Engineering Conferences International

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MacDonald, Eric

ADDITIVE MANUFACTURING OF ELASTOMER, CERAMIC AND METAL MULTI-FUNCTIONAL STRUCTURES   Eric MacDonald, UTEP  emac@utep.edu     Key Words: multi-functional structures.  3D printing has been historically relegated to fabricating conceptual models and prototypes; however, increasingly, research is now focusing on fabricating functional end-use products.  As patents for 3D printing expire, new low-cost desktop systems are being adopted more widely and this trend is leading to a diversity of new products, processes and available materials. However, currently the technology is generally confined to fabricating single material static structures. For additively manufactured products to be economically meaningful, additional functionalities are required to be incorporated in terms of electronic, electromechanical, electromagnetic, thermodynamic, chemical and optical content.  By interrupting the 3D printing and employing complementary manufacturing processes, additional functional content can be included in mass-customized structures. This presentation will review work in multi-process 3D printing for creating structures with consumer-anatomy-specific wearable electronics, electromechanical actuation, electromagnetics, propulsion, embedded sensors in soft tooling and including metal and ceramic structures.  Other projects to be presented include stereovision process monitoring of powder bed fusion, 3D printed smart molds for sand casting, complex ceramic lattices for electromagnetic lenses, elastomeric lattices for the athletic gear, computation geometry and complexity theory for 3D printing.      

English

Additive manufacturing of elastomer, ceramic and metal multi-functional structures

Compton, Brett

MATERIAL EXTRUSION ADDITIVE MANUFACTURING OF THERMOSET-BASED SHORT FIBER COMPOSITES  Brett Compton; Mechanical, Aerospace, and Biomedical Engineering Department; University of Tennessee, Knoxville, USA brettcompton@utk.edu   Key Words: Material extrusion, composites, thermoset polymer, fiber length, carbon fiber  This talk will discuss the challenges and opportunities associated with material extrusion additive manufacturing (AM) of short fiber composites, with an emphasis on thermoset-based systems. The talk will begin with a brief review the origin and early work in AM of thermosets and short fiber composites then proceed into current research that investigates the factors that control the fiber length distribution (FLD) in printed short-fiber composites and how FLD influences printability and mechanical properties. The talk will conclude with an introduction of novel printing approaches that enable higher fiber loading, unique material architecture, and greater control over fiber orientation.     Figure1: (a) Schematic illustrating tradeoff between printing behavior and mechanical performance in 3D-printed short fiber composites. (b) Example cumulative distribution function for fiber length in epoxy / short carbon fiber composites. (c) Volume-weighted average fiber length in 3D printed epoxy / short carbon fiber composites subject to different fiber loading and mixing times. (d-g) Optical micrographs of the same composites subject to different mixing times showing fiber pullout after flexural testing.  

Material extrusion additive manufacturing of thermoset-based short fiber composites

