Design Freedom Research Articles

Event Knowledge Graph for a Knowledge-Based Design Process Model for Additive Manufacturing

Additive manufacturing (AM) technology is gaining acceptance as a strategic manufacturing technique for allowing new product development. Due to ongoing process improvement, design for AM (DFAM) has become a major issue in harnessing AM’s production and development possibilities to achieve design freedom. The classical design process model does not encompass all the knowledge available to take advantage of design freedom. Therefore, a conceptual and in-depth analysis of design alternatives is necessary to determine the manufacturing process. As a result, this research proposed a design process model for a DFAM to attain design freedom with a unique approach and resource selection steps for fused deposition modeling (FDM) that uses an information model based on evolving knowledge and addressing the challenges. The proposed design process model uses an event knowledge graph (EKG) to outline the product manufacturability from the perspective of DFAM limitations. Event-based knowledge representation provides causality information for knowledge-based reasoning in causality analysis tasks. A relationship-aware mechanism is then used to express events on the graph that are directed from entities to occurrences to efficiently extract the most relevant details. Thus, this implements a step-by-step approach to process and resource specifications during the design stage. Consequently, it offers a comprehensive learning approach for establishing and modeling intrinsic relationships to attain flexibility and design freedom. The efficacy and feasibility of the proposed approach are verified by using an application case study of an intake system based on the airflow sensing rate and controls how much air is fed into the engine.

Extremal structures with embedded prefailure indicators

Preemptive identification of potential failure under loading of engineering structures is a critical challenge. Our study presents an innovative approach to design built-in prefailure indicators within multiscale structural designs with optimized load carrying capabilities utilizing the design freedom of topology optimization. The indicators are engineered to visibly signal load conditions approaching the global critical buckling load at predefined locations. By showing noncritical local buckling when activated, the indicators provide early warning without compromising the overall structural integrity of the design. This proactive safety feature enhances structural reliability. The method is particularly beneficial for offshore wind turbines, where many sensors are located below sea level and are inaccessible for maintenance. By allowing the placement of indicators in accessible predetermined locations, our method can reduce the number of required sensors and improve structural health monitoring. Additionally, the potential use of memory overload indicators exploiting plasticity offers a reliable means of detecting overloads during offline periods. Experimental testing of 3D-printed designs confirms a strong correlation between measurements and numerical simulations, demonstrating the feasibility of creating structures that can signal the need for load reduction or maintenance at predetermined locations. This research contributes to the design of safer structures by introducing built-in early-warning failure systems.

Multi-Lattice Topology Optimization Via Generative Lattice Modeling

Abstract Additive manufacturing enables the fabrication of multi-lattice structures, an advanced design approach featuring heterogeneous lattices at the mesoscale which are arranged to achieve a diverse and purposeful distribution of material properties at the macroscale. Compared to uniform lattice structures, multi-lattice structures permit greater design freedom and a larger design space, which makes it possible to achieve superior structure performance. However, the expanded design space introduces a substantial increase in the complexity that must be managed in order to achieve a multi-lattice structure solution. However, there is a lack of design automation approaches that can tractably create multi-lattice structures. This article introduces an innovative multi-scale topology optimization (TO) framework, called multi-lattice topology optimization with variational autoencoder (MulaTOVA), that is capable of concurrently addressing macro- and mesoscale design requirements. Neural networks (NNs) are employed in this framework to jointly represent the structural topology at the macroscale and the lattice heterogeneity at the mesoscale, enabling simultaneous optimization through the updating of the NNs’ weights. The connectivity between lattices is implicitly constrained by constraining the NNs, while the diversity of the lattices is guaranteed through a generative lattice model which is trained over a large lattice dataset. The performances of various NN types are compared, and Fourier neural operators (FNOs) demonstrated the best flexibility in balancing lattice diversity and local connectivity. Furthermore, our results show that the multi-lattice TO structures achieve a higher stiffness-to-weight ratio than solid TO structures.

