ISO standard on permeability characterization published

Digitalized Process & Material Development7News25

Liquid Composite Molding (LCM) processes are widely applied for manufacturing lightweight components for the automotive, aerospace, marine, and energy (e.g. wind turbine blades) industries. In all LCM processes, dry fibrous reinforcements are impregnated with a liquid resin system. To obtain short cycle times and high component quality, a suitable process design is required, based on knowledge of material properties, specifically resin viscosity and the reinforcement permeability for fluid flow. For decades, researchers around the world have been trying to unravel the influences on reinforcement permeability. Of course, experimental permeability characterization played a crucial role in this context, as it allowed for systematic studies and generation of input for process simulations – the basis for process and material optimization. The research field grew rapidly and very soon the experimental moved into the focus. It soon became clear that methodological, systematic and statistical errors were causing tremendous differences between the results from different labs. Despite the popularity of LCM processes and the crucial relevance of permeability, until recently there was no standard for its measurement.

Since the 1990s, several benchmark studies have been initiated to address this obstacle for industrial use. The topic really gained momentum, when the community of FPCM (Flow Processes in Composite Materials) conference series tackled it and organized three consecutive international benchmark studies, particularly on in-plane permeability measurement. Within these studies, of which the most recent was organized by IVW, guidelines have been elaborated.

Using these guidelines as a starting point, IVW researchers David May and Sebastian Schmeer initiated and led an ISO standardization project in 2018. In this project, an international team of about 30 collaborators from more than 20 research institutes and industry companies, conducted studies to clarify remaining questions and to come up with distinct procedures for preparing and executing the experiments as well as for post-processing the acquired measurement data. After more than 25 years of dedicated research, an industry standard is finally available.

Further information on IVW’s standardization activities can be found here: https://www.ivw.uni-kl.de/en/projects/international-standardization

Link to the standard: https://www.iso.org/standard/79944.html

PD Dr.-Ing. habil.

David May

Research Director Digitalization & Manager Digitalized Process & Material Development

Special expertise: Process monitoring, experimental-simulative characterization of processing behavior (esp. permeability), Resin injection/infusion, Preforming

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