Romberg, Stian

Lehrman, Sarah

Snyder, Chad

Seppala, Jonathan

Kotula, Anthony

NOVEL RHEOLOGICAL MEASUREMENTS TO UNDERSTAND STRUCTURAL STABILITY OF DIW-PRINTED EPOXY COMPOSITES DURING THERMAL CURING  Stian Romberg, National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA stian.romberg@nist.gov Paul Roberts, NIST, Gaithersburg, MD, USA Sarah Lehrman, NIST, Gaithersburg, MD, USA & University of Maryland, Baltimore County, Baltimore, MD, USA Chad Snyder, NIST, Gaithersburg, MD, USA Jonathan Seppala, NIST, Gaithersburg, MD, USA Anthony Kotula, NIST, Gaithersburg, MD, USA   Key Words: Direct ink write, thermoset composite, rheology, Raman spectroscopy, curing  Current literature frequently presents geometrically complex thermoset composites with excellent chemical, mechanical, and thermal stability produced via material extrusion. However, non-empirical strategies to avoid structural collapse during curing are rarely presented, because traditional measurement techniques are not equipped to directly relate temperature and conversion to the rheological properties responsible for structural stability. Further, identifying the moment at which the printed material is no longer susceptible to self-weight structural collapse (i.e., the chemical gel point) is not straightforward. Traditional definitions of the chemical gel point are difficult to apply to these physically gelled composites due to their unique rheological profile and rapid curing rate. This gap in literature may be addressed with two recently developed measurement technologies – the rheo-Raman instrument and Optimally Windowed Chirp (OWCh) measurements. In 2016, Kotula et al. developed a rheo-Raman instrument [1] to simultaneously capture rheological measurements and Raman spectra, which can be used to measure conversion. This technique provides direct relationships between rheological properties, conversion, and temperature without introducing ambiguity created by taking measurements on separate samples in different instruments. These measurements can be used to determine the conversion at which key rheological transitions occur, like the chemical gel point, provided that we can accurately identify where the gel point occurs for printable thermoset composites. In 2018, Geri et al. presented a way to find the gel point using OWCh measurements, which impart a frequency-varying sinusoidal strain to quickly obtain the viscoelastic spectrum without applying high strains [2]. Printable thermoset composites often have modest linear viscoelastic regimes and cure rapidly, making OWCh measurements ideal for tracking the evolution of the viscoelastic spectrum during curing. The resulting time-resolved viscoelastic spectra help to understand the solidification process of these materials that do not conform to the traditional definitions of the chemical gel point.    [1] A.P. Kotula, M.W. Meyer, F.D. Vito, J. Plog, A.R.H. Walker, K.B. Migler, 2016. Rev. Sci. Instrum. 87(10), 105105. https://doi.org/10.1063/1.4963746. [2] M. Geri, B. Keshavarz, T. Divoux, C. Clasen, D.J. Curtis, G.H. McKinley, 2018. Phys. Rev. X 8(4), 041042. https://doi.org/10.1103/PhysRevX.8.041042.  

Novel rheological measurements to understand structural stability of DIW- printed epoxy composites during thermal curing

Jin, Qing-Ye

Lee, Wookjin

ANCHORING-BASED CONTROL OF DISSIMILAR MATERIAL INTERFACE FOR MULTI-MATERIAL LASER DIRECT ENERGY DEPOSITION  Qing-Ye Jin, Pusan National University sub6953@pusan.ac.kr Wookjin Lee, Pusan National University   Key Words: Laser direct energy deposition; Multi-material additive manufacturing; Interfaces.  Multi-material additive manufacturing can be used to fabricate components with multiple materials possessing new functionalities that cannot be realized by a single material. Laser direct energy deposition (L-DED) is a well-known metal additive manufacturing technology which are relevant to multi-material fabrication. However, for many combinations of dissimilar metallic materials, brittle intermetallic phases are easily formed at interfaces that often result in delamination cracking and make the materials difficult to be joined. In this study, a L-DED processing method is developed to achieve multi-material components with a strong interface bonding, based on anchor-like structures produced during the L-DED. Multi-material L-DED of Fe-Al dissimilar materials – a well-known combination of materials that are difficult to join – is demonstrated.                 Figure 1 – Fe-Al multi-material samples produced by L-DED. 

Anchoring-based control of dissimilar material interface for multi-material laser direct energy deposition

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Biggs, Matthew

OVERCOMING THE RISKS IN SYNTHETIC BIOLOGY PRODUCT DEVELOPMENT THROUGH RAPID, GENOME SCALE METABOLIC ENGINEERING  Matthew Biggs, Sr. Computational Biologist, Inscripta matthew.biggs@inscripta.com   Key Words: Genome-scale Enzyme Engineering  New genome engineering approaches for the efficient development and manufacturing of sustainable, cost-effective bioproducts are sorely needed.  Long development timelines, massive investments and high risks of failure are holding the industry back. To address these acute challenges, Inscripta developed GenoScaler™, a first of its kind, rapid microbial genome engineering platform.  GenoScaler™ is a scalable, cost-effective, high-throughput CRISPR-based genome engineering technology stack that can rapidly design, build, and test 10,000+ precision edits across E. coli and S. cerevisiae genomes to efficiently survey and optimize over many enzymes in parallel, effectively engineering at the pathway and genome scales. Along with integrated, state-of-the-art methods for high-throughput phenotyping, smart automation, scale-up, informatics, and artificial intelligence, the platform is broadly applicable and can accelerate the process of synthetic biology product development by orders of magnitude, resulting in unprecedented gains in scale-up performance compared to traditional methods for microbial strain development.  Learn about the challenges facing genome scale engineering and how the platform enables Inscripta and its partners fuller access to the bioeconomy, from concept through to scale-up and commercial production and ingredient supply, using the newly developed principles of Lean Bioengineering™.  