Focal beam position and shape manipulation enabled by polarization and plasmonic metasurfaces

Abstract Over the past few years, plasmonic metasurfaces have shown significant potential for the manipulation of the focal beam shape and position. However, traditional hole-type plasmonic metasurfaces have lower optical transmission (< 5%) and lack design freedom because most areas are opaque. Herein, we propose an island-type plasmonic metasurface design that achieves high optical transmission (approximately 50%), while allowing the focal position to be controlled via incident polarization. This plasmonic metasurface exhibits the geometric phase characteristics of anisotropic nano-ellipses, and an additional phase shift is induced by varying the nano-ellipse rotation angles. The metasurface can achieve phase modulation via a spatial nano-ellipse arrangement and enables focus at the desired location under specific incident polarization handedness. Moreover, the number of radial multiplexing in this plasmonic metasurface can be increased to provide multiple focal points to endow the metasurface with an extended focal depth (12.2 times the incident wavelength). The plasmonic metasurface performance was demonstrated through simulations and experiments. The proposed metasurface has a highly versatile design and has significant and diverse applications across multiple optical fields.

Parallel six-mode-selective converter based on photonic crystal fiber without holes in the cladding.

Mode-selective converters (MSCs) play an indispensable role in mode division multiplexing (MDM) systems, and the commonly used cascaded waveguide-based MSCs not only have a relatively large size but also increase the insertion loss and mode crosstalk during the conversion process. In this paper, a parallel six-mode-selective converter (6-MSC) is proposed to enhance the integration of the device, which consists of a photonic crystal fiber (PCF) and six step-index fibers (SIFs). Here, a PCF without any holes in the cladding is proposed. Based on this structure, the distance between the PCF core and the SIF core can be arbitrarily adjusted, which greatly improves the design freedom of multi-core optical fiber devices. Simulation results show that at a wavelength of 1.55 µm, the proposed 6-MSC can achieve parallel conversion from the fundamental mode in each SIF to the corresponding modes (L P01x, L P01y, L P11a x, L P11a y, L P11b x and L P11b y) in the PCF at a device length of 800 µm. The maximum coupling efficiency is 96.22% and the crosstalk is below 3.45%. Moreover, the coupling efficiencies of all six mode pairs exceed 80% within the wavelength range of 1.538∼1.560 µm, and the 3-dB coupling efficiency bandwidth covers the entire C-band. To the best of our knowledge, this is the first report of parallel conversion between six orthogonal fiber modes and fundamental modes based on PCF. The proposed 6-MSC holds promising prospects for future integrated high-capacity MDM systems.

Towards an Automated Design Evaluation Method for Wire Arc Additive Manufacturing

Freedom of design and the cost-effective production of structural parts have led to much research interest in Wire Arc Additive Manufacturing (WAAM). Nevertheless, WAAM is subject to design constraints and fundamentally differs from other additive manufacturing processes. Consequently, design guidelines and supporting design evaluation tools adapted to WAAM are needed. One geometric approach to design evaluation is the use of a three-dimensional medial axis transformation (3D-MAT) to derive local geometry indicators. Previous works define the thickness and radius indicators. In this work, the angle between opposing faces and a mass gradient indicator are added. To apply the literature design rules regarding wall thickness, clearance, bead angle, and edge radius to specific geometry regions, features are classified by the indicators. Following a literature suggestion, wall and corner regions are differentiated by the angle indicator. An angle of 65° is identified as an effective separation limit. Additionally, the analogy of Heuvers’ spheres to the MAT helps estimate a limit of kH−1kH+1 for the mass gradient (kH: Heuvers’ factor). Finally, tests on example parts demonstrate the method’s effectiveness in verifying compliance to the specified rules. With a numerical complexity of O(n2), this method is more efficient than finite element analyses, providing early feedback in the design process.

Dynamic Interferometry for Freeform Surface Measurement Based on Machine Learning-Configured Deformable Mirror.

