Fiber mat deformation in liquid composite molding. I: Experimental analysis

Han, Kunsoo; Trevino, L.; Lee, L. James; Liou, Ming J.

doi:10.1002/pc.750140208

Cited by 42 publications

(12 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because the fiber mats were compress ible, when the initial injection pressure was higher than the clamping pressure, the impact of injection caused the fiber mat to consolidate and further increased the pressure rise. Mat consolidation also resulted in a channel near the inlet, which reduced the flow resistance and the injection pressure (22). As the injection proceeded, these combined effects tended to keep the inlet pressure nearly constant, instead of increasing as predicted by simulation.…”

Section: Three-dimensional Mold Filling Simulationmentioning

confidence: 85%

“…Impregnation-pressure-induced permeability change should be taken into account in the mold filling prccess. In SRIM processes, it has been reported that a dry spot formed near the inlet when a high resin flow rate was applied (22). This is a n extreme case resulting from the flow-induced fiber mat consolidation.…”

Section: Effect Of Fiber Mat Consolidation On Trans-plane Permeabilitymentioning

confidence: 99%

See 1 more Smart Citation

Trans‐plane fluid permeability measurement and its applications in liquid composite molding

Wang

Lee

1994

Polymer Composites

View full text Add to dashboard Cite

This work discusses tow independent methods to measure and analyze the trans‐plane fjuid permeability of various fiber reinforcements. In the unidirectional flow method, the measured injection pressure and flow rate, together with a one‐dimensional Darcy's law were used to calculate the trans‐plane permeability of fiber mats was independent of flow rate only at low injection pressure. Flow‐induced fiber mat permeability change occurred when the injection pressure exceeded the clamping pressure. Measured permeability in conjunction with a three‐dimensional mold filling computer program was used to simulate the effect of stacking sequence for a combination of different fiber mats on the mold filling pattern. Finally, a method is proposed to simplify the simulation of a three‐dimensional flow through the fiber perform.

show abstract

Section: Three-dimensional Mold Filling Simulationmentioning

confidence: 85%

Section: Effect Of Fiber Mat Consolidation On Trans-plane Permeabilitymentioning

confidence: 99%

Trans‐plane fluid permeability measurement and its applications in liquid composite molding

Wang

Lee

1994

Polymer Composites

View full text Add to dashboard Cite

show abstract

“…A brief startup period is observed in which curve fits do not match measured pressure values due to hose bulging and possibly inlet effects, especially at higher volume fraction. It has been shown that mat deformation at the inlet gate may have considerable effect on fill pressure [41,42], which may also contribute to the observed startup effects. Deviation in pressure from the theoretical values at the startup is minimized by reinforcing the hose leading to mold inlet and reducing the total hose length.…”

Section: Permeability Resultsmentioning

confidence: 99%

Effect of Preform Thickness and Volume Fraction on Injection Pressure and Mechanical Properties of Resin Transfer Molded Composites

Olivero

Hamidi

Aktas

et al. 2004

Journal of Composite Materials

View full text Add to dashboard Cite

An experimental study is performed to characterize the effect of the thickness of random preforms on injection pressure and mechanical properties of resin transfer molded (RTM) parts. Center-gated, disk-shaped parts are molded using two different chopped-strand glass fiber preforms. Both preforms have random microstructure but different planar densities (i.e., different uncompressed layer thicknesses). Tensile strength, short-beam shear strength, and elastic modulus are measured for parts molded with each preform type at three different fiber volume fractions of 6.84, 15.55, and 24.83%. Although mechanical properties are found to increase linearly with volume fraction, significant difference is not observed between disks containing thick and thin mats at equivalent fiber volume fraction.However at the same fiber content, parts molded with thin mats require significantly lower injection pressures compared to parts containing thick mats. To characterize this phenomenon, a pressure-matching method to determine planar permeability is presented. Permeability values for each preform would provide a quantitative description of the required injection pressure due to changes in preform thickness, with lower permeabilities resulting in higher injection pressure. Transient pressure data is collected at a fixed radial location within the mold cavity during filling for both preforms at three different volume fractions. Permeability is obtained by fitting the theoretical pressure equation derived from Darcy's law to the transient pressure data. Permeability values are found to be as much as 227% higher for thin mats compared with thick mats at the same fiber content. The results demonstrate that equivalent mechanical properties can be obtained at lower injection pressures by using thinner random mats.

show abstract

“…However, several papers show or qualitatively describe deformation of the solid preform [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19] (see also [20] for a recent review of the subject).…”

Section: Introductionmentioning

confidence: 99%

Modeling Injection Molding Processes with Deformable Porous Preforms

Ambrosi¹,

Preziosi²

2000

SIAM J. Appl. Math.

View full text Add to dashboard Cite

This paper deduces a new model aimed at simulating injection molding processes under isothermal conditions. These processes can be generally stated as infiltration problems in initially dry porous materials. The spatial domain is then divided by the infiltration front into two time-dependent subdomains, the dry and the wet porous preforms, both being allowed to deform under the action of the liquid pressure. It is shown that the model calls for the definition of the stress-deformation relationship of both the dry and the wet preforms, which are assumed to behave elastically and inelastically, respectively. The coupled flow/deformation problem in the two regions (separated by an interface) is formulated with the corresponding boundary conditions and with the proper evolution equations determining the motion of the boundaries.The mathematical problem is solved numerically, highlighting the importance of inertial terms in the early stage of the infiltration and focusing on the influence of the mechanical properties of the material and on the deformation of the preform during the infiltration process.

show abstract

Fiber mat deformation in liquid composite molding. I: Experimental analysis

Cited by 42 publications

References 7 publications

Trans‐plane fluid permeability measurement and its applications in liquid composite molding

Trans‐plane fluid permeability measurement and its applications in liquid composite molding

Effect of Preform Thickness and Volume Fraction on Injection Pressure and Mechanical Properties of Resin Transfer Molded Composites

Modeling Injection Molding Processes with Deformable Porous Preforms

Contact Info

Product

Resources

About