scholarly journals Designing Cellular Structures for Additive Manufacturing Using Voronoi–Monte Carlo Approach

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1158
Author(s):  
Liu ◽  
Guessasma ◽  
Zhu ◽  
Zhang
Keyword(s):  
Monte Carlo ◽  
Relaxation Time ◽  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Cellular Structure ◽  
Cellular Structures ◽  
Monte Carlo Approach ◽  
Aided Design ◽  
Fully Connected ◽  
Seed Points

This study aims at reporting a strategy of designing cellular materials based on Voronoi–Monte Carlo approach for additive manufacturing. The approach is implemented to produce a fully connected cellular structure in the design space without producing material discontinuity. The main characteristics of the cellular structure, such as the density and the cell size, are controlled by means of two generation parameters, namely the number of seed points and the relaxation time. The generated cellular structures representing various designs of generated cellular wrenches are converted into surface tessellations and manufactured using stereolithography. Bending experiments are performed up to the rupture point and main attributes representing the performance of the SL-based cellular wrenches are studied with respect to the generation parameters. The results show only slight difference between CAD (Computer-Aided Design) models of the design and the real printed parts. The number of seed points is found to control the main feature of the wrench performance whereas the relaxation time is found to have a secondary effect.

Efficient design optimization of variable-density cellular structures for additive manufacturing: theory and experimental validation

2017 ◽  
Vol 23 (4) ◽  
pp. 660-677 ◽  
Author(s):  
Lin Cheng ◽  
Pu Zhang ◽  
Emre Biyikli ◽  
Jiaxi Bai ◽  
Joshua Robbins ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Cellular Structure ◽  
Lightweight Design ◽  
Scaling Law ◽  
Variable Density ◽  
Cellular Structures ◽  
Efficient Design ◽  
Content Type

Purpose The purpose of the paper is to propose a homogenization-based topology optimization method to optimize the design of variable-density cellular structure, in order to achieve lightweight design and overcome some of the manufacturability issues in additive manufacturing. Design/methodology/approach First, homogenization is performed to capture the effective mechanical properties of cellular structures through the scaling law as a function their relative density. Second, the scaling law is used directly in the topology optimization algorithm to compute the optimal density distribution for the part being optimized. Third, a new technique is presented to reconstruct the computer-aided design (CAD) model of the optimal variable-density cellular structure. The proposed method is validated by comparing the results obtained through homogenized model, full-scale simulation and experimentally testing the optimized parts after being additive manufactured. Findings The test examples demonstrate that the homogenization-based method is efficient, accurate and is able to produce manufacturable designs. Originality/value The optimized designs in our examples also show significant increase in stiffness and strength when compared to the original designs with identical overall weight.

scholarly journals Digital Workflow to Fabricate Complete Dentures for Edentulous Patients Using a Reversing and Superimposing Technique

2021 ◽  
Vol 11 (13) ◽  
pp. 5786
Author(s):  
Hwa-Jung Lee ◽  
Jeongho Jeon ◽  
Hong Seok Moon ◽  
Kyung Chul Oh
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Digital Data ◽  
Complete Dentures ◽  
Intraoral Scanner ◽  
Digital Workflow ◽  
Denture Base ◽  
Scan Data ◽  
Edentulous Patients ◽  
Aided Design

This technical procedure demonstrates a 4-step completely digital workflow for the fabrication of complete dentures in edentulous patients. The digital scan data of the edentulous arches were obtained using an intraoral scanner, followed by the fabrication of modeless trial denture bases using additive manufacturing. Using the trial denture base and a wax rim assembly, the interarch relationship was recorded. This record was digitized using an intraoral scanner and reversed for each maxillary and mandibular section individually. The digital scan data directly obtained using the intraoral scanner were superimposed over the reversed data, establishing a proper interarch relationship. The artificial teeth were arranged virtually and try-in dentures were additively manufactured. Subsequently, the gingival and tooth sections were additively manufactured individually and characterized. Thus, fabrication of digital complete dentures can be accomplished using digital data characteristics. The workflow includes data acquisition using an intraoral scanner, data processing using reverse engineering and computer-aided design software programs, and additive manufacturing.