Optical freeform surfaces are widely used in imaging and non-imaging systems due to their high design freedom. In freeform surface manufacturing and assembly, dynamic freeform surface measurement that can guide the next operation remains a challenge. To meet this urgent need, we propose a dynamic interferometric method based on a machine learning-configured deformable mirror (DM). In this method, a dynamic interferometric system is developed. By using coaxial structure and polarization interference, transient measurement of the measured surface can be realized to meet dynamic requirements, and at the same time, DM transient monitoring can be realized to reduce the accuracy loss caused by DM surface changes and meet dynamic requirements. A transient phase modulation scheme using machine learning to configure the DM surface is proposed, which keeps the system in a measurable state. Compared with the traditional phase modulation scheme that relies on iteration, the scheme proposed in this paper is more efficient and is conducive to meeting dynamic requirements. The feasibility is verified by practical experiments. The research in this paper has significance for guiding the application of dynamic interferometry in the measurement of dynamic surfaces.

New design of two‐dimensional LQ control for batch processes with iterative learning error compensation

AbstractThis paper proposes a two‐dimensional infinite horizon linear quadratic iterative learning control (2D‐IHLQILC) strategy based on error compensation. The strategy aims to address the shortcomings of one‐dimensional infinite horizon linear quadratic control (1D‐IHLQC), which is unable to utilize historical batch information. Firstly, a novel extended state space model is established to describe the batch process, which provides more degrees of freedom for the controller design and enables additional adjustment of the batch process input increment and output increment. Secondly, an error compensation strategy is introduced using historical batch information, which extends the novel extended state‐space model from one to two dimensions and can effectively deal with the time delay problem. Finally, a novel 2D‐IHLQILC controller is designed, which empowers the controller to learn iteratively from historical batch information to improve the control performance batch by batch and to achieve full tracking of the setpoint trajectory. The effectiveness of the 2D‐IHLQILC is tested on the holding pressure control in the injection moulding process as an example.

Triangulated Transmitter Coils With High Design Freedom for Free-Positioning and Omnidirectional Wireless Power Transfer System

Triangulated Transmitter Coils With High Design Freedom for Free-Positioning and Omnidirectional Wireless Power Transfer System

Unlocking multiscale metallic metamaterials via lithography additive manufacturing

ABSTRACT Metamaterials possess properties not found in nature and are expected to revolutionise the design of structural components. However large-scale production of metallic metamaterials remains locked due to the compromise between print size and resolution in existing metal 3D printing methods. We unlock the possibility of 3D printing of stainless steel metamaterials across scales using lithography metal manufacturing, a vat photopolymerisation technology that uses digital light processing (DLP) on metal-filled resin to 3D print a green body for further debinding and sintering in a furnace. Here in, were explore the effects of energy dose on overpolymerisation, minimal feature size, and print resolution as well as the effects of sintering temperature on microstructure, shape stability, and mechanical properties of 3D printed metamaterials. It has become possible to 3D print steel metamaterials with a twist and auxetic metamaterials with micro-scaled structures on a decimetre scale. Our benchmarking experiments demonstrate that lithography metal manufacturing competes with laser powder bed fusion regarding print accuracy, surface roughness, and design freedom and provides a viable solution for translating metallic metamaterials from laboratories to markets.

3D printed microfluidic devices produced by material extrusion: effect of ironing parameters on mixing efficiency and gradient generation

Purpose This study aims to describe the effect of ironing process parameters on mixing efficiency and gradient generation in Y-micromixers and microfluidic gradient generators (MGGs), respectively. Design/methodology/approach Material extrusion (MEX) enables the production of miniaturized devices with the advantage of lower manufacturing costs and higher design freedom. However, surface finishing is the most important drawback when it comes to microfluidic applications where flow splitting is not required. First, the effect of ironing line spacing (LS) and speed (IS) on mixing efficiency in Y-micromixers was experimentally investigated. Then, the best ironing settings were chosen to further study the spatial stability of the normalized concentration gradient in MGGs. Findings Lower ironing LS and IS enhance the microchannel surface smoothness. The best combination of ironing parameters (lowest values of LS and IS) leads to an increase in mixing length of 191% at Q = 10 µL/min and 198% at Q = 20 µL/min, with respect to a similar Y-micromixer geometry where ironing was not performed. These findings were applied in the production of a MGG, showing that the normalized concentration gradient in the crosswise flow direction does not depend on the streamwise position when ironing is performed. Originality/value To the best of the authors’ knowledge, for the first time, the possibility of optimizing ironing parameters to enhance the surface roughness in MEX microfluidic devices has been investigated. Ironing of the channel bottom surface allows to reduce ridges-induced flow convection, thus delaying mixing in Y-micromixers and achieving stable concentration gradient in MGGs.

