Structure and mechanical behavior of Big Area Additive Manufacturing (BAAM) materials

2017 ◽  
Vol 23 (1) ◽  
pp. 181-189 ◽  
Author(s):  
Chad E. Duty ◽  
Vlastimil Kunc ◽  
Brett Compton ◽  
Brian Post ◽  
Donald Erdman ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Performance ◽  
Research Effort ◽  
Small Scale ◽  
Second Phase ◽  
Initial Development ◽  
Imperfect Contact ◽  
Content Type ◽  
Oak Ridge ◽  
Printed Materials

Purpose This paper aims to investigate the deposited structure and mechanical performance of printed materials obtained during initial development of the Big Area Additive Manufacturing (BAAM) system at Oak Ridge National Laboratory. Issues unique to large-scale polymer deposition are identified and presented to reduce the learning curve for the development of similar systems. Design/methodology/approach Although the BAAM’s individual extruded bead is 10-20× larger (∼9 mm) than the typical small-scale systems, the overall characteristics of the deposited material are very similar. This study relates the structure of BAAM materials to the material composition, deposition parameters and resulting mechanical performance. Findings Materials investigated during initial trials are suitable for stiffness-limited applications. The strength of printed materials can be significantly reduced by voids and imperfect fusion between layers. Deposited material was found to have voids between adjacent beads and micro-porosity within a given bead. Failure generally occurs at interfaces between adjacent beads and successive layers, indicating imperfect contact area and polymer fusion. Practical implications The incorporation of second-phase reinforcement in printed materials can significantly improve stiffness but can result in notable anisotropy that needs to be accounted for in the design of BAAM-printed structures. Originality/value This initial evaluation of BAAM-deposited structures and mechanical performance will guide the current research effort for improving interlaminar strength and process control.

The influence of load direction, microstructure, raster orientation on the quasi-static response of fused deposition modeling ABS

2019 ◽  
Vol 25 (3) ◽  
pp. 462-472 ◽  
Author(s):  
Oluwakayode Bamiduro ◽  
Gbadebo Owolabi ◽  
Mulugeta A. Haile ◽  
Jaret C. Riddick
Keyword(s):  
Additive Manufacturing ◽  
Fused Deposition Modeling ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Bead Geometry ◽  
Static Response ◽  
Load Direction ◽  
Content Type ◽  
Fused Deposition ◽  
Deposition Modeling

Purpose The continual growth of additive manufacturing has increased tremendously because of its versatility, flexibility and high customization of geometric structures. However, design hurdles are presented in understanding the relationship between the fabrication process and materials microstructure as it relates to the mechanical performance. The purpose of this paper is to investigate the role of build architecture and microstructure and the effects of load direction on the static response and mechanical properties of acrylonitrile butadiene styrene (ABS) specimens obtained via the fused deposition modeling (FDM) processing technique. Design/methodology/approach Among additive manufacturing processes, FDM is a prolific technology for manufacturing ABS. The blend of ABS combines strength, rigidity and toughness, all of which are desirable for the production of structural materials in rapid manufacturing applications. However, reported literature has varied widely on the mechanical performance due to the proprietary nature of the ABS material ratio, ultimately creating a design hurdle. While prior experimental studies have studied the mechanical response via uniaxial tension testing, this study has aimed to understand the mechanical response of ABS from the materials’ microstructural point of view. First, ABS specimen was fabricated via FDM using a defined build architecture. Next, the specimens were mechanically tested until failure. Then finally, the failure structures were microstructurally investigated. In this paper, the effects of microstructural evolution on the static mechanical response of various build architecture of ABS aimed at FDM manufacturing technique was analyzed. Findings The results show that the rastering orientation of 0/90 exhibited the highest tensile strength followed by fracture at its maximum load. However, the “45” bead direction of the ABS fibers displayed a cold-drawing behavior before rupture. The morphology analyses before and after tensile failure were characterized by a scanning electron microscopy (SEM) which highlighted the effects of bead geometry (layers) and areas of stress concentration such as interstitial voids in the material during build, ultimately compromising the structural integrity of the specimens. Research limitations/implications The ability to control the constituents and microstructure of a material during fabrication is significant to improving and predicting the mechanical performance of structural additive manufacturing components. In this report, the effects of microstructure on the mechanical performance of FDM-fabricated ABS materials was discussed. Further investigations are planned in understanding the effects of ambient environmental conditions (such as moisture) on the ABS material pre- and post-fabrication. Originality/value The study provides valuable experimental data for the purpose of understanding the inter-dependency between build parameters and microstructure as it relates to the specimens exemplified strength. The results highlighted in this study are fundamental to the development of optimal design of strength and complex ultra-lightweight structure efficiency.

