Virtual prototyping and digital twin

Chronicles of sieges to castles or fortresses, using "machinae", can often be found in historical sources. Moreover, archaeological excavations of castles or fortresses has brought to light rocks or projectiles whose carving suggests a military usage. Nevertheless, chronicles and discoveries alone, are seldom enough to propose a faithful reconstruction of these machines. Therefore, the aim of this research is the development of methodologies for reconstructing virtual scenarios of sieges, starting from the scarce information available. In order to achieve it, a procedure for the virtual reconstruction of the siege machine has been set up, focusing on typology and dimensions of the machines, also investigating possible fire positions according to topography. The entire procedure has been developed using the siege of Cervara di Roma's Rocca as a case study. Late medieval chronicles (end of 13th Century) report the siege brought by the papal army in order to restore the jurisdiction on the Cervara's stronghold, following the insurrection of a group of vassals headed by a monk named Pelagio. The discovery, in the area of the Rocca, of a stone that could have been used as a projectile confirms what reported. The proposed methodology is composed of two parts. The first one is connected to the study of the "internal ballistics", to understand the performances and to build virtual models of siege machines. The second part is the study of the "external ballistics", then to the positioning and shooting ability of possible machines, analysing the topography of the area. In this paper, we present the feasibility of this methodology through the preliminary results achieved correlating internal and external ballistics.

In a context more and more oriented towards customized medical solutions, we propose a mechanobiology-driven algorithm to determine the optimal geometry of scaffolds for bone regeneration that is the most suited to specific boundary and loading conditions. In spite of the huge number of articles investigating different unit cells for porous biomaterials, no studies are reported in the literature that optimize the geometric parameters of such unit cells based on mechanobiological criteria. Parametric finite element models of scaffolds with rhombicuboctahedron unit cell were developed and incorporated into an optimization algorithm that combines them with a computational mechanobiological model. The algorithm perturbs iteratively the geometry of the unit cell until the best scaffold geometry is identified, i.e. the geometry that allows to maximize the formation of bone. Performances of scaffolds with rhombicuboctahedron unit cell were compared with those of other scaffolds with hexahedron unit cells. We found that scaffolds with rhombicuboctahedron unit cell are particularly suited for supporting medium-low loads, while, for higher loads, scaffolds with hexahedron unit cells are preferable. The proposed algorithm can guide the orthopaedic/surgeon in the choice of the best scaffold to be implanted in a patient-specific anatomic region.

Keywords: Computational mechanobiology , Morphology optimization , Rhombicuboctahedron , Scaffold unit cell

Design of scaffolds for tissue engineering entails multi-disciplinary and multi-scale aspects. Since in vivo analysis of the tissue regeneration process is quite difficult in terms of selecting experimental protocols and requires considerable amount of time, a variety of numerical models have been developed to simulate mechanisms of tissue differentiation. The tremendous enhancement in computing power led researchers to develop more and more sophisticated models mostly based on finite element techniques and mechano-regulation computational models. In this article, we present an algorithm that combines the finite element model of an open-porous scaffold, a numerical optimization routine and a mechanobiological model. This algorithm has been utilized to determine both, the best scaffold geometry and the best load value (to apply on the scaffold) that allow the bone formation to be maximized.

Keywords: Bone tissue scaffold , Computational mechanobiology , Geometry optimization , Scaffold micro-architecture

The Bronze Age crossbar wheel found in the XIX century in Mercurago (Italy) is an amazing example of the technical innovations stimulated by the diffusion of horse draught war chariots in Europe across the third and second millennium b.C. In this paper the tools of modern engineering were used to study the structural issues concerning the wheel and the chariot it should be attached to. In particular, the laser-scanner technology and finite element analysis were used for investigating the dimensional, shape and assembly issues of the wheel, as well as for assessing its structural integrity under operating conditions. The role of the inserted nave, which could be similar to modern bushings, was particularly emphasised, as it is a very innovative solution for that time. The performance of a war chariot equipped by this wheel was studied by means of a vehicle dynamics simulation software, hypothesizing two different chariot structures on the basis of Armenian and Egyptian evidences respectively. The former is probably more similar to the chariot to whom the Mercurago wheel was attached; the latter is technically much more advanced. The results of the analysis allowed obtaining important information about the chariot stability, reliability and structural integrity.

