Alessandro Greco

A Preventive Ergonomic Approach Based on Virtual and Immersive Reality

The introduction of new information and communication technologies (ICT) in factory environment is leading the world of manufacturing industry to a change. Indeed, we talk about Industry 4.0, the fourth industrial revolution, that facilitates the vision of a Smart Factory in which systems become cyber-physical, interact between themselves, monitor and validate physical processes, creating a virtual copy of the physical world and making decisions based on complex numerical analysis. Virtualization and simulation of production processes generate several benefits, in terms of costs and time, optimizing the assembly line design and studying human-machine interaction. Regarding the last topic, this paper proposes an innovative method for ergonomic analysis of workplaces on automotive assembly lines in a virtual environment. The method can represent an innovation for human-centered design of workplace in developing new products, reducing costs and improving job quality thanks to a preventive ergonomic approach.

Human Posture Tracking System for Industrial Process Design and Assessment

One of the critical issues characterizing the manufacturing industries, which within Industry 4.0 era are experiencing the new human-centered approach in design, is related to working postures assumed by the workers in assembly activities.

Investigation on the static and dynamic structural behaviors of a regional aircraft main landing gear by a new numerical methodology

In this paper, a new methodology supporting the design of landing gears is proposed. Generally, a preliminary step is performed with simplified FE model, usually one-dimensional, to achieve the reaction forces involving each component during all aforementioned aircraft operations. Though this approach gives a valid support to the designer, it is characterized by several problems, such as the related approximations. So, it is important, by a numerical point of view, to develop an isostatic FE model equivalent to the real one. In fact, if the landing gear is modelled as hyperstatic, the static equilibrium equations are insufficient for determining the internal forces and reactions on each sub-component; so, the modelled material properties and geometries assume an increasing importance, which gets the model too approximating. The proposed methodology consists of achieving the reaction forces by means of multibody simulations, by overcoming such problems, since each component is modelled as rigid. In this paper, also a FE model for the investigation of the structural response is proposed. Aimed to Certification by Analysis purposes, the developed multibody and the FE models have been assessed against an experimental landing gear drop test carried out by Magnaghi Aeronautica S.p.A., according to the EASA CS 25 regulations.

Numerical and experimental evaluation of stress relaxation in hybrid composite-metal bolted joints

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.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 phenome...

IMU-Based Motion Capture Wearable System for Ergonomic Assessment in Industrial Environment

The study of human factors is fundamental for the human-centered design of Smart Workplaces. IIoT (Industrial Internet of Things) technologies, mainly wearable devices, are becoming necessary to acquire data, whose analysis will be used to make decision in a smart way. For industrial applications, motion-tracking systems are strongly developing, being not invasive and able to acquire high amounts of data related to human motion in order to evaluate the ergonomic indexes in an objective way, as well as suggested by standards. For these reasons, a modular inertial motion capture system has been developed at the Department of Engineering of the University of Campania Luigi Vanvitelli. By using low cost Inertial Measurement Units – IMU and sensor fusion algorithms based on Extended Kalman filtering, the system is able to estimate the orientation of each body segment, the posture angles trends and the gait recognition during a working activity in industrial environment. From acquired data it is possible to develop further algorithms to online asses ergonomic indexes according to methods suggested by international standards (i.e. EAWS, OCRA, OWAS). In this paper, the overall ergonomic assessment tool is presented, with an extensive result campaign in automotive assembly lines of Fiat Chrysler Automobiles to prove the effectiveness of the system in an industrial scenario.

Biomechanical Load Evaluation by Means of Wearable Devices in Industrial Environments: An Inertial Motion Capture System and sEMG Based Protocol

Biomechanical overload is one of the main risk factors for musculoskeletal disorders among manufacturing workers and so far, it has been evaluated with observational methods. The aim of this research was to introduce a procedure for quantitative biomechanical overload risk assessment in which surface electromyography integrates with a motion capture system. The paper deals with actual test cases performed in an automotive company, using surface electromyography and a homemade inertial motion capture system. The quality of the data produced by it demonstrates that these devices can be integrated, worn in actual working conditions and are not influenced by electromagnetic interference.

A Human Postures Inertial Tracking System for Ergonomic Assessments

Since the early development for health purposes in 1950s, motion tracking systems have been strongly developed for several applications. Nowadays, using Micro Electro-Mechanics Systems (MEMS) technologies, these systems have become compact and light, being popular for several applications. Looking at the manufacturing industry, such as the automotive one, ergonomic postural analyses are a key step in the workplaces design and motion tracking systems represent fundamental tools to provide data about postures of workers while carrying out working tasks, in order to assess the critical issues according to ISO 11226 standard.

Biomechanical Overload Evaluation in Manufacturing: A Novel Approach with sEMG and Inertial Motion Capture Integration

Biomechanical overload represents one of the main risks in the industrial environment and the main possible source of musculoskeletal disorders and diseases. The aim of the this study is to introduce new technologies for quantitative risk assessment of biomechanical overload, by integrating surface electromyography (sEMG) with an innovative motion-capture system based on inertial measurement units (IMU).

Simulation Techniques for Ergonomic Performance Evaluation of Manual Workplaces During Preliminary Design Phase

Among the technologies included in Industry 4.0, the fourth industrial revolution, Digital Manufacturing (DM) represents a new approach to evaluate the performance of production processes in a virtual environment.

Established Numerical Techniques for the Structural Analysis of a Regional Aircraft Landing Gear

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 three-dimensional 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. Therefore, the first goal of this paper consists of assessing the effectiveness of such approaches against a 3D full-FE model. Three numerical models of the main landing gear of a regional airliner have been developed, according to MB, “stick,” and 3D full-FE methods, respectively. The 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.