An improved lattice structure design optimization framework considering additive manufacturing constraints

2017 ◽  
Vol 23 (2) ◽  
pp. 305-319 ◽  
Author(s):  
Recep M. Gorguluarslan ◽  
Umesh N. Gandhi ◽  
Yuyang Song ◽  
Seung-Kyum Choi
Keyword(s):  
Additive Manufacturing ◽  
Lattice Structure ◽  
Structure Optimization ◽  
Optimization Methods ◽  
Structure Design ◽  
Second Phase ◽  
Manufacturing Constraints ◽  
Ground Structure ◽  
Content Type ◽  
Optimization Framework

Purpose Methods to optimize lattice structure design, such as ground structure optimization, have been shown to be useful when generating efficient design concepts with complex truss-like cellular structures. Unfortunately, designs suggested by lattice structure optimization methods are often infeasible because the obtained cross-sectional parameter values cannot be fabricated by additive manufacturing (AM) processes, and it is often very difficult to transform a design proposal into one that can be additively designed. This paper aims to propose an improved, two-phase lattice structure optimization framework that considers manufacturing constraints for the AM process. Design/methodology/approach The proposed framework uses a conventional ground structure optimization method in the first phase. In the second phase, the results from the ground structure optimization are modified according to the pre-determined manufacturing constraints using a second optimization procedure. To decrease the computational cost of the optimization process, an efficient gradient-based optimization algorithm, namely, the method of feasible directions (MFDs), is integrated into this framework. The developed framework is applied to three different design examples. The efficacy of the framework is compared to that of existing lattice structure optimization methods. Findings The proposed optimization framework provided designs more efficiently and with better performance than the existing optimization methods. Practical implications The proposed framework can be used effectively for optimizing complex lattice-based structures. Originality/value An improved optimization framework that efficiently considers the AM constraints was reported for the design of lattice-based structures.

Microstructure of In738Lc Fabricated Using Laser Powder Bed Fusion Additive Manufacturing

2021 ◽  
pp. 1-19
Author(s):  
Nandana Menon ◽  
Tanjheel Hasan Mahdi ◽  
Amrita Basak
Keyword(s):  
Additive Manufacturing ◽  
Electron Backscatter Diffraction ◽  
Small Scale ◽  
Second Phase ◽  
Face Centered Cubic ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Nickel Base Superalloys ◽  
Nickel Base

Abstract Nickel-base superalloys are extensively used in the production of gas turbine hot-section components as they offer exceptional creep strength and superior fatigue resistance at high temperatures. Such improved properties are due to the presence of precipitate-strengthening phases such as Ni3Ti or Ni3Al (gγ phases) in the normally face-centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvements in properties, the presence of such phases also results in increased processing difficulties as these alloys are prone to crack formation. In this work, specimens of IN738LC are fabricated on a Coherent Creator laser powder bed fusion (L-PBF) additive manufacturing (AM) equipment. Optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-Ray diffraction (XRD) are carried out to characterize the deposit region. Metallurgical continuity is achieved in the entire deposit region and the specimens do not show any warpage. However, the specimens show voids (e.g., pores and cracks) in the deposit region. The results show that the percentage void area decreases along the build height direction. The deposited IN738LC shows polycrystalline grains in the entire deposit region as confirmed by XRD and EBSD. The grain size also shows variations along the build direction. In summary, the results open opportunities for academic researchers and small scale businesses in fabricating high-gγ nickel-base superalloys on a desktop laser powder bed fusion AM equipment

