scholarly journals Manufacturing and Characterization of 3D Miniature Polymer Lattice Structures Using Fused Filament Fabrication

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 635 ◽  
Author(s):  
Rafael Guerra Silva ◽  
María Josefina Torres ◽  
Jorge Zahr Viñuela ◽  
Arístides González Zamora
Keyword(s):  
Additive Manufacturing ◽  
Good Control ◽  
Design Guidelines ◽  
Critical Parameters ◽  
Manufacturing Processes ◽  
Lattice Structures ◽  
Fused Filament Fabrication ◽  
Strut Thickness ◽  
Custom Made ◽  
Overhang Angle

The potential of additive manufacturing to produce architected lattice structures is remarkable, but restrictions imposed by manufacturing processes lead to practical limits on the form and dimension of structures that can be produced. In the present work, the capabilities of fused filament fabrication (FFF) to produce miniature lattices were explored, as they represent an inexpensive option for the production of polymer custom-made lattice structures. First, fused filament fabrication design guidelines were tested to assess their validity for miniature unit cells and lattice structures. The predictions were contrasted with the results of printing tests, showing some discrepancies between expected outcomes and resulting printed structures. It was possible to print functional 3D miniature open cell polymer lattice structures without support, even when some FFF guidelines were infringed, i.e., recommended minimum strut thickness and maximum overhang angle. Hence, a broad range of lattice structures with complex topologies are possible, beyond the cubic-type cell arrangements. Nevertheless, there are hard limits in 3D printing of miniature lattice structures. Strut thickness, length and orientation were identified as critical parameters in miniature lattice structures. Printed lattices that did not fully comply with FFF guidelines were capable of bearing compressive loads, even if surface quality and accuracy issues could not be fully resolved. Nevertheless, 3D printed FFF lattice structures could represent an improvement compared to other additive manufacturing processes, as they offer good control of cell geometry, and does not require additional post-processing.

scholarly journals Design Data and Finite Element Analysis of 3D Printed Poly(ε-Caprolactone)-Based Lattice Scaffolds: Influence of Type of Unit Cell, Porosity, and Nozzle Diameter on the Mechanical Behavior

Eng ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 9-23
Author(s):  
Riccardo Sala ◽  
Stefano Regondi ◽  
Raffaele Pugliese
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Computer Aided Design ◽  
Unit Cell ◽  
Critical Parameters ◽  
Lattice Structures ◽  
Fused Filament Fabrication ◽  
Element Analysis ◽  
Custom Made ◽  
3D Printed

Material extrusion additive manufacturing (MEAM) is an advanced manufacturing method that produces parts via layer-wise addition of material. The potential of MEAM to prototype lattice structures is remarkable, but restrictions imposed by manufacturing processes lead to practical limits on the form and dimension of structures that can be produced. For this reason, such structures are mainly manufactured by selective laser melting. Here, the capabilities of fused filament fabrication (FFF) to produce custom-made lattice structures are explored by combining the 3D printing process, including computer-aided design (CAD), with the finite element method (FEM). First, we generated four types of 3D CAD scaffold models with different geometries (reticular, triangular, hexagonal, and wavy microstructures) and tunable unit cell sizes (1–5 mm), and then, we printed them using two nozzle diameters (i.e., 0.4 and 0.8 mm) in order to assess the printability limitation. The mechanical behavior of the above-mentioned lattice scaffolds was studied using FEM, combining compressive modulus (linear and nonlinear) and shear modulus. Using this approach, it was possible to print functional 3D polymer lattice structures with some discrepancies between nozzle diameters, which allowed us to elucidate critical parameters of printing in order to obtain printed that lattices (1) fully comply with FFF guidelines, (2) are capable of bearing different compressive loads, (3) possess tunable porosity, and (3) overcome surface quality and accuracy issues. In addition, these findings allowed us to develop 3D printed wrist brace orthosis made up of lattice structures, minimally invasive (4 mm of thick), lightweight (<20 g), and breathable (porosity >80%), to be used for the rehabilitation of patients with neuromuscular disease, rheumatoid arthritis, and beyond. Altogether, our findings addressed multiple challenges associated with the development of polymeric lattice scaffolds with FFF, offering a new tool for designing specific devices with tunable mechanical behavior and porosity.

