Accurate predictions of orientation dependent modulus in short‐fiber‐reinforced composite with experimental validation

Tseng, Huan-Chang; Chang, Rong‐Yeu; Hsu, Chia-Hsiang

doi:10.1002/pc.24277

Cited by 15 publications

(15 citation statements)

References 25 publications

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“…Unfortunately, the RSC model is difficult to apply in practice because it is strongly influenced by the variable numerical values of inlet conditions 33 . Recently, in regard to this issue, Tseng et al 34,35 proposed a new model, called the improved anisotropic rotary diffusion and retarding principal rate (iARD‐RPR), which was experimentally verified to accurately predict the orientation distribution of short fibers in melts. The expression of the model is as follows:

\overset{A}{true} = {\dot{A}}^{HD} + {\dot{A}}^{iARD} ((),, C_{I}, C_{M}) + {\dot{A}}^{PRP} ((), α)

{\dot{A}}^{HD} = ((), W \cdot A - A \cdot W) + ξ ((), D \cdot A + A \cdot D - 2 A_{4} : D)

W = 1 / 2 ((), L - L^{T})

D = 1 / 2 ((), L + L^{T})

{\dot{A}}^{iARD} = \overset{γ}{true} ([], 2 D_{r} - 2 italictr ((), D_{r}) - 5 D_{r} \cdot A - 5 A \cdot D_{r} + 10 A_{4} : D_{r})

D_{r} = C_{I} ((), normalI ‐ C_{M} \frac{D^{2}}{‖D^{2}‖})

…”

Section: Numerical Simulation Theory Of Waim Analysismentioning

confidence: 99%

Formationmechanism of high‐pressure water penetration induced fiber orientation in overflow water‐assisted injection molded short glass fiber‐reinforced polypropylene

Zhang

Liu

Jiang

et al. 2021

J of Applied Polymer Sci

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Recently, there has been growing interest in water‐assisted injection molding (WAIM) not only for its advantages over gas‐assisted molding (GAIM) and conventional injection molding (CIM), but also for its great potential advantages in industrial applications. To understand the formation mechanism of water penetration induced fiber orientation in overflow water‐assisted injection molding (OWAIM) parts of short glass fiber‐reinforced polypropylene (SGF/PP), in this work, the external fields and water penetration process within the mold cavity were investigated by experiments and numerical simulations. The results showed that the difference of fiber orientation distribution in thickness direction between WAIM moldings and CIM moldings was mainly ascribed to the great external fields generated by water penetration. Besides, fiber orientation depended on the position both across the part thickness and along the flow direction. Especially in the radial direction, fiber orientation varied considerably. The results also showed that the melt temperature is the principal parameter affecting the fiber orientation along the flow direction, and a higher melt temperature significantly facilitated more fibers to be oriented along the flow direction, which is quite different from the results as previously reported in short‐shot water‐assisted injection molding (SSWAIM). A higher water pressure, shorter water injection delay time, and higher melt temperature significantly induced more fibers to be orderly oriented in OWAIM moldings, which may improve their mechanical performances and broaden their application scope.

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\overset{A}{true} = {\dot{A}}^{HD} + {\dot{A}}^{iARD} ((),, C_{I}, C_{M}) + {\dot{A}}^{PRP} ((), α)

{\dot{A}}^{HD} = ((), W \cdot A - A \cdot W) + ξ ((), D \cdot A + A \cdot D - 2 A_{4} : D)

W = 1 / 2 ((), L - L^{T})

D = 1 / 2 ((), L + L^{T})

{\dot{A}}^{iARD} = \overset{γ}{true} ([], 2 D_{r} - 2 italictr ((), D_{r}) - 5 D_{r} \cdot A - 5 A \cdot D_{r} + 10 A_{4} : D_{r})

D_{r} = C_{I} ((), normalI ‐ C_{M} \frac{D^{2}}{‖D^{2}‖})

…”

Section: Numerical Simulation Theory Of Waim Analysismentioning

confidence: 99%

Formationmechanism of high‐pressure water penetration induced fiber orientation in overflow water‐assisted injection molded short glass fiber‐reinforced polypropylene

Zhang

Liu

Jiang

et al. 2021

J of Applied Polymer Sci

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“…12,13 The iARD-RPR model can restore the standard Folgar–Tucker model, while the RPR model 13 has been demonstrated to be identical to the RSC model. The iARD-RPR model has been useful not only for predicting the skin–shell–core structure, but also in discussing the core width with respect to operation conditions, 14 mold geometries, 14 long/short fibers, 15 carbon/glass fibers, 15 and low/high fiber concentration, 16 as well as effect of the packing stage on fiber orientation. 17 The iARD-RPR model’s application value for allowing good orientation predictions has been virtually authenticated in the long carbon-fiber composite project of the Oak Ridge National Laboratory in the United States.…”

Section: Introductionmentioning

confidence: 99%

Comparison of recent fiber orientation models in injection molding simulation of fiber-reinforced composites

