Recent advances in modelling and simulation of surface integrity in machining - A review

Machining is one of the final steps in the manufacturing value chain, where the dimensional tolerances are fine-tuned, and the functional surfaces are generated. Many factors such as the process type, cutting parameters, tool geometry and wear can influence the surface integrity (SI) in machining. Being able to predict and monitor the influence of different parameters on surface integrity provides an opportunity to produce surfaces with predetermined properties. This paper presents an overview of the recent advances in computational and artificial intelligence methods for modelling and simulation of surface integrity in machining and the future research and development trends are highlighted

Recent advances in modelling and simulation of surface integrity in machining - A review

Machining is one of the final steps in the manufacturing value chain, where the dimensional tolerances are fine-tuned, and the functional surfaces are generated. Many factors such as the process type, cutting parameters, tool geometry and wear can influence the surface integrity (SI) in machining. Being able to predict and monitor the influence of different parameters on surface integrity provides an opportunity to produce surfaces with predetermined properties. This paper presents an overview of the recent advances in computational and artificial intelligence methods for modelling and simulation of surface integrity in machining and the future research and development trends are highlighted

SMP Prototype Design and Fabrication for Thermo-responsive Façade Elements

The aim to attain sustainability in the built environment introduced the innovative application of advanced material technologies for low-energy, but aesthetically intriguing, building design strategies. Adaptive and responsive building skins as embedded and intrinsic control systems can be delivered with smart materials, and thus have the potential to minimise the energy consumption of buildings by maximising the natural and passive adjustment of façade components for shading, air-flow, daylight, and view. The dynamic smart material façade, adaptable to changing outdoor environments, is considered to be a holistic design approach that integrates the behavioural performance effects with the appearance and aesthetics of kinetic ability provided by smart materials acting as actuators, by adjusting their properties according to external stimuli. Of the various environmental inputs sensed by, and actuating, active and dynamic building façade systems, this research focuses on temperature as the stimulus to activate a dynamic shading device with the mechanism of opening and closing, specifically considering Seoul’s climate. Among currently available thermo-responsive smart materials, the shape memory polymer (SMP) is investigated as an activator of shading devices to be implemented to adaptive building skin strategies. As the first stage of SMP prototype design and fabrication study toward the thermo-responsive building façade elements, SMP prototypes are proposed in cell types. Among the general thermo-mechanical cycle of thermo-responsive SMP, only programming of the permanent shape via additive manufacturing and recovery at the activation temperature are focused upon in this research. This study proposes a design-to-fabrication workflow integrating computational tools, 3d printing and recalibration of relevant variables in digital design process, G code generation, and manufacturing using commercially available SMP filaments. To verify the 3d printing process, and to demonstrate the shape-changing behaviour of SMP actuators, reproduction of a referenced prototype was conducted, in addition to fabrication experiments of SMP surfaces with various thicknesses and SMP hinges with customised rotating angles. In addition, a base-line prototype combining the static ABS plate and the active SMP hinge is developed to set up the heat test and a digital motion simulation from data of shape changing behaviour acquired from a hands-on model test. After the demonstration of the baseline prototype in design and additive manufacturing process, various SMP prototypes were designed with reference to kinetic prototype researches, but with the consistent 100mm-diameter circular surface, in a scale of 1:3. They were also fabricated with a 3d printer for both open and closed positions to testify to their constructability, and thus to comparatively evaluate the design and fabrication outcomes. Furthermore, after conducting radiation and thermal simulation analysis, shading performance validation is noted for selecting potential prototypes. Lastly, the needs to further develop reversible reiterative shape-changing materials or systems are briefly discussed

