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At least 1,459 records · Page 81

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DOE OSTI2018

Increasing Interlaminar Strength in Large Scale Additive Manufacturing

Interlaminar strength of extrusion-based additively manufactured parts is known to be weaker than the strength seen in the printed directions (X and Y). With Big Area Additive Manufacturing (BAAM), large parts lead to long layer times that are prone to splitting, sometimes referred to as delamination, between the layers. Fiber filled materials, such as carbon fiber reinforced ABS, are used to counter-act the effects of thermal expansion, but the fibers stay in-plane meaning that no fibers span from layer to layer, which helps counteract the weak interlaminar strength that causes splitting. A solution to this is a patent pending approach known as “z-pinning”. The process involves strategically positioning voids across multiple layers that will be backfilled with hot extrudate. This paper will explore the benefits and results of using “z-pinning” in large scale additive manufacturing.

Roschli, Alex↗

DOE OSTI2017

Role of Cyclic Phase Transitions in Additive Manufacturing of Metals and Alloys - Lessons Learned from Welding Science

Additive manufacturing (also known as 3D printing) of metals is considered to be a disruptive technology, able to produce limited number of high value components with topologically optimized geometries and functionalities. Realization of the above potential for real-world applications is stifled by lack of standard computational design tools; component certifications, varied starting powder feed stock compositions, methods to probe thermomechanical processes, microstructural homogeneity, residual stress, as well as, anisotropic static- and dynamic-material properties. Detailed research of direct energy deposition, laser- and electron-powder bed additive manufacturing demonstrates that the underlying physics of these processes are very similar to welding, except for complex boundary conditions. This paper will review published literature and on-going research with reference to fundamental aspects of heat and mass transfer, solidification under large (103 to 105 K/m) thermal gradients and (10-3 to 100 m/s) liquid solid-interface velocities, as well as, solid->solid transformation under repeated thermal excursions. Case studies on model based qualification of Ni- and Ti- alloy builds made by additive manufacturing (AM), based on the above fundamental knowledge will be discussed.

Babu, Sudarsanam Suresh↗

DOE OSTI2019

Additive manufacturing via direct writing of pure metal and eutectics through latent heat position control

An additive manufacturing system for producing metal parts from pure metal or eutectic alloys. The system includes an additive manufacturing print head, a print head heater system, an agitation system, a nozzle in the additive manufacturing print head, a reservoir for melting the metal, and a long heated tube for conditioning the alloy for extrusion in the semi-solid state through a nozzle.

Pascall, Andrew J.↗

DOE OSTI2019

Method and computer-readable model for additively manufacturing ducting arrangement for a gas turbine engine

Method and computer-readable model for additively manufacturing a ducting arrangement (10) for a gas turbine engine are provided. Ducting arrangement (10) may include a duct (18) to be fluidly coupled to receive a cross-flow of combustion gases from a main combustion stage. Duct (18) includes a duct segment (23) with an expanding cross-sectional area (24) where one or more injector assemblies (26) are disposed. Injector assembly (26) includes one or more reactant-guiding structures (27) arranged to deliver a flow of reactants to be mixed with the cross-flow of combustion gases. The ducting arrangement is effective to reduce total pressure loss while providing an effective level of mixing of the injected reactants with the passing cross-flow. Respective duct components or the entire ducting arrangement may be formed as a unitized structure, such as a single piece using a rapid manufacturing technology, such as 3D Printing/Additive Manufacturing (AM) technologies.

Chen, Yuntao↗

DOE OSTI2018

MICRO-CELLULOSE FIBER REINFORCED BIOCOMPOSITES FOR ADDITIVE MANUFACTURING

Polymer additive manufacturing (AM) technology is rapidly growing and it is transitioning from being primarily a prototyping method to an advanced manufacturing technique. Melt extrusion/fused deposition modeling, a method in which molten thermoplastic-based feedstock material is deposited in a raster pattern layer by layer, is the most commonly used technique in polymer AM. The technique enables direct digital manufacturing of desired geometry with controlled anisotropic distribution of reinforcing phase. While thermoplastic composites are being used in many areas of industry including AM, due to increasing environmental and long-term sustainability concerns, there is an increasing interest in bio-based renewable alternatives. Nano-to-mm scale plant-based fibers are utilized to improve properties of thermoplastics and produce bio-composites. The effect of commercially available micro-scale cellulose fibers (MFC) on the mechanical and rheological behavior of polylactic acid to produce fully bio-based composites are being investigated and selected formulations will be 3D-printed to investigate the effect of printing process on MFC alignment. Significant increases in both tensile strength and elastic modulus of compression-molded MFC-PLA composites were observed at 40 % (by wt) fiber levels.

