Virtual prototyping and digital twin

In this work, optimal control theory is applied to minimum lap time simulation of a GP2 car, using a multibody car model with enhanced load transfer dynamics. The mathematical multibody model is formulated with use of the symbolic algebra software MBSymba and it comprises 14 degrees of freedom, including full chassis motion, suspension travels and wheel spins. The kinematics of the suspension is exhaustively analysed and the impact of tyre longitudinal and lateral forces in determining vehicle trim is demonstrated. An indirect optimal control method is then used to solve the minimum lap time problem. Simulation outcomes are compared with experimental data acquired during a qualifying lap at Montmeló circuit (Barcelona) in the 2012 GP2 season. Results demonstrate the reliability of the model, suggesting it can be used to optimise car settings (such as gearing and aerodynamic setup) before executing track tests.

Keywords: Car , control , GP2 , lap , minimum , optimal , race , simulation , time

The growing attention on sustainable development themes, in line with an increasing awareness of the exhaustibility of natural resources, has made the traditional linear economic model obsolete. Therefore, the concept of "Circular Economy" was developed to favour products and materials recovery and regeneration. To this end Industrial Symbiosis represents a promising approach to foster the transformation towards this type of economy, based on resource efficiency, sustainable manufacturing, materials, energy, water and/or by-products exchange and sharing between different companies. In this context, the aim of this paper is to present a classification and a critical discussion about existing industrial symbiosis models. According to the presented literature review, industrial symbiosis can be realized thorough the implementation of three different models: (i) industrial symbiosis districts that develop from a bottom-up approach and are based on resources sharing and materials exchanging, (ii) eco-industrial parks that develop from a top down approach and are determined by eco-sustainable infrastructures and systems, and (iii) networks for industrial symbiosis that evolve through cognitive/relational tools and are based on resources supply and demand intersection. The final objective of this study is to evaluate strengths and weaknesses of each model, to explore the applicability in real contexts, and to identify potential economic and environmental benefits (e.g. reduction of polluting emissions and landfilled wastes, economic savings due to reuse of scraps, energy sharing). The study concludes by identifying research gaps, reflecting on possible application of industrial symbiosis and proposing suggestions for future work.

Keywords: Collaborative platform , Eco-industrial parks , Industrial symbiosis , Industrial symbiosis districts , Resource efficiency

The steering system of a vehicle impacts on the vehicle performance, safety and on the driver's comfort. Moreover, in off-road vehicles using hydrostatic steering systems, the energy dissipation also becomes a critical issue. These aspects push and motivate innovation, research and analysis in the field of agricultural tractors. This paper proposes the modelling and analysis of a hydrostatic steering system for an agricultural tractor to calculate the performance of the system and determine the influence of its main design parameters. The focus here is on the driver's steering feel, which can improve the driver's behavior reducing unnecessary steering corrections during the working conditions. The hydrostatic steering system is quite complex and involves a hydraulic circuit and a mechanical mechanism to transmit the steering to the vehicle tires. The detailed lumped parameters model here proposed allows to simulate the dynamic behavior of the steering system and to both enhance the understanding of the system and to improve the design through parameters sensitivity analysis.

Keywords: Agricultural tractors , Hydrostatic steering system , Rotary valve analysis , Sensitivity analysis , Simulation

In the present paper, the preload reduction over the time attributed to the relaxation phenomenon which involves hybrid (composite-metal) bolted joints has been experimentally and numerically investigated. Unlike conventional materials (steel, aluminium, etc.), composite ones, due to the presence of the polymeric matrix with viscoelastic properties, feel more considerably the relaxation phenomenon, which begins at room temperature (around 20°C). As a result, the loss in the mechanical fastening is a very critical aspect to consider when composite components have to be bolted to other; further investigations are still mandatory to increase the effectiveness of such jointing techniques. The test article consists of two bolted plates made of mild steel and a composite laminate made by E720 770gms 3×1 T E-Glass roving 1200 Tex 35% RW, respectively. Under this purpose, the preload reduction in the bolt has been experimentally emphasized by developing a novel strain-gauged bolt. Moreover, the relaxation phenomenon has been numerically simulated by developing a complex Finite Element (FE) model.

