Toward better build volume packing in additive manufacturing: classification of existing problems and benchmarks

In many cases, the efficient operation of Additive Manufacturing (AM) technology relies on build volumes being packed effectively. Packing algorithms have been developed in response to this requirement. The configuration of AM build volumes is particularly challenging due to the multitude of irregular geometries encountered and the potential benefits of nesting parts. Currently proposed approaches to address this packing problem are routinely evaluated on data sets featuring shapes that are not representative of targeted manufacturing products. This study provides a useful classification of AM build volume packing problems and an overview of existing benchmarks for the analysis of such problems. Additionally, this paper discusses characteristics of future, more realistic, benchmarks with the intention of promoting research toward effective and efficient AM build volume packing being integrated into AM production planning methodologies

Toward better build volume packing in additive manufacturing: classification of existing problems and benchmarks

In many cases, the efficient operation of Additive Manufacturing (AM) technology relies on build volumes being packed effectively. Packing algorithms have been developed in response to this requirement. The configuration of AM build volumes is particularly challenging due to the multitude of irregular geometries encountered and the potential benefits of nesting parts. Currently proposed approaches to address this packing problem are routinely evaluated on data sets featuring shapes that are not representative of targeted manufacturing products. This study provides a useful classification of AM build volume packing problems and an overview of existing benchmarks for the analysis of such problems. Additionally, this paper discusses characteristics of future, more realistic, benchmarks with the intention of promoting research toward effective and efficient AM build volume packing being integrated into AM production planning methodologies

Tailored Iterated Greedy metaheuristic for a scheduling problem in metal 3D printing

This article contributes to the additive manufacturing-based production planning literature by developing a Mixed-Integer Linear Programming (MILP) formulation for the Identical Parallel 3D-Printing Machines Scheduling Problem considering batching, multiple build platforms of restricted sizes, and sequence-independent setup times. Besides, a customized metaheuristic, named the Tailored Iterated Greedy (TIG) Algorithm is developed to solve the new optimization problem. TIG’s performance is evaluated through extensive numerical analysis and using a new testbed. It is shown that the customized computational mechanisms improve the optimization performance; statistical analysis is supportive of the significance of the resulting improvements. The developed mathematical model and optimization algorithm can be considered the basis for future developments in the optimization literature of additive manufacturing

Nouvelles voies de fabrication d'alliages métalliques à hautes performances à partir de poudres

La fusion sélective par laser (Selective Laser Melting, SLM), une des techniques de la fabrication additive (AM), permet la production de pièces en trois dimensions (3D) de formes complexes directement à partir de poudres métalliques. Elle présente de nombreux avantages significatifs par rapport aux méthodes traditionnelles de fabrication mais se heurte encore à une faible disponibilité des matériaux en poudre.Le travail effectué dans cette étude a donc consisté à étudier et à développer un nouveau moyen pour réaliser in situ des pièces en alliages et en composites à partir de mélanges de poudres.Au niveau expérimental le choix s est porté sur le système Fer-Aluminium et sur un renforcement par des particules de SiC.Les essais ont permis de constater que dans le processus de fabrication de pièces par SLM la puissance du laser et la vitesse de balayage déterminent au premier chef la densité, la microstructure, la composition de phase et les propriétés mécaniques.À partir d un mélange de poudres, des phases intermétalliques ont été obtenues en contrôlant les paramètres SLM. Un traitement thermique ultérieur influence les paramètres cristallins, le degré d ordre et les propriétés mécaniques des pièces ainsi formées.Avec l utilisation de poudres préalliées, un phénomène de texture a été observé prenant la forme de grains allongés/colonnaires orientés dans la direction de construction.Le renforcement de la matrice de fer par des particules de SiC de différentes tailles conduit à une modification structurale avec la formation de produits d interaction, perlitie et martensite, conduisant à une amélioration de la résistance à la traction par rapport au Fe pur.Selective laser melting (SLM), as one of the additive manufacturing (AM) technologies, enables the production of three dimensional (3D) complex parts directly from metal powders. It offers many significant advantages compared with traditional manufacturing methods; however it faces a limited availability of powder materials.The work done during this study consisted in investigating and developing a new way of in situ producing alloys and composites from powder mixtures.The iron-aluminum system and reinforcement by SiC particles were considered.Experiments have shown that the laser power and scanning speed primarily determine the density, microstructure, phase composition and mechanical properties in the manufacturing process of SLM parts.Using pre-alloyed powders, a phenomenon of texture was observed in the form of elongated/columnar grains oriented in the building direction.Using powder mixtures, intermetallic phases were obtained by controlling the SLM parameters. A heat treatment influences the crystal parameters, the degree of order and the mechanical properties of the formed parts.The reinforcement of the iron matrix by SiC particles of several sizes leads to a structural change with the formation of interaction products, perlite and martensite, leading to an improvement in tensile strength compared to pure Fe.BELFORT-UTBM-SEVENANS (900942101) / SudocSudocFranceF

Fibre-reinforced additive manufacturing: from design guidelines to advanced lattice structures

In pursuit of achieving ultimate lightweight designs with additive manufacturing (AM), engineers across industries are increasingly gravitating towards composites and architected cellular solids; more precisely, fibre-reinforced polymers and functionally graded lattices (FGLs). Control over material anisotropy and the cell topology in design for AM (DfAM) offer immense scope for customising a part’s properties and for the efficient use of material. This research expands the knowledge on the design with fibre-reinforced AM (FRAM) and the elastic-plastic performance of FGLs. Novel toolpath strategies, design guidelines and assessment criteria for FRAM were developed. For this purpose, an open-source solution was proposed, successfully overcoming the limitations of commercial printers. The effect of infill patterns on structural performance, economy, and manufacturability was examined. It was demonstrated how print paths informed by stress trajectories and key geometric features can outperform conventional patterns, laying the groundwork for more sophisticated process planning. A compilation of the first comprehensive database on fibre-reinforced FGLs provided insights into the effect of grading on the elastic performance and energy absorption capability, subject to strut-and surface-based lattices, build direction and fibre volume fraction. It was elucidated how grading the unit cell density within a lattice offers the possibility of tailoring the stiffness and achieving higher energy absorption than ungraded lattices. Vice versa, grading the unit cell size of lattices yielded no effect on the performance and is thus exclusively governed by the density. These findings help exploit the lightweight potential of FGLs through better informed DfAM. A new and efficient methodology for predicting the elastic-plastic characteristics of FGLs under large strain deformation, assuming homogenised material properties, was presented. A phenomenological constitutive model that was calibrated based upon interpolated material data of uniform density lattices facilitated a computationally inexpensive simulation approach and thus helps streamline the design workflow with architected lattices.Open Acces

Interface Oral Health Science 2016: Innovative Research on Biosis–Abiosis Intelligent Interface

Dentistry; Oral and Maxillofacial Surgery; Regenerative Medicine/Tissue Engineerin