scholarly journals Numerical Simulation and Experimental Validation of Hybrid Injection Molded Short and Continuous Fiber-Reinforced Thermoplastic Composites

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3846
Author(s):  
Patrick Hirsch ◽  
Marianne John ◽  
Daniel Leipold ◽  
André Henkel ◽  
Sylvia Gipser ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Injection Molding ◽  
Mechanical Behavior ◽  
Test Structure ◽  
Thermoplastic Composites ◽  
Fiber Reinforced ◽  
Continuous Fiber ◽  
Injection Molded ◽  
Hybrid Test ◽  
Hybrid Injection

In-situ thermoforming and overmolding of continuous fiber-reinforced thermoplastic composites by hybrid injection molding enables the mass production of thermoplastic lightweight structures with a complex geometry. In this study, the anisotropic mechanical behavior of such hybrid injection molded short and continuous fiber-reinforced thermoplastics and the numerical simulation of the resulting mechanical properties under flexural loading were investigated. For this, the influence of the volume flow rate between 25 and 100 cm3/s during injection molding of a PP/GF30 short fiber-reinforced overmolding material was studied and showed a strong effect on the fiber orientation but not on the fiber length, as investigated by computer tomography and fiber length analysis. Thus, the resulting anisotropies of the stiffness and strength as well as the strain hardening investigated by tensile testing were considered when the mechanical behavior of a hybrid test structure of short and continuous fiber-reinforced thermoplastic composites was predicted by numerical simulations. For this, a PP/GF60 and PP/GF30 hybrid injection molded test structure was investigated by a numerical workflow with implemented injection molding simulation data. In result, the prediction of the mechanical behavior of the hybrid test structure under flexural loading by numerical simulation was significantly improved, leading to a reduction of the deviation of the numerically predicted and experimentally measured flexural strength from 21% to 9% in comparison to the isotropic material model without the implementation of the injection molding data.

scholarly journals A General and Efficient Approach for the Dual-Scale Infiltration Flow Balancing in In Situ Injection Molding of Continuous Fiber Reinforced Thermoplastic Composites

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2689
Author(s):  
Xiansong He ◽  
Yi Liu ◽  
Wangqing Wu
Keyword(s):  
Injection Molding ◽  
Capillary Number ◽  
Injection Rate ◽  
Thermoplastic Composites ◽  
Fiber Bundles ◽  
Capillary Effect ◽  
Fiber Reinforced ◽  
Continuous Fiber ◽  
Dual Scale

In situ injection molding of continuous fiber reinforced thermoplastic composites is challenged by unbalanced dual-scale infiltration flow due to the pronounced capillary effect. In this paper, a general and efficient approach was proposed for dual-scale infiltration flow balancing based on numerical simulation. Specifically, Stokes and Brinkman equations were used to describe the infiltration flow in inter- and intra-fiber bundles. In particular, capillary pressure drop was integrated in the Brinkmann equation to consider the capillary effect. The infiltration flow front is tracked by the level set method. Numerical simulation and experimental results indicate that the numerical model can accurately demonstrate the unbalanced infiltration flow in inter- and intra-fiber bundles caused by the changes of the injection rate, the resin viscosity, the injection rate, the fiber volume fraction and the capillary number. In addition, the infiltration flow velocity in inter- and intra-fiber bundles can be efficiently tuned by the capillary number, which is mainly determined by the injection rate for a specified resin system. The optimal capillary numbers obtained by simulation and experiment are 0.022 and 0.026, which are very close to each other. Finally, one-dimensional in situ injection molding experiments with constant injection pressure were conducted to prepare fiber reinforced polymerized cyclic butylene terephthalate composite laminate with various flow rates along the infiltration direction. The experimental results confirmed that the lowest porosity and the highest interlaminar shear strength of the composite can only be obtained with the optimized capillary number, which is basically consistent with the simulation results.

Impacts of thermoplastics content on mechanical properties of continuous fiber-reinforced thermoplastic composites

2021 ◽  
Vol 216 ◽  
pp. 108859
Author(s):  
Dong-Jun Kwon ◽  
Neul-Sae-Rom Kim ◽  
Yeong-Jin Jang ◽  
Hyun Ho Choi ◽  
Kihyun Kim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermoplastic Composites ◽  
Fiber Reinforced ◽  
Continuous Fiber

Potentiality of Continuous Fiber Reinforced Thermoplastic Composites

2021 ◽  
pp. 408-412
Author(s):  
Koji Kameo ◽  
Georg Bechtold ◽  
Hiroyuki Hamada ◽  
Klaus Friedrich
Keyword(s):  
Thermoplastic Composites ◽  
Fiber Reinforced ◽  
Continuous Fiber

Elastic properties of injection molded short glass fiber reinforced thermoplastic composites

2020 ◽  
Vol 254 ◽  
pp. 112850
Author(s):  
Yucheng Zhong ◽  
Ping Liu ◽  
Qingxiang Pei ◽  
Viacheslav Sorkin ◽  
Athanasius Louis Commillus ◽  
...  
Keyword(s):  
Glass Fiber ◽  
Elastic Properties ◽  
Thermoplastic Composites ◽  
Fiber Reinforced ◽  
Short Glass Fiber ◽  
Glass Fiber Reinforced ◽  
Injection Molded ◽  
Short Glass

Restraint of Voids Generated Inside Injection Molded Products by In-Mold Pressing Method

2018 ◽  
Vol 12 (6) ◽  
pp. 930-939 ◽  
Author(s):  
Atsushi Motegi ◽  
Tomohiro Hishida ◽  
Yasuhiko Murata ◽  
◽  
Keyword(s):  
Injection Molding ◽  
High Strength ◽  
Compression Molding ◽  
Fiber Reinforced ◽  
Pressing Method ◽  
Glass Fiber Reinforced Plastic ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Injection Molded ◽  
Injection Compression Molding

In recent years, long glass fiber reinforced plastic and carbon fiber reinforced plastic have begun to be used for structural components that require high strength. As a result, thick-walled injection molded products are being manufactured. However, defects, known as voids, are generated inside the molded product and decrease the strength of the molded product, posing a significant problem at molding production sites. The partial compression method, which is a type of injection compression molding, is effective in preventing voids in thick-walled injection molding. However, there have been limited studies that comprehensively investigated the effects of the compression conditions on void prevention in thick-walled injection molding products or the shape and dimension of the molded product, or the issues in the molded product produced by applying compression. The authors have previously proposed the in-mold pressing (IMP) method, which allows the application of partial compression without the use of an injection compression molding machine and verified its validity. In this study, we proposed a compression device in which a servomotor-driven hydraulic pump actuator is used to propel a movable rod to apply compression to the melt inside the mold cavity. The IMP method using this device was applied to mold thick-walled products with thicknesses of 10 mm and greater, and the effects of compression on the generation of voids inside the molded product and the shape and dimensions of the product were investigated. The results indicate that the generation of voids can be prevented by application of this method. In addition, it was found that marginal deformations, which can pose issues, occur in the molded product when compressive stresses generated inside the molded product by compression are released after demolding.

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