Tseng¹,

Chang²,

Hsu³

2018

Journal of Thermoplastic Composite Materials

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In the structural analysis of automotive products made of lightweight fiber-reinforced thermoplastics (FRT), the primary mechanical requirement is their relation to the orientation states of fibers. The famous Folgar–Tucker equation of fiber orientation has hitherto been used to predict the skin–shell–core structure of fiber orientation patterns for injection-molded fiber composites. However, this model results in inaccurate predictions regarding the thinner core width. To enhance the reliability of fiber orientation predictions, Tucker and coworkers rigorously derived the reduced strain closure and anisotropic rotary diffusion (ARD) models in relation to the theoretical rheology of fiber suspension. More recently, the improved ARD and retarding principal rate model and the Moldflow rotational diffusion model were developed and made available in the industry dealing with the state-of-the-art software of injection molding simulation. A deep understanding of these fiber models is important for achieving successful FRT structural analysis. In this work, we therefore investigate the accuracy of these fiber orientation models, as well as the changes in fiber orientation distribution related to model parameters and model objectivity.

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“…However, the RSC model is hard to be applied to the practical application of numerical simulation, because of the difficulty of deriving its reliable inlet conditions when handling complex geometries 38 . Recently, Tseng et al 28,38 developed a new model, namely Improved ARD and Retarding Principal Rate (iARD‐RPR) model, which proved that the numerical prediction of short fiber orientation obtained by this model was quite consistent with the experimental results. In this work, the iARD‐RPR model was adopted, and its expression is as below:

\overset{•}{A} goodbreak= {\overset{•}{A}}^{HD} goodbreak+ {\overset{•}{A}}^{iARD} ((),, C_{I}, C_{M}) goodbreak+ {\overset{•}{A}}^{PRP} ((), α)

{\overset{•}{A}}^{HD} goodbreak= ((), W \cdot A goodbreak- A \cdot W) goodbreak+ ξ ((), D \cdot A goodbreak+ A \cdot D goodbreak- 2 A_{4} : D)

W goodbreak= 1 / 2 ((), L goodbreak- L^{T})

D goodbreak= 1 / 2 ((), L goodbreak+ L^{T})

{\overset{•}{A}}^{iARD} goodbreak= \overset{•}{γ} ([], 2 D_{r} goodbreak- 2 italictr ((), D_{r}) goodbreak- 5 D_{r} \cdot A goodbreak- 5 A \cdot D_{r} goodbreak+ 10 A_{4} : D_{r})

D_{r} goodbreak= C_{I} ((), normalI ‐ C_{M} \frac{D^{2}}{‖D^{2}‖})

…”

Section: Theoretical Partmentioning

confidence: 75%

Numerical and experimental investigations on the mechanism of flow‐induced fiber orientation in short‐shot water‐assisted injection‐molded short‐glass‐fiber‐reinforced polypropylene

Zhang

Kuang

Liu

et al. 2022

J of Applied Polymer Sci

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It is a critical requirement to have an insight into the mechanism of flow-induced fiber orientation in short-shot water-assisted injection molding (SSWAIM) of fiberreinforced polymer for improving the structural rigidity and service life of molded parts. However, this mechanism is still unclear, which stunts the development of SSWAIM. In this work, the mechanism of flow-induced fiber orientation in SSWAIM parts of short-glass-fiber-reinforced polypropylene (SGF/PP) was clarified through numerical research and experimental verification. The results showed that the difference of fiber orientation distribution at different positions both in the radial direction and along the flow direction between SSWAIM parts and conventional injection molding (CIM) parts was mainly due to the strong flow field caused by the high-pressure water penetration in SSWAIM. Moreover, fiber orientation in the SSWAIM part depended not only on its position both in the radial direction and along the flow direction, but also on the processing parameters. At the front of SSWAIM part, fiber orientation changed greatly in the radial direction and presented an obvious "shell layer-core layer-water channel layer" hierarchical structure across the part thickness, whereas this phenomenon became more inconspicuous with increasing the distance of the selected position from the water injection inlet.Short-shot size is the principal parameter affecting the fiber orientation, and within the range of investigated processing parameters, smaller short-shot size, shorter water injection delay time, higher water pressure, and lower melt temperature could significantly facilitate fiber orientation across the part thickness.

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Accurate predictions of orientation dependent modulus in short‐fiber‐reinforced composite with experimental validation

Cited by 15 publications

References 25 publications

Formationmechanism of high‐pressure water penetration induced fiber orientation in overflow water‐assisted injection molded short glass fiber‐reinforced polypropylene

Formationmechanism of high‐pressure water penetration induced fiber orientation in overflow water‐assisted injection molded short glass fiber‐reinforced polypropylene

Comparison of recent fiber orientation models in injection molding simulation of fiber-reinforced composites

Numerical and experimental investigations on the mechanism of flow‐induced fiber orientation in short‐shot water‐assisted injection‐molded short‐glass‐fiber‐reinforced polypropylene

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