Fused deposition modelling (FDM) is one of the fastest-growing additive manufacturing methods used in printing fibre-reinforced composites (FRC). The performances of the resulting printed parts are limited compared to those by other manufacturing methods due to their inherent defects. Hence, the effort to develop treatment methods to overcome these drawbacks has accelerated during the past few years. The main focus of this study is to review the impact of those defects on the mechanical performance of FRC and therefore to discuss the available treatment methods to eliminate or minimize them in order to enhance the functional properties of the printed parts. As FRC is a combination of polymer matrix material and continuous or short reinforcing fibres, this review will thoroughly discuss both thermoplastic polymers and FRCs printed via FDM technology, including the effect of printing parameters such as layer thickness, infill pattern, raster angle and fibre orientation. The most common defects on printed parts, in particular, the void formation, surface roughness and poor bonding between fibre and matrix, are explored. An inclusive discussion on the effectiveness of chemical, laser, heat and ultrasound treatments to minimize these drawbacks is provided by this review.

FDM-Based 3D Printing of Polymer and Associated Composite: A Review on Mechanical Properties, Defects and Treatments.

The application of additive manufacturing (AM) in construction has been increasingly studied in recent years. Large robotic arm- and gantry-systems have been created to print building parts using aggregate-based materials, metals, or polymers. Significant benefits of AM are the automation of the production process, a high degree of design freedom, and the resulting potential for optimization. However, the building components and 3D-printing processes need to be modeled appropriately. In this paper, the current state of AM in construction is reviewed. AM processes and systems as well as their application in research and construction projects are presented. Moreover, digital methods for planning 3D-printed building parts and AM processes are described.

Additive manufacturing in construction: A review on processes, applications, and digital planning methods

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Recent progress in additive manufacturing of fiber reinforced polymer composite

A critical review on 3D printed continuous fiber-reinforced composites: History, mechanism, materials and properties

Recent developments in polymers/polymer nanocomposites for additive manufacturing

Recent advancements in the Additive Manufacturing (AM) Fused Filament Fabrication (FFF) approach are described with focus on the application to tooling and molds for composite materials and structures. A detailed summary of mechanical properties of printed parts for different composite material systems is presented and discussed. These material systems are comprised of discontinuous fiber-reinforced polymers characterized by fiber orientation dominantly parallel to the direction of the extrudate. An overview of the FFF process and its physical phenomena is given including the flow and resulting fiber orientation, the bond formation between adjacent beads and the thermomechanical solidification behavior of the deposited material. Based on reviewed research in these different phenomena, future research needs are discussed and desirable objectives are formulated.

Fused filament fabrication of fiber-reinforced polymers: A review

The process simulation tool Additive3D has been developed in Abaqus© 2017 to model the Extrusion Deposition Additive Manufacturing (EDAM) process for fiber-reinforced thermoplastic composites. This additive manufacturing (AM) method encompasses material deposition processes where geometries are constructed layer by layer and the resulting layer properties are highly anisotropic. The goal is to predict final deformed shapes and residual stresses of printed geometries due to the printing process and the material anisotropy. The resulting design tool allows to assess the outcomes of the printing process based on the part geometry, the printing material and the position control parameters. Material properties were characterized, and validation experiments, without additional calibration, show an excellent agreement between modeled and measured part deformation states with relative deviations below 7%. Due to the physics-based nature of the developed simulation tools, the simulations can be extended to account for different part scales, printing materials and printing histories.

Development and validation of extrusion deposition additive manufacturing process simulations

A simulation framework for extrusion deposition additive manufacturing (ADDITIVE3D) is presented in this chapter that shows promising results for capturing the physics-based phenomena that occur in the extrusion deposition printing process By simulating the full physics of the manufacturing process and using this information to describe the state of the printed geometry, the outcomes of the printing process and consequences in performance can be predicted before the physical print begins This manufacturing-informed performance can be used to drive design decisions and anticipate the success or failure of a given print Unsuccessful and unfavorable designs can be discovered in silico without expending material, machine time, and operator effort ADDITIVE3D offers designers and machine operators access to the ability to utilize the full multi-physics simulation capability for the EDAM process in a stand-alone fashion, requiring no expertise in FEA software or computer programming The machine type (machine card) defines the processing conditions that govern applicable bead geometry, ambient conditions, print bed boundary conditions, compaction mechanism, and interpretation of the event series The event series information contains the part specific information for the print including both the time-dependent bead location and the printing options available on the specified machine The goal of ADDITIVE3D and the simulation workflow presented herein is to bring the power of simulation to the additive manufacturing community The integrated nature of the ADDITIVE3D workflow also presents a platform for leveraging machine learning to further explore material, machine, and part design

Extrusion deposition additive manufacturing with fiber-reinforced thermoplastic polymers

Extrusion Deposition Additive Manufacturing (EDAM) is a technology where 3-D digital objects are manufactured extruding beads of molten material in a layer-by-layer basis. This technology offers the flexibility for processing pelletized material, and thus a semi-crystalline polymer highly-filled with carbon fiber has been used for printing. Significant technology improvements in the EDAM technology have been made recently, however, the design of the printing strategy is still mostly driven by empirical development. Hence, there is a need for simulation tools that capture the phenomena involved in the EDAM process to drive the development and optimization of this technology. Currently, one limitation of printed parts in terms of mechanical properties is the strength of the interface developed between printed layers. Therefore, the focus of this work is to couple the phenomena involved in the bonding process of adjacent layers to predict the degree of bonding, such as the temperature history, the melting and crystallization of the semi-crystalline polymer and the diffusion of polymer chains. The models utilized to describe these phenomena and their couplings were implemented in a UMATHT user subroutine in Abaqus to predict the evolution of the degree of bonding during the EDAM process. The effects of the couplings implemented in this approach are demonstrated by predicting the evolution of the degree of bonding throughout the simulation of the printing process of a geometry with sections that undergo different cooling and crystallization rates.

Fusion Bonding Simulations of Semi-Crystalline Polymer Composites in the Extrusion Deposition Additive Manufacturing Process

This work focuses on the evolution of interlayer fracture toughness properties of fiber-reinforced, semi-crystalline polymers in the extrusion deposition additive manufacturing (EDAM) process. Further, this work bridges the gap between the additive process conditions (time-temperature history) and the effective layer-to-layer fracture properties developed within a printed component. This is the first step to predict delamination that can occur during printing, during cooling to room temperature after printing, and during service performance of an additively manufactured geometry. A phenomenological model is developed for fusion bonding of semi-crystalline polymer matrix composites by coupling the interdiffusion of polymer chains with the evolution of polymer crystallinity. While the interdiffusion is captured by reptation theory of polymer dynamics, the evolution of crystallinity is modeled by phenomenological crystallization kinetics and crystal melting dynamics. Further, a methodology is developed to determine the critical strain energy release rate, GICof the interlayer interface and experiments are conducted utilizing the double cantilever beam fracture test geometry. Predictions of GIC as a function of thermal history are compared with experiments. 

Bastian Brenken

Papers

Fused filament fabrication of fiber-reinforced polymers: A review

Development and validation of extrusion deposition additive manufacturing process simulations

Extrusion deposition additive manufacturing with fiber-reinforced thermoplastic polymers

Fusion Bonding Simulations of Semi-Crystalline Polymer Composites in the Extrusion Deposition Additive Manufacturing Process

Interlayer fusion bonding of semi-crystalline polymer composites in extrusion deposition additive manufacturing