Assessment of Analytical Orientation Prediction Models for Suspensions Containing Fibers and Spheres
, Fatih Bosna 1, Harald Kruggel-Emden 2, Torsten Kraft 1 and Claas Bierwisch 1Round 1
Reviewer 1 Report
The primary discussion of the article is the ability of the Folgar-Tucker model to capture the orientation evolution of a multiphase material (matrix, fiber, sphere). This, however, is only part of the discussions in the article. The authors have an intermediate grasp of the current state of the art and the scientific reasoning leading to that state of the art and the discussions reflect this. I have provided some article suggests which may illuminate some of the existent questions in the present manuscript. I recommend publication with editing primarily of the conclusions and some of the introduction to better discuss the limitations of the work as discussed in the points below.
In [1], Tucker and Advani discuss the difference in increasing trends with particle factor vs decreasing trends. In Table 1.1 the authors miss the pARD and pARD-RPR models by Huang-Chang Tseng [2]. I recommend the authors review the article by Favaloro and Tucker [3] which critically evaluated the various diffusion models.
In the conclusion, the authors note that the advanced rheology models do not show a significant benefit. This is due to 2 reasons. First, the models that “slow” the orientation kinetics (models with RSC and RPR) will not be required to fit their simulation data as to date direct numerical simulations have been unable to capture the slow orientation kinetics seen in physical data. Next, the 2D simulations do not require a complex model which captures the difference in diffusion between the 2nd and 3rd direction because there is no 3rd direction. The anisotropic diffusion models (ARD, iARD, pARD, MRD) all exist to solve this problem which cannot be captured in 2D. Again, the authors should review the article by Favaloro and Tucker and adjust discussions accordingly.
In the conclusion, the authors recommend rheology models which depend upon the orientation state. These do exist though have been difficult to apply to real problems (full part simulations). However, recent rheology models in [4-6] have been successful in full part filling simulations with a coupled rheology model.
[1] Tucker CL, Advani SG. Processing of Short-Fiber Systems. Flow Rheol. Polym. Compos. Manuf., Elsevier Science B.V.; 1994, p. 147–203.
[2] Tseng H-C, Chang R-Y, Hsu C-H. The use of principal spatial tensor to predict anisotropic fiber orientation in concentrated fiber suspensions. J Rheol (N Y N Y) 2018;62:313–20. doi:10.1122/1.4998520.
[3] Favaloro AJ, Tucker CL. Analysis of anisotropic rotary diffusion models for fiber orientation. Compos Part A Appl Sci Manuf 2019;126:105605. doi:10.1016/j.compositesa.2019.105605.
[4] Favaloro AJ, Tseng HC, Pipes RB. A new anisotropic viscous constitutive model for composites molding simulation. Compos Part A Appl Sci Manuf 2018;115:112–22. doi:10.1016/j.compositesa.2018.09.022.
[5] Tseng H-C, Favaloro AJ. The use of informed isotropic constitutive equation to simulate anisotropic rheological behaviors in fiber suspensions. J Rheol (N Y N Y) 2019;63:263–74. doi:10.1122/1.5064727.
[6] Li T, Luyé J-F. Flow-Fiber Coupled Viscosity in Injection Molding Simulations of Short Fiber Reinforced Thermoplastics. Int Polym Process 2019;34:158–71. doi:10.3139/217.3706.
Author Response
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Author Response.docx
Reviewer 2 Report
The authors have investigated the prediction of the orientation of particles of two different aspect ratios based on the analytical model of Folgar Tucker (FT). The have clearly specified three questions to address during this study:
1) Can the FT model predict the orientation of suspensions of two aspect ratios fibers with circular particles?
2) Is it possible to formulate the Folgar Tucker model parameter that is based on the suspension composition?
3) Is there an advantage to choose more complex orientation prediction models, which require the adjustment of additional model parameters?
The structure of the paper, results and the provided interpretations are solid enough. The reviewer appreciates the paper in its current form.
Author Response
We thank the reviewer for the comments and the time spent to review our manuscript.
Round 2
Reviewer 1 Report
The authors have done well to improve the clarity of their manuscript with their voluntary edits and incorporation of the suggested edits. I recommend publication.