Overcoming the risks in synthetic biology product development through rapid, genome scale metabolic engineering

Gupta, Nikhil

Karri, Ramesh

ENABLING DIGITAL MANUFACTURING CYBER-PHYSICAL SYSTEM FOR FUTURE MANUFACTURING  Nikhil Gupta, New York University, Mechanical and Aerospace Engineering Department ngupta@nyu.edu Ramesh Karri, New York University, Electrical and Computer Engineering Department   Key Words: Digital manufacturing, design, microstructure, imaging methods.  Digital Manufacturing is a cyber-physical system (CPS), where design, manufacturing and testing phases are integrated by implementing sensors, data driven models and network connectivity. Additive manufacturing and machine learning (ML) are among the enabling technologies in the larger digital manufacturing CPS. It is envisioned that ML methods will be able to automate the design process, material development and manufacturing process parameter optimization. While the state of the art in ML is able to provide reliable results for several tasks, integrating the entire manufacturing CPS on the same platform is very challenging and aspirational. In addition to the benefits, connectivity also brings several challenges related to cybersecurity. The effect of cyber-attacks on the quality of raw materials, manufactured products and test data needs to be understood and robust defense strategies need to be developed based on the design principles and materials characteristics. This talk will demonstrate the manufacturing CPS attack surface and many defense strategies rooted in product design principles or material microstructure.  One of the critical areas of need in the digital manufacturing CPS is to develop characterization methods that can be implemented in the build chamber of a 3D printer. A major benefit of additive manufacturing (AM) is the possibility of manufacturing customized products in small production runs. The current combination of non-destructive and destructive characterization methods is not conducive to such testing regime because the requirement of manufacturing additional specimens will make the product more expensive. Hence, methods that can be implemented inside the build chamber to identify the defects as they initiate and allow intervention strategies will be immensely useful to salvage the print and maintain high quality. Such characterization methods and principles need to be developed to obtain the full benefits of additive manufacturing. Fig. 1 shows the use of in-situ acquired image and the digital twin to check for defect as the part is being printed. In addition, infrared cameras, ultrasonic transducers and many other sensors can be implemented in 3D printers. The information obtained from all the sensors should be compatible with the ML-based platforms that will be developed to support the manufacturing CPS.     .   Figure 1 – Comparison of (a) optical image with (b) digital twin to identify the defects. (c) shows the layering pattern in close-up. 

Enabling digital manufacturing cyber-physical system for future manufacturing

Cortes, Pedro

3D PRINTED CERAMICS STRUCTURES - CHALLENGES AND APPLICATIONS  Pedro Cortes, Youngstown State University, OH. pcortes@ysu.edu Eric MacDonald, The University of Texas at El Paso, TX.   Key Words: Ceramics, Sintering, Characterization, Digital-Light-Processing, Binder-Jetting-Process   In contrast to the conventional material used in additive manufacturing, ceramics provide beneficial features at high temperature such as hardness and rigidity, as well as electrical and magnetic properties that made them attractive systems for a wide range of applications. However, ceramics also present a number of limitations including ductility, shock resistance, and dimensional tolerance when compared to polymers and metals. The 3D printing process of ceramic materials remains a challenging procedure given their difficulty of manufacturing dense parts while avoiding cracking and delamination, especially during the post-thermal sintering process. Several 3D printing technologies have been used to manufacture ceramics, however, vat photopolymerization and binder jetting remain the two main processes to manufacture ceramic structures. The present work addresses the structure-property relationship of 3D printed ceramics materials using binder jetting. The influence of particle size, spread speed, binder saturation, layer thickness and sintering temperature have been investigated and related to the mechanical performance of the manufactured ceramics (see figure 1). This research program also addresses the work performed on a NanoJetting and a Digital Light Processing (DLP) technology to produce a wide range of ceramic materials ranging from zirconia systems used on electromagnetic platforms to electrode-based materials for batteries such as LiFePO4 (see figure 1). Here, the challenges associated with their printing and sintering stages will be discussed. Indeed, it seems that whilst long sintering cycles and slow heating ramp represent an effective procedure to ensure mechanically robust structures; in several cases, especially on ceramic materials for battery applications, a balance between the mechanical and electrochemical performance needs to be assessed in terms of the post-thermal treatment to guarantee successful electrical features.         Figure 1 –Top Left: Effect of printing parameters and sintered temperature on the density of sintered ceramics using a BJ Process. Top Right: Sintering study of a NanoJetted 3D printed zirconia ceramic - (a) thermal post-processing profiles; and (b) effect of the sintering profile on the sintered flexural strength. Bottom: 3D printed ceramic electrodes in their green and sintered state for battery applications. 

