scholarly journals Prediction of Young’s Modulus for Injection Molded Long Fiber Reinforced Thermoplastics

2018 ◽  
Vol 2 (3) ◽  
pp. 47 ◽  
Author(s):  
Hongyu Chen ◽  
Donald Baird
Keyword(s):  
Elastic Properties ◽  
Fourth Order ◽  
Fiber Orientation ◽  
Tensile Tests ◽  
Elastic Stiffness ◽  
Fiber Content ◽  
Fiber Bundles ◽  
Fiber Concentration ◽  
High Fiber ◽  
Injection Molded

In this article, the elastic properties of long-fiber injection-molded thermoplastics (LFTs) are investigated by micro-mechanical approaches including the Halpin-Tsai (HT) model and the Mori-Tanaka model based on Eshelby’s equivalent inclusion (EMT). In the modeling, the elastic properties are calculated by the fiber content, fiber length, and fiber orientation. Several closure approximations for the fourth-order fiber orientation tensor are evaluated by comparing the as-calculated elastic stiffness with that from the original experimental fourth-order tensor. An empirical model was developed to correct the fibers’ aspect ratio in the computation for the actual as-formed LFTs with fiber bundles under high fiber content. After the correction, the analytical predictions had good agreement with the experimental stiffness values from tensile tests on the LFTs. Our analysis shows that it is essential to incorporate the effect of the presence of fiber bundles to accurately predict the composite properties. This work involved the use of experimental values of fiber orientation and serves as the basis for computing part stiffness as a function of mold filling conditions. The work also explains why the modulus tends to level off with fiber concentration.

Weld Lining Strength of Injection Molded Jute/PLA and Jute/PP

2012 ◽  
Author(s):  
Cuntao Wang ◽  
Yuqiu Yang ◽  
Masuo Urakami ◽  
Hiroyuki Hamada
Keyword(s):  
Fiber Orientation ◽  
Line Strength ◽  
Weld Line ◽  
Fiber Bundles ◽  
Interfacial Property ◽  
Fiber Distribution ◽  
Molded Parts ◽  
Injection Molded ◽  
Hybrid Mixtures ◽  
Better Than

Weld lines are formed inevitably when two separate melt fronts rejoin during injection molding. It has been reported that weld lines greatly weaken the strength of injection-molded parts. Therefore, in this paper the weld property of injection molded jute /PLA and jute/PP dumbbell shape specimen with weld line was investigated by changing pellets materials. In the study pultrusion technique was adopted to fabricate jute/PLA and jute/PP long fiber pellets (LFT) and it was found that fiber bundles in LFT specimens were not separated and dispersed well. As a result, in this paper re-compound pellets of LFT, i.e. RP was made. Then LFT, RP, and hybrid mixtures with the hybrid ratios of LFT50:RP50 were used to mold dumbbell shape specimens with or without weld line. In particular, the influence of different pellets on weld line strength of injection molded jute/PLA and jute/PP dumbbell shape specimens with weld line was discussed based on tensile test and SEM observation. It was found that tensile strength of RP specimens was higher than that of LFT both for jute/PLA and jute/PP, because fiber distribution and interfacial property of RP was much better than that of LFT. Weld line strength of RP was improved than that of LFT both for jute/PLA and jute/PP. RP of jute/PLA was more effective to improve the weld property than that of jute/PP. Weld line strength of jute/PP LFT increased as holding pressure increased from 44 to 88 MPa and decreased at 132 MPa holding pressure. It depends on the co-effect of fiber orientation and voids content.

Correlation between fiber orientation distribution and mechanical anisotropy in glass-fiber-reinforced composite materials

2019 ◽  
Vol 39 (7) ◽  
pp. 653-660 ◽  
Author(s):  
Senji Hamanaka ◽  
Chisato Nonomura ◽  
Thanh Binh Nguyen Thi ◽  
Atsushi Yokoyama
Keyword(s):  
Glass Fiber ◽  
Fiber Orientation ◽  
Flexural Modulus ◽  
Orientation Distribution ◽  
Fiber Content ◽  
Mechanical Anisotropy ◽  
Bending Test ◽  
Flat Plates ◽  
Fiber Orientation Distribution ◽  
Injection Molded

