Customer: National Taiwan University of Science and TechnologyCountry: TaiwanIndustry: Academy & EducationSolution: Moldex3D Advanced; Fiber Module, FEA Interface

National Taiwan University of Science and Technology (NTUST) was established on August 1, 1974, as the first higher education institution dedicated specifically for the technical and vocational education purpose in Taiwan. By expanding the different course offerings since the foundation of the institution, their goal is to create an environment to nurture the next generation of highly skilled engineers and managers in order to meet the needs created by the rapid economic and industrial developments. (Source: http://www-e.ntust.edu.tw)

Although lightweight demands in plastics manufacturing is continuously rising, the requirement of rigidity and strength is still necessary. With the addition of fiber, degradable materials can not only help reduce the carbon emission effectively but also enhance the product strength. In this study, National Taiwan University of Science and Technology (Taiwan Tech) selects a degradable material, Poly Lactic Acid (PLA), for simulation and to investigate the effects of fiber orientation on warpage and stress.

Image Courtesy of National Taiwan University of Science and Technology

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Integrating Moldex3D and ANSYS to ValidateFiber’s Effects on PLA Products

Executive Summary

　● To find out how fiber can enhance the product strength　● Lack of standard test method and simulation process of PLA

Challenges

Fig. 1 Mesh building in Moldex3D

Fig. 2 The element convergence test

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Utilizing Moldex3D Advanced and Fiber Module to build mesh (Fig. 1), proceed convergence test (Fig. 2) and complete injection molding simulation

Solutions

Cavity(Part)

Heating Rod

Cold RunnerHexa

Triangle & QuadraticHexa

Triangle & Quadratic

Tetra

84ElementNumner (K) 120 150 200 310 340 360 420

Fig. 3 Moldex3D simulation is verified consistent with the real case in filling pattern and sink mark

Fig. 4 Compared with short fiber, long fiber has better resistance to deformation

Taiwan Tech knew that adding fiber can enhance the strength of PLA products. However, they had no idea about what proportion would be the most effective and what type of fiber would be better for strength enhancement. In this study, they found Moldex3D was able to accurately predict the fiber orientation in the manufacturing phase. The simulation results can be easily exported from Moldex3D FEA Interface to ANSYS for structural analysis.

Taiwan Tech added fiber to pure PLA to enhance the strength. The results also displayed that compared with short fiber, long fiber had better resistance to deformation (Fig. 4).

This case features a specimen made of PLA. PLA has lower crystallization rate, poor strength and heat resistance, so Taiwan Tech team planned to add fiber to improve them. First, Taiwan Tech team verified Moldex3D’s simulation results through experiments, and found consistent filling patterns (Fig. 3). Then they tried to predict the effect of short and long fiber on the product deformation resistance, and find different effects in fiber proportions. Finally, they verified the prediction results of Moldex3D and ANSYS in product deformation and stress.

Case Study

　● Compared with short fiber, long fiber has better resistance of deformation and tensile force.　● The integration of Moldex3D and ANSYS provides a complete and accurate simulation for PLA materials.　● To find out that adding fiber can enhance product strength

Benefits

3

24.25

29.1

60.6%

72.7%

Material

Pure PLA

PLA/Fiber (short fiber)

PLA/Fiber (long fiber)

Warpage: X-axis

0.213 mm

0.139 mm

0.136 mm

Material

Pure PLA

PLA/Fiber (short fiber)

PLA/Fiber (long fiber)

Warpage: X-axisdisplacement

0.3387 mm

0.01496 mm

0.01476 mm

Boundary Conditions: - Force = 0.5kgw - Displacement = 0mm

More addition of fiber will reduce deformation. In this study, 25% fiber will cause the lowest deformation (Fig. 5).

Next, Taiwan Tech utilized ANSYS to verify Moldex3D’s analysis of deformation and stress. The results showed that the deformation and stress were very identical in ANSYS and Moldex3D. (Fig. 6)

From the experience with Moldex3D, fiber effect with different variables can be investigated effectively. Through Moldex3D FEA Interface, users can easily export fiber orientation results and connect to ANSYS for FEA analysis. This truly is a powerful and reliable integrated solution for considering manufacturing process in FEA prediction. This case study is also supposed to help facilitate PLA’s applications in the potential market of mobile device covers.

Results

Fig.5 Displacement results of different fiber proportion

Fig. 6 Moldex3D and ANSYS verification of simulation results

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Material

5% Fiber

15% Fiber

25% Fiber

Warpage: X-axisdisplacement

0.335 mm

0.213 mm

0.152 mm

Pure PLA

Ansys

Moldex3D 0.338

X-directiondisplacement(mm)

0.339

27.508

von Misesstress(Mpa)

27.562

0.338

Total directiondisplacement(mm)

0.339

Pure PLA + 30% short fiber

Ansys

Moldex3D 0.015

X-directiondisplacement(mm)

0.017

32.377

von Misesstress(Mpa)

29.126

0.015

Total directiondisplacement(mm)

0.017