Material Evaluation and Dynamic Powder Deposition Modeling of PEEK/CF Composite for Laser Powder Bed Fusion Process

Abstract

Polymeric composites such as Poly-ether-ether-ketone (PEEK)/carbon fiber (CF) have been widely utilized due to outstanding performances such as high specific strength and specific modulus. The PEEK/CF components via powder bed fusion additive manufacturing usually show brittle fracture behaviors induced by their poor interfacial affinity and inner voids. These defects are strongly associated with powder packing quality upon deposition. The particle dynamic model has been widely employed to study the interactions of particle motions. Powder property, bulk material property, and interfacial features of composite powders are key factors in the particle dynamic model. In this work, an efficient and systematic material evaluation is developed for composite powders to investigate their deposition mechanism. The discrete element method is utilized to simulate the dynamic behaviors of PEEK/CF composite powders. The powder properties, bulk material properties, and interfacial features of powders are calibrated and justified by experimental measurement, numerical simulation, and design of experiments. The particle dynamic model can explain the powder flow behaviors and interactions. The experimental and simulation AOR results show a maximal deviation of 4.89%. It reveals that the addition of short CF particles can assist the flow of PEEK powders and improve the packing quality of the composite powders. The results show an experimental improvement of 31.3% and 55.2% for PEEK/CF_30wt% and PEEK/CF_50wt%, with a simulated improvement of 27.4% and 50.2% for corresponding composite powders.

Keywords: additive manufacturing; composite polymers; discrete element method; laser powder bed fusion; material characterization.

Figure 1

Interaction between particles and particle modeling method: (a) the relationship between particle force and particle diameter [30]; (b) contact force diagram between particles; (c) multiple-sphere method to model the CF particle.

Figure 2

Hertz–Mindlin contact model.

Figure 3

Parameter classification and calibration methods of the DEM model.

Figure 4

The AOR experiment according to the GB11986-89.

Figure 5

Measurement for the bulk density.

Figure 6

FEM simulation of the restitution coefficient: (a) initial moment; (b) contact with bottom plate; (c) bouncing to maximum height.

Figure 7

The powder deposition process of experiment and simulation: (a) the powder deposition process and the surface morphology observation; (b) the flat surface of the spread powder with the naked eye; (c) the observation zone; (d) the cross-section position of the simulated powder layer.

Figure 7

The powder deposition process of experiment and simulation: (a) the powder deposition process and the surface morphology observation; (b) the flat surface of the spread powder with the naked eye; (c) the observation zone; (d) the cross-section position of the simulated powder layer.

Figure 8

The results of SEM experiments: (a) particle morphology of PEEK; (b) particle morphology of PEEK/CF_30wt%.

Figure 9

Particle size distribution: (a) PEEK; (b) CF.

Figure 10

The experimental and simulation results of AORs for PEEK, PEEK/CF_30wt%, and PEEK/CF_50wt%: (a) experimental results; (b) simulation results.

Figure 10

The experimental and simulation results of AORs for PEEK, PEEK/CF_30wt%, and PEEK/CF_50wt%: (a) experimental results; (b) simulation results.

Figure 11

The experimental micro-pictures of the surface topography and undulation: (a) PEEK; (b) PEEK/CF_30wt%; (c) PEEK/CF_50wt%.

Figure 12

The cross-section of the simulated powder deposition of PEEK, PEEK/CF_30wt%, and PEEK/CF_50wt%.

Figure 13

Experimental and simulation results of standard deviation of powder surface profile.