The working principle of a Phase Change Memory (PCM) cell exploits the repeated reversible transition between a crystalline and an amorphous phase of chalcogenide alloys typically Ge2Sb2Te5, that are characterized respectively by a high (SET) and a low (RESET) conductive state. The change in density between the two phases (6%) induces a very high compressive stress to the active amorphous region by the surrounding crystalline materials. Moreover, the physical iterative transformation between crystalline and amorphous phase transformation introduces a swelling and deswelling effect. This is one of the key failure mechanisms that are limiting the reliability of the final integration of the PCM system. Knowledge of the mechanical properties of the amorphous phase is then an important factor. Amorphous structure, i. e. its short-range order, depends on the adopted formation procedure. In this paper we analyze the mechanical characteristics of sputtered amorphous Ge2Sb2Te5 thin layers and the modification introduced by ion irradiation, a procedure adopted to simulate the amorphous state produced by melt quenching. Measurements of Young's Modulus and Hardness were performed using Ultra High-Nano Indentation on plane samples. The values of both quantities increase of about 10–20% in the 30 keV Ge+ irradiated samples. This trend is due to the reduction of homopolar wrong bonds (Ge–Ge and Te–Te) present in the as deposited film. Thermal spikes associated to the impinging ion cause a local atomic rearrangement that results in a structure similar to that of the crystalline phase. The investigation was extended to cantilevers of length in the range 10–200 μm, with a layer of 100 nm Ge2Sb2Te5 deposited on 280 nm thick SiN. The cantilever modal analysis and the out of plane deflection measurements were correlated using a Finite Element modeling, that makes use of the mechanical values measured by Ultra high Nano Indentation. After deposition the amorphous Ge2Sb2Te5 layer is subject to a compressive mechanical shrinkage, this internal stress is released after ion implantation.

Keywords: Cantilever , Nano-indentation , Phase change material

In the present work, we investigate some mechanical and electrical properties of a Chemical Vapor Deposition (CVD)-grown graphene layer transferred on 50 nm-thick Ge2Sb2Te5 chalcogenide and discuss the possible application of graphene as a scaled contact replacing metal lines in phase-change memory devices. At first, the graphene-chalcogenide interface was extensively investigated. The expected chemical composition was confirmed by means of Electron Energy Loss Spectrometry (EELS), and the absence of bond distortions in the chalcogenide layer after graphene transfer was proved through Raman spectroscopy. The latter evidenced also the presence of defects, further confirmed by Transmission Electron Microscopy (TEM) investigations. The quality of the contact stack was evaluated by means of the adhesion among layers and by the sheet resistance of the layers themselves. Scratch tests and numerical simulations revealed a stress distribution compatible with a failure of the interface where the graphene layer features a 2 %-void. Next, the contact resistance proved an effective good Ohmic quality with a high graphene sheet resistance, about 1400 Ohm/square, which suggests that a better optimized transfer process should be applied to reduce it more than one order of magnitude.

Keywords: CTLM , CVD-Grown graphene , Nano-scratch , PCM

An impulsive thruster propulsion system that could be used in a multi-modal UAV capable of sustained aerial flight, locomotion in water and deployment from a tube filled with compressed air is under development. This paper covers the design and optimisation process of the propulsive system, as well as its modelling with analytical and CFD simulations to predict the performances. The system is designed to fulfil vehicle mission requirements in terms of altitude and velocity after water/air transition. The thruster uses a common CO2 cartridge available off-the-shelf to accelerate water stored inside a water chamber along with an inflator to activate and regulate the mechanism remotely for efficient and sustained thrust. Water is chosen as vectorial fluid since it is available from the surroundings. Water chamber sizing process uses an analytical model calibration through CFD approach to refine an analytical model and predict propulsion performances. After thruster sizing, an experimental prototype was fabricated and tested for model validation. A comparison and discussion of the results as future work is also proposed with areas for improvement and development.

