A Scalable Framework for Process-Aware Thermal Simulation of Additive Manufacturing Processes

Author(s):  
Yaqi Zhang ◽  
Vadim Shapiro ◽  
Paul Witherell

Abstract Many additive manufacturing (AM) processes are driven by a moving heat source. Thermal field evolution during the manufacturing process plays an important role in determining both geometric and mechanical properties of the fabricated parts. Thermal simulation of AM processes is challenging due to the geometric complexity of the manufacturing process and inherent computational complexity that requires a numerical solution at every time increment of the process. We propose a new general computational framework that supports scalable thermal simulation at path scale of any AM process driven by a moving heat source. The proposed framework has three novel ingredients. First, the path-level discretization is process-aware, which is based on the manufacturing primitives described by the scan path and the thermal model is formulated directly in terms of manufacturing primitives. Second, a spatial data structure, called contact graph, is used to represent the discretized domain and capture all possible thermal interactions during the simulation. Finally, the simulation is localized based on specific physical parameters of the manufacturing process, requiring at most a constant number of updates at each time step. The latter implies that the constructed simulation not only scales to handle three-dimensional (3D) printed components of arbitrary complexity but also can achieve real-time performance. To demonstrate the efficacy and generality of the framework, it has been successfully applied to build thermal simulations of two different AM processes, fused deposition modeling (FDM) and powder bed fusion (PBF).

Author(s):  
Yaqi Zhang ◽  
Vadim Shapiro ◽  
Paul Witherell

Abstract Powder bed fusion (PBF) has become a widely used additive manufacturing (AM) technology to produce metallic parts. Since the PBF process is driven by a moving heat source, consistency in part production, particularly when varying geometries, has proven difficult. Thermal field evolution during the manufacturing process determines both geometric and mechanical properties of the fabricated components. Simulations of the thermal field evolution can provide insight into desired process parameter selection for a given material and geometry. Thermal simulation of the PBF process is computationally challenging due to the geometric complexity of the manufacturing process and the inherent computational complexity that requires a numerical solution at every time increment of the process. We propose a new thermal simulation of the PBF process based on the laser scan path. Our approach is unique in that it does not restrict itself to simulations on the part design geometry, but instead simulates the formation of the geometry based on the process plan of a part. The implication of this distinction is that the simulations are in tune with the as-manufactured geometry, meaning that calculations are more aligned with the process than the design, and thus could be argued is a more realistic abstraction of real-world behavior. The discretization is based on the laser scan path, and the thermal model is formulated directly in terms of the manufacturing primitives. An element growth mechanism is introduced to simulate the evolution of a melt pool during the manufacturing process. A spatial data structure, called contact graph, is used to represent the discretized domain and capture all thermal interactions during the simulation. The simulation is localized through exploiting spatial and temporal locality, which is based on known empirical data. This limits the need to update to at most a constant number of elements at each time step. This implies that the proposed simulation not only scales to handle three-dimensional (3D) printed components of arbitrary complexity but also can achieve real-time performance. The simulation is fully implemented and validated against experimental data and other simulation results.


Author(s):  
Yaqi Zhang ◽  
Vadim Shapiro ◽  
Paul Witherell

Abstract Powder bed fusion (PBF) has become a widely used additive manufacturing technology to produce metallic parts. In PBF, thermal field evolution during the manufacturing process plays an important role in determining both geometric and mechanical properties of the fabricated parts. Thermal simulation of the PBF process is computationally challenging due to the geometric complexity of the manufacturing process and the inherent computational complexity that requires a numerical solution at every time increment of the process. We propose a new thermal simulation of the PBF process based on the laser scan path. Our approach is unique in that it simulates the thermal history of the process on the discretization of the geometry implied by the process plan, as opposed to voxelization or meshing of the design geometry. The discretization is based on the laser scan path, and the thermal model is formulated directly in terms of the manufacturing primitives. An element growth mechanism is introduced to simulate the evolution of the melt pool during the manufacturing process. A spatial data structure, called contact graph, is used to represent the discretized domain and capture all thermal interactions. The simulation is localized through exploiting spatial and temporal locality. This limits the need to update to at most a constant number of elements at each time step, which implies that the proposed simulation not only scales to handle 3D components of arbitrary complexity but also can achieve real-time performance. The simulation is fully implemented and validated against experimental data and other simulation results.