Additive manufacturing in the wood-furniture sector

2018 ◽  
Vol 29 (2) ◽  
pp. 350-371 ◽  
Author(s):  
Federica Murmura ◽  
Laura Bravi
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Small Scale ◽  
Computer Assisted ◽  
Scale Production ◽  
Content Type ◽  
Advantages And Disadvantages ◽  
Wood Furniture ◽  
Manufacturing Techniques ◽  
Manufacturing Technologies

Purpose In the world economy there is the emergence of advanced manufacturing technologies that are enabling more cost and resource-efficient small-scale production. Among them, additive manufacturing, commonly known as 3D printing, is leading companies to rethink where and how they conduct their manufacturing activities. The purpose of this paper is to focus in the Italian wood-furniture industry to understand if the companies in this sector are investing in additive manufacturing techniques, to remain competitive in their reference markets. The research also attempts to investigate the potential sustainable benefits and limitations to the implementation of 3D printing in this specific sector, considering the companies that have already implemented this technology. Design/methodology/approach Data were collected using a structured questionnaire survey performed on a sample of 234 Italian companies in this sector; 76 companies claimed to use 3D printing in their production system. The questionnaire was distributed via computer-assisted web interviewing and it consisted of four sections. Findings The research has highlighted how Italian 3D companies have a specific profile; they are companies aimed at innovating through the search for new products and product features, putting design and Made in Italy in the first place. They pay high attention to the image they communicate to the market and are highly oriented to the final customer, and to the satisfaction of its needs. Originality/value The study is attempting to expand a recent and unexplored research line on the possible advantages and disadvantages of the implementation of emerging production technologies such as 3D printing.

Microstructure of IN738LC Fabricated Using Laser Powder Bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Nandana Menon ◽  
Tanjheel Hassan Mahdi ◽  
Amrita Basak
Keyword(s):  
Additive Manufacturing ◽  
Electron Backscatter Diffraction ◽  
Small Scale ◽  
Second Phase ◽  
Face Centered Cubic ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Nickel Base Superalloys ◽  
Nickel Base

Abstract Nickel-base superalloys are extensively used in the production of gas turbine hot-section components as they offer exceptional creep strength and superior fatigue resistance at high temperatures. Such improved properties are due to the presence of precipitate-strengthening phases such as Ni3Ti or Ni3Al (γ′ phases) in the normally face-centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvements in properties, the presence of such phases also results in increased processing difficulties as these alloys are prone to crack formation. In this work, specimens of IN738LC are fabricated on a Coherent Creator laser powder bed fusion (L-PBF) additive manufacturing (AM) equipment. Optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-Ray diffraction (XRD) are carried out to characterize the deposit region. Metallurgical continuity is achieved in the entire deposit region and the specimens do not show any warpage. However, the specimens show voids (e.g., pores and cracks) in the deposit region. The results show that the percentage void area decreases along the build height direction. The deposited IN738LC shows polycrystalline grains in the entire deposit region as confirmed by XRD and EBSD. The grain size also shows variations along the build direction. In summary, the results open opportunities for academic researchers and small-scale businesses in fabricating high-γ′ nickel-base superalloys on a desktop laser powder bed fusion AM equipment.

A bid generation problem for combinatorial transportation auctions considering in-vehicle consolidations

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fang Yan ◽  
Kai Chen ◽  
Manjing Xu
Keyword(s):  
Computation Time ◽  
Mixed Integer ◽  
Small Scale ◽  
Second Phase ◽  
Two Phase ◽  
Content Type ◽  
Numerical Examples ◽  
Proposed Model ◽  
Vehicle Capacity ◽  
Generation Problem

