The Effect of Impacted Fracture in Glass Fiber Orientation with Injection Molding & Structural Coupled Analysis

2017 ◽  
Vol 25 (1) ◽  
pp. 35-41
Author(s):  
Woong Kim ◽  
JongRyang Kim
Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 360 ◽  
Author(s):  
Hyun Kim ◽  
Joo Sohn ◽  
Youngjae Ryu ◽  
Shin Kim ◽  
Sung Cha

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.


2018 ◽  
Vol 38 (6) ◽  
pp. 513-523 ◽  
Author(s):  
Wiranphat Thodsaratpreeyakul ◽  
Putinun Uawongsuwan ◽  
Akio Kataoka ◽  
Takanori Negoro ◽  
Hiroyuki Hamada

Abstract Improving the applicability of polyethylene terephthalate (PET) by carbon fiber/glass fiber reinforcement is of great interest. Glass fiber (GF)/carbon fiber (CF)/PET hybrid composites were fabricated by direct fiber feeding injection molding (DFFIM) process. The aim of DFFIM is to obtain longer fibers in composites in order to improve their mechanical properties. In this study, the mechanical properties of GF/PET composites fabricated by conventional injection molding and hybrid GF/CF/PET composites fabricated by DFFIM process were investigated. The influence of GF and CF volume fractions on fiber distribution, fiber orientation, and fiber length is discussed. Fiber distribution status was quantitatively measured by the fiber distribution index. Fiber agglomeration problem was observed by scanning electron microscopy. The results indicate that incorporating CF in GF/CF/PET hybrid composites by the DFFIM process greatly enhances mechanical performance even when only a small amount of CF is added. Too high GF content leads to less effective CF hybridization because it causes poor fiber distribution and poor fiber orientation and intensifies fiber attrition. The ideal volume fractions of GF and CF for fabricating GF/CF/PET hybrid composites by using DFFIM are provided.


2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Jang Min Park ◽  
Seong Jin Park

We review the fundamental modeling and numerical simulation for a prediction of fiber orientation during injection molding process of polymer composite. In general, the simulation of fiber orientation involves coupled analysis of flow, temperature, moving free surface, and fiber kinematics. For the governing equation of the flow, Hele-Shaw flow model along with the generalized Newtonian constitutive model has been widely used. The kinematics of a group of fibers is described in terms of the second-order fiber orientation tensor. Folgar-Tucker model and recent fiber kinematics models such as a slow orientation model are discussed. Also various closure approximations are reviewed. Therefore, the coupled numerical methods are needed due to the above complex problems. We review several well-established methods such as a finite-element/finite-different hybrid scheme for Hele-Shaw flow model and a finite element method for a general three-dimensional flow model.


2005 ◽  
Vol 13 (2) ◽  
pp. 121-130 ◽  
Author(s):  
V. Rizov ◽  
T. Harmia ◽  
A. Reinhardt ◽  
K. Friedrich

The fracture toughness of discontinuous long glass fiber reinforced injection-molded polypropylene has been characterized by using the microstructural efficiency concept in combination with a numerical prediction of the fiber orientation during injection molding. The latter was performed by using the SIGMASOFT commercial software. In a three-dimensional numerical scheme, input data such as fiber volume fractions, shear viscosity and mean fiber aspect ratio have been used in order to perform the mold filling analysis. The resulted local fiber orientation parameters for injection molded square plates of long glass fiber reinforced polypropylene allowed to calculate the local fracture toughness with microstructural efficiency concept. The latter were compared with the experimental toughness values obtained by the use of compact tension test specimens. The good correlation between the calculated fracture toughness data and the measured ones shows that a fiber orientation prediction by the SIGMASOFT finite element computer code can be used in combination with the microstructural efficiency concept for the determination of local fracture toughness values in injection molded long glass fiber reinforced thermoplastics. The combined approach opens good opportunities for optimization of a thermoplastic workpiece in its design with respect to local fracture resistance. This will enable the material performance levels to be significantly extended, with consequent increases in engineering applicability.


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