Resting hand splint model from topology optimization to be produced by additive manufacturing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Paulo Reis ◽  
Mariana Volpini ◽  
Joana Pimenta Maia ◽  
Igor Batista Guimarães ◽  
Cristiane Evelise ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Thermal Comfort ◽  
Temperature Variation ◽  
Heat Diffusion ◽  
Mechanical Resistance ◽  
Manufacturing Cost ◽  
Traditional Model ◽  
Content Type ◽  
Novel Model

Purpose The purpose of this study is to validate a novel model of resting hand splint manufactured by additive manufacturing (AM) and compare it with the traditional model manufactured by high temperature thermoplastic in terms of cost, weight, volume and thermal comfort. Design/methodology/approach A novel resting hand splint model was created from the topology optimization (TO) and analyzed, by finite-element analysis, manufacturing cost and weight, with a traditional resting hand splint. A pilot clinical study was carried out to verify heat diffusion during the use of the two splints. Findings The results showed that compared with the traditional model, the novel model reduced the volume of material used by 35.48%, the weight of the orthosis by 17.56% and the maximum surface deformation by 171.17% when subjected to actuation forces. It was also verified that, when manufactured with Nylon by AM, the new model is 1.5 times cheaper than the traditional model made of Polypropylene. The result of the thermographic analysis showed greater temperature variation in the use of the traditional splint (+4.6°C) compared to the temperature variation observed in the nylon splint (2.1°C). Practical implications These results have as clinical relevance the demonstration of the feasibility of manufacturing functional orthoses that are more comfortable, cheaper and lighter than traditional ones. Originality/value This study describes the use of TO to manufacture a novel resting hand splint, which was compared with the commonly used traditional splint in terms of mechanical resistance, weight, cost and thermal comfort.

scholarly journals Comparative study of the flexural properties of ABS, PLA and a PLA–wood composite manufactured through fused filament fabrication

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
J.A. Travieso-Rodriguez ◽  
R. Jerez-Mesa ◽  
Jordi Llumà ◽  
Giovanni Gomez-Gras ◽  
Oriol Casadesus
Keyword(s):  
Additive Manufacturing ◽  
Acrylonitrile Butadiene Styrene ◽  
Nozzle Diameter ◽  
Bending Test ◽  
Mechanical Resistance ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Layer Height ◽  
Maximum Deformation ◽  
Materials Used

Purpose The aim of this paper is to analyze the mechanical properties of acrylonitrile-butadiene-styrene (ABS) parts manufactured through fused filament fabrication and compare these results to analogous ones obtained on polylactic acid (PLA) and PLA–wood specimens to contribute for a wider understanding of the different materials used for additive manufacturing. Design/methodology/approach With that aim, an experimental based on an L27 Taguchi array was used to combine the specific parameters taken into account in the study, namely, layer height, nozzle diameter, infill density, orientation and printing velocity. All samples were subjected to a four-point bending test performed according to the ASTM D6272 standard. Findings Young’s modulus, elastic limit, maximum stress and maximum deformation of every sample were computed and subjected to an analysis of variance. Results prove that layer height and nozzle diameter are the most significant factors that affect the mechanical resistance in pieces generated through additive manufacturing and subjected to bending loads, regardless of the material. Practical implications The best results were obtained by combining a layer height of 0.1 mm and a nozzle diameter of 0.6 mm. The comparison of materials evidenced that PLA and its composite version reinforced with wood particles present more rigidity than ABS, whereas the latter can experience further deflection before break. Originality/value This study is of interest for manufacturers that want to decide which is the best material to be applied for their application, as it derives in a practical technical recommendation of the best parameters that should be selected to treat the material during the fused filament fabrication process.

scholarly journals An optimisation framework for designs for additive manufacturing combining design, manufacturing and post-processing

2021 ◽  
Vol 27 (11) ◽  
pp. 90-105
Author(s):  
Anton Wiberg ◽  
Johan Persson ◽  
Johan Ölvander
Keyword(s):  
Additive Manufacturing ◽  
Design Methodology ◽  
Manufacturing Cost ◽  
Design For Additive Manufacturing ◽  
Post Processing ◽  
Process Selection ◽  
Content Type ◽  
Post Process ◽  
Alternative Designs

Purpose The purpose of this paper is to present a Design for Additive Manufacturing (DfAM) methodology that connects several methods, from geometrical design to post-process selection, into a common optimisation framework. Design/methodology/approach A design methodology is formulated and tested in a case study. The outcome of the case study is analysed by comparing the obtained results with alternative designs achieved by using other design methods. The design process in the case study and the potential of the method to be used in different settings are also discussed. Finally, the work is concluded by stating the main contribution of the paper and highlighting where further research is needed. Findings The proposed method is implemented in a novel framework which is applied to a physical component in the case study. The component is a structural aircraft part that was designed to minimise weight while respecting several static and fatigue structural load cases. An addition goal is to minimise the manufacturing cost. Designs optimised for manufacturing by two different AM machines (EOS M400 and Arcam Q20+), with and without post-processing (centrifugal finishing) are considered. The designs achieved in this study show a significant reduction in both weight and cost compared to one AM manufactured geometry designed using more conventional methods and one design milled in aluminium. Originality/value The method in this paper allows for the holistic design and optimisation of components while considering manufacturability, cost and component functionality. Within the same framework, designs optimised for different setups of AM machines and post-processing can be automatically evaluated without any additional manual work.

