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System engineering (SE) methods and principles are nowadays widely adopted in the product development processes, especially in the industrial sector, where saving production time and costs are primary goals. This work describes an application of a particular SE methodology, the V-model-based design, in which the system development lifecycle is divided on the basis of a graphical V-shaped scheme, called V-model. Following this approach, a new concept of charging arm for Robotic Train Inspection Monorail (TIM) of Large Hadron Collider (LHC) at CERN (Conseil Européen pour la Recherche Nucléaire) has been developed. The current charging arm version is affected by several issues and limits that have led to the necessity of a new solution. Starting from the first stages of functional requirements (FRs) definition and decomposition (left side of the "V"), a new concept has been implemented, in order to be tested for its verification and validation (right side of the "V"). As part of the principles of SE, the process has been based on virtual models of the product and on virtual simulations of its operation, rather than on the realization of time-consuming and expensive physical models and tests, even if a final physical prototype has also been built and some physical operative tests have also been carried out on it. These tests have showed that the new product appears to fulfill each one of its FRs and overcome the limits imposed by the previous version. The future commissioning and operative tests in the real operating condition and location shall definitely validate the new product. [ABSTRACT FROM AUTHOR]

A fatigue test on a full scale panel with complex loading condition and geometry configuration has been carried out using a triaxial test machine. The demonstrator is made up of two skins which are linked by a transversal butt-joint, parallel to the stringer direction. A fatigue load was applied in the direction normal to the longitudinal joint, while a constant load was applied in the longitudinal joint direction. The test panel was instrumented with strain gages and previously quasi-static tests were conducted to ensure a proper load transferring to the panel. In order to support the tests, geometric nonlinear shell finite element analyses were conducted to predict strain and stress distributions. The demonstrator broke up after about 177000 cycles. Subsequently, a finite element analysis (FEA) was carried out in order to correlate failure events; due to the biaxial nature of the fatigue loads, Sines criterion was used. The analysis was performed taking into account the different materials by which the panel is composed. The numerical results show a good correlation with experimental data, successfully predicting failure locations on the panel. [ABSTRACT FROM AUTHOR]

Purpose – The major objectives of this study are the engineering development and the structural analysis with finite element method (FEM) of a refrigerated container having a passive equipment and a remote control system to carry both fresh (+4°C÷±1°C) and frozen (−18°C÷−20°C) goods. The purpose of this paper is to offer some solutions to the many disadvantages of using phase change material (PCM) to refrigerate the insulated container for transporting both fresh and frozen goods. Design/methodology/approach – In order to transport both fresh products (+4°C÷±1°C) and frozen products (−18°C÷−20°C), the PCM elements are filled with one eutectic liquid only, so as to avoid problems related to filling and emptying the eutectic plates, and to plate corrosion. Moreover, specially shaped air ducts and a cool flow control system are designed to maintain a uniform circulation of cool air and constant humidity values. All the structures of the container are correctly designed by means of FEM calculations to assure that all the structural, safety standards parameters are satisfied. Findings – An innovative refrigerated container with PCM and a remote control system used to transport both fresh (+4°C÷±1°C) and frozen (−18°C÷−20°C) products, in which it is possible to maintain the temperature values for almost seven days, has been considered here. Many disadvantages due to the use of PCM have been eliminated. It is possible to maintain a uniform circulation cool air and humidity values within the design parameters by means of fans; moreover, this container is light and environmentally friendly. All structures of the container are designed using FEM. Originality/value – This paper presents a refrigerated container with passive equipment and a remote control system to carry both fresh (+4°C÷±1°C) and frozen (−18°C÷−20°C) goods in which it is possible to maintain the temperature values necessary for almost seven days. The container is equipped with a remote control system powered by photovoltaic panels which works in real time, is capable of giving information about the environmental parameters set in it and monitors the state of products by means of a network of sensors. Furthermore, the remote control system can send information about the position of the container to a remote control centre. The relevant structural conditions are numerically (FEM) evaluated and reported. [ABSTRACT FROM AUTHOR]

Sintered gears manufactured through powder metallurgy technology contain residual porosity that can make them inadequate for high power supply. Crack propagation is significantly enhanced by both residual porosity and cyclical stresses involving the teeth. The use of densification processes can highly improve their performances, permitting the reduction of the residual porosity. Among the densification processes, the rolling assumes a key-role. The process permits the densification of the tooth flanks, the most stressed parts of the wheel. However, the performances of the rolled wheel depend on several process parameters, whose setup phase requires several efforts and many experiments. Finite element (FE) model can be a helpful tool, allowing a faster estimation of the process parameters, reducing waste and costs linked to the experimental tests. In this sense, FE modelling techniques discussed in literature only cover the simulation of spur gears densification process, since they consist of in-plane 2D finite elements. In this paper, different numerical modelling techniques, based on 2D finite elements, are proposed to simulate the densification process of spur gears and used to perform a tendency analysis to explore the effects of wheelbase reduction between the forming rollers on the material densification. Material densification appeared higher for reduced wheelbases, but an increasing cavity was observed at the tooth root as the wheelbases decreases. Moreover, a FE model based on 3D finite elements is proposed to reproduce numerically the rolling process of a helical gear. The accuracy of the 3D FE model was measured against the results provided by some experimental tests, herein discussed too. A good agreement between numerical and experimental results was observed. [ABSTRACT FROM AUTHOR]