Axial performances of the steel rebar reinforced column confined by the steel cable reinforced 3D concrete printing permanent formwork

ABSTRACT Among reinforcement methods for 3D concrete printing (3DCP) structures, steel cable reinforcement and reinforced concrete confined by 3DCP formwork (RC-3DPF) methods offer high design freedom and automation. However, the former lacks reinforcement in directions perpendicular to the printing direction, and the latter cannot satisfy constructional requirements. This paper proposed a hybrid approach: the steel rebar reinforced concrete column confined by the steel cable reinforced 3DCP permanent formwork (RC-SC-3DPF). Axial compression tests and theoretical analysis were conducted to study axial performances. Test results showed steel cables and fibres added to 3DCP formwork benefit RC-SC-3DPF structural performances. With a steel cable confinement ratio above 0.534%, RC-SC-3DPF outperforms the traditional case. Steel fibre, compared to PVA fibre, demonstrates greater potential for RC-SC-3DPF due to improved axial load resistance and reduced ductility loss. A theoretical model, based on experimental results, existing standards, and M&T model, was developed to effectively evaluate RC-SC-3DPF structural behaviour.

Metasurface‐Enabled Cascaded Multispectral Polarization Structures Along the Longitudinal Direction

AbstractGeneration and manipulation of polarization structures have attracted significant interest due to their unusual optical features and extensive applications. Multispectral information can further increase the information capacity of polarization structures. However, generating multiple cascaded multispectral polarization numbers (letters) at multiple planes arranged along light propagation has not been reported. A geometric metasurface is used to experimentally realize eight cascaded multispectral polarization numbers (letters) at predesigned observation planes along the longitudinal direction. The efficacy of this approach is demonstrated by encoding a single polarization number (letter) with two wavelengths and cascading two polarization numbers with orthogonal polarization rotation angles. Different two‐color polarization numbers (letters) are generated by controlling the incident wavelength, while their polarization distributions are modulated by controlling the incident linear polarization. This approach integrates two‐dimentional (2D) polarization generation, multiple colors, longitudinal control, and cascading design, providing extra degrees of freedom for customized polarization design and enabling small‐volume polarization systems for color display, image steganography, and optical encryption.

A Universal Strategy for Microcapsule Diversity via Interfacial Surfactant Complexation in Fluorocarbon Oil‐Based Triple Emulsions

AbstractMicrofluidic emulsion‐templating offers the preparation of functional microcapsules with tunable compositions and structures that are otherwise inaccessible using conventional methods. However, the inherent nature of emulsions relying on the immiscibility of phases comprising the emulsion limits the use of a single platform for the realization of microcapsules with diversity in shell materials. Herein, fluorocarbon oil‐based triple emulsions are utilized as templates to achieve microcapsule diversity through a single platform. By introducing fluorocarbon oil with omniphobicity as the interstitial phase between the core and the shell phase, additional degrees of freedom are provided in the library of shell materials applicable in the design of functional microcapsules. Moreover, it is demonstrated that surfactant complexation at the emulsion interface effectively enhances the stability of the emulsion. This grants the use of various solidification methods including polymerization, freezing, and even solvent removal without delicate control of spreading coefficients or complex surfactant synthesis processes. The showcased microcapsule diversity signifies pivotal breakthroughs in microencapsulation technologies, illustrating how the synergistic use of fluorocarbon oil and interfacial complexation of surfactants in emulsions provides true freedom in universal microcapsule shell design for various applications including cosmetics, food, drug delivery, and cell therapy to name a few.