PurposeThis paper studied a bid generation problem in combinatorial transportation auctions that considered in-vehicle consolidations. The purpose of this paper seeks to establish mixed integer programming to the most profitable transportation task packages.Design/methodology/approachThe authors proposes a mathematical model to identify the most profitable transportation task packages under vehicle capacity, flow balance and in-vehicle consolidation operational constraints, after which a two-phase heuristic algorithm was designed to solve the proposed model. In the first phase, a method was defined to compute bundle synergy, which was then combined with particle swarm optimization (PSO) to determine a satisfactory task package, and in the second phase, the PSO was adopted to program vehicle routings that considered in-vehicle consolidation.FindingsThree numerical examples were given to analyze the effects of the proposed model and method, with the first two small-scale examples coming from the same data base and the third being a larger scale example. The results showed that: (1) the proposed model was able to find a satisfactory solution for the three numerical examples; (2) the computation time was significantly shorter than the accurate algorithm and (3) considering in-vehicle consolidations operations could increase the carrier profits.Originality/valueThe highlights of this paper are summarized as following: (1) it considers in-vehicle consolidation when generating bids to maximize profits; (2) it simultaneously identifies the most valuable lane packages and reconstructs vehicle routes and (3) proposes a simple but effective synergy-based method to solve the model.

scholarly journals Building Block Synthesis of Self-Supported Three-Dimensional Compliant Elements for Metallic Additive Manufacturing

2020 ◽  
Vol 143 (5) ◽  
Author(s):  
Aschraf N. Danun ◽  
Philip D. Palma ◽  
Christoph Klahn ◽  
Mirko Meboldt
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Performance ◽  
Compliant Mechanisms ◽  
Three Dimensional ◽  
Building Blocks ◽  
Small Scale ◽  
Bistable Switch ◽  
Powder Bed ◽  
Switch Mechanism ◽  
Metallic Additive

Abstract Compliant mechanisms gain motion through the elastic deformation of the monolithic flexible elements. The geometric design freedom of metallic additive manufacturing enables the fabrication of complex and three-dimensional (3D) compliant elements within mechanisms previously too complicated to produce. However, the design of metallic additive manufactured mechanisms faces various challenges of manufacturing restrictions, such as avoiding critical overhanging geometries and minimizing the amount of support structure, which has been reported in a few cases. This paper presents a synthesis approach for translational compliant elements, involving building blocks based on leaf-type springs and covering building orientations between 0 deg and 90 deg. In particular, this range is approached by the synthesis of self-supported 3D building blocks with orientations of 0 deg, 45 deg and 90 deg. The compliant elements are built based on linear and circular plane curves and compared numerically according to their mechanical performance to create preferable building blocks. The applicability of the presented procedure and the manufacturability of the compliant mechanisms are proven by printing individual 3D building blocks and their serial aggregation with laser-based powder bed fusion. Consequently, several prototypes are demonstrated, including a bistable switch mechanism and a large displaceable rotational spring joint. In addition, a small-scale highly maneuverable segment of a surgical instrument with a grasping mechanism at the distal end is proposed.

scholarly journals Multi-solution nature of topology optimization and its application in design for additive manufacturing

2019 ◽  
Vol 25 (9) ◽  
pp. 1475-1481 ◽  
Author(s):  
Hassan Rezayat ◽  
Jared Richard Bell ◽  
Alex J. Plotkowski ◽  
Sudarsanam S. Babu
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Cantilever Beam ◽  
Mechanical Performance ◽  
Design Tool ◽  
Image Correlation ◽  
Content Type ◽  
Fused Deposition ◽  
Starting Point ◽  
Initial Starting

Purpose The purpose of this paper is to introduce the multi-solution nature of topology optimization (TO) as a design tool for additive manufacturing (AM). The sensitivity of topologically optimized parts and manufacturing constraints to the initial starting point of the optimization process leading to structures with equivalent performance is explored. Design/methodology/approach A modified bi-directional evolutionary structural optimization (BESO) code was used as the numerical approach to optimize a cantilever beam problem and reduce the mass by 50 per cent. Several optimized structures with relatively equivalent mechanical performance were generated by changing the initial starting point of the TO algorithm. These optimized structures were manufactured using fused deposition modeling (FDM). The equivalence of strain distribution in FDM parts was tested with the digital image correlation (DIC) technique and compared with that from the modified BESO code. Findings The results confirm that TO could lead to a wide variety of non-unique solutions based on loading and manufacturability constraints. The modified BESO code was able to reduce the support structure needed to build the simple two-dimensional cantilever beam by 15 per cent while keeping the mechanical performance at the same level. Originality/value The originality of this paper lies in introduction and application of the multi-solution nature of TO for AM as a design tool for optimizing structures with minimized features in the overhang condition and the need for support structures.