Keywords: Bolted Joints , Polymeric and Composite Materials , Preload , Stress Relaxation

Usually during the design of landing gear, simplified Finite Element (FE) models, based on one-dimensional finite elements (stick model), are used to investigate the in-service reaction forces involving each subcomponent. After that, the design of such subcomponent is carried out through detailed Global/Local FE analyses where, once at time, each component, modelled with threedimensional finite elements, is assembled into a one-dimensional finite elements based FE model, representing the whole landing gear under the investigated loading conditions. Moreover, the landing gears are usually investigated also under a kinematic point of view, through the multibody (MB) methods, which allow achieving the reaction forces involving each subcomponent in a very short time. However, simplified stick (FE) and MB models introduce several approximations, providing results far from the real behaviour of the landing gear. 'erefore, the first goal of this paper consists of assessing the effectiveness of such approaches against a 3D full-FE model. 'ree numerical models of the main landing gear of a regional airliner have been developed, according to MB, "stick," and 3D full-FE methods, respectively. 'e former has been developed by means of ADAMS® software, the other two by means of NASTRAN® software. Once this assessment phase has been carried out, also the Global/Local technique has verified with regard to the results achieved by the 3D full-FE model. Finally, the dynamic behaviour of the landing gear has been investigated both numerically and experimentally. In particular, Magnaghi Aeronautica S.p.A. Company performed the experimental test, consisting of a drop test according to EASA CS 25 regulations. Concerning the 3D full-FE investigation, the analysis has been simulated by means of Ls-Dyna® software. A good level of accuracy has been achieved by all the developed numerical methods.

A numerical investigation is conducted in order to identify optimum trimming attitudes for resistance reduction in the application of high performance sailing yacht hulls. A lumped parameters model based on general unsteady equations of motion is developed and implemented in combination with a numerical scheme to conduct parametric studies and predict the overall performances of a specific sailing hull. Existing semi-empirical formulas for hydrodynamic coefficients are modified and applied in order to extend the speed range of application and obtain good agreement with available experimental data. Brief discussion of the numerical results is presented with emphasis on the possible applications in the field of modern sailing yachts.

Keywords: Hull , Lumped Parameters model , Performance , Planing occurrence , Resistance , Trim

In the present work a novel rear suspension for motorcycles, able to achieve the required progressiveness in terms of rigidity by using a constant-stiffness spring and an innovative compact mechanism, is studied. The key component is an eccentric system inserted in the shock absorber head. As reference, the rear suspension of the Ducati Multistrada MY 2010, characterized by the use of a variable-stiffness spring, is analyzed. The aim of the paper is to prove that the novel proposed solution can obtain a response, in terms of wheel load, similar to that of the reference system. At first, a mathematical model to simulate the kinematics of the novel suspension is presented. This model is able to evaluate the influence of geometric dimensions of the components, checking successfully the ability to reproduce the behavior of the original suspension. After the preliminary design, the kinetostatic model is included within an optimization algorithm ad-hoc created to obtain the optimum dimensions of each component. In order to obtain the inertial parameters, two 3D models of both the suspensions are created. Finally, two multibody models of the two suspensions are implemented in Adams environment in order to evaluate their dynamic behaviour. Results confirm the goodness of the novel solution being comparable to the reference one in terms of dynamic response during the simulation of a typical experimental test performed in Ducati.