Tekinalp, Halil↗

DOE OSTI2019

MELT POOL MONITORING FOR CONTROL AND DATA ANALYTICS IN LARGE-SCALE METAL ADDITIVE MANUFACTURING

Laser-wire based Directed Energy Deposition (DED) processes are being developed at Oak Ridge National Laboratory’s Manufacturing Demonstration Facility, in collaboration with GKN Aerospace, for large volume metal additive manufacturing of metallic structures. The technology has the potential to deliver reduced costs and lead times when compared to conventional methods of manufacturing in several industries. While complex structures are being produced with relatively high deposition rates and at near-net shape, issues persist with achieving consistent geometric accuracy and thermal stability. A significant research effort is focused on developing coordinated, multi-modal sensing and control for addressing these issues. An introduction to this large-volume metal process will be provided, followed by investigations into real-time thermal monitoring capabilities that support control and data analytics frameworks. Studies focused on melt pool monitoring via infrared thermography, thermal and geometric effects on melt pool size measurement, and interactions between process variables and thermal monitoring metrics are presented.

Gibson, Brian↗

DOE OSTI2018

High Performance GPU-Based FEM Code for Simulating Welding and Additive Manufacturing

An in-house HPC finite element code with novel computational schemes provides fast and high-fidelity simulation capability for welding processes and allied manufacturing processes such as metal additive manufacturing. Benchmark comparison confirmed that, for the testing cases studied, the newly developed in-house code resulted in increases in computational speed in the ranges of 100x to 1000x depending on the size and complexity of the testing cases, when compared to today's commercial welding process simulation tools. For a reference problem in nuclear reactor repair welding, ORNL's in-house high fidelity code was able to complete the simulation in 3.2 days, which would take estimated 10 to 20 years using today's commercial code. Similar order of magnitudes of reduction in computational times for metal additive manufacturing process were also achieved.

Feng, Zhili↗

DOE OSTI2019

Device for controlling additive manufacturing machinery

A computing device for controlling the operation of an additive manufacturing machine comprises a memory element and a processing element. The memory element is configured to store a three-dimensional model of a part to be manufactured, wherein the three-dimensional model defines a plurality of cross sections of the part. The processing element is in communication with the memory element. The processing element is configured to receive the three-dimensional model, determine a plurality of paths, each path including a plurality of parallel lines, determine a radiation beam power for each line, such that the radiation beam power varies non-linearly according to a length of the line, and determine a radiation beam scan speed for each line, such that the radiation beam scan speed is a function of a temperature of a material used to manufacture the part, the length of the line, and the radiation beam power for the line.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2019

Method for reducing springback using electrically-assisted manufacturing

A process for forming a sheet metal component. The process includes rigidly clamping a piece of sheet metal to a clamping fixture and plastically deforming the sheet metal to produce a shaped component during a first manufacturing step. The shaped component has a first amount of springback. During a second manufacturing step, a pair of electrodes applies one or more pulses of electrical current at one or more locations on the shaped component while the shaped component is still rigidly clamped to the clamping fixture during. The one or more pulses of electrical current applied to the shaped component provide an electrically-assisted manufactured (EAM) shaped component. The EAM shaped component has a second amount of springback that is less than the first amount of springback.

Roth, John Timothy↗

DOE OSTI2019

Wire Co-Extrusion with Big Area Additive Manufacturing

Oak Ridge National Laboratory’s Manufacturing Demonstration Facility is developing a system that will deposit and embed conductive and resistive elements within a printed bead of material. The system was implemented on a Big Area Additive Manufacturing (BAAM) system using a co-extruding nozzle. It has already been demonstrated that BAAM is useful for the tooling industry, but this could be a great improvement on an established application of BAAM parts. This system will provide the ability to control and monitor the surface of additively manufactured (AM) parts. It will also enable self-heating surfaces of AM parts, which is particularly useful in tooling applications. This system could even be used in the future for embedding other materials not found in pellet form in BAAM parts. This work will cover the development of the co-extrusion system and its integration with the dual-port nozzle and the BAAM system.