Abstract This study investigates the correlation between the fiber orientation distribution along the thickness and mechanical anisotropy in injection-molded products using a thermoplastic resin reinforced by short fibers. To this end, polyamide-6 samples containing 15, 30, 50, and 65 wt% of short fiberglass were compounded, and flat plates with side gates were injection-molded. The fiber orientation distribution near the center of the plates was observed via X-ray computed tomography and that along the thickness was quantified via a fiber orientation tensor. Coupon test pieces were cut from the plates along the machine and transverse directions, and a three-point bending test was performed. Mechanical anisotropy was evaluated from the ratio of the flexural modulus in each direction. Evaluation results of the fiber orientation distribution and mechanical anisotropy were compared. As a result of the above investigation, a clear correlation was found between the fiber orientation distribution and mechanical anisotropy when the glass fiber content was 15–50 wt%. In the anisotropic expression under the condition of high glass fiber content (65 wt%), contributions of parameters other than the fiber orientation distribution became evident.

scholarly journals Prediction of elastic anisotropic thermo-dependent properties of discontinuous fiber-reinforced composites

2019 ◽  
Vol 54 (14) ◽  
pp. 1913-1923
Author(s):  
D Lopez ◽  
S Thuillier ◽  
Y Grohens
Keyword(s):  
Elastic Properties ◽  
Glass Fibers ◽  
Tensile Tests ◽  
Rectangular Plates ◽  
Temperature Dependent ◽  
Orientation Tensor ◽  
Numerical Predictions ◽  
Discontinuous Fiber ◽  
Injection Molded ◽  
Polypropylene Matrix

This study focuses on the micromechanical prediction of temperature-dependent elastic properties of a composite made of a polypropylene matrix reinforced with discontinuous glass fibers. Firstly, an experimental investigation of the mechanical behavior is presented. Specimen are cut from injection-molded rectangular plates using a pattern based on fiber orientation. The microstructure is investigated by X-ray tomography at the specimen center and an average orientation tensor is calculated. Tensile tests are performed over a temperature range from ambient temperature to 85℃ and dispersion of mechanical properties is rather low; moreover, they are representative of the ones measured out of an industrial injected part. Then, the evolution of elastic properties with orientation and temperature is analyzed and compared with numerical predictions calculated with Mori–Tanaka homogenization scheme.

scholarly journals Fiber Orientation and Concentration in an Injection-Molded Ethylene-Propylene Copolymer Reinforced by Hemp

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2771
Author(s):  
Antoine Dupuis ◽  
Jean-Jacques Pesce ◽  
Paulo Ferreira ◽  
Gilles Régnier
Keyword(s):  
Injection Molding ◽  
Fiber Orientation ◽  
Glass Fibers ◽  
Thermomechanical Properties ◽  
Fiber Content ◽  
Hemp Fibers ◽  
Shear Rates ◽  
High Shear Rates ◽  
Injection Molded ◽  
The One

This paper characterizes and analyzes the microstructures of injection-molded polypropylene parts reinforced with 20 wt% of hemp fibers in order to understand the process induced variations in thermomechanical properties. In-thickness fiber orientation and fiber content were determined by X-ray tomography along the flow. The fiber content along the flow path was also determined by direct fiber content measurements after matrix dissolution, showing an increase of 2%/100 mm for a 2.2 mm-thick plate due to fiber migration during the filling stage. A typical shell/core structure for fiber orientation in injection molding was observed, but with a very clear transition between the layer solidified under high shear rates and the core in which the fiber content was reduced by more than 50%. The orientation of hemp fibers is lower than the one of glass fibers, especially in thickness direction. However, the overall fiber orientation in the injection direction induces significant anisotropic thermomechanical properties, which cannot be explained by simple micromechanical models that consider isotropic mechanical properties for hemp fibers. These phenomena must be taken into account in process simulation codes for injection molding to better predict thermomechanical properties as well as part shrinkage and warpage to design molds.

