The Story of Permeability in Liquid Composite Molding (LCM): How to Devise and Validate Process Simulation Software? | Francois Trochu

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:globe_with_meridians: Expert Lecture Spotlight | Prof. François Trochu
The Story of Permeability in Liquid Composite Molding (LCM): How to Devise and Validate Process Simulation Software

In the world of Liquid Composite Molding (LCM), permeability is a fundamental yet elusive parameter—crucial to simulating resin flow, mold filling, and ultimately ensuring high-quality composite parts. But what exactly is permeability in the context of LCM? And how can we measure it with confidence?

In this illuminating lecture, Prof. François Trochu traces the evolution of permeability modeling from its early roots in the 1980s, when Darcy’s Law was first applied to Resin Transfer Molding (RTM), to today’s nuanced understanding that underpins process simulation tools used across academia and industry.

:magnifying_glass_tilted_left: Key insights from the lecture include:

  • The debate between saturated permeability (Darcy-based) and unsaturated process permeability unique to LCM
  • Challenges due to the intrinsic variability of fibrous reinforcements
  • Why measurement techniques still yield divergent results, and how test setup and process variant (e.g., RTM, VARI) influence outcomes

Prof. Trochu introduces the concept of “process permeability”—a practical definition tailored to simulation validation—and explores specialized variants:

  • Rigid mold permeability characterization (1D, 2D, through-thickness)
  • “Flexible permeability” for Vacuum-Assisted Resin Infusion (VARI) without distribution media
  • “Apparent permeability” for indirect infusion with flow media
  • A novel single-experiment approach that combines permeability measurement with preform compaction data for predictive mold filling and thickness variation

:wrench: Throughout the talk, experimental results are systematically compared with simulation predictions, offering a clear path toward validation of LCM modeling tools.

Whether you’re a researcher, engineer, or software developer in composites, this talk delivers a deep dive into why permeability matters, how we define it, and how we can measure it reliably to improve simulation accuracy and process control.

:television: Watch now on the cdmHUB YouTube channel as part of the Global Composites Expert Webinar Series.