Infill Optimization Research Articles

Topology optimization design of graded infills for 3D curved volume by a conformal sweeping method

Swept volumes are widely existed in various significant engineering applications. However, an effective design method for the lightweight swept volume with porous infills is lacking. This paper develops a novel topology optimization method for the design of curved volumes filled with spatially-varying microstructures. The infill optimization formulation for the curved swept volume is established to concurrently optimize both the microstructural geometry and the macroscopic distribution of the graded infills, aiming at minimizing the structural compliance subject to a global volume constraint. A conformal sweeping approach is developed to map the curved volume into a regular parameterization​ cube along the sweeping trajectory. In this fashion, the graded infills defined in a regular unit cell can be first filled into this cubic parameterization space, and then reversely mapped into the original volume to conformally match the curved geometry. A numerical homogenization method for parallelepiped microstructures is introduced to evaluate several sampling microstructures. The local level sets approach is used to create a family of connectable microstructures, while a polynomial interpolation is employed to rapidly interpolate the graded property of the generated microstructures based on the properties of sampling microstructures. Two different sweeping volume types are investigated. Several examples with respect to the infill optimization design of curved swept volumes are provided to illustrate the characteristics of the proposed method.

Graded infill design within free-form surfaces by conformal mapping

The infill design for free-form surfaces is challenging due to the mismatch of both the geometric feature and physical response between the curved surface on the macroscale and the regular-shaped infill unit cells on the meso/micro scale. Thus, this study proposes a novel optimization method to provide insight into the optimal design for the free-form surfaces consisting of micro-structured infills, where both the microstructural geometry and macroscopic distribution of the spatial-varying infills are optimized concurrently. In this method, a local level sets approach is proposed to generate a series of graded and connectable infill microstructures that are related to the volume fraction of each unit cell. The cubic polynomials interpolation is utilized to predict the effective properties for those graded infills rapidly. A computational conformal mapping technology is used to map the geometries between a 3D free-form surface and a regular 2D parameter space, such that the graded infills can be properly filled into the parameter domain, and then conformally mapped back onto the free-form surface to allow the infill unit cells to fit the curved surface without losing any geometric feature. Conformal shell finite element analysis defined in an orthogonal curvilinear coordinate system is derived in the lower-dimensional parameter domain to calculate the physical responses for the infill optimization during the conformal mapping. The infill optimization formulation for the free-form surface is established, which is recast as a 2D optimization problem defined in the parameter domain, aiming at minimizing the structural compliance subject to a global volume constraint. Thus, the dimension of the 3D free-form surface design problem is reduced. Several examples of the free-form surface demonstrate the features of the proposed method.

Stress topology analysis for porous infill optimization

The optimization of porous infill structures via local volume constraints has become a popular approach in topology optimization. In some design settings, however, the iterative optimization process converges only slowly, or not at all even after several hundreds or thousands of iterations. This leads to regions in which a distinct binary design is difficult to achieve. Interpreting intermediate density values by applying a threshold results in large solid or void regions, leading to sub-optimal structures. We find that this convergence issue relates to the topology of the stress tensor field that is simulated when applying the same external forces on the solid design domain. In particular, low convergence is observed in regions around so-called trisector degenerate points. Based on this observation, we propose an automatic initialization process that prescribes the topological skeleton of the stress field into the density field as solid simulation elements. These elements guide the material deposition around the degenerate points, but can also be remodelled or removed during the optimization. We demonstrate significantly improved convergence rates in a number of use cases with complex stress topologies. The improved convergence is demonstrated for infill optimization under homogeneous as well as spatially varying local volume constraints.

Stress Focused Infill Optimization In Additive Manufacturing For An Office Chair Armrest

Bu çalışmada; katmanlı imalat yönteminden biri olan Ergiyik Biriktirmeli Modelleme ile üretilen bir ofis koltuğu kolçağının, TS EN 1335 Standardı gerekliliklerini karşılayabilecek şekilde; tasarım, analiz, optimizasyon ve testleri gerçekleştirilmiştir. Kolçak modelinin tasarımı standart gerekliliklerine göre yapılarak, %50 doluluk oranına sahip olacak şekilde kolçak modeli iç hacmi için iki farklı optimizasyon çalışması yapılmıştır. Bu optimizasyon çalışmaları; kolçak iç dolgusunun homojen dağılım gösterdiği uygun dış kesit kalınlığı ile iç hücresel boyut değişiminin optimizasyon çalışması ve kolçak üzerindeki gerilimin yüksek olduğu bölgelerin dolu ile diğer bölgelerin homojen düşük yoğunluklu olarak tanımlandığı optimizasyon çalışmalarıdır. Homojen yoğunluklu optimizasyon çalışmasında; sonlu elemanlar analizi sonuçlarına göre kolçak modelinde iyileştirmeler yapılabileceği gözlenmiş; fakat belirlenen doluluk oranı ile emniyetli sınır gerilme değerlerini aşmayan uygun sonuç elde edilememiştir. Bölgesel yoğunluklu optimizasyon çalışmasında ise; sonlu elemanlar analizi sonuçlarına göre genel olarak homojen yoğunluklu optimizasyon çalışmasından daha düşük gerilme değerleri elde edilmiştir. Elde edilen model belirlenen emniyetli gerilme kriterine göre de uygun sonuç vermiştir. Uygun sonucun elde edildiği bu kolçak modelinin üretimi gerçekleştirilmiş; ardından doğrulama testlerine tabi tutulmuştur. Testler sonucunda, bölgesel yoğunluklu iç hacme sahip modelin gereklilikleri yerine getirdiği görülmüştür.