A multi-modal UAV capable of sustained aerial flight, locomotion in water and deployment from a tube filled with compressed air is under development. This paper covers the design and integration process of a CO 2 thruster previously designed in a vehicle designed to fulfil mission requirements in terms of altitude and velocity after water/air transition. The thruster uses a common CO 2 cartridge available off-the-shelf to accelerate water stored inside a water chamber for efficient and sustained thrust. Water is chosen as vectorial fluid since it is available from the surroundings. Analytical model, described in the paper, evaluates water to air transition phase in terms of trajectory, reached altitude and velocity. After thruster performances evaluation thanks to the analytical model, an experimental prototype was fabricated and tested for model validation. High speed camera is used to track vehicle transition and Kinovea software exports resulting data from a recorded video to spreadsheet formats for scientific study and post-processing. A comparison and discussion of the results as future work is also proposed with areas for improvement and development.

Keywords: Bimodal vehicle , Bio-inspired vehicle , Testing , Transition , Unmanned vehicle

Race car performance is strongly affected by aerodynamics. Due to downforce generated by the vehicle floor (i.e. diffuser), vehicle ride heights are key parameters to improve performance, and the coupling of aerodynamics and suspension is one of the key points of race car setting. This work focuses on the suspension and aerodynamic coupling from the vertical dynamics point of view. Besides road holding performance, for race cars, aerodynamic performance and stability are major factors. Downforce decreases laptime (the main performance target) but pitch instability is a non-desired effect that can happen in high downforce race cars. A new vertical dynamic performance index is proposed through the use of simulation to improve aerodynamic performance and understand the pitch instability phenomenon. This new index uses all relevant vehicle nonlinearities related to vertical dynamics and can handle a specific track profile and vehicle speed range, allowing the analysis be conducted according to a circuit specification. A previously validated Formula 3 car model was used as an example.

Keywords: Aerodynamics , stability analysis , suspension systems

The paper presents a comparison between the emission levels produced along the most used standard driving cycles (NEDC, WLTC, CADC) by a Light Commercial Vehicle (LCV). A proven simulation tool based on real-world emission data (RDE, Real Driving Emissions) has been used instead of a demanding test campaign. Emission levels have been computed for each cycle in three conditions (urban, combined, extra-urban/highway). Then the results have been compared with Euro 5 limits and real-world emission levels to highlight each driving cycle objectivity and representativeness. Among others, the WLTC driving cycle seems to be the most plausible one yet, as expected, it is not very representative of the real world.

Keywords: Diesel Emissions , Driving Cycle , Emissions Simulation , European Driving Cycles

Lightweight engineering is a current topic in mechanical industry. The mass reduction is a common design objective to reduce product cost and environmental impacts. Virtual prototyping tools are widely applied to study new lightened solutions and check the compliance with regulations and standards. However, an integrated approach, involving simulations and life-cycle analysis, is necessary to support design optimization and decision-making. The scope of this study concerns the definition of an Ecodesign approach to support the lightweight engineering of cast iron parts through the redesign of the product shape. In particular, this paper deals with the optimization of a ductile cast iron manhole. The test case shows a redesign method which considers structural analysis with environmental impacts. The structural analysis has been evaluated using a finite element method tool. In particular, the simulation results have been compared and validated with physical tests. The environmental analysis is based on the methodology provided by the standardized ISO 14040:2006 and ISO 14044:2006. The proposed LCA study considers the phases of manufacturing and transport related to one ductile iron product. The described manufacturing phase is related to a Chinese foundry which produces roughly 12,000 tons of ductile cast-iron castings. The results show the possibility to achieve about 20% of mass reduction for one casting. Considering such mass decreasing, the related reduction in terms of carbon emission is about 7%. Summarizing, this paper shows a design approach to integrate the structural improvements with the reduction of the environmental impacts related to a lighter weight casting.