Effect of Laser Energy on Anisotropic Material Properties of a Novel Austenitic Stainless Steel with a Fine-Grained Microstructure

Laser powder bed fusion (LPBF) provides a novel approach with high complexity and freedom for material processing and design, and its special thermal history endows the material with anisotropic properties. By adding micro-alloying elements Nb and Ti into conventional 316L, the anisotropy of the novel austenitic stainless steel fabricated by LPBF, which is related to the laser heat input, was investigated. The refined microstructure of this steel was further strengthened with in situ-generated Nb-, Cr-, and Ti-rich nanoprecipitates at a specific location. The heat input affects the material anisotropy, and a lower heat input leads to stronger anisotropy in this steel. The as-built parts at a low heat input in the horizontal and vertical planes exhibited finer microstructures compared to those fabricated at a high heat input. The epitaxial growth of the grains associated with the thermal gradient resulted in the vertical-section grain size being generally larger than that of the horizontal section. As a result, the low-heat-input parts with a finer grain are also stronger in the horizontal direction, with yield and tensile strengths approaching 0.9 and 1.2 GPa, respectively. Meanwhile, the microstructural changes due to the high heat input imparted a better ductility of parts in different sections (a 3.15% and 4.4% increase in the horizontal and vertical directions, respectively). Its mechanical properties depend mainly on the direction of stress coupled with intergranular friction during deformation in both coarse and fine grains.

Inkjet Printed Multifunctional Graphene Sensors for Flexible and Wearable Electronics

AbstractThe exceptional electrical properties of graphene with high sensitivity to external stimuli make it an ideal candidate for advanced sensing technologies. Inkjet printing of graphene (iGr) can provide a versatile platform for multifunctional sensor manufacturing. Here the multifunctional sensor enabled by combining the design freedom of inkjet printing with the unique properties of graphene networks is reported on. A fully inkjet printed multimaterial device consists of two layers of iGr stripes separated by a dielectric polymeric layer of tripropylene glycol diacrylate (TPGDA). In these devices, the bottom iGr layer, capped with TPGDA, provides temperature sensing, the top uncapped iGr is sensitive to the external atmosphere, while the capacitance between the two iGr layers is sensitive to the applied pressure. The fast, sensitive, and reproducible performance of these sensors are demonstrated in response to environmental stimuli, such as pressure, temperature, humidity, and magnetic field. The devices are capable of simultaneous sensing of multiple factors and are successfully manufactured on a variety of substrates, including Si/SiO2, flexible Kapton films and textiles, demonstrating their potential impact in applications compatible with silicon technologies as well as wearable and healthcare devices.

Advancing Towards Higher Contrast, Energy-Efficient Screens with Advanced Anti-Glare Manufacturing Technology

The pervasive use of screens, averaging nearly 7 h per day globally between mobile phones, computers, notebooks and TVs, has sparked a growing desire to minimize reflections from ambient lighting and enhance readability in harsh lighting conditions, without the need to increase screen brightness. This demand highlights a significant need for advanced anti-glare (AG) technologies, to increase comfort and eventually reduce energy consumption of the devices. Currently used production technologies are limited in their texture designs, which can lead to suboptimal performance of the anti-glare texture. To overcome this design limitation and improve the performance of the anti-glare feature, this work reports a new, cost-effective, high-volume production method that enables much needed design freedom over a large area. This is achieved by combining mastering via large-area Laser Beam Lithography (LBL) and replication by Nanoimprint Lithography (NIL) processes. The environmental impact of the production method, such as regards material consumption, are considered, and the full cycle from design to final imprint is discussed.

Broadband polarization-maintaining anti-resonant fiber design via swarm intelligence.

In this study, we utilized a discrete point configuration method in conjunction with genetic algorithm (GA) and particle swarm optimization (PSO) to design broadband polarization-maintaining anti-resonant fibers (PM-ARFs). The resulting structure features a confinement loss (CL) below 0.17 dB/m, birefringence of approximately 8.2 × 10-5, and a polarization loss ratio (PLR) close to 297 at 1550 nm, providing a usable bandwidth of 340 nm across a range from 1.27 μm to 1.61 μm. This design approach provides additional design freedom beyond parameter optimization and component stacking typical of intelligent design methods. Our study offers a robust design methodology for broadband PM-ARFs, with significant implications for the design of other non-uniform optical waveguides.