Author(s):  
Paul Witherell ◽  
Shaw Feng ◽  
Timothy W. Simpson ◽  
David B. Saint John ◽  
Pan Michaleris ◽  
...  

In this paper, we advocate for a more harmonized approach to model development for additive manufacturing (AM) processes, through classification and metamodeling that will support AM process model composability, reusability, and integration. We review several types of AM process models and use the direct metal powder bed fusion AM process to provide illustrative examples of the proposed classification and metamodel approach. We describe how a coordinated approach can be used to extend modeling capabilities by promoting model composability. As part of future work, a framework is envisioned to realize a more coherent strategy for model development and deployment.


Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1946 ◽  
Author(s):  
Héctor García-Martínez ◽  
Ernesto Ávila-Navarro ◽  
Germán Torregrosa-Penalva ◽  
Alberto Rodríguez-Martínez ◽  
Carolina Blanco-Angulo ◽  
...  

This work presents a study on the implementation and manufacturing of low-cost microwave electronic circuits, made with additive manufacturing techniques using fused deposition modeling (FDM) technology. First, the manufacturing process of substrates with different filaments, using various options offered by additive techniques in the manufacture of 3D printing parts, is described. The implemented substrates are structurally analyzed by ultrasound techniques to verify the correct metallization and fabrication of the substrate, and the characterization of the electrical properties in the microwave frequency range of each filament is performed. Finally, standard and novel microwave filters in microstrip and stripline technology are implemented, making use of the possibilities offered by additive techniques in the manufacturing process. The designed devices were manufactured and measured with good results, which demonstrates the possibility of using low-cost 3D printers in the design process of planar microwave circuits.


2015 ◽  
Vol 21 (3) ◽  
pp. 250-261 ◽  
Author(s):  
Brian N. Turner ◽  
Scott A Gold

Purpose – The purpose of this paper is to critically review the literature related to dimensional accuracy and surface roughness for fused deposition modeling and similar extrusion-based additive manufacturing or rapid prototyping processes. Design/methodology/approach – A systematic review of the literature was carried out by focusing on the relationship between process and product design parameters and the dimensional and surface properties of finished parts. Methods for evaluating these performance parameters are also reviewed. Findings – Fused deposition modeling® and related processes are the most widely used polymer rapid prototyping processes. For many applications, resolution, dimensional accuracy and surface roughness are among the most important properties in final parts. The influence of feedstock properties and system design on dimensional accuracy and resolution is reviewed. Thermal warping and shrinkage are often major sources of dimensional error in finished parts. This phenomenon is explored along with various approaches for evaluating dimensional accuracy. Product design parameters, in particular, slice height, strongly impact surface roughness. A geometric model for surface roughness is also reviewed. Originality/value – This represents the first review of extrusion AM processes focusing on dimensional accuracy and surface roughness. Understanding and improving relationships between materials, design parameters and the ultimate properties of finished parts will be key to improving extrusion AM processes and expanding their applications.


Proceedings ◽  
2020 ◽  
Vol 56 (1) ◽  
pp. 21
Author(s):  
Simon P. Stier ◽  
Holger Böse

Conventional machining and shaping processes for polymers and elastomers such as injection molding exhibit significant disadvantages, as specific tools have to be manufactured, the method of machining is highly dependent on the material properties, and the cost of automation is usually high. Therefore, additive manufacturing processes (3D printing) have established themselves as an alternative. This eliminates the expensive production of tools and the production is individualized. However, the specific (additive) manufacturing process remains highly dependent on the properties of the material. These processes include selective laser sintering (SLS) for powdered thermoplastic polymers and metals, extrusion such as fused deposition modeling (FDM) for thermoplastic polymers in wire form, or optical curing such as digital light processing (DLP) for liquid resins. Especially for elastomer sensors or circuit boards (structure of several alternately constituted approx. 100 µm-thick elastomer films made with different types of liquid silicone rubber), there is no suitable additive manufacturing process that combines liquid, partly non-transparent source materials, multi-component printing, and very fine layer thicknesses. In order to enable a largely automated, computer-aided manufacturing process, we have developed the concept of ablative multilayer and multi-material laser-assisted manufacturing. Here, the layers (conductive and non-conductive elastomers, as well as metal layers for contacting) are first coated over the entire surface (e.g., spray, dip, or doctor blade coating, as well as galvanic coating) and then selectively removed with a CO2 or fiber laser. These steps are repeated several times to achieve a multi-layer structured design. Is it not only possible to adjust and improve the work previously carried out manually, but also to introduce completely new concepts, such as fine through-plating between the layers to enable much more compact structures to be possible. As an exemplary application, we have used the process for manufacturing a thin and surface solderable pressure sensor and a stretchable circuit board.