Keywords: Cast ductile iron , Design optimization , Life-cycle assessment , Lightweight engineering , Manhole , Virtual prototyping

Nowadays, product configuration and optimization are very important topics in several industrial applications such as the manufacturing of Engineered-to-order (ETO) products, where there is a fierce increase in market competition. The product configuration allows past design solutions to be reused and new product variants to be defined and pre-designed. However, the delivery of new configurations of products requires a technical feasibility analysis before closing the contract of the order with the customer. There is a lack of commercial tools which can support the designer from the early configuration phase to the product optimization with the automatic generation of geometric models and simulations. While traditional software tools can be used for the product configuration, with automation in the CAD modeling, other ones can combine optimization algorithms with numerical simulations. However, the combination of all these design levels requires the development of a dedicated platform tools. The research aims to reduce time and cost related to the early design phase of an oil & gas system, focusing on gas turbine ducts. The paper proposes a methodological approach to integrate the design optimization with the product configuration using Model-Based simulations to verify the technical feasibility and to optimize the product design. As a test case, the early design of a gas turbine chimney is proposed.

Keywords: Model-Based simulation , oil & gas , Product configuration , Product optimization , Virtual prototyping

Nowadays, several consumer goods are sold with an energy label which provides energy information about consumption, efficiency, noise, and performance. These labels are regulated by local energy policy and governments. Because of this, customers are becoming increasingly aware about the energy efficiency and consumption of products such as household appliances. In Europe, several household appliances are involved in the European Energy Labelling Directive. Therefore, the manufacturers are paying attention to Ecodesign tools and methods to support the development of eco-innovation and sustainable products. In this context, the paper proposes a design methodology to support the development of efficient cooker hoods using an approach based on a constraints satisfaction problem model. The scope of the proposed research is to reduce the time-to-market of household appliances considering the energy efficiency optimization from the early design phases to the embodiment design. A Case Based Reasoning is also implemented to define a pre-configured model of product before the CSP optimization. The CSP model has been developed as an analytical system, which can predict the energy label achieved by a final prototype of a cooker hood. The interaction of such tools can fill the gap between traditional design methods and eco-innovation approaches, in order to support the designer in the decision-making activity. The test case shows a cooker hoods optimization based on a CSP tool, developed using a programming framework based on Gecode platform.

Keywords: Case-based reasoning , Constraints satisfaction problem , Design optimization , Ecodesign , Energy label , Virtual prototyping

Mold heating is an important key factor for the mold cycle which affects the quality of the molded product. The involved molding processes regards polymers foaming, plastics injection, or resin-curing with composites. While the manufacturing cycle of plastics injection molding requires a heating/cooling system, other processes do not require the cooling phase. Polymers foaming and resin-curing require specific values of temperature to provide full chemical reactions and a good product quality on the surface. Induction heating systems are suitable for such applications; however, many industrial cases require customized solutions to support the molding cycle of different parts. A temperature control is always mandatory to reduce the energy cost and increase the heating efficiency. This paper studies a molds temperature control applied in the polyurethane foaming of footwear soles. The proposed induction heating system and its control have been studied using the Hardware-In-the-Loop simulations. Due to a high mold thermal inertia, which increases the mold temperature even if the control system turns off the thermal power, tailored controllers have been analyzed to achieve the desired temperature set-point. The thermal model of the foaming mold and the induction heating system have been modelled and developed in the MATLAB/Simulink® framework. An ATMEGA processor was used to implement and test a discrete PID controller while Simulink induction-heating system model was running, creating an Hardware-In-The-loop platform.

Keywords: Footwear Industry , Hardware-In-the-Loop , Induction Heating , Mold Heating , Polyurethane Foaming , Temperature Control

In this work, a PI-Sliding mode controller is developed in feedback loop from a non-inverting buck boost converter, in order to control the recharge of a Li-Ion battery of a Laser Guided Vehicle (LGV), which is the last stage of an industrial wireless recharge power station. In detail, the industrial case study regards the wireless recharge of a LGV employed to transport molds used for footwear soles production. The proposed solution has been modelled and developed in the MATLAB/Simulink® framework, and the performances of this controller are compared with the classical PID industrial controller. The obtained results depend only from the developed recharge system and can be applied in other industrial cases (e.g., car battery recharge). In particular, the numerical simulations show that the proposed solution has an important impact on the energy consumptions.