Keywords: Constant stiffness spring , Eccentric mechanism , Integrated simulation , Motorcycle rear suspension , Multibody dynamics

The Marchetti-Vicenzi's nail is an intramedullary device where six curved nails are kept straight by a closing ring in order to allow their insertion into the medullary canal of a long bone; in a following step, these nails stabilize the fracture due to the ring withdrawal and to the consequent elastic expansion of the nails. Pre-clinical testing of this sort of device is strongly advocated in order to be able to foresee their stability inside the medullary canal and to quantify their stiffening action on a broken bone. In this numerical work, an MB (Multi Body) model of the device has been developed, with the dual purpose of evaluating forces between the bone and the systemcomponents during its progressive opening and verifying the behavior of the stabilized bone when it undergoes external loading. Different solutions, for flexible body modeling (discretization with lumped parameters, "flexible body," "FE Part"), have been analyzed and compared in terms of accuracy of results and required computational resources. Contact parameters have been identified and criteria to simplify geometries and therefore to reduce simulation times have been given. Results have allowed to demonstrate how amoderate lateral force is able to dislocate the fracture and how the final position of the retention nut can be optimized. On the whole, a tool for the pre-clinical testing of elastic intramedullary nails has been given.

Keywords: FE analysis , Flexible bodies , Intramedullary nails , Marchetti-Vicenzi's nail , Multibody analysis , Sliding contacts

The analysis of workers' ergonomics and human factors is assuming a great importance in product and process design for modern industry. However, there is a lack of common references and structured protocols for the assessment of workers' experience in industrial practices in an effective and predictive way. As a result, designers are poorly supported in the application of digital technologies, which are demonstrating to have a great potential. This ascertainment suggested defining a reference model to analyse the so-called user experience (UX) of workers and a proper technological set-up based on virtual simulations in order to support human-centred product-process design. Indeed, the recent advances in ubiquitous computing, wearable technologies and low-cost connected devices offer a huge amount of new tools for human data monitoring. However, the open issue is selecting the most proper devices for industrial application area in respect with design goals, using virtual simulation and digital manufacturing tools. The research proposed a structured procedure to use existing digital technologies to support product-process design to analyse the workers behaviours and assess the perceived experience for industrial scopes. The paper defined a structured protocol analysis to objectify and measure the workers' experience with the final aim to support the requirements definition in product-process design by using digital technologies. In particular, the model has been defined for the automotive sector. The paper contribution is the definition of the protocol analysis and the development of a mixed reality (MR) set-up to involve real users' and to improve the digital models. Such a protocol has been applied to different industrial cases related to product and process design, developed in collaboration with CNH Industrial. The comparison with traditional design procedures highlighted the benefits of adopting virtual mock-up and digital simulation within a MR environment to shorten design time and improve the design overall quality.

Design for serviceability begins with understanding the customer needs related to availability, reliability, accessibility and visibility, and aims at designing optimized systems where maintenance operations are easy and intuitive in order to reduce the time to repair and service costs. However, service actions are difficult to predict in front of a traditional CAD model. In this context, digital manufacturing tools and virtual simulation technologies can be validly used to create mixed digital environments where service tasks can be simulated in advance to support product design and improve maintenance actions. Furthermore, the use of human monitoring sensors can be used to detect the stressful conditions and to optimize the human tasks. The paper proposes a mixed reality (MR) set-up where operators are digitalized and monitored to analyse both physical and cognitive ergonomics. It is useful to predict design criticalities and improve the global system design. An industrial case study has been developed in collaboration with CNH Industrial to demonstrate how the proposed set-up is used for design for serviceability, on the basis of experimental evidence.

Keywords: Design for serviceability , Digital Manufacturing (DM) , Ergonomics , Human-Centred Design (HCD) , Sustainability , Virtual Simulation

Human-centred design is based on the satisfaction of the user needs related to performances, aesthetics, reliability, usability, accessibility and visibility issues, costs, and many other aspects. The combination of all these aspects has been called as “perceived quality”, that is definitely a transdisciplinary topic. However, the “real” perceived quality is usually faithfully assessed only at the end of the design process, while it is very difficult to predict on 3D CAD model. In this context, digital manufacturing tools and virtual simulation technologies can be validly used according to a transdisciplinary approach to create interactive digital mock-ups where the human-system interaction can be simulated and the perceived quality assessed in advance. The paper proposes a mixed reality (MR) set-up where systems and humans interacting with them are digitalized and monitored to easily evaluate the human-machine interaction. It is useful to predict the design criticalities and to improve the global system design. An industrial case study has been developed in collaboration with CNH Industrial to demonstrate how the proposed set-up can be validly used to support human-centred design.