scholarly journals Macro-, meso- and microstructural characterization of metallic lattice structures manufactured by additive manufacturing assisted investment casting

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
V. H. Carneiro ◽  
S. D. Rawson ◽  
H . Puga ◽  
P. J. Withers
Keyword(s):  
Additive Manufacturing ◽  
Investment Casting ◽  
A356 Alloy ◽  
Microstructural Characterization ◽  
Lattice Structures ◽  
Secondary Phases ◽  
Micro Computed Tomography ◽  
Fused Filament Fabrication ◽  
Promising Alternative ◽  
Heterogeneous Microstructures

AbstractCellular materials are recognized for their high specific mechanical properties, making them desirable in ultra-lightweight applications. Periodic lattices have tunable properties and may be manufactured by metallic additive manufacturing (AM) techniques. However, AM can lead to issues with un-melted powder, macro/micro porosity, dimensional control and heterogeneous microstructures. This study overcomes these problems through a novel technique, combining additive manufacturing and investment casting to produce detailed investment cast lattice structures. Fused filament fabrication is used to fabricate a pattern used as the mold for the investment casting of aluminium A356 alloy into high-conformity thin-ribbed (~ 0.6 mm thickness) scaffolds. X-ray micro-computed tomography (CT) is used to characterize macro- and meso-scale defects. Optical and scanning electron (SEM) microscopies are used to characterize the microstructure of the cast structures. Slight dimensional (macroscale) variations originate from the 3D printing of the pattern. At the mesoscale, the casting process introduces very fine (~ 3 µm) porosity, along with small numbers of (~ 25 µm) gas entrapment defects in the horizontal struts. At a microstructural level, both the (~ 70 μm) globular/dendritic grains and secondary phases show no significant variations across the lattices. This method is a promising alternative means for producing highly detailed non-stochastic metallic cellular lattices and offers scope for further improvement through refinement of filament fabrication.

scholarly journals Suitability of Recycled PLA Filament Application in Fused Filament Fabrication Process

2021 ◽  
Vol 15 (4) ◽  
pp. 491-497
Author(s):  
Tomislav Breški ◽  
Lukas Hentschel ◽  
Damir Godec ◽  
Ivica Đuretek
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Polylactic Acid ◽  
Design Of Experiment ◽  
Experimental Approach ◽  
Manufacturing Processes ◽  
Support Structures ◽  
Fused Filament Fabrication ◽  
Layer Height ◽  
Printing Parameters

Fused filament fabrication (FFF) is currently one of the most popular additive manufacturing processes due to its simplicity and low running and material costs. Support structures, which are necessary for overhanging surfaces during production, in most cases need to be manually removed and as such, they become waste material. In this paper, experimental approach is utilised in order to assess suitability of recycling support structures into recycled filament for FFF process. Mechanical properties of standardized specimens made from recycled polylactic acid (PLA) filament as well as influence of layer height and infill density on those properties were investigated. Optimal printing parameters for recycled PLA filaments are determined with Design of Experiment methods (DOE).

Variance Quantification of Different Additive Manufacturing Processes for Acoustic Meta Materials

2021 ◽  
Vol 263 (4) ◽  
pp. 2708-2723
Author(s):  
Manuel Bopp ◽  
Arn Joerger ◽  
Matthias Behrendt ◽  
Albert Albers
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Production Process ◽  
Laser Scanning ◽  
Mode Shapes ◽  
Manufacturing Processes ◽  
3D Laser Scanning ◽  
Fused Filament Fabrication ◽  
Manufacturing Techniques ◽  
Different Levels