Multiphysics processes in solid thermal energy storage

Um die zuverlässige Integration von Solarthermieanwendungen (ST), z.B. konzentrierte Solarenergie (concentrating solar power, CSP) bei steigendem Energiebedarf und trotz des fluktuierenden Charakters von ST zu ermöglichen, werden thermische Energiespeichertechnologien (TES) als attraktive Lösungen eingesetzt, um ST-basierte Systeme auf dem Energiemarkt wettbewerbsfähiger zu machen. Darüber hinaus werden Feststoff-TES-Systeme als vielversprechende Alternative zu herkömmlichen Flüssigkeitsspeicherlösungen betrachtet, um die Investitionskosten für die TES-Einheit weiter zu senken. Sowohl aus technischer als auch aus kommerzieller Sicht können sie vorteilhaft mittels der Komponentenfertigung bis hin zum kompletten modularen Aufbau ausgelegt werden, um die vorgesehene Beladungsmenge für verschiedene Leistungsbereiche von CSP-Anlagen abzudecken. Die erfolgreiche Integration von feststoffbasierten, sensiblen Wärmespeichern (SWS) in Parabolrinnen-Kraftwerken hat sich in den letzten zehn Jahren bewährt. Gegenwärtig gewinnt die TES-Technologie für niedrige Temperaturen neben Hochtemperaturanwendungen zur Stromerzeugung zunehmend an Bedeutung. Dies bietet die Möglichkeit, neue gemischte Feststoff-Flüssigkeits-Speichermaterialien zu entwickeln, um die Wärmespeicherdichte zu erhöhen, wie hier am Beispiel eines neuartigen, wassergesättigten zementartigen Materials demonstriert wird, das im Rahmen eines nationalen Projekts zur Speicherung von mit Solarkollektoren gewonnener Energie (IGLU-Projekt) entwickelt wurde. Wegen typischer Eigenschaften der Feststoffe müssen jedoch wichtige spezifische Probleme gelöst werden, um die Leistungsfähigkeit und Stabilität von festen TES-Systemen über einen langen Zeitraum zu gewährleisten. Die gegenwärtigen Bemühungen von Wissenschaft und Industrie konzentrieren sich auf thermische Aspekte als zentrales Hauptanliegen. Feststoffbasierte TES sind jedoch multiphysikalischen Prozessen unterworfen, d.h. das thermische Verhalten ist ein Produkt der gegenseitigen Wechselwirkung mehrerer beteiligter physikalischer Felder und beeinflusst selbst wiederum diese Felder. Das damit verbundene mechanische Verhalten der Wärmespeicherkomponenten hat einen großen Einfluss auf die Zuverlässigkeit und Haltbarkeit des Systems sowie die thermische Leistung, da mögliche Strukturschäden den Wärmetransport durch die TES-Struktur erheblich beeinflussen und die Integrität der Struktur selbst gefährden können. Die Motivation dieses Beitrags liegt in der Entwicklung eines innovativen feststoffbasierten TES-Moduls (IGLU TES) für das oben genannte IGLU-Projekt. Ziel dieses Beitrags ist es, die Leistungsfähigkeit und Integrität von feststoffbasierten TES mit Röhrenwärmetauschern unter multiphysikalischen Bedingungen zu untersuchen, um insbesondere die Möglichkeiten und Folgen eines Versagens durch mechanische Schädigung oder thermische Degradation zu identifizieren. Die Arbeit geht von einer verallgemeinerten thermo-hydro-mechanischen (THM) Analyse des IGLU TES aus, um einen ersten Einblick in die Kopplungseffekte zwischen den verschiedenen physikalischen Feldern und deren relative Bedeutung zu gewinnen. Kritische Bereiche in den Zonen um den Röhrenwärmetauscher werden dann anhand der sich einstellenden Spannungsfelder als kritisch identifiziert, da sie die strukturelle Integrität des Speichermoduls beeinträchtigen können, indem in diesen Zonen die Festigkeit charakterisierende oder bruchmechanische Kriterien überschritten werden. Die so ermittelten kritischen Bereiche erlauben eine vertiefte, strukturspezifische Analyse eines feststoffbasierten TES mit eingebetteten Röhrenwärmetauschern. Insbesondere wird ein analytischer Ansatz vorgeschlagen, indem geeignete Vereinfachungen auf der Grundlage der vorangegangenen numerischen Analysen vorgenommen werden, um eine robuste Analyse derjenigen materialspezifischen und geometrischen Größen durchzuführen, die den größten Einfluss auf die strukturelle Zuverlässigkeit des Speichermoduls ausüben. Die abgeleitete analytische Lösung kann zur Quantifizierung der Abhängigkeit kritischer Spannungen von mehreren Systemparametern, Materialkennwerten und Geometriegrößen herangezogen werden, um unter gewählten Gesichtspunkten eine Systemoptimierung mit großer Designflexibilität für die Speicherkonfiguration durchzuführen. Der analytische Ansatz erfordert nur minimalen Aufwand und eignet sich für frühe Designphasen. Dabei zeigte sich, dass das Risiko von Material- und Strukturversagen auch bei optimaler Auslegung nicht beliebig reduziert werden kann. Daher wird ein Phasenfeld-Ansatz zur Modellierung von Risswachstumsprozessen entwickelt, um wahrscheinliche Schädigungsmuster zu erfassen, die durch die Nichtübereinstimmung der thermischen Ausdehnungskoeffizienten der Systemkomponenten verursacht werden, und den Einfluss der resultierenden Risstopologien auf das thermische Verhalten eines festen TES-Systems zu quantifizieren. Der vorgeschlagene Phasenfeldansatz, formuliert innerhalb eines gekoppelten thermomechanischen Ansatzes, wird auf zwei repräsentative feste SWS-Konfigurationen angewendet, die sich sowohl hinsichtlich des Speichermediums als auch der Speichertemperatur unterscheiden. Innerhalb des Festkörpers wird ein Bruchvorgang beobachtet und die daraus resultierende thermische Leistungsabnahme durch eine Wärmetransportbehinderung in Abhängigkeit des eingeschlossenen flüssigen Mediums mit potentiell niedriger Wärmeleitfähigkeit untersucht, was zu erheblichen Schwankungen der Heizleistung in einem laufenden System führen kann

