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.

Efficient Design-Optimization of Variable-Density Hexagonal Cellular Structure by Additive Manufacturing: Theory and Validation

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Pu Zhang ◽  
Jakub Toman ◽  
Yiqi Yu ◽  
Emre Biyikli ◽  
Mesut Kirca ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Cellular Structure ◽  
Structural Parameters ◽  
Experimental Tests ◽  
Variable Density ◽  
Cellular Structures ◽  
Efficient Design ◽  
Element Analysis ◽  
Micromechanics Models ◽  
Lower Material

Cellular structures are promising candidates for additive manufacturing (AM) due to their lower material and energy consumption. In this work, an efficient method is proposed for optimizing the topology of variable-density cellular structures to be fabricated by certain AM process. The method gains accuracy by relating the cellular structure's microstructure to continuous micromechanics models and achieves efficiency through conducting continuum topology optimization at macroscopic scale. The explicit cellular structure is then finally reconstructed by mapping the optimized continuous parameters (e.g., density) to cell structural parameters (e.g., strut diameter). The proposed method is validated by both finite element analysis and experimental tests on specimens manufactured by stereolithography.

Experimental-assisted design development for an octahedral cellular structure using additive manufacturing

2015 ◽  
Vol 21 (2) ◽  
pp. 168-176 ◽  
Author(s):  
Li Yang
Keyword(s):  
Additive Manufacturing ◽  
Size Effect ◽  
Cellular Structure ◽  
Beam Theory ◽  
Unit Cell ◽  
Cellular Structures ◽  
Design Development ◽  
Content Type ◽  
Softening Behavior ◽  
3D Cellular Structures

Purpose – This paper aims to demonstrate the design and verification of a 3D reticulate octahedral cellular structure using both analytical modeling and additive manufacturing. Traditionally, it has been difficult to develop and verify designs for 3D cellular structures due to their design complexity. Design/methodology/approach – Unit cell modeling approach was used to model the octahedral cellular structure. By applying structural symmetry simplification, the cellular structure was simplified into a representative geometry that could be further designed with a standard beam theory. The verification samples were fabricated with EBM process using Ti6Al4V as materials, and compressive testing were performed to evaluate their properties. In addition, designs with different number of unit cells were investigated to evaluate their size effect. Findings – Explicit mechanical property design (including modulus and compressive strength) of the octahedral cellular structure was realized via parametric equations driven by geometrical designs and material types. In addition, it was verified both numerically and experimentally that the octahedral cellular structure exhibit unusual size effect, which is highly predictable. Unlike some of the other cellular structures, the octahedral cellular structure exhibits softening behavior when the number of unit cell increases between the sandwich skins, which could be explained by the upsetting effect commonly observed in bulk deformation processes. Originality/value – This paper established a more comprehensive understanding in the design of octahedral cellular structures, which could enable this type of structure to be designed for sandwich structures with higher fidelity. Therefore, this study not only demonstrated an efficient methodology to design 3D cellular structures using additive manufacturing, but also facilitated the development of design for an additive manufacturing theory.

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.

Design and optimization of nonuniform cellular structures

2017 ◽  
Vol 232 (7) ◽  
pp. 1280-1293 ◽  
Author(s):  
Xin Jin ◽  
Guo-Xi Li ◽  
Meng Zhang
Keyword(s):  
Topology Optimization ◽  
Cellular Structure ◽  
Mechanical Performance ◽  
Design Method ◽  
Lightweight Design ◽  
Structure Design ◽  
Cellular Structures ◽  
Manufacturing Constraints ◽  
Element Analysis ◽  
Design And Optimization

Topology optimization and cellular structure infilling are two important approaches to achieve a lightweight design while meeting the relevant mechanical property requirements. In this work, we present a density-variable cellular structure design method combined with topology optimization while ensuring the manufacturability. The effective mechanical properties are reported as functions of the relative density to combine cellular structures with the topology optimization model. The manufacturing constraints are analyzed and expressed in topology optimization. In addition, density-variable cellular structures are rapidly modeled by mapping the topology optimization results to the relative densities of cells and via the use of user-defined features. It is shown by means of finite element analysis that the proposed design approach can improve the mechanical performance compared to the uniform cellular structure under the same weight reduction. And the choice of cell size for higher stiffness of the designed structure varies with different values of manufacturing constraints.