In this work, the stress relaxation behavior of 3D printed PLA was experimentally investigated and analytically modeled. First, a quasi-static tensile characterization of additively manufactured samples was conducted by considering the effect of printing parameters like the material infill orientation and the outer wall presence. The effect of two thermal conditioning treatments on the material tensile properties was also investigated. Successively, stress relaxation tests were conducted, on both treated and unconditioned specimens, undergoing three different strains levels. Analytical predictive models of the viscous behavior of additive manufactured material were compared, highlighting and discussing the effects of considered printing parameters. [ABSTRACT FROM AUTHOR]

This article lists some tips for reducing gear case noise. With this aim, a static analysis was carried out in order to describe how stresses resulting from meshing gears affect the acoustic emissions. Different parameters were taken into account, such as the friction, material, and lubrication, in order to validate ideas from the literature and to make several comparisons. Furthermore, a coupled Eulerian–Lagrangian (CEL) analysis was performed, which was an innovative way of evaluating the sound pressure level of the aforementioned gears. Different parameters were considered again, such as the friction, lubrication, material, and rotational speed, in order to make different research comparisons. The analytical results agreed with those in the literature, both for the static analysis and CEL analysis—for example, it was shown that changing the material from steel to ductile iron improved the gear noise, while increasing the rotational speed or the friction increased the acoustic emissions. Regarding the CEL analysis, air was considered a perfect gas, but its viscosity or another state equation could have also been taken into account. Therefore, the above allowed us to state that research into these scientific fields will bring about reliable results. [ABSTRACT FROM AUTHOR]

The demand of adhesive bonding as technique for the strengthening of existing structures is currently increasing in many engineering fields. Therefore, the prediction of bonded joints fracture behavior is an open issue for the structural safety of repairs. With this aim, a cohesive zone approach is adopted to determine the shear fracture behavior of epoxy resin interface layer of end notched flexure (ENF) specimen. Experimental tangential slip displacements of adherends are evaluated by digital image correlation (DIC) analysis. The identified traction‐separation law can be implemented in a finite element (FE) code to predict the decohesion of adhesively bonded joints. [ABSTRACT FROM AUTHOR]

Predictive models play an important role for increasing the reliability of composite structures over time, but a great deal of experimental data is requested. In this paper, results from creep experiments on uniaxial E‐glass fiber reinforced polymer (FRP) single ply laminates, performed at different stress levels, are presented. The tests duration was of 42 months. Analytical modeling of the viscous behavior of the tested GFRP composite, under linear and nonlinear viscoelastic hypotheses, is reported. A discussion on the comparison of creep strain response by Burgers model, with parameters obtained from fitting of data for different test duration, is also proposed. Finally, predictive finite element method (FEM) simulations were carried out for discussing the deferred behavior induced by creep, for composite layers used for repair purposes in hydrogen transportation pipes. Numerical results highlighted a non‐negligible difference in creep strain values, pointing out that a model based on experimental tests with shorter duration leads to a conservative composite design. [ABSTRACT FROM AUTHOR]

Amorphous polymers, such as epoxy resins, are commonly used in the realization of adhesively bonded joints. In this paper an evaluation of mode I fracture toughness of bonded joints is presented. Moreover, an identification of cohesive zone model parameters via Rice's J‐integral is described. Experimental tests are performed on double cantilever beam specimens and relative displacements between adherends are acquired by using the digital image correlation technique. The obtained interface law can be implemented in a finite element code for simulating the decohesion process of complex bonded structures. [ABSTRACT FROM AUTHOR]

This paper presents a novel numerical model, based on the finite element (FE) method, for the simulation of a welding process aimed to make a two‐pass V‐groove butt joint, paying attention on the prediction of residual stresses and distortions. The 'element birth and death' technique for the simulation of the weld filler supply has been considered within this paper. The main advancements with respect to the state of the art herein proposed concern: (i) the development of a modelling technique able to simulate the plates interaction during the welding operation when an only plate is modelled. This phenomenon is usually neglected in literature; (ii) the heat amount is supplied to the FEs as volumetric generation of the internal energy, allowing overcoming the time‐consuming calibration phase needed to use the Goldak's model, commonly adopted in literature. Predicted results showed a good agreement with experimental ones. [ABSTRACT FROM AUTHOR]

This paper deals with technological solutions of innovative engine encapsulation systems for automotive. The aim of this device is to insulate acoustically and thermally the engine from the environment, in order to keep its temperature higher for more hours after it has been switched off. If the engine is subsequently started within this interval, the higher temperature involving the lubricating oil will allow reducing its viscosity, resulting in a lower level of energy dissipation due to friction losses, a lower fuel consumption and, consequently, a lower CO2 emission level. In this paper, a finite element model is carried out in order to investigate on the thermo‐mechanical behavior of the proposed engine encapsulation system. [ABSTRACT FROM AUTHOR]