Development of a post-form strength prediction model for a 6xxx aluminium alloy in a novel forming process

Accurate prediction of the post-form strength of structural components made from 6xxx series aluminium alloys has been a challenge, especially when the alloy undergoes complex thermo-mechanical processes such as the Fast light Alloys Stamping Technology (FAST). This process involves ultra-fast heating, high temperature plastic deformation, rapid quenching and is followed by multi-stage artificial ageing heat treatment. The strength of the material evolves with the formation of second phase precipitates during the entire process. The widely accepted precipitation sequence is SSSS - clusters - β” - β’ - β. However, due to the complexity of deformations and thermal profile during the process, the classic theory is not applicable. Therefore, in this research, precipitation behaviour during ultra-fast heating, viscoplastic behaviour, effect of residual dislocations generated during high temperature deformation, quenching sensitivity and multi-stage artificial ageing response have been comprehensively studied. A set of experiments, including ultra-fast heating tests, uniaxial tensile tests, pre-straining uniaxial tensile tests, quenching tests, artificial ageing tests and TEM observations were conducted to provide a thorough understanding of the novel forming technology. The underlying mechanisms for the FAST process were investigated through the in-depth analysis of experimental results. ·Under ultra-fast heating conditions, most of the precipitates are dissolved and the spherical pre-β” precipitates are formed and finely dispersed in the aluminium matrix, which are beneficial to accelerate the subsequent precipitation process. ·The residual dislocations, generated during plastic deformation, strengthen the material and act as nucleation sites for precipitates. The peak strength is reduced owing to the uneven accumulation of precipitates around dislocations. ·The coarse β’ and β precipitates induced due to the insufficient quenching are detrimental to precipitation response. These quench-induced precipitates consume both solute atoms and vacancies, which are unable to be reversely transferred to the preferred needle-shaped β” precipitates. Based on the scientific achievements, a mechanism-based unified post-form strength (PFS) prediction model was developed ab-initio to predict the strength evolution of the material during the entire complex FAST process with highly efficient computation. Constitutive equations were proposed to model the viscoplastic behaviour at elevated temperature. Important microstructural parameters, including dislocation density, volume fraction, radius of precipitates and solute concentration were correlated to predict the material strength. The particle size distribution (PSD) sub-model was further established to accurately interpret the detailed microstructural changes during the complex thermo-mechanical processes. Furthermore, the model has been programmed into an advanced functional module ‘Tailor’ and implemented into a cloud based FEA platform. The predictive capability of the module was verified by conducting forming tests of a U-shaped component in a dedicated pilot production line. It was found that the ‘Tailor’ module was able to precisely predict the post-form strength in agreement with experiments, with a deviation of less than 7% compared to experimental results.Open Acces