The role of robotics in additive manufacturing: review of the AM processes and introduction of an intelligent system

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
J. Norberto Pires ◽  
Amin S. Azar ◽  
Filipe Nogueira ◽  
Carlos Ye Zhu ◽  
Ricardo Branco ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Intelligent System ◽  
Material Selection ◽  
High Strength Steels ◽  
Industrial Applications ◽  
Layer By Layer ◽  
Content Type ◽  
Functional Components

Purpose Additive manufacturing (AM) is a rapidly evolving manufacturing process, which refers to a set of technologies that add materials layer-by-layer to create functional components. AM technologies have received an enormous attention from both academia and industry, and they are being successfully used in various applications, such as rapid prototyping, tooling, direct manufacturing and repair, among others. AM does not necessarily imply building parts, as it also refers to innovation in materials, system and part designs, novel combination of properties and interplay between systems and materials. The most exciting features of AM are related to the development of radically new systems and materials that can be used in advanced products with the aim of reducing costs, manufacturing difficulties, weight, waste and energy consumption. It is essential to develop an advanced production system that assists the user through the process, from the computer-aided design model to functional components. The challenges faced in the research and development and operational phase of producing those parts include requiring the capacity to simulate and observe the building process and, more importantly, being able to introduce the production changes in a real-time fashion. This paper aims to review the role of robotics in various AM technologies to underline its importance, followed by an introduction of a novel and intelligent system for directed energy deposition (DED) technology. Design/methodology/approach AM presents intrinsic advantages when compared to the conventional processes. Nevertheless, its industrial integration remains as a challenge due to equipment and process complexities. DED technologies are among the most sophisticated concepts that have the potential of transforming the current material processing practices. Findings The objective of this paper is identifying the fundamental features of an intelligent DED platform, capable of handling the science and operational aspects of the advanced AM applications. Consequently, we introduce and discuss a novel robotic AM system, designed for processing metals and alloys such as aluminium alloys, high-strength steels, stainless steels, titanium alloys, magnesium alloys, nickel-based superalloys and other metallic alloys for various applications. A few demonstrators are presented and briefly discussed, to present the usefulness of the introduced system and underlying concept. The main design objective of the presented intelligent robotic AM system is to implement a design-and-produce strategy. This means that the system should allow the user to focus on the knowledge-based tasks, e.g. the tasks of designing the part, material selection, simulating the deposition process and anticipating the metallurgical properties of the final part, as the rest would be handled automatically. Research limitations/implications This paper reviews a few AM technologies, where robotics is a central part of the process, such as vat photopolymerization, material jetting, binder jetting, material extrusion, powder bed fusion, DED and sheet lamination. This paper aims to influence the development of robot-based AM systems for industrial applications such as part production, automotive, medical, aerospace and defence sectors. Originality/value The presented intelligent system is an original development that is designed and built by the co-authors J. Norberto Pires, Amin S. Azar and Trayana Tankova.

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 Multiscale, thermomechanical topology optimization of self-supporting cellular structures for porous injection molds

2019 ◽  
Vol 25 (9) ◽  
pp. 1482-1492
Author(s):  
Tong Wu ◽  
Andres Tovar
Keyword(s):  
Topology Optimization ◽  
Mechanical Performance ◽  
Mechanical Load ◽  
Design Method ◽  
Three Dimensional ◽  
Optimization Method ◽  
Cellular Structures ◽  
Injection Mold ◽  
Computationally Efficient ◽  
Content Type