Оценка качества и механических свойств получаемых слоев металла из низкоуглеродистой стали методом WAAM с использованием дополнительной механической и ультразвуковой обработки

Introduction. Additive manufacturing is a technology that enables three-dimensional (3D) components to be printed layer by layer according to digital models. Completely different from traditional manufacturing methods such as casting, forging, and machining, additive manufacturing is a near net shape manufacturing process that can greatly enhance design freedom and reduce manufacturing runtime. The material processing challenges in Wire and Arc Additive Manufacturing (WAAM) are related to achieving performance metrics related to geometric, physical, and material properties. Tight tolerances and stringent surface integrity requirements cannot be achieved by utilizing stand-alone AM technologies. Therefore, WAAM parts typically require some post-processing to meet requirements related to surface finish, dimensional tolerances and mechanical properties. It is therefore not surprising that the integration of AM with post-processing technologies into single and multi-setup machining solutions, commonly referred to as hybrid AM, has become a very attractive proposition for industry. The purpose of the work is to evaluate the quality and mechanical properties of the resulting metal layers of mild steel by WAAM method using additional mechanical and ultrasonic processing. Research Methods. To conduct the experiments, a set of welding equipment was used — a single-phase inverter device KEMPPI Kempomat 1701, designed for welding with wire in shielding gases. A mixture of argon and carbon dioxide (80 % argon and 20 % CO2) was used as a shielding gas. SV-08G2S (0.8 C-2 Mg-Si) wire was used as the surfacing material. A plate made of steel St3 with overall dimensions 150×100×5 mm was used as a base for surfacing. The surface of the plate before surfacing was thoroughly cleaned from the layer of oxides, oil, rust and other contaminants. For this purpose mechanical cleaning of the surface was used with BOSCH abrasive wheel with a diameter of 125 mm diameter and a grit size of 120. Before surfacing the surface of the product was degreased with white spirit. The gas flow rate was set at 8 dm3/min. To select the optimal wire feed rate and volt-ampere characteristic, surfacing was performed at each adjustment step of wire feed rate, and voltage. Mechanical statistical tensile tests, chemical composition analysis and metallographic studies were also performed. Results and Discussion. Gas porosity is a typical defect that occurs during the WAAM process and should be eliminated because it adversely affects the mechanical properties. Initially, gas porosity leads to a reduction in the mechanical strength of the part due to damage from microcrack formation. In addition, it often causes the surfaced layer to have worse fatigue properties due to the spatial distribution of different shape and size structures. In our experiments we found that a wire feed speed range of 5–6 m/min is optimal. Increasing the flow rate of shielding gas in the range of 8–14 l/min allows reducing porosity in the surfaced metal to almost zero. The mechanical properties of the surfaced beads show that the average value of yield strength after machining is higher than that of unprocessed specimens. The data obtained from these experiments are in good agreement with those reported in the literature. The presented results can be used in real WAAM technological processes.

Revealing the γ′ and γ″ Phase Fractions of Additively Manufactured and Differently Heat‐Treated Nickel‐Base Superalloy IN718 by Atom Probe Tomography and Their Impact on Mechanical Properties

Powder bed fusion using a laser beam (PBF‐LB) has great potential for the production of geometrically complex industrial components, allowing for unprecedented geometrical optimization and freedom of design. This potential is particularly relevant in the case of turbine components, whose microstructure and properties are directly affected by the extreme PBF‐LB processing conditions. In this context, this study aims to investigate the impact of PBF‐LB on the microstructure and mechanical behavior of Inconel alloy 718 (IN718) when heat treated according to different sequences. Atom probe tomography is used to analyze the composition, morphology, configuration, and volume fraction of γ′ and γ″ precipitates as a function of heat treatment conditions. Their impact on the material is evaluated using compression tests under different build orientations. It is shown that when PBF‐LB IN718 is subject to solution annealing at 930 °C and subsequently aged, δ needles form in its microstructure at the expense of γ′ and γ″, thus reducing mechanical strength. Such is not the case when the solution annealing step is omitted or when its temperature is increased to 1000 °C, conditions whose superior mechanical behavior have been attributed to a high dislocation density and a large volume fraction of aging phases, respectively.