ne–xt facades: Proceedings of the COST Action TU1403 Adaptive Facades Network Mid-term Conference

The ne-xt facades conference is the official International Mid-term Conference of the European COST Action TU1403 ‘Adaptive Facades Network’, an international scientific cooperation with the aim to harmonise, share and disseminate technological knowledge on adaptive facades on the European level. During the mid-term conference first results are presented to stakeholders from industry and design and to the public. The goal is to share knowledge and discuss novel facade concepts, effective evaluation tools and design methods for adaptive facades. Alongside the contributions from members of the COST Action, the conference received many contributions from external researchers and the industry. This added to the interesting debate about adaptive facades we believe it was an excellent stage to test the first results of the COST Action

AI-based design methodologies for hot form quench (HFQ®)

This thesis aims to develop advanced design methodologies that fully exploit the capabilities of the Hot Form Quench (HFQ®) stamping process in stamping complex geometric features in high-strength aluminium alloy structural components. While previous research has focused on material models for FE simulations, these simulations are not suitable for early-phase design due to their high computational cost and expertise requirements. This project has two main objectives: first, to develop design guidelines for the early-stage design phase; and second, to create a machine learning-based platform that can optimise 3D geometries under hot stamping constraints, for both early and late-stage design. With these methodologies, the aim is to facilitate the incorporation of HFQ capabilities into component geometry design, enabling the full realisation of its benefits. To achieve the objectives of this project, two main efforts were undertaken. Firstly, the analysis of aluminium alloys for stamping deep corners was simplified by identifying the effects of corner geometry and material characteristics on post-form thinning distribution. New equation sets were proposed to model trends and design maps were created to guide component design at early stages. Secondly, a platform was developed to optimise 3D geometries for stamping, using deep learning technologies to incorporate manufacturing capabilities. This platform combined two neural networks: a geometry generator based on Signed Distance Functions (SDFs), and an image-based manufacturability surrogate model. The platform used gradient-based techniques to update the inputs to the geometry generator based on the surrogate model's manufacturability information. The effectiveness of the platform was demonstrated on two geometry classes, Corners and Bulkheads, with five case studies conducted to optimise under post-stamped thinning constraints. Results showed that the platform allowed for free morphing of complex geometries, leading to significant improvements in component quality. The research outcomes represent a significant contribution to the field of technologically advanced manufacturing methods and offer promising avenues for future research. The developed methodologies provide practical solutions for designers to identify optimal component geometries, ensuring manufacturing feasibility and reducing design development time and costs. The potential applications of these methodologies extend to real-world industrial settings and can significantly contribute to the continued advancement of the manufacturing sector.Open Acces

A cost effective approach to enhance surface integrity and fatigue life of precision milled forming and forging dies