Atkins, Celeste↗

DOE OSTI2019

Efficient thermo-mechanical simulation approaches for arc-and-wire based additive manufacturing

This study aims at the thermo-mechanical features inherent with the arc and wire metal deposition process to advance the structural simulation of additive manufacturing. Simulation approaches including iterative substructure method (ISM), dynamic mesh refining method (DMRM), and graphics processing unit (GPU) based explicit FEM code (GPU code) were developed for accelerating stress analysis and compared in terms of efficiency and accuracy. ISM and DMRM both take advantage of the strong nonlinearity phenomenon near the moving heat source, by reducing the global iterations and refining the local mesh respectively. The explicit FEM code was accelerated by a mass scaling technique based on the inherent strain concept. Two large parts by wire and arc additive manufacturing were analyzed, and the numerical results agreed very well with each other. The predicted distortion and residual stresses in the deposited layers were validated by experimental measurement. Compared with commercial software ABAQUS, the novel approaches reduced the computation cost substantially without compromising on accuracy. GPU code shows the highest computation efficiency (x30~70), while DMRM and ISM has an acceleration factor of x9 and x3 respectively. Owing to the minimum model simplification, such advanced simulation approaches will be very useful for structural analysis of additive manufacturing with complex deposition paths and product geometry.

Huang, Hui↗

DOE OSTI2020

Device for controlling additive manufacturing machinery

Barr, Christian↗

DOE OSTI2020

Device for controlling additive manufacturing machinery

Barr, Christian↗

DOE OSTI2020

CHARACTERIZATION ON ANISOTROPIC THERMAL CONDUCTIVITY FOR BIG AREA ADDITIVE MANUFACTURING WITH POLYMERS

Additive manufacturing with polymers has been used mainly for prototyping. A recent development of Big Area Additive Manufacturing (BAAM) at Oak Ridge National Laboratory has opened its applications in the mold and die industry. A numerical simulation and prediction for a mold heating performance requires accurate anisotropic thermal properties of the printed material, which are challenging to obtain, and often requires the use of multiple techniques. The transient plane source (TPS) technique has been widely used due to its ability to measure the thermal properties of an extensive range of materials (solids, liquids, powder). Despite the capability to characterize thermal conductivity k of isotropic and anisotropic materials, the measurements of latter materials are limited to the cases, where the samples have the same thermal conductivity k along x- and y-axis that form the radial plane. In this work, the method for a characterization of k in all three dimensions is developed, and the application of TPS is extended to the determination of thermal properties along the x-, y-, and z-axis individually. The materials are represented by additively manufactured polymers including polylactic acid (PLA) and styrene maleic anhydride (SMA). The developed method consists of (1) a determination of the heat capacity of the polymers by means of TPS in combination with the developed in this work data analysis procedure, (2) a machining three types of cylindrical samples from the same material, with the height corresponding either to x-, y-, or z-direction of printing, and (3) a determination of axial thermal conductivity employing anisotropic model and using previously determined heat capacity

Trofimov, Artem↗

DOE OSTI2021

Lifting and removal device for additive manufacturing system

An attachment device for lifting and removing build plates and additive manufactured parts built on the build plates from an additive manufacturing machine. The attachment device may fit onto a lift trolley to cooperatively engage with and lift the build plate upward off of a surface of the additive manufacturing machine. The attachment device may include a support bar, two lifting arms, and a mounting bracket. The support bar may have a slider track formed therethrough, so that the lifting arms can be adjusted to correspond with a width of the build plate. The lifting arms may each having a channel formed along a length thereof and an interfacing portion slidably located within the slider track. The channels may be sized and shaped to engage with a bottom surface and/or opposing edges of the build plates. The mounting bracket may attach to a lifting device of the lift trolley.

Barr, Cary B.↗

DOE OSTI2021

Additive manufacturing power map to mitigate defects

A laser powder bed fusion additive manufacturing system for producing a part by creating a power map that is an intelligent feed forward model to control the laser powder bed fusion additive manufacturing for producing the part and using the power map to control the laser powder bed fusion additive manufacturing for producing the part. This includes an apparatus for producing a part including a powder bed, a laser that produces a laser beam, a proportional integral derivative controller that creates a power map that describes laser power requirements as the laser moves along a path, wherein the laser power requirements prevent defects in the part.

Khairallah, Saad A.↗

DOE OSTI2021

Additive manufacturing of multi-component parts for customizable energetic systems

An apparatus, system, and method utilizes at least two separate components during the process of producing the final product. At least one component during the process is produced using additive manufacturing, and additional components are components that are combined with the additively manufactured part. The apparatus, system, and method includes at least one energetic component and at least one second inert component. An additive manufacturing system produces a scaffold of said first energetic component(s). A system adds the second component(s) to the scaffold to produce the energetic material product.

Sullivan, Kyle T.↗

DOE OSTI2021

Regulatory Development for Advanced Manufacturing

Advanced Methods of Manufacturing (AMM) are new, novel manufacturing processes that have the potential to bring significant cost and schedule reductions to many industries, including the nuclear industry. These methods produce components faster and cheaper than many traditional methods. This includes replacing obsolete components at currently operating plants as well as manufacturing components of all sizes for advanced reactors.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