3D printed ceramics structures - Challenges and applications

Kadok, Joris

Bulou, Simon

Choquet, Patrick

LUNAR REGOLITH AS A FEEDSTOCK FOR SELECTIVE LASER MELTING  Joris Kadok, Luxembourg Institute of Science and Technology Joris.Kadok@LIST.lu Simon Bulou, Luxembourg Institute of Science and Technology Patrick Choquet, Luxembourg Institute of Science and Technology   Key Words: In-situ resource utilization, lunar regolith, space manufacturing, selective laser melting  In the context of space exploration and colonization, In-Situ Resource Utilization (ISRU) is a concept aimed at harnessing available resources in space environments, such as the Moon, Mars, or asteroids, instead of relying solely on supplies from Earth. This pioneering approach not only reduces the immense costs and logistical challenges associated with extraterrestrial missions but also holds promise for additive manufacturing. By using locally sourced materials, ISRU allows the crafting of tools, equipment, and even habitats directly on distant celestial bodies, representing a significant step toward sustainable and self-sufficient space missions. In the case of the Moon, lunar regolith is the most readily available and primary target for such endeavors. It consists of fragmented rock, dust, and soil covering the Moon's surface due to billions of years of meteoroid impacts and micrometeorite collisions. This valuable resource is highly sought after for its potential applications across various manufacturing technologies, and we will specifically address the use of selective laser melting (SLM) in this study. Some authors have previously succeeded in 3D printing simple objects from a lunar regolith simulant [1], but the heterogeneous nature of this material posed challenges to the quality of the results. Problems arise, for example, from the sharp shapes of the particles and the wide particle size distribution (PSD), affecting the material's flowability. Additionally, challenges arise due to the presence of multiple metallic oxides, each with its own melting point, affecting the melt pool. In this work, we will investigate the benefits of a spheroidization pre-treatment of a lunar regolith simulant (see Figure 1). This task has been carried out with a dedicated apparatus utilizing inductively coupled plasma technology, where the sample passes through a plasma jet that can reach temperatures of up to 10,000 K. Different sample batches have been prepared with varying PSDs and treated separately. We will explore the impact of adding various amounts of H2 during the spheroidization process. Following this preparation, we will examine different properties such as hall flow, PSD, tapped density, and material rheology to validate its suitability for use in an SLM environment. The results will namely demonstrate the positive effect of the pre-treatment on the material's flowability.                                                                                             [1] M. Fateri, A. Gebhardt. Process parameters development of selective laser melting of lunar regolith for on-site manufacturing applications. International Journal of Applied Ceramic Technology 1-7 (2014). DOI:10.1111/ijac.12326  Figure 1 – SEM images of a batch of raw (top) and spheroidized (bottom) lunar regolith simulant 