Purpose This paper aims to establish a multiscale topology optimization method for the optimal design of non-periodic, self-supporting cellular structures subjected to thermo-mechanical loads. The result is a hierarchically complex design that is thermally efficient, mechanically stable and suitable for additive manufacturing (AM). Design/methodology/approach The proposed method seeks to maximize thermo-mechanical performance at the macroscale in a conceptual design while obtaining maximum shear modulus for each unit cell at the mesoscale. Then, the macroscale performance is re-estimated, and the mesoscale design is updated until the macroscale performance is satisfied. Findings A two-dimensional Messerschmitt Bolkow Bolhm (MBB) beam withstanding thermo-mechanical load is presented to illustrate the proposed design method. Furthermore, the method is implemented to optimize a three-dimensional injection mold, which is successfully prototyped using 420 stainless steel infiltrated with bronze. Originality/value By developing a computationally efficient and manufacturing friendly inverse homogenization approach, the novel multiscale design could generate porous molds which can save up to 30 per cent material compared to their solid counterpart without decreasing thermo-mechanical performance. Practical implications This study is a useful tool for the designer in molding industries to reduce the cost of the injection mold and take full advantage of AM.

Topology optimization design of hydraulic valve blocks for additive manufacturing

2020 ◽  
Vol 234 (10) ◽  
pp. 1899-1912
Author(s):  
Guanlin Xie ◽  
Yongjia Dong ◽  
Jing Zhou ◽  
Zhongqi Sheng
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Hydraulic System ◽  
Optimization Design ◽  
Lightweight Design ◽  
Block Design ◽  
Reduction Rate ◽  
Material Strength ◽  
Hydraulic Valve ◽  
Valve Block

The hydraulic valve block is a core component of an integrated hydraulic system. In practical usage, it exhibits problems such as material waste, long manufacturing cycle, significant energy loss, and leakage. Based on the aforementioned existing problems, this study presents the design of the hydraulic system valve block based on the valve block design principle. The internal valve channel of the hydraulic valve block is optimized for additive manufacturing technology to avoid auxiliary drilling, solve the problem of potential liquid leakage, and shorten the manufacturing cycle. Thus, it is more suitable for the production of customized complex hydraulic valve blocks. The multiobjective topology optimization method is applied to the lightweight design of the hydraulic valve block to save resources and decrease energy consumption. The results indicate that when compared with the original model, the minimum reduction rate of pressure loss in each oil circuit orifice after optimization of the hydraulic valve block corresponds to 32.02%, the maximum corresponds to 71.38%; the maximum stress of the final design corresponds to 542.9 MPa, which satisfies the material strength requirement; and the mass is decreased by 68.9%. Thus, the lightweight design of the hydraulic valve block is realized.

Direct slicing of T-spline surfaces for additive manufacturing

2018 ◽  
Vol 24 (4) ◽  
pp. 709-721 ◽  
Author(s):  
Jiawei Feng ◽  
Jianzhong Fu ◽  
Zhiwei Lin ◽  
Ce Shang ◽  
Bin Li
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Content Type ◽  
Geometrical Properties ◽  
Direct Slicing ◽  
Spline Surface ◽  
Spline Surfaces ◽  
Complex Models ◽  
Aided Design ◽  
Design And Manufacture

Purpose T-spline is the latest powerful modeling tool in the field of computer-aided design. It has all the merits of non-uniform rational B-spline (NURBS) whilst resolving some flaws in it. This work applies T-spline surfaces to additive manufacturing (AM). Most current AM products are based on Stereolithograph models. It is a kind of discrete polyhedron model with huge amounts of data and some inherent defects. T-spline offers a better choice for the design and manufacture of complex models. Design/methodology/approach In this paper, a direct slicing algorithm of T-spline surfaces for AM is proposed. Initially, a T-spline surface is designed in commercial software and saved as a T-spline mesh file. Then, a numerical method is used to directly calculate all the slicing points on the surface. To achieve higher manufacturing efficiency, an adaptive slicing algorithm is applied according to the geometrical properties of the T-spline surface. Findings Experimental results indicate that this algorithm is effective and reliable. The quality of AM can be enhanced at both the designing and slicing stages. Originality/value The T-spline and direct slicing algorithm discussed here will be a powerful supplement to current technologies in AM.

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