Effects of manufacturing micro-structure on vibration of FFF 3D printing plates: Material characterisation, numerical analysis and experimental study

摘要

This paper presents the effects of manufacturing micro-structure on the elastic properties of FFF (fused filament fabrication) 3D printing material and the vibration characteristics of FFF 3D printing plates. According to the results of scanning electron microscopy, three different material directions are defined to describe the orthotropy of FFF 3D printing material including fibre direction, intra-layer direction, and inter-layer direction. Then, the constitutive model of the orthotropic elastic 3D printing material is established based on static experimental results and plane stress rotation formula. Static experimental results (totally 27 kinds of specimens) show that the largest difference of Young's moduli in different material directions is 1104.684 MPa which is even larger than the Young's modulus in the intra-layer direction. Finite element models of FFF 3D printing plates with six different printing directions (alpha - 0 =, alpha - 90 =, /3 - 0 =, /3 - 90 =, lambda - 0 =, lambda - 90 = ) and three different layer thicknesses (0.2 mm, 0.25 mm, 0.3 mm) are built and their natural frequencies are determined. Simulation results show that the largest difference of the natural frequencies among plates with different printing directions are 10.645 Hz, 39.588 Hz, 66.710 Hz, 123.780 Hz, and 185.720 Hz when the mode of the plates changes from one to five. Meanwhile, these differences are relative large when compared with the first five outof-plane natural frequencies of these plates. Additionally, vibration experiments of FFF 3D printing plates are carried out to verify the validity of the simulation process and all the relative errors of the natural frequencies between simulation and the experimental results are found to be very small. Therefore, the accuracy of the finite element models is good enough and one can confirm that the effects of manufacturing micro-structure on the vibration characteristics are significant.