Previously held under moratorium from 8 August 2019 until 19 January 2022The machining process determines the overall quality of produced forming and forging dies, including surface integrity. Previous research found that surface integrity has a significant influence on the fatigue life of the dies. This thesis aims to establish a cost-effective approach for precision milling to obtain forming and forging dies with good surface integrity and long fatigue life. It combined experimental study accompanied by Finite Element Modelling and Artificial Intelligence soft modelling to predict and enhance forming and forging die life. Four machining parameters, namely Surface Speed, Depth of cut, Feed Rate and Tool Lead Angle, each with five levels, were investigated experimentally using Design of Experiment. An ANOVA analysis was carried out to identify the key factor for every Surface Integrity (SI) parameter and the interaction of every factor. It was found that the cutting force was mostly influenced by the tool lead angle. The residual stress and microhardness were both significantly influenced by the surface speed. However, on the surface roughness it was found that the feed rate had the most influence. After the machining experiments, four-point bending fatigue tests were carried out to evaluate the fatigue life of precision milled parts at an elevated temperature in a low cycle fatigue set-up imitated for the forming and forging production. It was found that surface roughness and hardness were the most influential factors for fatigue life. A 3D-FE-Modelling framework including a new material model subroutine was developed; this led to a more comprehensive material model. A fractional factorial simulation with over 180 simulations was carried out and validated with the machining experiment. Based on the experimental and simulation results, a soft prediction model for surface integrity was established by using Artificial Neural Networks (ANN) approach. These predictions for SI were then used in a Genetic Algorithm model to optimise the SI. The confirmation tests showed that the machining strategy was successfully optimised and the average fatigue duration was increased by at least a factor of two. It was found that a surface speed of 270 m/min, a feed rate of 0.0589 mm/tooth, a depth of cut of 0.39 mm and a tool lead angle of 16.045° provided the good surface integrity and increased fatigue performance. Overall, these findings conclude that the fundamentals and methodology utilised have developed a further understanding between machining and forming/forging process, resulting in a good foundation for a framework to generate FE and soft prediction models which can be used to in optimisation of precision milling strategy for different materials.The machining process determines the overall quality of produced forming and forging dies, including surface integrity. Previous research found that surface integrity has a significant influence on the fatigue life of the dies. This thesis aims to establish a cost-effective approach for precision milling to obtain forming and forging dies with good surface integrity and long fatigue life. It combined experimental study accompanied by Finite Element Modelling and Artificial Intelligence soft modelling to predict and enhance forming and forging die life. Four machining parameters, namely Surface Speed, Depth of cut, Feed Rate and Tool Lead Angle, each with five levels, were investigated experimentally using Design of Experiment. An ANOVA analysis was carried out to identify the key factor for every Surface Integrity (SI) parameter and the interaction of every factor. It was found that the cutting force was mostly influenced by the tool lead angle. The residual stress and microhardness were both significantly influenced by the surface speed. However, on the surface roughness it was found that the feed rate had the most influence. After the machining experiments, four-point bending fatigue tests were carried out to evaluate the fatigue life of precision milled parts at an elevated temperature in a low cycle fatigue set-up imitated for the forming and forging production. It was found that surface roughness and hardness were the most influential factors for fatigue life. A 3D-FE-Modelling framework including a new material model subroutine was developed; this led to a more comprehensive material model. A fractional factorial simulation with over 180 simulations was carried out and validated with the machining experiment. Based on the experimental and simulation results, a soft prediction model for surface integrity was established by using Artificial Neural Networks (ANN) approach. These predictions for SI were then used in a Genetic Algorithm model to optimise the SI. The confirmation tests showed that the machining strategy was successfully optimised and the average fatigue duration was increased by at least a factor of two. It was found that a surface speed of 270 m/min, a feed rate of 0.0589 mm/tooth, a depth of cut of 0.39 mm and a tool lead angle of 16.045° provided the good surface integrity and increased fatigue performance. Overall, these findings conclude that the fundamentals and methodology utilised have developed a further understanding between machining and forming/forging process, resulting in a good foundation for a framework to generate FE and soft prediction models which can be used to in optimisation of precision milling strategy for different materials