scholarly journals Improving Mechanical Properties for Extrusion-Based Additive Manufacturing of Poly(Lactic Acid) by Annealing and Blending with Poly(3-Hydroxybutyrate)

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1529 ◽  
Author(s):  
Sisi Wang ◽  
Lode Daelemans ◽  
Rudinei Fiorio ◽  
Maling Gou ◽  
Dagmar R. D’hooge ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Additive Manufacturing ◽  
Mechanical Performance ◽  
Softening Temperature ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Poly Lactic Acid ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry

Based on differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, polarizing microscope (POM), and scanning electron microscopy (SEM) analysis, strategies to close the gap on applying conventional processing optimizations for the field of 3D printing and to specifically increase the mechanical performance of extrusion-based additive manufacturing of poly(lactic acid) (PLA) filaments by annealing and/or blending with poly(3-hydroxybutyrate) (PHB) were reported. For filament printing at 210 °C, the PLA crystallinity increased significantly upon annealing. Specifically, for 2 h of annealing at 100 °C, the fracture surface became sufficiently coarse such that the PLA notched impact strength increased significantly (15 kJ m−2). The Vicat softening temperature (VST) increased to 160 °C, starting from an annealing time of 0.5 h. Similar increases in VST were obtained by blending with PHB (20 wt.%) at a lower printing temperature of 190 °C due to crystallization control. For the blend, the strain at break increased due to the presence of a second phase, with annealing only relevant for enhancing the modulus.

Processability of pure Zn and pure Fe by SLM for biodegradable metallic implant manufacturing

2017 ◽  
Vol 23 (3) ◽  
pp. 514-523 ◽  
Author(s):  
Marco Montani ◽  
Ali Gökhan Demir ◽  
Ehsan Mostaed ◽  
Maurizio Vedani ◽  
Barbara Previtali
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Incomplete Fusion ◽  
Second Phase ◽  
Aisi 316L ◽  
Laser Melting ◽  
Content Type ◽  
Biodegradable Metals ◽  
Degradation Rates ◽  
Superior Mechanical Properties

Purpose This paper aims to investigate the processability by selective laser melting (SLM) of materials of potential interest for innovative biodegradable implants, pure Fe and pure Zn. The processability of these materials is evaluated with a more established counterpart in permanent implants, stainless steel. In particular, the processing conditions were studied to reduce porosity due to incomplete fusion of the powder. Design/methodology/approach In the first phase of the experiments, SLM of AISI 316L was studied through design of experiments method. The study was used to identify the significant parameters in the experimental range and estimate the fluence ranges for pure Fe and pure Zn using the lumped heat capacity model. In the second phase, SLM of pure Fe and pure Zn were studied using estimated fluence ranges. In the final phase, best conditions were characterized for mechanical properties. Findings The results showed that complete melting of AISI 316L and pure Fe could be readily achieved, whereas laser melting generated a foam-like porous structure in Zn samples. The mechanical properties of laser melt implant materials were compared to as-cast and rolled counterparts. Laser melted AISI 316L showed superior mechanical performance compared to as-cast and rolled material, whereas Fe showed mechanical performance similar to rolled mild steel. Despite 12 per cent apparent porosity, laser melted Zn exhibited superior mechanical properties compared to as-cast and wrought material because of reduced grain size. Originality/value The paper provides key processing knowledge on the SLM processability of new biodegradable metals, namely, pure Fe, which has been studied sparingly, and pure Zn, on which no previous work is available. The results prefigure the production of new biodegradable metallic implants with superior mechanical properties compared to their polymeric counterparts and with improved degradation rates compared to magnesium alloys, the reference material for biodegradable metals.

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