2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Yuanbin Wang ◽  
Robert Blache ◽  
Pai Zheng ◽  
Xun Xu

Design for additive manufacturing (DfAM) is gaining increasing attention because of the unique capabilities that additive manufacturing (AM) technologies provide. While they have the ability to produce more complex shapes at no additional cost, AM technologies introduce new constraints. A detailed knowledge of the AM process plays an important role in the design of parts in order to achieve the desired print result. However, research on knowledge management in this area is still limited. The large number of different AM processes, their individual sets of critical parameters and the variation in printing all contribute to a high level of uncertainty in this knowledge domain. Applying AM at the early stages of design projects introduces another source of uncertainty, as requirements are often not well defined at that point. In this paper, a knowledge management system using Bayesian networks (BNs) is proposed to model AM knowledge in cases where there is some uncertainty and fill the knowledge gap between designers and AM technologies. The structure of the proposed model is defined here by introducing the overview layer and detailed information layer. In each layer, different types of nodes and their causal relationships are defined. The system can learn conditional probabilities in the model from different sources of information and inferences can be conducted in both forward and backward directions. To verify the accuracy of the BNs, a sample model for dimensional accuracy in the fused deposition modeling (FDM) process is presented and the results are compared with other methods. A case study is provided to illustrate how the proposed system can help designers with different design questions understand the capabilities of AM processes and find appropriate design and printing solutions.


Author(s):  
Alberto Cattenone ◽  
Simone Morganti ◽  
Gianluca Alaimo ◽  
Ferdinando Auricchio

Additive manufacturing (or three-dimensional (3D) printing) is constantly growing as an innovative process for the production of complex-shape components. Among the seven recognized 3D printing technologies, fused deposition modeling (FDM) covers a very important role, not only for producing representative 3D models, but, mainly due to the development of innovative material like Peek and Ultem, also for realizing structurally functional components. However, being FDM a production process involving high thermal gradients, non-negligible deformations and residual stresses may affect the 3D printed component. In this work we focus on meso/macroscopic simulations of the FDM process using abaqus software. After describing in detail the methodological process, we investigate the impact of several parameters and modeling choices (e.g., mesh size, material model, time-step size) on simulation outcomes and we validate the obtained results with experimental measurements.


2015 ◽  
Vol 21 (3) ◽  
pp. 230-243 ◽  
Author(s):  
Abby Megan Paterson ◽  
Richard Bibb ◽  
R. Ian Campbell ◽  
Guy Bingham

Purpose – The purpose of this paper is to compare four different additive manufacturing (AM) processes to assess their suitability in the context of upper extremity splinting. Design/methodology/approach – This paper describes the design characteristics and subsequent fabrication of six different wrist splints using four different AM processes: laser sintering (LS), fused deposition modelling (FDM), stereolithography (SLA) and polyjet material jetting via Objet Connex. The suitability of each process was then compared against competing designs and processes from traditional splinting. The splints were created using a digital design workflow that combined recognised clinical best practice with design for AM principles. Findings – Research concluded that, based on currently available technology, FDM was considered the least suitable AM process for upper extremity splinting. LS, SLA and material jetting show promise for future applications, but further research and development into AM processes, materials and splint design optimisation is required if the full potential is to be realised. Originality/value – Unlike previous work that has applied AM processes to replicate traditional splint designs, the splints described are based on a digital design for AM workflow, incorporating novel features and physical properties not previously possible in clinical splinting. The benefits of AM for customised splint fabrication have been summarised. A range of AM processes have also been evaluated for splinting, exposing the limitations of existing technology, demonstrating novel and advantageous design features and opportunities for future research.


2019 ◽  
Vol 26 ◽  
pp. 180-192 ◽  
Author(s):  
Kohei Oyama ◽  
Spyros Diplas ◽  
Mohammed M'hamdi ◽  
Anette E. Gunnæs ◽  
Amin S. Azar

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