Keywords: Buck-boost , Energy Saving , Industrial Automation , LGV , PID , Sliding Mode , Wireless power charging

In this research, a localization system for a particular Automated Guided Vehicle (AGV), namely a Laser Guided Vehicle (LGV), which takes advantage of RSSI data, is described. The vehicle, its sensors and the wireless sensor network are virtualized, in order to provide a software replica of that available in a real factory. A Co-Simulator, composed by two simulation environments, has been implemented: from one hand, Robot Operating System (ROS), the RVIZ and GAZEBO for modeling and simulating the virtual system, and from the other hand, COOJA for reproducing the Wireless Sensor Network (WSN) behavior and RSSI signals. The virtualized LGV in ROS, together with its virtual sensors set, is integrated with the WSN in COOJA, so that localization can be performed by sensor fusion of odometric and RSSI data according to a Kalman Filter approach. The Co-simulator can be used to deploy path-Tracking policies and test them before actual implementation in a Cyber Physical System (CPS) scenario.

Keywords: Automated Guided Vehicle , Cyber-Physical System , Industry 4.0 , Robot Operating System , Wireless Sensor Network

Induction cooktops are very used as an efficient alternative to traditional cooking systems such as gas hobs. Even if the energy efficiency of induction cooktops is twice as much as the traditional gas burners, the differences in terms of energy price can limit the diffusion and marketing of induction cooktops. Recent eco-normative are regulating the energy consumption of this kind of household appliances sold in different countries. This paper proposes an automatic temperature control to reduce the energy consumption for induction cooktops. The water boiling test was used as case study to simulate and validate the proposed approach.

Keywords: Hardware-In-The-Loop , Induction heating , PID control

Design optimization is a common practice in industry. Different mathematical algorithms have been developing to support the optimization in engineering design. The integration between optimization methods and simulations is an interesting issue in engineering design. A typical optimization workflow can include simulation steps; however, the Virtual Prototyping analysis is more time-consuming than analytical calculations. The study of Constraints Satisfaction Problems is a mathematical topic which can be applied for solving engineering issues in design. The strength of this approach is the velocity on searching the satisfied solutions. This paper proposes a design methodology which considers the use of CSP models and calculation tools to optimize the sizing of columns and beams in the design of a steel structure. The calculation tools regard analytical models and numerical analysis. While the analytical approach regards the computing of cost and weight, the numerical analysis is used to verify and check the engineering performance in terms of deformation and stress state. A customized application, based on MiniZinc platform, has been developed and proposed to solve the CSP model for a test case steel structure. The CSP problem has been limited to the calculation of analytical constraints such as cost and weight. Finally, the resultant set of solutions has been evaluated using numerical solution to complete the optimization analysis.

Keywords: Constraints Satisfaction Problems (CSP) , MiniZinc , Optimization , Steel Structures , Virtual Prototyping

Current trends in product development process highlight the increasing adoption of digital data and virtual processes. Nowadays, a huge amount of product data are collected without a clear management strategy and, oftentimes, they dont even cover the whole product development process. A global and integrated planning about information needed to sustain product design process is not a trivial task and, usually, companies underrates this issue. From the perspective of virtualization of processes, and then their automation, the lack of structured knowledge is certainly awful. This paper aims at making a critical analysis how product data evolve throughout the product design or configuration process and how they impact the product development activities. Efficient digital product twin allows companies to vir-tualize processes and leverage their automation, but it is important to understand how the knowledge management should be carried out. Three case studies, directly experienced by the authors, have been investigated analyzing digital data and virtual tools that allow companies to automate the design process, each one bringing a peculiar perspective of the problem.

The paper defines a framework called virtual eco-design aiming to support designers and engineers in the development of sustainable energy-related products. Virtual prototyping is used to perform energy consumption tests according with ecodesign and energy label regulations. The goal is to build a knowledge-based repository in which virtual tests are stored and classified to create eco-knowledge. Induction hob has been analysed to verify the applicability of the approach and the integration in a traditional product development process. Results highlight how the proposed methodology increases company eco-knowledge providing a tangible support in the definition of energy-label compliant products.

Keywords: eco-design , eco-knowledge , energy labelling , energy-related products , virtual prototyping