Keywords: Digital manufacturing , Human-centred design , Human-machine interaction , Virtual simulation

In this article, the information value is used in numeric analysis as both a method for data approximation and a measure of data equality among a set of values. To this end, a surface segmentation, based on a study for constructing a hierarchy for vectors clustering using certain similarity criteria, is presented. The technique is based on the analysis of vectors representing regions associated with given types of critical points. An approach based on the Max Entropy in Metric Space (MEMS) is introduced in the paper, in order to extract a cluster of local features and to obtain an analysis of mechanical systems in the 2D and/or 3D spaces. The approach proposed in the paper can be effectively used in virtual prototyping and optimal designing of mechanical systems.

Keywords: Computer Aided Design (CAD) , Max Entropy in Metric Space (MEMS) , Maxinf principle , Multibody Mechanical Systems (MBS) , Optimal design , Virtual prototyping

Purpose: To study the influence of the resin bonding layer thickness and the bulk filling material stiffness in adhesive class II mesio-occlusal-distal (MOD) restorations using numerical finite element analysis (FEA). Methods: Four 3D-FE models of teeth restored with different filling material stiffness and resin bonding layer thickness were built-up and analyzed. The 3D model of a sound lower molar was also analyzed and compared with restored ones. The tooth tissues . (enamel, dentin), dental restoration and bolus on the occlusal surface, was divided into 3D solid CTETRA elements with four grid points. The adhesive bonding around the dental restoration was modeled with shell elements. Polymerization shrinkage was simulated with a thermal expansion approach. Mechanical behavior of restored models in terms of stress and displacement distributions, under the combination effects of polymerization shrinkage and occlusal load (600 N), was analyzed. All the materials were assumed to behave as elastic materials throughout the entire deformation. Results: Numerical results show that the mechanical response of the restored models was very different compared to the sound tooth ones, where the stress was uniformly distributed from enamel to dentin with no critical stress concentration. In the | restored models, the highest stress values were detected in the enamel, near the enamel-dentin interface and in the bulk ' restorative material. Tooth preparations A and B showed lower gradient stresses than corresponding C and D. The value of the vertical displacement components in models A and B were higher than corresponding C and D. The maximum displacement values were mainly located around the groove and were higher by an order of magnitude than the sound models. The results showed better mechanical response with models A and B compared to C and D. It is also evident that resin bonding thickness slightly affected the stress level of the restored teeth.

Simulation results are not representative of a real system behavior up to its model validation. Validation activity needs a model characterization to match real system and model parameters. This activity impacts more on mechatronics systems which are affected by both physical and control characterizations. This work deals with single bowden power window systems; it improves a system model, previously developed, by deepening window aspects and force system. Force types and modules have been obtained by several experimental tests, in different operating conditions. Experimental automated tests have been carried out by means of a new virtual instrument developed in LabVIEW® environment. Comparison of test results highlights three main components related to: sliding friction, window friction and gravity. These components are affected by window shape which induces module variations. We named these variations 'window shape effect and these results bring to a new procedure for system validation.

Keywords: experimental test , mechatronic system , single bowden power window system , system model validation , validation

This paper presents the foundation of a new class of input shapers, designed using a predictive approach. The method is used to control the transient and residual vibrations in flexible nonlinear systems with time-varying parameters. The motivation is the development of simple algorithms and architectures for controlling the motion in flexible nonlinear systems with minimal modeling effort. The approach trains an artificial neural network to obtain closed-form expressions used for calculating, in real time, the amplitudes and the time locations of the impulses required by a common input-shaping technique. In this work we use this idea to design a command shaper for controlling the motion of the simplest flexible nonlinear system, an overhead crane with a suspended payload. We validate the approach using simulations and experiments. The benefits of such a control system will, in the end, enable using this method for controlling the motion of complex nonlinear systems, resulting in almost zero vibrations.

