Nonisothermal welding in fused filament fabrication

Advances in modeling transport phenomena in material-extrusion additive manufacturing: Coupling momentum, heat, and mass transfer

“…The authors validated their simulation results by performing experiments on a modified extruder setup and found that their model was in good agreement with model predictions, especially at a nozzle wall temperature range of 210°C-260°C [60]. A non-isothermal welding model was developed by Coasey et al [63] and experimentally verified by interlaminar fracture toughness measurements. The model describes the effect of processing parameters and rheological properties on the degree of healing of the printed parts [63].…”

“…A non-isothermal welding model was developed by Coasey et al [63] and experimentally verified by interlaminar fracture toughness measurements. The model describes the effect of processing parameters and rheological properties on the degree of healing of the printed parts [63]. The melting behavior of PLA inside a MatEx nozzle was computationally modeled and validated using experiments [64].…”

Structure and Fracture Visualization of Tilted ABS Specimens Processed via Fused Filament Fabrication Additive Manufacturing

“…1) [11]. The inter-layers and intra-layers bond strength depends on the local temperature between adjacent rasters as determined by the dynamics of the molten polymer that governs the diffusion rate [12]- [15]. The mechanical properties of FFF parts depend on the thermoplastic polymer properties, the product's geometric details, the FFF process parameters and they are expected to be anisotropic because of the inherent layered structure.…”

“…The bonds between rasters and between layers result in the anisotropic properties of the printed part, with the highest strength in the longitudinal direction (parallel to the direction of printing), and the weakest strength in the z-axis direction between layers. So far, no material model has been capable of considering the dissimilar material behavior of ABS between tension and compression and an advanced and complex constitutive material model is highly required [1]- [9], [12]- [16]. It has been widely publicized that the typical defects found in the printed parts are poor bonding between rasters inside and in between the layers, porosity located between the rasters and porosity between the contour beads and rasters [1]- [9], [12], [16], [17].…”

“…So far, no material model has been capable of considering the dissimilar material behavior of ABS between tension and compression and an advanced and complex constitutive material model is highly required [1]- [9], [12]- [16]. It has been widely publicized that the typical defects found in the printed parts are poor bonding between rasters inside and in between the layers, porosity located between the rasters and porosity between the contour beads and rasters [1]- [9], [12], [16], [17]. Contact pressure is a critical determinant of the bond strength; higher contact pressures leading to larger contact surface area, provide improved mechanical properties.…”