Stereolithography Specimen to Calibrate Permeability Measurements for RTM Flow Simulations

Abstract

The simulation of a resin flow through a porous medium by FE-models has become a very important aspect for the design of a high-performance RTM produced composite part. The key parameter to perform RTM flow simulations is the fibre reinforcement permeability. Unfortunately, permeability measurements are not yet fully standardized and thus many different set-ups have been proposed. A major problem in comparing different set-ups has always been the fact that there exists no reliable reference material on which a comparative permeability measurement can be performed. This paper presents a solid test specimen, produced with a stereolithography technique, which can be used as a reference sample for calibration of test rigs and for comparison of results from different test rigs. Since the permeability properties of the specimen do not vary from test to test, an excellent repeatability of the experiments is obtained and any measured difference must be attributed to the set-up.

Design and Evaluation of an Idealized Porous Medium for Calibration of Permeability Measuring Devices

“…In Table 1, the cited principle permeability values for the unit cell are listed along with values obtained through the CFD simulations. As can be seen from the table, results for K 1 from simulation closely match that listed in the literature [9]. The observed small discrepancy is expected.…”

“…This gap was to be filled with a gasket as described in section 4.1. Similarly, the thickness of the material was less than the thickness [9] and the Fluent © simulation results for the original unit-cell. of the mold cavity.…”

“…In these equations, r 0 is the radius of the inlet, x 1 is the x-coordinate of the first pressure transducer, y 2 is the y-coordinate of the second pressure transducer, h is the thickness of the preform, and Q is the constant volumetric flow-rate of the test fluid. Using the pressure and flow rate data collected during steady-state operation of the radial flow experiment, Eqs (12) and (13) can be solved simultaneously for α and Κ eff , which are defined according to Eqs (8) and (9). These values can then be substitute into Eqs (10) and (11) to find the principle permeability values [14].…”

“…The values for the principle permeabilities of the unit-cell structure adopted for the present work are listed by Morren et al [9]. To validate these values, the unit-cell structure shown in Figs.…”

Calibration of one‐dimensional flow setup used for estimating fabric permeability using three different reference media

“…The lattice‐like reference medium, based on the design proposed by Morren et al , was created by repeating a unit‐cell structure in plastic with stereo‐lithography (Fig. b), with the dimensions of each unit‐cell being much smaller than the overall medium dimensions.…”