Many concepts for acoustic meta materials rely on additive manufacturing techniques. Depending on the production process and material of choice, different levels of precision and repeatability can be achieved. In addition, different materials have different mechanical properties, many of which are frequency dependent and cannot easily be measured directly. In this contribution the authors have designed different resonator elements, which have been manufactured utilizing Fused Filament Fabrication with ABSplus and PLA, as well as PolyJet Fabrication with VeroWhitePlus. All structures are computed in FEA to obtain the calculated Eigenfrequencies and mode shapes, with the respective literature values for each material. Furthermore, the dynamic behavior of multiple instances of each structure is measured utilizing a 3D-Laser-Scanning Vibrometer under shaker excitation, to obtain the actual Eigenfrequencies and mode shapes. The results are then analyzed in regards to variance between different print instances, and in regards to accordance between measured and calculated results. Based on previous work and this analysis the parameters of the FEA models are updated to improve the result quality.

An Algorithm for Generating 3D Lattice Structures Suitable for Printing on a Multi-Plane FDM Printing Platform

2018 ◽  
Author(s):  
Ismayuzri B. Ishak ◽  
Mark B. Moffett ◽  
Pierre Larochelle
Keyword(s):  
Additive Manufacturing ◽  
Fused Deposition Modeling ◽  
Lattice Structure ◽  
Geometric Model ◽  
Three Dimensional ◽  
Manufacturing Processes ◽  
Lattice Structures ◽  
Fused Deposition ◽  
Structure Generator ◽  
Conventional Machining

Manufacturing processes for the fabrication of complex geometries involve multi-step processes when using conventional machining techniques with material removal processes. Additive manufacturing processes give leverage for fabricating complex geometric structures compared to conventional machining. The capability to fabricate 3D lattice structures is a key additive manufacturing characteristic. Most conventional additive manufacturing processes involve layer based curing or deposition to produce a three-dimensional model. In this paper, a three-dimensional lattice structure generator for multi-plane fused deposition modeling printing was explored. A toolpath for an input geometric model with an overhang structure was able to be generated. The input geometric model was able to be printed using a six degree of freedom robot arm platform. Experimental results show the achievable capabilities of the 3D lattice structure generator for use with the multi-plane platform.

scholarly journals AM-FFF of Objects Using Commercial PLA Based Shape Memory Polymer Printed by an Open-Source 3D Printer

2020 ◽  
Vol 31 ◽  
pp. 30-34
Author(s):  
N. Dresler ◽  
A. Ulanov ◽  
M. Aviv ◽  
D. Ashkenazi ◽  
A. Stern
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Shape Memory ◽  
Open Source ◽  
Shape Memory Polymer ◽  
Manufacturing Processes ◽  
3D Printer ◽  
4D Printing ◽  
Fused Filament Fabrication ◽  
Memory Cycle

The 4D additive manufacturing processes are considered today as the "next big thing" in R&D. The aim of this research is to provide two examples of commercial PLA based shape memory polymer (SMP) objects printed on an open-source 3D printer in order to proof the feasibility of such novel 4D printing process. To that purpose, a PLA based filament of eSUN (4D filament e4D-1white, SMP) was chosen, and two applications, a spring and a vase, were designed by 3D-printing with additive manufacturing (AM) fused filament fabrication (FFF) technique. The 4D-printed objects were successfully produced, the shape memory effect and their functionality were demonstrated by achieving the shape-memory cycle of programming, storage and recovery.

Topology Optimization for Multi-Material Lattice Structures With Tailorable Material Properties for Additive Manufacturing

2019 ◽  
Author(s):  
Vysakh Venugopal ◽  
Matthew McConaha ◽  
Sam Anand
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Lattice Structure ◽  
Manufacturing Processes ◽  
Lattice Structures ◽  
High Mechanical Strength ◽  
Unit Cells ◽  
Significant Attention

Abstract Structurally optimized lattices have gained significant attention since the commercialization of additive manufacturing (AM). These lattices, which can be categorized as metamaterials, are used in aviation and aerospace industries due to their capacity to perform well under extreme structural, thermal, or acoustic loading conditions. This research focuses on the design of a unit cell of a multi-material lattice structure using topology optimization to be manufactured using multi-material additive manufacturing processes. The algorithm combined with octant symmetry and support elimination filters yields optimized unit cells with overall reduction in effective coefficient of thermal expansion and thermal conductivity with high mechanical strength. Such unit cells can be used in multi-material additive manufacturing to generate lattice structures with optimized structural and thermal properties.