Animal orthosis fabrication with additive manufacturing – a case study of custom orthosis for chicken

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wiktoria Maria Wojnarowska ◽  
Jakub Najowicz ◽  
Tomasz Piecuch ◽  
Michał Sochacki ◽  
Dawid Pijanka ◽  
...  
Keyword(s):  
Veterinary Medicine ◽  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Fused Deposition Modelling ◽  
Content Type ◽  
Fused Deposition ◽  
Secondary Objective ◽  
Traditional Manufacturing ◽  
Aided Design

Purpose Chicken orthoses that cover the ankle joint area are not commercially available. Therefore, the main purpose of this study is to fabricate a customised temporary Ankle–Foot Orthosis (AFO) for a chicken with a twisted ankle using computer-aided design (CAD) and three-dimensional (3D) printing. The secondary objective of the paper is to present the specific application of Additive Manufacturing (AM) in veterinary medicine. Design/methodology/approach The design process was based on multiple sketches, photos and measurements that were provided by the owner of the animal. The 3D model of the orthosis was made with Autodesk Fusion 360, while the prototype was fabricated using fused deposition modelling (FDM). Evaluation of the AFO was performed using the finite element method. Findings The work resulted in a functional 3D printed AFO for chicken. It was found that the orthosis made with AM provides satisfactory stiffen and a good fit. It was concluded that AM is suitable for custom bird AFO fabrication and, in some respects, is superior to traditional manufacturing methods. It was also concluded that the presented procedure can be applied in other veterinary cases and to other animal species and other parts of their body. AM provides veterinary with a powerful tool for the production of well-fitted and durable orthoses for animals. Research limitations/implications The study does not include the chicken's opinion on the comfort or fit of the manufactured AFO due to communication issues. Evaluation of the final prototype was done by the researchers and the animal owner. Originality/value No evidence was found in the literature on the use of AM for chicken orthosis, so this study is the first to describe such an application of AM. In addition, the study demonstrates the value of AM in veterinary medicine, especially in the production of devices such as orthoses.

scholarly journals DECOMPOSITION ALGORITHM FOR TOOL PATH PLANNING FOR WIRE-ARC ADDITIVE MANUFACTURING

2018 ◽  
Vol Vol.18 (No.1) ◽  
pp. 96-107 ◽  
Author(s):  
Lam NGUYEN ◽  
Johannes BUHL ◽  
Markus BAMBACH
Keyword(s):  
Additive Manufacturing ◽  
Path Planning ◽  
Computer Aided Design ◽  
Tool Path ◽  
Heuristic Method ◽  
Support Material ◽  
Build Time ◽  
Cad Models ◽  
Aided Design ◽  
Wire Arc Additive Manufacturing

Three-axis machines are limited in the production of geometrical features in powder-bed additive manufacturing processes. In case of overhangs, support material has to be added due to the nature of the process, which causes some disadvantages. Robot-based wire-arc additive manufacturing (WAAM) is able to fabricate overhangs without adding support material. Hence, build time, waste of material, and post-processing might be reduced considerably. In order to make full use of multi-axis advantages, slicing strategies are needed. To this end, the CAD (computer-aided design) model of the part to be built is first partitioned into sub-parts, and for each sub-part, an individual build direction is identified. Path planning for these sub-parts by slicing then enables to produce the parts. This study presents a heuristic method to deal with the decomposition of CAD models and build direction identification for sub-entities. The geometric data of two adjacent slices are analyzed to construct centroidal axes. These centroidal axes are used to navigate the slicing and building processes. A case study and experiments are presented to exemplify the algorithm.

scholarly journals ADDITIVE MANUFACTURING - APPLICATION OPPORTUNITIES FOR THE AVIATION INDUSTRY

2015 ◽  
Vol 6 (2) ◽  
pp. 63-86
Author(s):  
Dipesh Dhital ◽  
Yvonne Ziegler
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Computer Aided Design ◽  
Free Form ◽  
Aviation Industry ◽  
Layer By Layer ◽  
Printing Technology ◽  
3D Printing Technology ◽  
Subtractive Manufacturing ◽  
Aided Design

Additive Manufacturing also known as 3D Printing is a process whereby a real object of virtually any shape can be created layer by layer from a Computer Aided Design (CAD) model. As opposed to the conventional Subtractive Manufacturing that uses cutting, drilling, milling, welding etc., 3D printing is a free-form fabrication process and does not require any of these processes. The 3D printed parts are lighter, require short lead times, less material and reduce environmental footprint of the manufacturing process; and is thus beneficial to the aerospace industry that pursues improvement in aircraft efficiency, fuel saving and reduction in air pollution. Additionally, 3D printing technology allows for creating geometries that would be impossible to make using moulds and the Subtractive Manufacturing of drilling/milling. 3D printing technology also has the potential to re-localize manufacturing as it allows for the production of products at the particular location, as and when required; and eliminates the need for shipping and warehousing of final products.

