Topology optimization of the tool holder produced with additive manufacturing

This paper deals with the topology optimizations of tool holder where three different mass targets were required. The holder was loaded with 499 N. Weight reduction of the tool holder placed in tool turret can positively affect the bearing durability. Easier manipulation with the holder is one of the results. In the process of the topological optimization manufacturing constraints, such as overhang prevention, self-supporting and material spreading were defined for needs of Direct Metal Laser Sintering production technology. Structural analyses of three obtained geometries were simulated for evaluation of the stiffness in three main directions of the tool holder. Finally, the weight and the stiffness of each individual geometry was compared and prepared for manufacturing.

Design and Assembly of DNA Molecules Using Multi-Objective Optimisation

Rapid engineering of biological systems is currently hindered by limited integration of manufacturing constraints into the design process, ultimately reducing the yield of many synthetic biology workflows. Here we tackle DNA engineering as a multi-objective optimization problem aiming at finding the best tradeoff between design requirements and manufacturing constraints. We developed a new open-source algorithm for DNA engineering, called Multi-Objective Optimisation algorithm for DNA Design and Assembly (MOODA), available as a Python and Anaconda package, as well as a Docker image. Experimental results show that our method provides near optimal constructs and scales linearly with design complexity, effectively paving the way to rational engineering of DNA molecules from genes to genomes.

Local Redesign for Additive Manufacturability of Compliant Mechanisms Using Topology Optimization

Compliant mechanisms are crucial components in current and future high-precision applications. Topology optimization and additive manufacturing offer freedom to design complex compliant mechanisms that were impossible to realize using conventional manufacturing. Design for additive manufacturing constraints, such as the maximum overhang angle and minimum feature size, tend to drastically decrease the performance of topology optimized compliant mechanisms. It is observed that, among others, design for additive manufacturing constraints are only dominant in the flexure regions. Flexures are most sensitive to manufacturing errors, experience the highest stress levels and removal of support material carries the highest risk of failure. It is crucial to impose these constraints on the flexure regions, while in others part of the compliant mechanism design, these constraints can be relaxed. We propose to first design the global compliant mechanism layout in the full domain without imposing any design for additive manufacturing constraints. Subsequently we redesign selected refined local redesign domains with design for additive manufacturing constraints, whilst simultaneously considering the mechanism performance. The method is applied to a single-input-multi-output compliant mechanism case study, limiting the maximum overhang angle, introducing manufacturing robustness and limiting the maximum stress levels of a selected refined redesign domain. The high resolution local redesigns are detailed and accurate, without a large additional computational effort or decrease in mechanism performance. Thereto, the method proves widely applicable, computationally efficient and effective in its purpose.

Additive Manufacturing of Thermoplastic M8 Fasteners Using Photopolymer Jetting Technology for Low-Strength Fastening Applications

This study investigates the spatial accuracy of additively manufactured M8 fasteners fabricated using photopolymer jetting technology. A number of M8 bolts and their mating M8 nuts are fabricated using Stratasys Object 260 Connex 3 polyjet printer with Vero cyan, Vero magenta, Vero white, and Vero grey thermoplastic resins. Vero series thermo-plastics were used as they offer durability, strength, and flexibility. The additively manufactured nuts and bolts are fabricated with the intention of introducing thermoplastic fasteners that could eventually substitute metal fasteners in certain low strength joining applications such as in fluidics, electronics, biomedical engineering, food packaging, and automobile industries. Manufacturing constraints and critical conditions for fabrication are presented. Vital printing and manufacturing constraints, dimensional stability analysis, and the subsequent dimensional changes for the fabricated fasteners are thoroughly illustrated. Dimensional stability of the printed structures was examined under an ultra-compact 3D laser sensor and the imaging results are also presented. The fabricated thread profile superimposed precisely with the CAD model’s ISO thread profile dimensions. The dimensional performance of the fabricated M8 fasteners was examined in every orientation and along each axis of the fasteners. The high-quality manufacturing of fasteners using photopolymer jetting reached the maximum precision requirements and fitted under IT 06 transition fit grade.

Topology optimization for infill in MEx

Purpose In furthering numerical optimization techniques for the light-weighting of components, it is paramount to produce algorithms that closely mimic the physical behavior of the specific manufacturing method under which they are created. The continual development in topology optimization (TO) has reduced the difference in the optimized geometry from what can be physically realized. As the reinterpretation stage inevitably deviates from the optimal geometry, each progression in the optimization code that renders the final solution more realistic is beneficial. Despite the efficacy of material extrusion (MEx) in producing complex geometries, select manufacturing constraints are still required. Thus, the purpose of this paper is to develop a TO code which demonstrates the incorporation of MEx specific manufacturing constraints into a numerical optimization algorithm. Design/methodology/approach A support index is derived for each element of the finite element mesh that is used to penalize elements, which are insufficiently supported, discouraging their existence. The support index captures the self-supporting angle and maximum allowable bridging distance for a given MEx component. The incorporation of the support index into a TO code is used to demonstrate the efficacy of the method on multiple academic examples. Findings The case studies presented demonstrate the methodology is successful in generating a resulting topology that is self-supporting given the manufacturing parameters specified in the code. Comparative to a general TO problem formulation, the optimal material distribution results in a minimally penalized design on a compliance normalization metric while fully adhering to the MEx specific parameters. The methodology, thus, proves useful in generating an infill geometry is fully enclosed regions, where support material extraction is not a possibility. Originality/value The work presented is the first paper to produce a novel methodology that incorporates the manufacturing-specific constraint of bridging distance for MEx into TO code. The results generated allow for the creation of printed components with hollow inclusions that do not require any additional support material beyond the intended structure. Given the advancement, the numerical optimization technique has progressed to a more realistic representation of the physical manufacturing method.

Optimization of a High Pressure Industrial Fan

Fans are used in industrial refineries, power generation, petrochemistry, pollution control, etc. These fans can perform in sometimes extreme, mission-critical conditions. The design of fans has historically relied on turbomachinery affinity laws, resulting in oversized machines that are expensive to manufacture and transport. With the increasingly lower CPU cost of fluid modeling, designers can now turn to CFD optimization to produce the necessary machine performance and flow conditions while respecting manufacturing constraints. The objective of this study is to maximize the pressure rise across an industrial fan while respecting manufacturing constraints. First, a 3D scan of the baseline impeller is used to create the CFD model and validated against experimental data. The baseline impeller geometry is then parameterized with 21 free parameters driving the shape of the hub, shroud, blade lean and camber. A fully automated optimization process is conducted using Numeca’s Fine™/Design3D software, allowing for a CPU-efficient Design Of Experiment (DOE) database generation and a surrogate model using the powerful Minamo optimization kernel and data-mining tool. The optimized impeller coupled with a CFD-aided redesigned volute showed an increase in overall pressure rise over the whole performance line, up to 24% at higher mass flow rates compared to the baseline geometry.