RTMsim review
A focused, free RTM filling solver for teams working with composite preforms.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
RTMsim is an open-source Julia module for simulating resin-transfer-moulding filling in thin-walled fiber-reinforced polymer composites. It is aimed at engineers and researchers designing or validating RTM manufacturing concepts, including manufacturing teams that need to examine how resin fills a porous preform. Its specialized purpose makes it a more natural fit for RTM work than for teams seeking a general-purpose physics simulation environment.
The solver takes triangular shell meshes representing a part’s mid-surface and lets users specify porosity, thickness and directional permeability. Pressure inlet, vent and preform-region patches define the flow setup. GUI workflows support starting, continuing and interactively running simulations, with graphical inlet-port selection; mesh and cell-set inspection plots can help examine the model. These capabilities make the tool relevant when the key task is studying resin filling and pressure in a defined composite preform, rather than modeling unrelated physical systems.
Results include filling and pressure contour plots, and saved results can be used to restart simulations. RTMsim also provides command-line and Julia API functions, with package-manager installation, alongside its desktop GUI. The Windows GUI is available, while the Linux GUI is described as experimental; documentation was generated in March 2023. Teams comfortable with a focused Julia tool and desktop workflow may find its narrow solver a fit. Those needing a broader multiphysics package or a less experimental Linux GUI should consider alternatives.
RTMsim pros and cons
- Where it wins
- Models porous preforms with thickness, porosity and directional permeability.
- Supports pressure inlets, vents and preform-region patches on triangular shell meshes.
- Offers interactive runs, restartable simulations and filling and pressure plots.
- Where it doesn't
- Its scope is focused on RTM filling rather than broader physics simulation.
- The Linux GUI is experimental; the Windows GUI is also available.
- Documentation was generated in March 2023.
RTMsim fact sheet, pricing and score →
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