Predictions of fiber concentration in injection molding simulation of fiber-reinforced composites

2017 ◽  
Vol 31 (11) ◽  
pp. 1529-1544 ◽  
Author(s):  
Huan-Chang Tseng ◽  
Rong-Yeu Chang ◽  
Chia-Hsiang Hsu
Keyword(s):  
Injection Molding ◽  
Fiber Orientation ◽  
Short Fiber ◽  
Core Structure ◽  
Particle Migration ◽  
Migration Behavior ◽  
Fiber Concentration ◽  
Numerical Predictions ◽  
Injection Molding Simulation ◽  
Injection Molded

The microstructures of injection-molded short fiber composites, involving fiber orientation and fiber concentration, strikingly influence flow behaviors and mechanical properties. Through the use of certain commercial software, reported numerical predictions of fiber orientation for the shell–core structure have been obtained to date. However, no work has been done on fiber concentration prediction available in processing simulations. In the theoretical field of suspension rheology, the suspension balance (SB) model has proven successful in capturing particle migration behavior under the simple Couette shear flow of “spherical” particle suspension, hence the attempt to verify the SB model applied in the “like-rod” suspensions. To predict flow-induced variations of fiber concentration, the SB model is implemented in 3-D-injection molding simulation with more general flows. It is remarkable for the shell–core structure is explored to reflect the relationship between fiber orientation and fiber concentration.

The effect of fiber concentration on fiber orientation in injection molded film gated rectangular plates

2017 ◽  
Vol 40 (2) ◽  
pp. 615-629 ◽  
Author(s):  
Jens Kjær Jørgensen ◽  
Erik Andreassen ◽  
Dietmar Salaberger
Keyword(s):  
Fiber Orientation ◽  
Rectangular Plates ◽  
Fiber Concentration ◽  
Injection Molded

An anisotropic elasto-plastic material model for injection-molded long fiber-reinforced thermoplastics accounting for local fiber orientation distributions

2016 ◽  
Vol 51 (14) ◽  
pp. 2061-2078 ◽  
Author(s):  
L Schulenberg ◽  
T Seelig ◽  
F Andrieux ◽  
D-Z Sun
Keyword(s):  
Fiber Orientation ◽  
Plastic Material ◽  
Material Model ◽  
Tensile Tests ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Orientation Distributions ◽  
Injection Molded ◽  
Reinforced Thermoplastics ◽  
Fiber Reinforced Thermoplastics

This paper presents an anisotropic elasto-plastic material model for injection-molded long fiber-reinforced thermoplastics. It considers local heterogeneities which are attributed to process-induced variations of fiber orientation distributions and fiber volume fractions. These inhomogeneities have an effect on the mechanical properties and need to be considered in structural computations. In the material model, this is realized through a two-step homogenization procedure. First, an anisotropic stiffness tensor is approximated using mean field homogenization. Second, the plastic behavior is described using Hill’s transversely isotropic yield criterion averaged over the three principal directions of the fiber orientation. The advantage in combining these two approaches is a micro-mechanically based, yet fast numerical calculation of the composite material behavior within an explicit finite element code. The anisotropic material model is calibrated by simulating tensile tests on specimens taken in different directions from an injection-molded plate of fiber reinforced thermoplastic. The spatial variation of fiber orientation distribution and fiber volume fraction throughout the plate is determined from numerical mold filling simulations and is compared with computer tomography scans at different positions. A validation of the model is performed through simulating position-dependent tensile tests on smooth and notched specimens as well as a punch test which is well reproduced.

scholarly journals Fibers Effects on Contract Turbulence Using a Coupling Euler Model

2021 ◽  
Vol 11 (15) ◽  
pp. 7126
Author(s):  
Wei Yang ◽  
Pei Hu
Keyword(s):  
Boundary Layer ◽  
Velocity Profile ◽  
Fiber Orientation ◽  
Bottom Layer ◽  
Orientation Distribution ◽  
Industrial Applications ◽  
Dynamics Simulation ◽  
Fiber Concentration ◽  
Fibers Orientation ◽  
Process Strategy

Fiber additive will induce the rheological behavior of suspension, resulting in variation in velocity profile and fiber orientation especially for the non-dilute case. Based on the fluid-solid coupling dynamics simulation, it shows that the fiber orientation aligns along the streamline more and more quickly in the central turbulent region as the fiber concentration increases, especially contract ratio Cx > 4. However, fibers tend to maintain the original uniform orientation and are rarely affected by the contract ratio in the boundary layer. The fibers orientation in the near semi-dilute phase is lower than that in the dilute phase near the outlet, which may be the result of the hydrodynamic contact lubrication between fibers. The orientation distribution and concentration of the fibers change the viscous flow mechanism of the suspension microscopically, which makes a velocity profile vary with the phase concentration. The velocity profile of the approaching semi-dilute phase sublayer is higher than that of the dilute and semi-dilute phases on the central streamline and in the viscous bottom layer, showing weak drag reduction while the situation is opposite on the logarithmic layer of the boundary layer. The relevant research can provide a process strategy for fiber orientation optimization and rheological control in the industrial applications of suspension.