Improved Co-Scheduling of Printing Path Scanning for Collaborative Additive Manufacturing

2019 ◽  
Author(s):  
Zhengqian Jiang ◽  
Sean Psulkowski ◽  
Arriana Nwodu ◽  
Hui Wang ◽  
Tarik Dickens
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing System ◽  
Manufacturing Processes ◽  
Grand Challenge ◽  
Optimal Solutions ◽  
Improved Method ◽  
Fused Filament Fabrication ◽  
Printing Time

Abstract Additive manufacturing processes, especially those based on fused filament fabrication (FFF) mechanism, have relatively low productivity and suffer from production scalability issue. One solution is to adopt a collaborative additive manufacturing system that is equipped with multiple extruders working simultaneously to improve productivity. The collaborative additive manufacturing encounters a grand challenge in the scheduling of printing path scanning by different extruders. If not properly scheduled, the extruders may collide into each other or the structures built by earlier scheduled scanning tasks. However, there existed limited research addressing this problem, in particular, lacking the determination of the scanning direction and the scheduling for sub-path scanning. This paper deals with the challenges by developing an improved method to optimally break the existing printing paths into sub-paths and assign these generated sub-paths to different extruders to obtain the lowest possible makespan. A mathematical model is formulated to characterize the problem, and a hybrid algorithm based on an evolutionary algorithm and a heuristic approach is proposed to determine the optimal solutions. The case study has demonstrated the application of the algorithms and compared the results with the existing research. It has been found that the printing time can be reduced by as much as 41.3% based on the available hardware settings.

Bayesian Optimization of Energy-Absorbing Lattice Structures for Additive Manufacturing

2020 ◽  
Author(s):  
Nathan Hertlein ◽  
Kumar Vemaganti ◽  
Sam Anand
Keyword(s):  
Finite Element ◽  
Additive Manufacturing ◽  
Optimization Problems ◽  
Lattice Structure ◽  
Structure Design ◽  
Bayesian Optimization ◽  
Fe Model ◽  
Lattice Structures ◽  
Element Analysis ◽  
Overhang Angle

Abstract Additive manufacturing has enabled the production of intricate lattice structures that meet stringent design requirements with minimal mass. While many methods such as lattice-based topology optimization are being developed to design lightweight structures for static loading, there is a need for design tools for achieving dynamic loading requirements. Lattice structures have shown particular promise as low-mass energy absorbers, but the computational expense of nonlinear finite element analysis and the difficulty of obtaining objective gradient information has made their optimization for impact loading particularly challenging. This study proposes a Bayesian optimization framework to determine the lattice structure design that provides the best performance under a specified impact, while managing the structure’s mass. Considering nonlinear effects such as plasticity and strain rate sensitivity, a 2D explicit finite element (FE) model is constructed for two lattice unit cell types under impact, and parameterized with respect to geometric attributes such as height, width, and strut thickness. These parameters are considered design variables in a minimization problem with an objective function that balances part volume with a common injury metric, the head injury criterion (HIC). Penalty values are assigned to designs that fail to absorb the entire impact. Design for additive manufacturing (DFAM) constraints including minimum feature thickness and maximum overhang angle are applied to ensure that the optimal design can be manufactured without subsequent manual refinement or post-processing. The best optimizer hyperparameters are then carried over into larger optimization problems involving lattice structures. Future work could include expanding this framework to allow for lattice structure designs with arbitrary boundaries.

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