Enhancing Design for Additive Manufacturing Workflow: Optimization, Design and Simulation Tools

In the last few decades, complex light-weight designs have been successfully produced via additive manufacturing (AM), launching a new era in the thinking–design process. In addition, current software platforms provide design tools combined with multi-scale simulations to exploit all the technology benefits. However, the literature highlights that several stages must be considered in the design for additive manufacturing (DfAM) process, and therefore, performing holistic guided-design frameworks become crucial to efficiently manage the process. In this frame, this paper aims at providing the main optimization, design, and simulation tools to minimize the number of design evaluations generated through the different workflow assessments. Furthermore, DfAM phases are described focusing on the implementation of design optimization strategies as topology optimization, lattice infill optimization, and generative design in earlier phases to maximize AM capabilities. In conclusion, the current challenges for the implementation of the workflow are hence described.

Additive manufacturing infill optimization for automotive 3D-printed ABS components

PurposeLightweighting of components in the automotive industry is a prevailing trend influenced by both consumer demand and government regulations. As the viability of additively manufactured designs continues to increase, traditionally manufactured components are continually being replaced with 3D-printed parts. The purpose of this paper is to present experimental results and design considerations for 3D-printed acrylonitrile butadiene styrene (ABS) components with non-solid infill sections, addressing a large gap in the literature. Information published in this paper will guide engineers when designing fused deposition modeling (FDM) ABS parts with infill regions.Design/methodology/approachUniaxial tensile tests and three-point bend tests were performed on 12 different build configurations of 20 samples. FDM with ABS was used as the manufacturing method for the samples. Failure strength and elastic modulus were normalized on print time and specimen mass to quantify variance between configurations. Optimal infill configurations were selected and used in two automotive case study examples.FindingsResults obtained from the uniaxial tensile tests and three-point bend tests distinctly showed that component strength is highly influenced by the infill choice selected. Normalized results indicate that solid, double dense and triangular infill, all with eight contour layers, are optimal configurations for component regions experiencing high stress, moderate stress and low stress, respectively. Implementation of the optimal infill configurations in automotive examples yielded equivalent failure strength without normalization and significantly improved failure strength on a print time and mass normalized index.Originality/valueTo the best of the authors’ knowledge, this is the first paper to experimentally determine and quantify optimal infill configurations for FDM ABS printed parts. Published data in this paper are also of value to engineers requiring quantitative material properties for common infill configurations.

Infill optimization for pieces obtained by 3D printing

This work exposes the development of an infill optimization methodology and its integration into a optimization global methodology previously developed by the authors.Optimization is usually focused on the main boundary geometry of the pieces and its infill is defined separately in the slicer software. By integrating the infill optimization into a mayor optimization methodology the design becomes more flexible and effective, increasing its stiffness while reducing amount of material and therefore its weight. Finite Element Method is applied to the lattice infill size optimization, therefore the infill structure is modified along the work piece depending on the load.

Additive Manufacturing of Porous Structures for Unmanned Aerial Vehicles Applications

Unmanned aerial vehicles (UAVs) have shown promising benefits in many applications. This has been enabled by the emergence of additive manufacturing (AM), which give the designers a large amount of geometrical freedom. In this paper, a novel design process of fused deposition modeling (FDM) combining both topology and infill optimization is introduced for AM of high performance porous structures. Tensile testing of FDM printed samples is first carried out to study the effect of the build orientation on the mechanical properties of acrylonitrile butadiene styrene (ABS) samples. It is found that samples built perpendicular to the load axis are the weakest with a tensile strength of 29 MPa and Young's modulus of 1960 MPa. The materials properties are fed to the finite elements analysis (FEA) for geometrical topology optimization, aiming to maximize stiffness and reduce weight of those parts. Afterwards, an infill optimization is carried out on the topology optimized parts using different mesostructures such as honeycomb, triangular, and rectangular to achieve high structural performance. The results showed that triangular pattern with 50% infill density had the lowest developed stresses, less mass, and strain energy when compared to other structures. Optimum UAVs parts of a quadcopter are successfully manufactured, assembled, and tested.

Infill Optimization for Additive Manufacturing-Approaching Bone-Like Porous Structures.

Porous structures such as trabecular bone are widely seen in nature. These structures are lightweight and exhibit strong mechanical properties. In this paper, we present a method to generate bone-like porous structures as lightweight infill for additive manufacturing. Our method builds upon and extends voxel-wise topology optimization. In particular, for the purpose of generating sparse yet stable structures distributed in the interior of a given shape, we propose upper bounds on the localized material volume in the proximity of each voxel in the design domain. We then aggregate the local per-voxel constraints by their p-norm into an equivalent global constraint, in order to facilitate an efficient optimization process. Implemented on a high-resolution topology optimization framework, our results demonstrate mechanically optimized, detailed porous structures which mimic those found in nature. We further show variants of the optimized structures subject to different design specifications, and we analyze the optimality and robustness of the obtained structures.

장수명주택 인증기준별 최적화를 위한 Infill 연구

장수명주택 인증기준별 최적화를 위한 Infill 연구

Surrogate-based infill optimization applied to electromagnetic problems

The increasing use of expensive computer simulations in engineering places a serious computational burden on associated optimization problems. Surrogate-based optimization becomes standard practice in analyzing such expensive black-box problems. This article discusses several approaches that use surrogate models for optimization and highlights one sequential design approach in particular, namely, expected improvement. The expected improvement approach is demonstrated on two electromagnetic problems, namely, a microwave filter and a textile antenna. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.