RTM simulation within Shaper

RTM simulation with Shaper

Simulation vs. Experiment



At iChrome we are proud to release the alpha version of our Resin Transfer Molding (RTM) solver, namely Shaper RTM.
Shaper RTM, is the result of an Innovate UK co-funded research project between iChrome Ltd, the Univ. of Bristol and Wilson Benesch with the ambition to set new standards for those SMEs that need affordable and reliable RTM manufacturing simulations (more information about the FastRTM project can be found HERE).

Resin Transfer Molding is largely used for the manufacturing of high-quality composite components and it is based around the idea of infusing resin within dry composite fibers. In RTM manufacturing a dry fibrous preform is thus placed in the mold cavity. The resin enters the mold through a number of injection inlets and slowly flows within the mold and the porous fibers.

Shaper RTM, as other well established products on the market such as PamRTM, LIMS and Polyworks, uses the so-called Darcy’s Law to correlate pressure field and resin velocity inside the fibrous domain. Shaper RTM uses a standard FE approach to compute the pressure field within the mold at each analysis step and a dual mesh to define a finite volume mesh to compute the resin front and velocity within the porous fibers.

This post is intended to be a first public and free benchmark of the Shaper RTM solver.

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The experimental Test:

The experimental benchmark is a relatively simple square panel of side 38mm. The panel preform is made up of 11 plies of C0475 carbon fibers. Plies are inserted into a 4mm mold, leading to a theoretical injection with fiber volume of 0.44.

The rationale of the test is to assess the resin front at a given time. Hence, Wilson Benesch performed 5 injections, with interruption time of 10 minutes. The resin flow is thus interrupted after 10 minutes, the panels are extracted from the mold and the resin front measured.

Injections were made at room temperature of T=20.5C. Inlet and outlet pressures were measured during the tests with an average differential in pressure of 198885 Pa.

Panel Coupon
Fig 1: A panel coupon – 10 minutes injection

Measured resin front:

Panel R1 (mm) R2 (mm)
Panel 01 131 122
Panel 02 134 131
Panel 03 132 122
Panel 04 133 125
Panel 05 138 131
Average 134 126

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Numerical Model Set up:

Shaper RTM was used to reproduce the experimental tests. Permeability values have been derived from permeability tests performed at the University of Nottingham, returning the following:

K11 m^2 K22 m^2
3.25E-11 2.83e-11

Resin viscosity at the test temperature of 20.5 C was derived from the data provided by the resin vendor, being of 0.374 Pa*s.

Despite Shaper RTM solver support a variety of FE elements (tria, quad, tetra and brick linear elements) a pure quadrilateral shell mesh was used to model the panel due to the relative simple geometry. This is also justified by the fact that the resin front is uniform through the thickness thanks to the central hole introduced in the experiments. Never the less quite a refined mesh of 4944 elements has been used.

FE meshFig 2: Finite Element Mesh

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This section briefly reports the obtained numerical results. Shaper RTM solver required about 4 minutes of running time to complete the analysis, i.e. to simulate the complete filling of the panel. Accordingly to the numerical simulation, a full injection will require 1995 seconds to complete, i.e. about 33 minutes.

Fill Factor at 300s

Fig 3: Filling Factors at 300 seconds

Fill Factor at 600s

Fig 4: Filling Factors at 600 seconds

When comparing the simulation flow front with the experimental one at a filling time of 10 minutes (600 seconds), the following results are achieved:

Description R1 R2
Experiment (average) 138 mm 131 mm
Numerical (Shaper RTM) 136 mm 125 mm
Difference 1.44 % 4.58 %

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This post provides a first valuable benchmark of our new solver for RTM simulation, namely Shaper RTM. Despite being an alpha release still under development, the Darcy solver available in Shaper is to be able to predict Resin Injection with accuracy levels similar to the other commercial products on the market.
You can download and have a trial of this first release of Shaper RTM from the main Fast RTM website .
Would you like to have any early commercial information about the solver, don’t hesitate to get in contact with us at info@ichrome.eu


This work is made possible thanks to Innovate UK funding. iChrome wishes to thank the FastRTM project partners for the work done so far.

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