A model for fiber length attrition in injection-molded long-fiber composites

Phelps, Jay H.; El-Rahman, Ahmed I. Abd; Kunc, Vlastimil; Tucker, Charles L.

doi:10.1016/j.compositesa.2013.04.002

Cited by 109 publications

(78 citation statements)

References 37 publications

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“…There are two parameters in the BR model closely related with fiber length: the half fiber length, ,lb and the flexibility parameter. With this feature, the BR model provides us an opportunity to investigate fiber breakage during the mold filling process.Based on Dinh [8]and Armstrong's work, Tucker's [9]group proposed an orientation based fiber breakage model. In this work, Tucker's hydrodynamic force model was coupled with the BR model, and both the average fiber length and the fiber orientation tensor were calculated at each time-step during the runner filling process of the GM sample.…”

Section: Preliminary Breakage Simulationmentioning

confidence: 99%

Progress in modeling long glass and carbon fiber breakage during injection molding

Chen¹,

Cieslinski²,

Baird³

2015

AIP Conference Proceedings

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Abstract. This work is concerned with the modeling of in-machine fiber breakage during injection molding. A lab-scale single screw extruder is used to evaluate fiber breakage in the screw. Our experiments show that as the initial glass fiber pellets length is reduced relative to the channel width, the overall percent of breakage is reduced. We believe that the ratio of initial pellet length to the screw channel width, or diameter, is an important parameter determining the percent of fiber breakage. Data have been fit using an exponential decay model with a kinetic decay constant and a critical length value. This empirical model has been tested on an injection molding machine with a screw 1.6 times larger than that of our single screw extruder. The predicted average fiber length leaving the nozzle shows reasonable agreement with the measured value. For the injection molded end-gated-plaque produced by the same machine, additional fiber breakage has been observed in the runner. A hydrodynamic force based breakage model is combined with mold filling simulation to simulate the fiber breakage in the runner. For carbon fibers, similar breakage trends were observed in the single screw extruder indicating the applicability of our empirical model to carbon fiber.

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Section: Preliminary Breakage Simulationmentioning

confidence: 99%

Progress in modeling long glass and carbon fiber breakage during injection molding

Chen¹,

Cieslinski²,

Baird³

2015

AIP Conference Proceedings

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“…Model parameters which have to be defined are: D g which is a drag coefficient, C B which is a phenomenological parameter scaling the breakage rate, and S which is an additional fitting parameter. All parameters are described in detail in [2].…”

Section: Prediction Of Fibre Length Attritionmentioning

confidence: 99%

“…In the last years newly developed FO-Models have been implemented into commercial software which claim to improve the orientation prediction for SFT on the one hand and enable to predict the orientation of long fibre-reinforced thermoplastics (LFT) on the other hand. Very recently also a Fibre Length (FL) attrition model has been published by Phelps et al [2] which is also implemented into the commercial filling simulation Moldflow, Autodesk Inc., San Rafael, CA, USA.…”

Section: Motivation and Introductionmentioning

confidence: 99%

A validation of the fibre orientation and fibre length attrition prediction for long fibre-reinforced thermoplastics

Hopmann

Weber

Haag

et al. 2015

AIP Conference Proceedings

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Abstract. To improve the mechanical performance of polymeric parts, fibre reinforcement has established in industrial applications during the last decades. Next to the widely used Short Fibre-reinforced Thermoplastics (SFT) the use of Long Fibre-reinforced Thermoplastics (LFT) is increasingly growing. Especially for non-polar polymeric matrices like polypropylene (PP), longer fibres can significantly improve the mechanical performance. As with every kind of discontinuous fibre reinforcement the fibre orientations (FO) show a high impact on the mechanical properties. On the contrary to SFT where the local fibre length distribution (FLD) can be often neglected, for LFT the FLD show a high impact on the material's properties and has to be taken into account in equal measure to the FOD. Recently numerical models are available in commercial filling simulation software and allow predicting both the local FOD and FLD in LFT parts. The aim of this paper is to compare i.) the FOD results and ii) the FLD results from available orientation-and fibre length attrition-models to those obtained from experimental data. The investigations are conducted by the use of different injection moulded specimens made from long glass fibre reinforced PP. In order to determine the FOD, selected part sections are examined by means of Computed Tomographic (CT) analyses. The fully three dimensional measurement of the FOD is then performed by digital image processing using grey scale correlation. The FLD results are also obtained by using digital image processing after a thermal pyrolytic separation of the polymeric matrix from the fibres. Further the FOD and the FLD are predicted by using a reduced strain closure (RSC) as well as an anisotropic rotary diffusionreduced strain closure model (ARD-RSC) and Phelps-Tucker fibre length attrition model implemented in the commercial filling software Moldflow, Autodesk Inc., San Rafael, CA, USA.

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“…The residual fiber length exhibited a linear decrease following an increase in the fiber content [14,35]. Several authors also suggested that the fiber breakage rate was proportional to the fiber length or fiber aspect ratio [12,36]. The calculated bundle size, d c , for those longer fibers is very large, especially for the 50 wt% fiber content.…”

Section: Resultsmentioning

confidence: 89%

Prediction of Young’s Modulus for Injection Molded Long Fiber Reinforced Thermoplastics

Chen

Baird

2018

J. Compos. Sci.

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Abstract:In this article, the elastic properties of long-fiber injection-molded thermoplastics (LFTs) are investigated by micro-mechanical approaches including the Halpin-Tsai (HT) model and the Mori-Tanaka model based on Eshelby's equivalent inclusion (EMT). In the modeling, the elastic properties are calculated by the fiber content, fiber length, and fiber orientation. Several closure approximations for the fourth-order fiber orientation tensor are evaluated by comparing the as-calculated elastic stiffness with that from the original experimental fourth-order tensor. An empirical model was developed to correct the fibers' aspect ratio in the computation for the actual as-formed LFTs with fiber bundles under high fiber content. After the correction, the analytical predictions had good agreement with the experimental stiffness values from tensile tests on the LFTs. Our analysis shows that it is essential to incorporate the effect of the presence of fiber bundles to accurately predict the composite properties. This work involved the use of experimental values of fiber orientation and serves as the basis for computing part stiffness as a function of mold filling conditions. The work also explains why the modulus tends to level off with fiber concentration.

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A model for fiber length attrition in injection-molded long-fiber composites

Cited by 109 publications

References 37 publications

Progress in modeling long glass and carbon fiber breakage during injection molding

Progress in modeling long glass and carbon fiber breakage during injection molding

A validation of the fibre orientation and fibre length attrition prediction for long fibre-reinforced thermoplastics

Prediction of Young’s Modulus for Injection Molded Long Fiber Reinforced Thermoplastics

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