Generating support structures for additive manufacturing with continuum topology optimization methods

2019 ◽  
Vol 25 (2) ◽  
pp. 232-246 ◽  
Author(s):  
Yang Liu ◽  
Zuyu Li ◽  
Peng Wei ◽  
Shikui Chen
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Rapid Development ◽  
Load Condition ◽  
Practical Significance ◽  
Heaviside Function ◽  
Optimal Topology ◽  
Support Structures ◽  
Content Type ◽  
Material Volume

PurposeThe purpose of this paper is to explore the possibility of combining additive manufacturing (AM) with topology optimization to generate support structures for addressing the challenging overhang problem. The overhang problem is considered as a constraint, and a novel algorithm based on continuum topology optimization is proposed.Design/methodology/approachA mathematical model is formulated, and the overhang constraint is embedded implicitly through a Heaviside function projection. The algorithm is based on the Solid Isotropic Material Penalization (SIMP) method, and the optimization problem is solved through sensitivity analysis.FindingsThe overhang problem of the support structures is fixed. The optimal topology of the support structures is developed from a mechanical perspective and remains stable as the material volume of support structures changes, which allows engineers to adjust the material volume to save cost and printing time and meanwhile ensure sufficient stiffness of the support structures. Three types of load conditions for practical application are considered. By discussing the uniform distributive load condition, a compromise result is achieved. By discussing the point load condition, the removal work of support structures after printing is alleviated. By discussing the most unfavorable load condition, the worst collapse situation of the printing model during printing process is sufficiently considered. Numerical examples show feasibility and effectiveness of the algorithm.Research limitations/implicationsThe proposed algorithm involves time-consuming finite element analysis and iterative solution, which increase the computation burden. Only the overhang constraint and the minimum compliance problem are discussed, while other constraints and objective functions may be of interest.Practical implicationsCompared with most of the existing heuristic or geometry-based support-generating algorithms, the proposed algorithm develops support structures for AM from a mechanical perspective, which is necessary for support structures particularly used in AM for mega-scale construction such as architectures and sculptures to ensure printing success and accuracy of the printed model.Social implicationsWith the rapid development of AM, complicated structures result from topology optimization are available for fabrication. The present paper demonstrates a combination of AM and topology optimization, which is the trend of fabricating manner in the future.Originality/valueThis paper remarks the first of attempts to use continuum topology optimization method to generate support structures for AM. The methodology used in this work is theoretically meaningful and conclusions drawn in this paper can be of important instruction value and practical significance.

scholarly journals Integrated component-support topology optimization for additive manufacturing with post-machining

2019 ◽  
Vol 25 (2) ◽  
pp. 255-265 ◽  
Author(s):  
Matthijs Langelaar
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
High Performance ◽  
Process Model ◽  
Process Models ◽  
Content Type ◽  
Wide Range ◽  
Support Layout ◽  
Overhang Angle ◽  
Subtractive Machining

PurposeThe purpose of this paper is to communicate a method to perform simultaneous topology optimization of component and support structures considering typical metal additive manufacturing (AM) restrictions and post-print machining requirements.Design/methodology/approachAn integrated topology optimization is proposed using two density fields: one describing the design and another defining the support layout. Using a simplified AM process model, critical overhang angle restrictions are imposed on the design. Through additional load cases and constraints, sufficient stiffness against subtractive machining loads is enforced. In addition, a way to handle non-design regions in an AM setting is introduced.FindingsThe proposed approach is found to be effective in producing printable optimized geometries with adequate stiffness against machining loads. It is shown that post-machining requirements can affect optimal support structure layout.Research limitations/implicationsThis study uses a simplified AM process model based on geometrical characteristics. A challenge remains to integrate more detailed physical AM process models to have direct control of stress, distortion and overheating.Practical implicationsThe presented method can accelerate and enhance the design of high performance parts for AM. The consideration of post-print aspects is expected to reduce the need for design adjustments after optimization.Originality/valueThe developed method is the first to combine AM printability and machining loads in a single topology optimization process. The formulation is general and can be applied to a wide range of performance and manufacturability requirements.

scholarly journals Multi-solution nature of topology optimization and its application in design for additive manufacturing