Lunar regolith as a feedstock for selective laser melting

Gonzalez-Gutierrez, Joamin

Staropoli, Mariapaola

Hentschel, Lukas

3D AND 4D PRINTING OF POLYPROPYLENE HAVING DIFFERENT CONTENT OF COPOLYMER  Joamin Gonzalez-Gutierrez, Functional Polymers, Luxembourg Institute of Science and Technology joamin.gonzalez-gutierrez@list.lu Mariapaola Staropoli, Functional Polymers, Luxembourg Institute of Science and Technology Lukas Hentschel, Polymer Processing, Montanuniversitaet Leoben   Key Words: polypropylene copolymer, shape memory response, material extrusion  Polypropylene (PP) is one of the most used thermoplastics in the world due to its versatility and relatively low cost. It has been demonstrated that PP can be shaped via additive manufacturing (AM) techniques like material extrusion (MEX) and powder bed fusion (PBF). The most common AM technique is MEX; however, problems of build-platform detachment and warpage are observed. One way to solve these issues is to use copolymers of propylene-ethylene. In addition, it has been observed that PP and its copolymers show a thermos-responsive shape memory response; hence, if a 3D printed specimen is exposed to thermal fluctuations, it can change shape, giving rise to 4D printing. This investigation studies the effect ethylene content has on the MEX processability and the shape memory response of propylene-ethylene copolymers.  Three polypropylene copolymers with an ethylene content of 4, 9 and 11 wt.% were extruded as filaments. Tensile tests and rheometry were performed on the three materials. The printability of the three copolymers was tested in two filament-based MEX printers, one with a direct extrusion head and another with a Bowden extrusion head. It was observed that copolymers with 4 and 9 wt.% of ethylene could be printed in both printers, but the copolymer with 11 wt.% was not printable in any of the tested printers due to buckling at the feeding mechanism. Even though the copolymer with the highest ethylene content showed a slightly lower viscosity (Figure 1a), it also had the lowest tensile modulus (Figure 1b) and thus becoming not AM-processable as a filament; demonstrating, once again, that during filament-based MEX, having the correct filament stiffness is crucial to achieving printability.  Bar specimens were fabricated using the Bowden MEX printer using the two copolymers that were printable. The bar specimens were tested in a rotational rheometer fitted with solid clamps. Their shape memory response was evaluated by calculating their fixing and recovery ratios. It was observed that the copolymer with the 9 wt.% had the highest fixing (Rf) and recovery (Rr) ratios (Figure 2).   The study demonstrates the versatility of propylene-ethylene copolymers as materials for 3D and 4D printing.     Figure 2 – Shape memory response  Figure 1 – (a) Viscosity and (b) tensile modulus 

3D and 4D printing of polypropylene having different content of copolymer

Yadav, Deepesh

Jaya, BN

Friday, January 12, 2024                                                                                                                           Session 9 TENSILE, FRACTURE AND DAMAGE RESISTANCE CHARACTERISATION OF 3D PRINTED PLA WITH MORSE CODE ARCHITECTURES  Deepesh Yadav, Department of Metallurgical Engineering and Materials Science, IIT Bombay, deepeshyadav95iitr@gmail.com BN Jaya, Department of Metallurgical Engineering and Materials Science, IIT Bombay, jaya86@gmail.com  Key Words: 3D printing, Mechanical Properties, Fracture, Damage tolerance, PLA  Fused deposition modelling (FDM) is one of the most popular additive manufacturing technologies. Therefore, understanding and improvement in mechanical properties and damage resistance of FDM fabricated structures have become important. In this study tensile and fracture properties of 3D printed PLA are quantified as function of, building direction, filling pattern and raster angle. Tensile strength and failure strain are found to be the same for hexagonal and line filling patterns. Highest fracture toughness and total damage resistance were found for the 90º raster angle [1] . In a previous study, Morse-code inspired architectures of dashes and dotes manufactured by laser machining in single edge notch bend specimens of a brittle polymethylmethacrylate (PMMA) were shown to improve damage tolerance of the material by 20-24 times [2]. In order to improve damage tolerance of 3D printed fabricated structures, a combination of dot and dash like architectures were printed. The dot-like features act a crack arrestors and the dash-like features work as crack deflectors. A combination of simulations and experiments have been performed to determine and quantify the effect of the size and arrangements of these features on crack driving force and fracture resistance. Crack initiation resistance has been defined in terms of initiation work of fracture per unit area (WOFo) and overall damage resistance has been defined in terms of total work of fracture per unit area (WOFT). WOFo per unit area of bulk is the highest and shows maximum load bearing capacity while WOFT is the lowest for bulk and highest for a combination of alternative layers of dashes and dots (Figure 1). A 1172% increase has been observed from WOFo to WOFT for SH case. This indicates that architecturing is an effective means to improve overall damage resistance of 3D printed structures.       [1] Yadav, Deepesh, Prerna Gupta, and Balila Nagamani Jaya. "Impact of Build Direction, Infill Pattern and Raster Angle on Mechanical Properties and Damage Tolerance of 3D Printed PLA." International Manufacturing Science and Engineering Conference. Vol. 86601. American Society of Mechanical Engineers, 2022 [2] D. Yadav, T. More, and B. N. Jaya, “Morse-Code inspired architectures for tunable damage tolerance in brittle material systems,” J. Mater. Res., vol. 37, no. 6, pp. 1201–1215, 2022, doi: 10.1557/s43578-022-00520-6 Figure 1 – Initiation and overall damage tolerance of 3D printed PLA with combinations of dot and dashes and crack trajectories for HR, SR and SH case.  

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