Keywords: command shaping , Nonlinear dynamical systems , predictive control , vibration control

The remote handling (RH) maintenance of components of International Fusion Materials Irradiation Facility (IFMIF) is one of the most challenging activities to be performed to guarantee the required high level of IFMIF plant availability. Among these components, the maintenance of the target assembly (TA) system appears to be critical, because it is located in the most severe region of neutron irradiation. The present European TA design is based on the so-called replaceable backplate (BP) bayonet concept. It was developed with the objective to reduce the waste material and to simplify the procedures for the target and BP replacement, thus reducing the intervention time for their substitution. The RH maintenance activity for the TA comprises a number of in situ refurbishment tasks, such as the removal of the BP, cleaning of surfaces from lithium solid deposition, inspection of the target body, installation of a new BP, and testing of the assembled system. However, there is also the possibility to replace the entire TA and to perform these refurbishment tasks offline in a dedicated hot cell. To accomplish all the refurbishment operations for the TA within the expected time for maintenance, the annual preventive maintenance period for IFMIF has been fixed in 20 days; several 3-D kinematic simulations in virtual reality environment and experimental activities aimed at developing and validating the implemented maintenance procedures for this component were carried out, in collaboration with the IDEAinVR Laboratory of CREATE/University of Naples Federico II, at the research center at ENEA Brasimone, Italy. The in situ refurbishment processes and the target replacement were simulated and tested and the feasibility of each maintenance operation was proved. In this paper, a description of the simulations and the validation activities carried out together with the main outcomes obtained are given.

Keywords: IFMIF , remote handling (RH) , target assembly (TA) , virtual simulations

The present work focused on the development of a new approach to the concept design of DEMO Divertor Cassette (DC) Remote Handling Equipment (RHE). The approach is based on three main assumptions: the DC remote handling activities and the equipment shall be simplified as much as possible; technologies well known and consolidated in the industrial context can be adopted also in the nuclear fusion field; the design of the RHE should be based on a simply supported beam approach instead of cantilever approach. In detail, during the maintenance activities the barycentre of the DC is centred with respect to DC supports. This solution could simplify the design of RHE with a consequent reduction of the design and development costs. Moreover also the DC remote handling tasks shall be simplified in order to better manage the DC maintenance processes. For this reason the DC assembly and disassembly process has been simplified dividing the main sequences in basic movements. For each movement a dedicated tool has been conceived.

Keywords: DEMO , Divertor cassette , Maintenance , Remote handling

Industrial process plants are increasingly becoming complex structures with high level of automation. Nonetheless, the final plant productivity and the overall equipment efficiency does not solely depend on an optimized engineering design/installation practice, but also on human operators supervision. In parallel, along with the classic demand to minimize costs and time-to-market during the design phases, issues concerning human safety and failure prevention play a crucial role, one of the highest target being the avoidance of dangerous process states. Within this context, Simulation-Based-Training (SBT) allows plant operators to learn how to command complex automated machineries within a secure virtual environment. Similar to its usage in medical, aerospace, naval and military fields, SBT for manufacturing systems can be employed in order to involve the user within a realistic scenario, thus providing an effective, lifelike, interactive training experience under the supervision of experienced personnel. In addition, also according to previous literature, industry-driven SBT may be effectively envisaged as a natural extension of the plant life-cycle simulation practice, comprising Design Simulation & Optimization, Virtual Commissioning, Operator Training, up to Plant Maintenance. In this context, since the overall system behavior depends both on manufacturing process dynamics and Control Logics, the main challenge for an effective SBT is related with the development of a real-time environment where control system responsiveness is fully reproduced. Owing to this consideration, this paper reports a successful industrial case study, concerning a novel SBT workbench used for steel plants operator training, discussing both the virtual prototyping phase and the development of a real-time simulation architecture. In particular, a hybrid process simulation is employed, where a virtual process model is coupled with physical PLC and Human–Machine Interface, thus achieving an accurate reproduction of the real plant/operator interaction.

Keywords: Hybrid virtual/physical simulation , Industrial case study , Simulation-based-training , Virtual commissioning , Virtual prototyping