2019 ◽  
Vol 25 (9) ◽  
pp. 1475-1481 ◽  
Author(s):  
Hassan Rezayat ◽  
Jared Richard Bell ◽  
Alex J. Plotkowski ◽  
Sudarsanam S. Babu
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Cantilever Beam ◽  
Mechanical Performance ◽  
Design Tool ◽  
Image Correlation ◽  
Content Type ◽  
Fused Deposition ◽  
Starting Point ◽  
Initial Starting

Purpose The purpose of this paper is to introduce the multi-solution nature of topology optimization (TO) as a design tool for additive manufacturing (AM). The sensitivity of topologically optimized parts and manufacturing constraints to the initial starting point of the optimization process leading to structures with equivalent performance is explored. Design/methodology/approach A modified bi-directional evolutionary structural optimization (BESO) code was used as the numerical approach to optimize a cantilever beam problem and reduce the mass by 50 per cent. Several optimized structures with relatively equivalent mechanical performance were generated by changing the initial starting point of the TO algorithm. These optimized structures were manufactured using fused deposition modeling (FDM). The equivalence of strain distribution in FDM parts was tested with the digital image correlation (DIC) technique and compared with that from the modified BESO code. Findings The results confirm that TO could lead to a wide variety of non-unique solutions based on loading and manufacturability constraints. The modified BESO code was able to reduce the support structure needed to build the simple two-dimensional cantilever beam by 15 per cent while keeping the mechanical performance at the same level. Originality/value The originality of this paper lies in introduction and application of the multi-solution nature of TO for AM as a design tool for optimizing structures with minimized features in the overhang condition and the need for support structures.

scholarly journals AN APPROACH FOR TOPOLOGY OPTIMIZATION-DRIVEN DESIGN FOR ADDITIVE MANUFACTURING

2020 ◽  
Vol 1 ◽  
pp. 325-334
Author(s):  
A. Nordin
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Lightweight Design ◽  
Manufacturing Cost ◽  
Design For Additive Manufacturing ◽  
Complex Tasks ◽  
Parametric Control

AbstractThis paper describes an approach for designing lightweight components produced through additive manufacturing (AM). Lightweight design is often done through topology optimization (TO). However, the process of manually interpreting mesh-based and imprecise results from a TO into a geometry that fulfils all requirements is complex. To aid in this process, this paper suggest an approach based on combining overhang-constrained TO with lattice-based TO to automate complex tasks, retain parametric control, and to minimize manufacturing cost. The approach is validated through a benchmark part.

Manufacturing cost constrained topology optimization for additive manufacturing

2019 ◽  
Vol 14 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Jikai Liu ◽  
Qian Chen ◽  
Xuan Liang ◽  
Albert C. To
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Manufacturing Cost

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.

Investigation on thermal comfort of the uniform for workers in tropical monsoon climates

2020 ◽  
Vol 32 (6) ◽  
pp. 849-868
Author(s):  
Jingxian Xu ◽  
Huijuan Liu ◽  
Yunyi Wang ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Thermal Comfort ◽  
Dynamic Condition ◽  
Thermal Manikin ◽  
Content Type ◽  
Wind Speeds ◽  
Subjective Perceptions ◽  
Tropical Monsoon ◽  
Four Levels ◽  
Thermal Insulations

PurposeThis study aims to investigate the heat transfer mechanism of the uniforms used by people working in hot, humid and windy environments. Furthermore, the effectiveness of an opening structure added to the armpit of the uniforms in improving thermal comfort was comparatively examined.Design/methodology/approachA set of uniforms was tested with the opening at the armpit alternatively zipped or unzipped. Thermal manikin and human tests were performed in a climatic chamber simulating the specific environmental conditions, including wind speeds at four levels (0.15, 0.5, 2, 4 m/s) and relative humidities at two levels (50 and 85%). Static and dynamic thermal insulations of clothing (IT) were examined by the thermal manikin tests. The human bodies' thermal responses, including heart rates (HR), eardrum temperatures (Te), skin temperatures (Tsk) and subjective perceptions, were given by the human tests.FindingsSpecial mechanisms of heat transfer in the specific uniforms used in tropical monsoon climates were revealed. Reductions on IT were caused by the movement of the human body and the environmental wind, and the empirical equations would underestimate this reduction. The opening at the armpit was able to prompt more heat transfer under dynamic condition, with reducing the IT by 11.8%, lowering the mean Tsk by 0.92°C, and significantly improving the subjective perceptions (p < 0.05). The heat exhaustion was alleviated with lowering the Te by 0.32°C.Originality/valueThis study managed to improve the thermal performance of uniforms for workers under unforgiving conditions. The evaluation and design methods introduced by this study provided practical guidance for similar products with strict dress codes and cost control requirements based on the findings from thorough product tests and analysis.

Sign in / Sign up

Export Citation Format

Share Document