scholarly journals Effect of the Post-Filling Stage on Fiber Orientation at the Mid-Plane in Injection Molding of Reinforced Thermoplastics

2012 ◽  
Vol 25 ◽  
pp. 79-85 ◽  
Author(s):  
Parvin Shokri ◽  
Naresh Bhatnagar
Keyword(s):  
Injection Molding ◽  
Fiber Orientation ◽  
Filling Stage ◽  
Reinforced Thermoplastics

Effect of the packing stage on fiber orientation for injection molding simulation of fiber-reinforced composites

2017 ◽  
Vol 31 (9) ◽  
pp. 1204-1218 ◽  
Author(s):  
Huan-Chang Tseng ◽  
Rong-Yeu Chang ◽  
Chia-Hsiang Hsu
Keyword(s):  
Injection Molding ◽  
Fiber Orientation ◽  
Mathematic Model ◽  
Fiber Reinforced Composites ◽  
Experimental Investigations ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Filling Stage ◽  
Packing Pressure ◽  
Injection Molding Simulation

During the packing or post-filling stage, a significant flow of polymer inside the cavity may result due to the compressibility of the polymer melt under the higher packing pressure of the injection molding process. In the meantime, the effect of the packing stage on the shell–core structure of the fiber orientation for the fiber-reinforced composites has always been a concern. Even though certain commercial packages have undergone unified simulations of the filling and packing stages, fiber orientation has usually been determined at the end of the filling stage. A recently proposed mathematic model, Improved Anisotropic Rotary Diffusion and Retarding Principal Rate, having incorporated the state-of-the-art technology of 3D injection molding simulation, has demonstrated its ability to provide reliable predictions of fiber orientation. The present numerical results concentrate on comparing and analyzing the difference in fiber orientation between the filling and packing stages, while the important effects of packing time and packing pressure are further revealed. A qualitative comparison of core thickness widths in related experimental investigations is discussed herein.

scholarly journals Calibration of Fiber Orientation Simulations for LFT—A New Approach

2020 ◽  
Vol 4 (4) ◽  
pp. 163
Author(s):  
Fabian Willems ◽  
Philip Reitinger ◽  
Christian Bonten
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Process Simulation ◽  
Fiber Orientation ◽  
Model Parameters ◽  
Fiber Reinforced ◽  
Orientation Model ◽  
Fiber Microstructure ◽  
Reinforced Thermoplastics ◽  
Fiber Reinforced Thermoplastics

Short fiber reinforced thermoplastics (SFT) are extensively used due to their excellent mechanical properties and low processing costs. Long fiber reinforced thermoplastics (LFT) show an even more interesting property profile and are increasingly used for structural parts. However, their processing by injection molding is not as simple as for SFT, and their anisotropic properties resulting from the fiber microstructure (fiber orientation, length, and concentration) pose a challenge with regard to the engineering design process. To reliably predict the structural mechanical properties of fiber reinforced thermoplastics by means of micromechanical models, it is also necessary to reliable predict the fiber microstructure. Therefore, it is crucial to calibrate the underlying prediction models, such as the fiber orientation model, within the process simulation. In general, these models may be adjusted manually, but this is usually ineffective and time-consuming. To overcome this challenge, a new calibration method was developed to automatically calibrate the fiber orientation model parameters of the injection molding simulation by means of optimization methods. This optimization routine is based on experimentally determined fiber orientation distributions and leads to optimized parameters for the fiber orientation prediction model within a few minutes. To better understand the influence of the model parameters, different versions of the fiber orientation model, as well as process and material influences on the resulting fiber orientation distribution, were investigated. Finally, the developed approach to calibrate the fiber orientation model was compared with a classical approach, a direct optimization of the whole process simulation. Thereby, the new optimization approach shows a calculation time reduced by the factor 15 with comparable error variance.

scholarly journals Warpage Reduction of Glass Fiber Reinforced Plastic Using Microcellular Foaming Process Applied Injection Molding

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 360 ◽  
Author(s):  
Hyun Kim ◽  
Joo Sohn ◽  
Youngjae Ryu ◽  
Shin Kim ◽  
Sung Cha
Keyword(s):  
Injection Molding ◽  
Glass Fiber ◽  
Fiber Orientation ◽  
Mechanical And Thermal Properties ◽  
Micro Ct ◽  
Fiber Reinforced ◽  
Foaming Process ◽  
Microcellular Foaming ◽  
Glass Fiber Reinforced ◽  
The Impact

This study analyzes the fundamental principles and characteristics of the microcellular foaming process (MCP) to minimize warpage in glass fiber reinforced polymer (GFRP), which is typically worse than that of a solid polymer. In order to confirm the tendency for warpage and the improvement of this phenomenon according to the glass fiber content (GFC), two factors associated with the reduction of the shrinkage difference and the non-directionalized fiber orientation were set as variables. The shrinkage was measured in the flow direction and transverse direction, and it was confirmed that the shrinkage difference between these two directions is the cause of warpage of GFRP specimens. In addition, by applying the MCP to injection molding, it was confirmed that warpage was improved by reducing the shrinkage difference. To further confirm these results, the effects of cell formation on shrinkage and fiber orientation were investigated using scanning electron microscopy, micro-CT observation, and cell morphology analysis. The micro-CT observations revealed that the fiber orientation was non-directional for the MCP. Moreover, it was determined that the mechanical and thermal properties were improved, based on measurements of the impact strength, tensile strength, flexural strength, and deflection temperature for the MCP.

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