Effect of Fiber Orientation on the Tensile Strength in Fiber-Reinforced Polymeric Composite Materials

2005 ◽  
Vol 297-300 ◽  
pp. 2897-2902 ◽  
Author(s):  
Jin Woo Kim ◽  
Jung Ju Lee ◽  
Dong Gi Lee
Keyword(s):  
Tensile Strength ◽  
Composite Material ◽  
Fiber Orientation ◽  
Polymeric Composite ◽  
Orientation Distribution ◽  
Fiber Content ◽  
Fiber Reinforced ◽  
Composite Sheet ◽  
Content Ratio ◽  
Fiber Orientation Distribution

The study for strength calculation of one way fiber-reinforced composites and the study measuring precisely fiber orientation distribution were presented. However, because the DB that can predict mechanical properties of composite material and fiber orientation distribution by the fiber content ratio was not constructed, we need the systematic study for that. Therefore, in this study, we investigated what effect the fiber content ratio and fiber orientation distribution have on the strength of composite sheet after making fiber reinforced polymeric composite sheet by changing fiber orientation distribution with the fiber content ratio. The result of this study will become a guide to design data of the most suitable parts design or fiber reinforced polymeric composite sheet that uses the fiber reinforced polymeric composite sheet in industry spot, because it was conducted in terms of developing products. We studied the effect the fiber orientation distribution has on tensile strength of fiber reinforced polymeric composite material and achieved this results below. We can say that the increasing range of the value of fiber reinforced polymeric composite’s tensile strength in the direction of fiber orientation is getting wider as the fiber content ratio increases. It shows that the value of fiber reinforced polymeric composite’s tensile strength in the direction of fiber orientation 90° is similar with the value of polypropylene’s intensity when fiber orientation function is J= 0.7, regardless of the fiber content ratio. Tensile strength of fiber reinforced polymeric composite is affected by the fiber orientation distribution more than by the fiber content ratio.

scholarly journals Worldwide gene pool of fiber flax at VIR, and breeding of rust-resistant varieties

2020 ◽  
Vol 181 (2) ◽  
pp. 57-64
Author(s):  
S. N. Kutuzova ◽  
E. A. Porokhovinova ◽  
N. B. Brutch ◽  
A. V. Pavlov
Keyword(s):  
Rust Resistance ◽  
Source Material ◽  
Fiber Content ◽  
High Yield ◽  
Present Moment ◽  
R Genes ◽  
Fiber Flax ◽  
High Fiber ◽  
Flax Cultivar ◽  
Almost All

Background. There are strict requirements for a modern flax cultivar. It must have a whole set of valuable characters, including rust resistance.Materials and methods. The flax collection of 2485 accessions held by VIR was evaluated using artificial provocative infection.Results. Almost all domestic and foreign accessions and varieties collected before 1957 were highly or extremely susceptible to rust. Five Russian kryazhs1 and cv. ‘GDS-3’ developed at VIR were found to retain rust resistance up to the present moment. Lines derived from them and from three foreign varieties, with an identified number of the original effective R genes, were submitted to breeders. Nineteen donors with a set of economically useful traits, analogous to cvs. ‘Orshansky 2’ and ‘Prizyv 81’ and carrying the same genes, were produced and distributed to breeders. The VIR collection holds 10 donors of rust resistance with high fiber content developed at the All-Russian Research Institute of Flax. Some donors of resistance to other diseases released by the same Institute also possess high rust resistance, thus forming a rich stock of source material. The first cultivar relatively resistant to rust (‘L-1120’) was released in 1951. Possessing polygenic resistance, it was also resistant to Fusarium wilt and lodging, so it was widely used for breeding other cultivars with similar characteristics. As their cultivation expanded, the harvest losses caused by rust dropped. The first rust-resistant cultivar with oligogenic resistance (‘Tomsky 16’) appeared in 1990. By now, many cultivars protected by R genes of rust resistance have been developed. They combine this trait with resistance to Fusarium and lodging, high yield, and high fiber content. Flax rust incidence is not a problem anymore.Conclusion. Plant breeders have at their disposal a rich stock of source material preserved in the VIR collection to produce resistant flax cultivars. The use of rust resistance donors in hybridization cannot disrupt the most important properties of a cultivar.

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