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.
- To find out how fiber can enhance the product strength
- Lack of standard test method and simulation process of PLA
Fig. 1 Mesh building in Moldex3D
Fig. 2 The element convergence test
- 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
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.
Fig. 3 Moldex3D simulation is verified consistent with the real case in filling pattern and sink mark
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).
Fig. 4 Compared with short fiber, long fiber has better resistance to deformation
More addition of fiber will reduce deformation. In this study, 25% fiber will cause the lowest deformation (Fig. 5).
Fig.5 Displacement results of different fiber proportion
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)
Fig. 6 Moldex3D and ANSYS verification of simulation results
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.