: ThesisDoctoral Thesis

Abstract

The main aim of this thesis was to provide an efficient approach for in-plane permeability determination, which is subsequently utilized to generate accurate and reliable in-plane permeability characteristics. For that purpose, an optical in-plane permeability measuring system was developed based on the state of the art. During the implementation and validation, a technological comparison between an optical and a capacitive in-plane permeability measuring system was conducted. It was found that the in-plane permeability values gained with the optical based in-plane permeability measuring system are significantly influenced by the mold deflection. Based on these results, a sensitivity analysis of a capacitive based in-plane permeability measuring technology was performed. It was shown that the capacitive in-plane permeability measuring system ensures a stable and efficient in-plane permeability characterization and offers the suitability to be used as a standardized measuring technology. In a parameter study, four different multiaxial reinforcements were characterized differing in the stitch length, the filament number and the grammage. It was confirmed that a transferability of in-plane permeability values cannot be achieved in a sufficient way. It was also shown that a correct determination of the grammage and the material density are crucial for a correct correlation of the measured in-plane permeability values and fiber volume contents. Moreover, no significant influence of the batch quality on the in-plane permeability was detected. Finally, the impact of the user-defined evaluation time range on the permeability results was investigated for the in-plane permeability calculation as derived from the data gained with the capacitive technology. The results showed that the subjective impact of the user, according to the manually set evaluation time range, can have an influence on the in-plane permeability values. The results and findings of this study quantify the influence of various factors in permeability determination. The findings can be used for future work in order to eliminate potential error sources during in-plane permeability test rig development, in-plane permeability measurements and in-plane permeability calculations.
Translated title of the contributionBeitrag zur Optimierung der Preform LCM Prozesskette: Permeabilität von Verstärkungstextilien
Original languageEnglish
QualificationDr.mont.
Supervisors/Advisors
  • Schledjewski, Ralf, Assessor A (internal)
  • Mitschang, Peter, Assessor A (external), External person
  • Antretter, Thomas, Assessor B (internal)
Publication statusPublished - 2015

Bibliographical note

embargoed until null

Keywords

  • Composite Processing
  • Processing Technologies
  • Permeability Characterization

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