Increasing Part Accuracy in Additive Manufacturing Processes Using a k-d Tree Based Clustered Adaptive Layering

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Neeraj Panhalkar ◽  
Ratnadeep Paul ◽  
Sam Anand
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Layer By Layer ◽  
Adaptive Slicing ◽  
Stl File ◽  
Build Time ◽  
Standard File Format ◽  
Aided Design ◽  
Profile Errors

Additive manufacturing (AM) is widely used in aerospace, automobile, and medical industries for building highly accurate parts using a layer by layer approach. The stereolithography (STL) file is the standard file format used in AM machines and approximates the three-dimensional (3D) model of parts using planar triangles. However, as the STL file is an approximation of the actual computer aided design (CAD) surface, the geometric errors in the final manufactured parts are pronounced, particularly in those parts with highly curved surfaces. If the part is built with the minimum uniform layer thickness allowed by the AM machine, the manufactured part will typically have the best quality, but this will also result in a considerable increase in build time. Therefore, as a compromise, the part can be built with variable layer thicknesses, i.e., using an adaptive layering technique, which will reduce the part build time while still reducing the part errors and satisfying the geometric tolerance callouts on the part. This paper describes a new approach of determining the variable slices using a 3D k-d tree method. The paper validates the proposed k-d tree based adaptive layering approach for three test parts and documents the results by comparing the volumetric, cylindricity, sphericity, and profile errors obtained from this approach with those obtained using a uniform slicing method. Since current AM machines are incapable of handling adaptive slicing approach directly, a “pseudo” grouped adaptive layering approach is also proposed here. This “clustered slicing” technique will enable the fabrication of a part in bands of varying slice thicknesses with each band having clusters of uniform slice thicknesses. The proposed k-d tree based adaptive slicing approach along with clustered slicing has been validated with simulations of the test parts of different shapes.

Laser Additive Manufacturing

3D Printing ◽  
2017 ◽  
pp. 154-171 ◽  
Author(s):  
Rasheedat M. Mahamood ◽  
Esther T. Akinlabi
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Computer Aided Design ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Cad Model ◽  
Laser Additive Manufacturing ◽  
Computer Aided ◽  
Manufacturing Technologies ◽  
Aided Design

Laser additive manufacturing is an advanced manufacturing process for making prototypes as well as functional parts directly from the three dimensional (3D) Computer-Aided Design (CAD) model of the part and the parts are built up adding materials layer after layer, until the part is competed. Of all the additive manufacturing process, laser additive manufacturing is more favoured because of the advantages that laser offers. Laser is characterized by collimated linear beam that can be accurately controlled. This chapter brings to light, the various laser additive manufacturing technologies such as: - selective laser sintering and melting, stereolithography and laser metal deposition. Each of these laser additive manufacturing technologies are described with their merits and demerits as well as their areas of applications. Properties of some of the parts produced through these processes are also reviewed in this chapter.

Towards computer-aided design of cellular structure

2020 ◽  
Vol 17 (2) ◽  
pp. 023001
Author(s):  
Simone Bianco ◽  
Yee-Hung Mark Chan ◽  
Wallace F Marshall
Keyword(s):  
Computer Aided Design ◽  
Cellular Structure ◽  
Computer Aided ◽  
Aided Design

Monte-Carlo aided design of neutron shielding concretes

2013 ◽  
Vol 61 (1) ◽  
pp. 161-171 ◽  
Author(s):  
D.B. Tefelski ◽  
T. Piotrowski ◽  
A. Polański ◽  
J. Skubalski ◽  
V. Blideanu
Keyword(s):  
Monte Carlo ◽  
Computer Aided Design ◽  
Neutron Transport ◽  
Physical And Mechanical Properties ◽  
Field Testing ◽  
Radiation Shielding ◽  
Nuclear Engineering ◽  
Neutron Shielding ◽  
Computer Tools ◽  
Aided Design

Abstract The process of design of building composites, like concrete is a complex one and involves many aspects like physical and mechanical properties, durability, shielding efficiency, costs of production and dismantlement etc. There are plenty of parameters to optimize and computer tools can help to choose the best solution. A computer aided design plays an important role nowadays. It becomes more accurate, faster and cheaper, so laboratories often apply computer simulation methods prior to field testing. In case of nuclear engineering, the radiation shielding problems are of much importance, because safety of such facilities is a key point. In this article the most effective methods for neutron shielding studies based on Monte-Carlo simulations of neutron transport and nuclide activation studies in concrete are presented. Two codes: MCNPX and CINDER’90 are extensively used to compare the shielding efficiency of commonly used concretes and to study the influence of concentration of B, Ba and Fe elements on shielding efficiency

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